Change behavior of grabType

Make grabType grab a single composite value that can be converted to the type being grabbed instead of just the fields of the type. The old behavior is available in grabTypeFlat and the alias `?:` still points there.
relays: fix runnaway closed connection loop
2024-05-07 15:44:53 +02:00 · 2024-05-04 00:31:00 +02:00 · 2024-04-30 12:52:40 +02:00 · 2024-04-24 20:28:28 +02:00 · 2024-04-24 16:11:17 +02:00 · 2024-04-24 16:10:34 +02:00
22 changed files with 774 additions and 661 deletions
--- a/README.md
+++ b/README.md
@ -54,7 +54,8 @@ The Syndicate DSL can be entered using `runActor` which calls a Nim body with a
 ### Publish

 ``` nim
-runActor("main") do (dataspace: Ref; turn: Turn):
+runActor("main") do (turn: Turn):
+  let dataspace = newDataspace()
  let presenceHandle = publish(turn, dataspace, Present(username: "Judy"))
    # publish <Present "Judy"> to the dataspace
    # the assertion can be later retracted by handle
@ -67,7 +68,8 @@ runActor("main") do (dataspace: Ref; turn: Turn):
 We can react to assertions and messages within dataspaces using [patterns](https://synit.org/book/glossary.html#dataspace-pattern). Patterns are constructed using a Nim type and the `?` operator. Again a Nim type is used rather than a raw Preserves for schema consistency.

 ``` nim
-runActor("main") do (dataspace: Ref; turn: Turn):
+runActor("main") do (turn: Turn):
+  let dataspace = newDataspace()
  during(turn, dataspace, ?Present) do (who: string):
    # This body is active when the ?Present pattern is matched.
    # The Present type contains two atomic values that can be matched
@ -89,17 +91,15 @@ runActor("main") do (dataspace: Ref; turn: Turn):

 ## Examples

-### [test_chat](./tests/test_chat.nim)
+ ### [test_chat](./tests/test_chat.nim)
 Simple chat demo that is compatible with [chat.py](https://git.syndicate-lang.org/syndicate-lang/syndicate-py/src/branch/main/chat.py).
 ```sh
 SYNDICATE_ROUTE='<route [<unix "/run/user/1000/dataspace">] [<ref {oid: "syndicate" sig: #x"69ca300c1dbfa08fba692102dd82311a"}>]>' nim c -r tests/test_chat.nim --user:fnord
 ```
-
-### [xdg_open_ng](https://git.syndicate-lang.org/ehmry/xdg_open_ng)
-Messaging, UNIX sockets, dynamic configuration, [Syndicate server](https://synit.org/book/operation/system-bus.html) interaction.
+### [syndicate_utils](https://git.syndicate-lang.org/ehmry/syndicate_utils)

 ---

 This work has been supported by the [NLnet Foundation](https://nlnet.nl/) and the European Commission's [Next Generation Internet programme](https://www.ngi.eu/). The [Syndicate Actor Model](https://syndicate-lang.org/projects/2021/system-layer/) through the [NGI Zero PET](https://nlnet.nl/PET/) program and this library as a part of the [ERIS project](https://eris.codeberg.page/) through [NGI Assure](https://nlnet.nl/assure/).

-[![NLnet](https://nlnet.nl/logo/banner.svg)](https://nlnet.nl/)
+[![NLnet](./nlnet.svg)](https://nlnet.nl/)
--- a/lock.json
+++ b/lock.json
@ -82,11 +82,11 @@
      "packages": [
        "preserves"
      ],
-      "path": "/nix/store/2hy124xgabz134dxj3wji7mp47fdwy3w-source",
-      "rev": "9ae435a83c6d5028405538af5d24a023af625b6e",
-      "sha256": "1k7ywcp1a53x2fpc6wc2b0qzb264dkifash0s1wcp66rw3lx15k2",
+      "path": "/nix/store/hzb7af7lbd4kgd5y4hbgxv1lswig36yj-source",
+      "rev": "fd498c6457cb9ad2f3179daa40da69eec00326dd",
+      "sha256": "182xvw04vjw83mlcrkwkip29b44h0v8dapg2014k9011h90mdsj4",
      "srcDir": "src",
-      "url": "https://git.syndicate-lang.org/ehmry/preserves-nim/archive/9ae435a83c6d5028405538af5d24a023af625b6e.tar.gz"
+      "url": "https://git.syndicate-lang.org/ehmry/preserves-nim/archive/fd498c6457cb9ad2f3179daa40da69eec00326dd.tar.gz"
    },
    {
      "method": "fetchzip",
@ -126,11 +126,11 @@
      "packages": [
        "taps"
      ],
-      "path": "/nix/store/n86g5fw60z1k53bn35zvrwlwmyk3ixdn-source",
-      "rev": "6ec1491c178bd37491ca55c012675bd525391e29",
-      "sha256": "0dp7ml3kj2fi6isvjkkxf02hwj0gshx6qra0ghnk2cbfykbcgfp8",
+      "path": "/nix/store/6y14ia52kr7jyaa0izx37mlablmq9s65-source",
+      "rev": "8c8572cd971d1283e6621006b310993c632da247",
+      "sha256": "1dp166bv9x773jmfqppg5i3v3rilgff013vb11yzwcid9l7s3iy8",
      "srcDir": "src",
-      "url": "https://git.sr.ht/~ehmry/nim_taps/archive/6ec1491c178bd37491ca55c012675bd525391e29.tar.gz"
+      "url": "https://git.sr.ht/~ehmry/nim_taps/archive/8c8572cd971d1283e6621006b310993c632da247.tar.gz"
    },
    {
      "date": "2024-04-02T15:38:57+01:00",
--- a/nlnet.svg
+++ b/nlnet.svg
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+        <path d="M542.48,296.48c3.563,-0 6.638,0.675 9.225,2.025c2.588,1.35 4.585,3.178 5.991,5.484c1.406,2.307 2.184,4.885 2.334,7.735c0.075,1.05 0.113,2.737 0.113,5.062c-0,2.288 -0.038,3.938 -0.113,4.95c-0.15,2.85 -0.928,5.428 -2.334,7.735c-1.406,2.306 -3.403,4.134 -5.991,5.484c-2.587,1.35 -5.662,2.025 -9.225,2.025c-3.562,-0 -6.637,-0.675 -9.225,-2.025c-2.587,-1.35 -4.584,-3.178 -5.99,-5.484c-1.407,-2.307 -2.185,-4.885 -2.335,-7.735c-0.075,-2.025 -0.112,-3.675 -0.112,-4.95c-0,-1.275 0.037,-2.962 0.112,-5.062c0.15,-2.85 0.928,-5.428 2.335,-7.735c1.406,-2.306 3.403,-4.134 5.99,-5.484c2.588,-1.35 5.663,-2.025 9.225,-2.025Zm7.144,15.525c-0.188,-1.988 -0.872,-3.572 -2.053,-4.753c-1.181,-1.181 -2.878,-1.772 -5.091,-1.772c-2.212,-0 -3.909,0.591 -5.09,1.772c-1.182,1.181 -1.866,2.765 -2.054,4.753c-0.112,1.237 -0.168,2.794 -0.168,4.669c-0,1.837 0.056,3.431 0.168,4.781c0.188,1.987 0.872,3.572 2.054,4.753c1.181,1.181 2.878,1.772 5.09,1.772c2.213,-0 3.91,-0.591 5.091,-1.772c1.181,-1.181 1.865,-2.766 2.053,-4.753c0.112,-1.35 0.169,-2.944 0.169,-4.781c-0,-1.875 -0.057,-3.432 -0.169,-4.669Z" style="fill:#231f20;fill-rule:nonzero;"/>
+        <path d="M627.868,297.042c0.412,0 0.768,0.15 1.068,0.45c0.3,0.3 0.45,0.657 0.45,1.069l0,22.444c0,3.375 -0.712,6.262 -2.137,8.662c-1.425,2.4 -3.422,4.219 -5.991,5.457c-2.568,1.237 -5.559,1.856 -8.972,1.856c-3.45,-0 -6.459,-0.619 -9.028,-1.856c-2.568,-1.238 -4.556,-3.057 -5.962,-5.457c-1.406,-2.4 -2.11,-5.287 -2.11,-8.662l0,-22.444c0,-0.412 0.15,-0.769 0.45,-1.069c0.3,-0.3 0.657,-0.45 1.069,-0.45l7.369,0c0.412,0 0.769,0.15 1.069,0.45c0.3,0.3 0.45,0.657 0.45,1.069l-0,22.219c-0,2.287 0.572,4.059 1.715,5.316c1.144,1.256 2.803,1.884 4.978,1.884c2.175,-0 3.835,-0.628 4.979,-1.884c1.143,-1.257 1.715,-3.029 1.715,-5.316l0,-22.219c0,-0.412 0.15,-0.769 0.45,-1.069c0.3,-0.3 0.656,-0.45 1.069,-0.45l7.369,0Z" style="fill:#231f20;fill-rule:nonzero;"/>
+        <path d="M691.43,336.417c-0.562,0 -1.05,-0.14 -1.462,-0.421c-0.413,-0.282 -0.694,-0.572 -0.844,-0.872l-12.881,-19.238l-0,19.013c-0,0.412 -0.15,0.768 -0.45,1.068c-0.3,0.3 -0.657,0.45 -1.069,0.45l-7.369,0c-0.412,0 -0.769,-0.15 -1.069,-0.45c-0.3,-0.3 -0.45,-0.656 -0.45,-1.068l0,-36.338c0,-0.412 0.15,-0.769 0.45,-1.069c0.3,-0.3 0.657,-0.45 1.069,-0.45l5.85,0c0.563,0 1.05,0.141 1.463,0.422c0.412,0.282 0.693,0.572 0.843,0.872l12.882,19.238l-0,-19.013c-0,-0.412 0.15,-0.769 0.45,-1.069c0.3,-0.3 0.656,-0.45 1.068,-0.45l7.369,0c0.413,0 0.769,0.15 1.069,0.45c0.3,0.3 0.45,0.657 0.45,1.069l-0,36.338c-0,0.412 -0.15,0.768 -0.45,1.068c-0.3,0.3 -0.656,0.45 -1.069,0.45l-5.85,0Z" style="fill:#231f20;fill-rule:nonzero;"/>
+        <path d="M768.83,312.736c0.075,2.1 0.113,3.45 0.113,4.05c-0,0.6 -0.038,1.913 -0.113,3.938c-0.112,3.075 -0.909,5.793 -2.39,8.156c-1.482,2.362 -3.516,4.209 -6.104,5.541c-2.587,1.331 -5.587,1.996 -9,1.996l-15.187,0c-0.413,0 -0.769,-0.15 -1.069,-0.45c-0.3,-0.3 -0.45,-0.656 -0.45,-1.068l0,-36.338c0,-0.412 0.15,-0.769 0.45,-1.069c0.3,-0.3 0.656,-0.45 1.069,-0.45l14.906,0c3.413,0 6.441,0.666 9.085,1.997c2.643,1.332 4.725,3.188 6.243,5.569c1.519,2.381 2.335,5.091 2.447,8.128Zm-23.794,-6.694l0,21.375l6.019,0c4.725,0 7.181,-2.156 7.369,-6.468c0.075,-2.175 0.112,-3.6 0.112,-4.275c0,-0.75 -0.037,-2.138 -0.112,-4.163c-0.113,-2.137 -0.816,-3.75 -2.109,-4.837c-1.294,-1.088 -3.141,-1.632 -5.541,-1.632l-5.738,0Z" style="fill:#231f20;fill-rule:nonzero;"/>
+        <path d="M835.936,334.336c0.15,0.375 0.225,0.656 0.225,0.844c0,0.337 -0.121,0.628 -0.365,0.872c-0.244,0.244 -0.535,0.365 -0.872,0.365l-7.088,0c-0.637,0 -1.134,-0.14 -1.49,-0.421c-0.356,-0.282 -0.591,-0.61 -0.703,-0.985l-1.575,-4.669l-14.963,0l-1.575,4.669c-0.112,0.375 -0.347,0.703 -0.703,0.985c-0.356,0.281 -0.853,0.421 -1.491,0.421l-7.087,0c-0.338,0 -0.628,-0.121 -0.872,-0.365c-0.244,-0.244 -0.366,-0.535 -0.366,-0.872c0,-0.188 0.075,-0.469 0.225,-0.844l12.263,-35.437c0.187,-0.525 0.487,-0.966 0.9,-1.322c0.412,-0.356 0.956,-0.535 1.631,-0.535l9.113,0c0.675,0 1.218,0.179 1.631,0.535c0.412,0.356 0.712,0.797 0.9,1.322l12.262,35.437Zm-14.793,-12.712l-4.557,-13.5l-4.556,13.5l9.113,-0Z" style="fill:#231f20;fill-rule:nonzero;"/>
+        <path d="M898.599,297.042c0.412,0 0.769,0.15 1.069,0.45c0.3,0.3 0.45,0.657 0.45,1.069l-0,5.963c-0,0.412 -0.15,0.768 -0.45,1.068c-0.3,0.3 -0.657,0.45 -1.069,0.45l-9.9,0l-0,28.857c-0,0.412 -0.15,0.768 -0.45,1.068c-0.3,0.3 -0.656,0.45 -1.069,0.45l-7.369,0c-0.412,0 -0.768,-0.15 -1.068,-0.45c-0.3,-0.3 -0.45,-0.656 -0.45,-1.068l-0,-28.857l-9.9,0c-0.413,0 -0.769,-0.15 -1.069,-0.45c-0.3,-0.3 -0.45,-0.656 -0.45,-1.068l-0,-5.963c-0,-0.412 0.15,-0.769 0.45,-1.069c0.3,-0.3 0.656,-0.45 1.069,-0.45l30.206,0Z" style="fill:#231f20;fill-rule:nonzero;"/>
+        <path d="M935.668,336.417c-0.413,0 -0.769,-0.15 -1.069,-0.45c-0.3,-0.3 -0.45,-0.656 -0.45,-1.068l-0,-36.338c-0,-0.412 0.15,-0.769 0.45,-1.069c0.3,-0.3 0.656,-0.45 1.069,-0.45l7.368,0c0.413,0 0.769,0.15 1.069,0.45c0.3,0.3 0.45,0.657 0.45,1.069l0,36.338c0,0.412 -0.15,0.768 -0.45,1.068c-0.3,0.3 -0.656,0.45 -1.069,0.45l-7.368,0Z" style="fill:#231f20;fill-rule:nonzero;"/>
+        <path d="M997.655,296.48c3.563,-0 6.638,0.675 9.225,2.025c2.588,1.35 4.585,3.178 5.991,5.484c1.406,2.307 2.184,4.885 2.334,7.735c0.075,1.05 0.113,2.737 0.113,5.062c-0,2.288 -0.038,3.938 -0.113,4.95c-0.15,2.85 -0.928,5.428 -2.334,7.735c-1.406,2.306 -3.403,4.134 -5.991,5.484c-2.587,1.35 -5.662,2.025 -9.225,2.025c-3.562,-0 -6.637,-0.675 -9.225,-2.025c-2.587,-1.35 -4.584,-3.178 -5.99,-5.484c-1.407,-2.307 -2.185,-4.885 -2.335,-7.735c-0.075,-2.025 -0.112,-3.675 -0.112,-4.95c-0,-1.275 0.037,-2.962 0.112,-5.062c0.15,-2.85 0.928,-5.428 2.335,-7.735c1.406,-2.306 3.403,-4.134 5.99,-5.484c2.588,-1.35 5.663,-2.025 9.225,-2.025Zm7.144,15.525c-0.188,-1.988 -0.872,-3.572 -2.053,-4.753c-1.181,-1.181 -2.878,-1.772 -5.091,-1.772c-2.212,-0 -3.909,0.591 -5.09,1.772c-1.182,1.181 -1.866,2.765 -2.054,4.753c-0.112,1.237 -0.168,2.794 -0.168,4.669c-0,1.837 0.056,3.431 0.168,4.781c0.188,1.987 0.872,3.572 2.054,4.753c1.181,1.181 2.878,1.772 5.09,1.772c2.213,-0 3.91,-0.591 5.091,-1.772c1.181,-1.181 1.865,-2.766 2.053,-4.753c0.112,-1.35 0.169,-2.944 0.169,-4.781c-0,-1.875 -0.057,-3.432 -0.169,-4.669Z" style="fill:#231f20;fill-rule:nonzero;"/>
+        <path d="M1076.35,336.417c-0.563,0 -1.05,-0.14 -1.463,-0.421c-0.412,-0.282 -0.693,-0.572 -0.843,-0.872l-12.882,-19.238l0,19.013c0,0.412 -0.15,0.768 -0.45,1.068c-0.3,0.3 -0.656,0.45 -1.068,0.45l-7.369,0c-0.413,0 -0.769,-0.15 -1.069,-0.45c-0.3,-0.3 -0.45,-0.656 -0.45,-1.068l0,-36.338c0,-0.412 0.15,-0.769 0.45,-1.069c0.3,-0.3 0.656,-0.45 1.069,-0.45l5.85,0c0.562,0 1.05,0.141 1.462,0.422c0.413,0.282 0.694,0.572 0.844,0.872l12.881,19.238l0,-19.013c0,-0.412 0.15,-0.769 0.45,-1.069c0.3,-0.3 0.657,-0.45 1.069,-0.45l7.369,0c0.412,0 0.769,0.15 1.069,0.45c0.3,0.3 0.45,0.657 0.45,1.069l-0,36.338c-0,0.412 -0.15,0.768 -0.45,1.068c-0.3,0.3 -0.657,0.45 -1.069,0.45l-5.85,0Z" style="fill:#231f20;fill-rule:nonzero;"/>
+      </g>
+    </g>
+  </g>
+</svg>
--- a/src/syndicate.nim
+++ b/src/syndicate.nim
@ -19,10 +19,10 @@ proc `!`*(typ: static typedesc): Pattern {.inline.} =
  patterns.dropType(typ)

 proc `?`*[T](val: T): Pattern {.inline.} =
-  patterns.grab[T](val)
+  patterns.drop[T](val)

 proc `?:`*(typ: static typedesc): Pattern {.inline.} =
-  patterns.grabType(typ)
+  patterns.grabTypeFlat(typ)

 proc `?:`*(typ: static typedesc; bindings: sink openArray[(int, Pattern)]): Pattern {.inline.} =
  patterns.grab(typ, bindings)
@ -30,25 +30,22 @@ proc `?:`*(typ: static typedesc; bindings: sink openArray[(int, Pattern)]): Patt
 proc `?:`*(typ: static typedesc; bindings: sink openArray[(Value, Pattern)]): Pattern {.inline.} =
  patterns.grab(typ, bindings)

-proc `??`*(pat: Pattern; bindings: openArray[(int, Pattern)]): Pattern {.inline.} =
-  patterns.inject(pat, bindings)
-
 type
-  PublishProc = proc (turn: var Turn; v: Value; h: Handle) {.closure.}
-  RetractProc = proc (turn: var Turn; h: Handle) {.closure.}
-  MessageProc = proc (turn: var Turn; v: Value) {.closure.}
+  PublishProc = proc (turn: Turn; v: Value; h: Handle) {.closure.}
+  RetractProc = proc (turn: Turn; h: Handle) {.closure.}
+  MessageProc = proc (turn: Turn; v: Value) {.closure.}
  ClosureEntity = ref object of Entity
    publishImpl*: PublishProc
    retractImpl*: RetractProc
    messageImpl*: MessageProc

-method publish(e: ClosureEntity; turn: var Turn; a: AssertionRef; h: Handle) =
+method publish(e: ClosureEntity; turn: Turn; a: AssertionRef; h: Handle) =
  if not e.publishImpl.isNil: e.publishImpl(turn, a.value, h)

-method retract(e: ClosureEntity; turn: var Turn; h: Handle) =
+method retract(e: ClosureEntity; turn: Turn; h: Handle) =
  if not e.retractImpl.isNil: e.retractImpl(turn, h)

-method message(e: ClosureEntity; turn: var Turn; a: AssertionRef) =
+method message(e: ClosureEntity; turn: Turn; a: AssertionRef) =
  if not e.messageImpl.isNil: e.messageImpl(turn, a.value)

 proc argumentCount(handler: NimNode): int =
@ -93,7 +90,7 @@ proc wrapPublishHandler(turn, handler: NimNode): NimNode =
    handlerSym = genSym(nskProc, "publish")
    bindingsSym = ident"bindings"
  quote do:
-    proc `handlerSym`(`turn`: var Turn; `bindingsSym`: Value; `handleSym`: Handle) =
+    proc `handlerSym`(`turn`: Turn; `bindingsSym`: Value; `handleSym`: Handle) =
      `varSection`
      if fromPreserves(`valuesSym`, bindings):
        `publishBody`
@ -105,7 +102,7 @@ proc wrapMessageHandler(turn, handler: NimNode): NimNode =
    handlerSym = genSym(nskProc, "message")
    bindingsSym = ident"bindings"
  quote do:
-    proc `handlerSym`(`turn`: var Turn; `bindingsSym`: Value) =
+    proc `handlerSym`(`turn`: Turn; `bindingsSym`: Value) =
      `varSection`
      if fromPreserves(`valuesSym`, bindings):
        `body`
@ -119,17 +116,17 @@ proc wrapDuringHandler(turn, entryBody, exitBody: NimNode): NimNode =
    duringSym = genSym(nskProc, "during")
  if exitBody.isNil:
    quote do:
-      proc `duringSym`(`turn`: var Turn; `bindingsSym`: Value; `handleSym`: Handle): TurnAction =
+      proc `duringSym`(`turn`: Turn; `bindingsSym`: Value; `handleSym`: Handle): TurnAction =
        `varSection`
        if fromPreserves(`valuesSym`, `bindingsSym`):
          `publishBody`
  else:
    quote do:
-      proc `duringSym`(`turn`: var Turn; `bindingsSym`: Value; `handleSym`: Handle): TurnAction =
+      proc `duringSym`(`turn`: Turn; `bindingsSym`: Value; `handleSym`: Handle): TurnAction =
        `varSection`
        if fromPreserves(`valuesSym`, `bindingsSym`):
          `publishBody`
-          proc action(`turn`: var Turn) =
+          proc action(`turn`: Turn) =
            `exitBody`
          result = action

--- a/src/syndicate/Tupfile
+++ b/src/syndicate/Tupfile
@ -1,3 +1,4 @@
 include_rules
 NIM_FLAGS += --path:$(TUP_CWD)/..
 : foreach *.nim |> !nim_check |>
+: patterns.nim |> !nim_bin |>
--- a/src/syndicate/actors.nim
+++ b/src/syndicate/actors.nim
@ -64,12 +64,13 @@ type
    facetIdAllocator: uint
    exiting, exited: bool

-  TurnAction* = proc (t: var Turn) {.closure.}
+  TurnAction* = proc (t: Turn) {.closure.}

-  Turn* = ref object
+  Turn* = var TurnRef
+  TurnRef* = ref object
    facet: Facet # active facet that may change during a turn
    work: Deque[tuple[facet: Facet, act: TurnAction]]
-    effects: Table[Actor, Turn]
+    effects: Table[Actor, TurnRef]
    when tracing:
      desc: TurnDescription

@ -84,7 +85,7 @@ type
    id: FacetId
    isAlive: bool

-var turnQueue {.threadvar.}: Deque[Turn]
+var turnQueue {.threadvar.}: Deque[TurnRef]

 when tracing:
  when defined(solo5):
@ -144,11 +145,6 @@ when tracing:
    result.facet = cap.target.facet.id
    result.oid = cap.target.oid.toPreserves

-method publish*(e: Entity; turn: var Turn; v: AssertionRef; h: Handle) {.base.} = discard
-method retract*(e: Entity; turn: var Turn; h: Handle) {.base.} = discard
-method message*(e: Entity; turn: var Turn; v: AssertionRef) {.base.} = discard
-method sync*(e: Entity; turn: var Turn; peer: Cap) {.base.} = discard
-
 converter toActor(f: Facet): Actor = f.actor
 converter toActor(t: Turn): Actor = t.facet.actor
 converter toFacet(a: Actor): Facet = a.root
@ -157,7 +153,7 @@ converter toFacet(t: Turn): Facet = t.facet
 using
  actor: Actor
  facet: Facet
-  turn: var Turn
+  turn: Turn
  action: TurnAction

 proc labels(f: Facet): string =
@ -206,27 +202,27 @@ proc nextHandle(facet: Facet): Handle =
  result = succ(facet.actor.handleAllocator[])
  facet.actor.handleAllocator[] = result

-template recallFacet(turn: var Turn; body: untyped): untyped =
+template recallFacet(turn: Turn; body: untyped): untyped =
  let facet = turn.facet
  block:
    body
  assert facet.actor == turn.facet.actor
  turn.facet = facet

-proc queueWork*(turn: var Turn; facet: Facet; act: TurnAction) =
+proc queueWork*(turn: Turn; facet: Facet; act: TurnAction) =
  assert not facet.isNil
  turn.work.addLast((facet, act,))

 proc queueTurn*(facet: Facet; act: TurnAction) =
-  var turn = Turn(facet: facet)
+  var turn = TurnRef(facet: facet)
  assert not facet.isNil
  turn.work.addLast((facet, act,))
  when tracing:
    turn.desc.id = nextTurnId()
  turnQueue.addLast(turn)

-proc queueTurn*(prev: var Turn; facet: Facet; act: TurnAction) =
-  var next = Turn(facet: facet)
+proc queueTurn*(prev: Turn; facet: Facet; act: TurnAction) =
+  var next = TurnRef(facet: facet)
  assert not facet.isNil
  next.work.addLast((facet, act,))
  when tracing:
@ -240,14 +236,14 @@ proc run*(facet: Facet; action: TurnAction) = queueTurn(facet, action)

 proc facet*(turn: Turn): Facet = turn.facet

-proc queueEffect*(turn: var Turn; target: Facet; act: TurnAction) =
+proc queueEffect*(turn: Turn; target: Facet; act: TurnAction) =
  let fremd = target.actor
  if fremd == turn.facet.actor:
    turn.work.addLast((target, act,))
  else:
    var fremdTurn = turn.effects.getOrDefault(fremd)
    if fremdTurn.isNil:
-      fremdTurn = Turn(facet: target)
+      fremdTurn = TurnRef(facet: target)
      turn.effects[fremd] = fremdTurn
    when tracing:
      fremdTurn.desc.id = nextTurnId()
@ -367,7 +363,9 @@ proc runRewrites*(a: Attenuation; v: Value): Value =
    result = examineAlternatives(stage, result)
    if result.isFalse: break

-proc publish(turn: var Turn; cap: Cap; v: Value; h: Handle) =
+method publish*(e: Entity; turn: Turn; v: AssertionRef; h: Handle) {.base.} = discard
+
+proc publish(turn: Turn; cap: Cap; v: Value; h: Handle) =
  var a = runRewrites(cap.attenuation, v)
  if not a.isFalse:
    let e = OutboundAssertion(handle: h, peer: cap)
@ -382,38 +380,42 @@ proc publish(turn: var Turn; cap: Cap; v: Value; h: Handle) =
        mapEmbeds(v) do (cap: Value) -> Value: discard
      act.enqueue.event.detail.assert.handle = h
      turn.desc.actions.add act
-    queueEffect(turn, cap.relay) do (turn: var Turn):
+    queueEffect(turn, cap.relay) do (turn: Turn):
      e.established = true
      when tracing:
        turn.desc.actions.add act.toDequeue
      publish(cap.target, turn, AssertionRef(value: a), e.handle)

-proc publish*(turn: var Turn; r: Cap; a: Value): Handle {.discardable.} =
+proc publish*(turn: Turn; r: Cap; a: Value): Handle {.discardable.} =
  result = turn.facet.nextHandle()
  publish(turn, r, a, result)

-proc publish*[T](turn: var Turn; r: Cap; a: T): Handle {.discardable.} =
+proc publish*[T](turn: Turn; r: Cap; a: T): Handle {.discardable.} =
  publish(turn, r, a.toPreserves)

-proc retract(turn: var Turn; e: OutboundAssertion) =
+method retract*(e: Entity; turn: Turn; h: Handle) {.base.} = discard
+
+proc retract(turn: Turn; e: OutboundAssertion) =
  when tracing:
    var act = initEnqueue(turn, e.peer)
    act.enqueue.event.detail = trace.TurnEvent(orKind: TurnEventKind.retract)
    act.enqueue.event.detail.retract.handle = e.handle
    turn.desc.actions.add act
-  queueEffect(turn, e.peer.relay) do (turn: var Turn):
+  queueEffect(turn, e.peer.relay) do (turn: Turn):
    when tracing:
      turn.desc.actions.add act.toDequeue
    if e.established:
      e.established = false
      e.peer.target.retract(turn, e.handle)

-proc retract*(turn: var Turn; h: Handle) =
+proc retract*(turn: Turn; h: Handle) =
  var e: OutboundAssertion
  if turn.facet.outbound.pop(h, e):
    turn.retract(e)

-proc message*(turn: var Turn; r: Cap; v: Value) =
+method message*(e: Entity; turn: Turn; v: AssertionRef) {.base.} = discard
+
+proc message*(turn: Turn; r: Cap; v: Value) =
  var a = runRewrites(r.attenuation, v)
  if not a.isFalse:
    when tracing:
@ -422,38 +424,43 @@ proc message*(turn: var Turn; r: Cap; v: Value) =
      act.enqueue.event.detail.message.body.value.value =
        mapEmbeds(a) do (cap: Value) -> Value: discard
      turn.desc.actions.add act
-    queueEffect(turn, r.relay) do (turn: var Turn):
+    queueEffect(turn, r.relay) do (turn: Turn):
      when tracing:
        turn.desc.actions.add act.toDequeue
      r.target.message(turn, AssertionRef(value: a))

-proc message*[T](turn: var Turn; r: Cap; v: T) =
+proc message*[T](turn: Turn; r: Cap; v: T) =
  message(turn, r, v.toPreserves)

-proc sync*(turn: var Turn; r, peer: Cap) =
+method sync*(e: Entity; turn: Turn; peer: Cap) {.base.} =
+  queueTurn(e.facet) do (turn: Turn):
+    message(turn, peer, true.toPreserves)
+      # complete sync on a later turn
+
+proc sync*(turn: Turn; r, peer: Cap) =
  when tracing:
    var act = initEnqueue(turn, peer)
    act.enqueue.event.detail = trace.TurnEvent(orKind: TurnEventKind.sync)
    act.enqueue.event.detail.sync.peer = peer.toTraceTarget
    turn.desc.actions.add act
-  queueEffect(turn, r.relay) do (turn: var Turn):
+  queueEffect(turn, r.relay) do (turn: Turn):
    when tracing:
      turn.desc.actions.add act.toDequeue
    r.target.sync(turn, peer)

-proc replace*[T](turn: var Turn; cap: Cap; h: Handle; v: T): Handle =
+proc replace*[T](turn: Turn; cap: Cap; h: Handle; v: T): Handle =
  result = publish(turn, cap, v)
  if h != default(Handle):
    retract(turn, h)

-proc replace*[T](turn: var Turn; cap: Cap; h: var Handle; v: T): Handle {.discardable.} =
+proc replace*[T](turn: Turn; cap: Cap; h: var Handle; v: T): Handle {.discardable.} =
  var old = h
  h = publish(turn, cap, v)
  if old != default(Handle):
    retract(turn, old)
  h

-proc stop*(turn: var Turn)
+proc stop*(turn: Turn)

 proc newFacet(actor; parent: Facet; initialAssertions: OutboundTable): Facet =
  inc actor.facetIdAllocator
@ -482,7 +489,7 @@ proc preventInertCheck*(turn: Turn) =

 proc terminateActor(turn; reason: ref Exception)

-proc terminateFacetOrderly(turn: var Turn) =
+proc terminateFacetOrderly(turn: Turn) =
  let facet = turn.facet
  if facet.isAlive:
    facet.isAlive = false
@ -495,7 +502,7 @@ proc terminateFacetOrderly(turn: var Turn) =
      retract(turn, e)
    clear facet.outbound

-proc inertCheck(turn: var Turn) =
+proc inertCheck(turn: Turn) =
  if (not turn.facet.parent.isNil and
        (not turn.facet.parent.isAlive)) or
      turn.facet.isInert:
@ -506,7 +513,7 @@ proc inertCheck(turn: var Turn) =
      turn.desc.actions.add act
    stop(turn)

-proc terminateFacet(turn: var Turn) =
+proc terminateFacet(turn: Turn) =
  let facet = turn.facet
  for child in facet.children:
    queueWork(turn, child, terminateFacetOrderly)
@ -517,14 +524,14 @@ proc terminateFacet(turn: var Turn) =
    # self-termination

 proc stopIfInertAfter(action: TurnAction): TurnAction =
-  proc work(turn: var Turn) =
+  proc work(turn: Turn) =
    queueEffect(turn, turn.facet, inertCheck)
    action(turn)
  work

-proc newFacet(turn: var Turn): Facet = newFacet(turn.facet.actor, turn.facet)
+proc newFacet(turn: Turn): Facet = newFacet(turn.facet.actor, turn.facet)

-proc inFacet*(turn: var Turn; bootProc: TurnAction): Facet {.discardable.} =
+proc inFacet*(turn: Turn; bootProc: TurnAction): Facet {.discardable.} =
  result = newFacet(turn)
  recallFacet turn:
    turn.facet = result
@ -557,7 +564,7 @@ proc bootActor*(name: string; bootProc: TurnAction): Actor {.discardable.} =
  ## Boot a top-level actor.
  result = newActor(name, nil)
  new result.handleAllocator
-  var turn = Turn(facet: result.root)
+  var turn = TurnRef(facet: result.root)
  assert not result.root.isNil
  turn.work.addLast((result.root, bootProc,))
  when tracing:
@ -566,9 +573,9 @@ proc bootActor*(name: string; bootProc: TurnAction): Actor {.discardable.} =
    turn.desc.cause.external.description = "bootActor".toPreserves
  turnQueue.addLast turn

-proc spawnActor*(turn: var Turn; name: string; bootProc: TurnAction; initialAssertions = initHashSet[Handle]()): Actor {.discardable.} =
+proc spawnActor*(turn: Turn; name: string; bootProc: TurnAction; initialAssertions = initHashSet[Handle]()): Actor {.discardable.} =
  let actor = newActor(name, turn.facet)
-  queueEffect(turn, actor.root) do (turn: var Turn):
+  queueEffect(turn, actor.root) do (turn: Turn):
    var newOutBound: Table[Handle, OutboundAssertion]
    for key in initialAssertions:
      discard turn.facet.outbound.pop(key, newOutbound[key])
@ -579,12 +586,12 @@ proc spawnActor*(turn: var Turn; name: string; bootProc: TurnAction; initialAsse
    run(actor, bootProc, newOutBound)
  actor

-proc spawn*(name: string; turn: var Turn; bootProc: TurnAction; initialAssertions = initHashSet[Handle]()): Actor {.discardable.} =
+proc spawn*(name: string; turn: Turn; bootProc: TurnAction; initialAssertions = initHashSet[Handle]()): Actor {.discardable.} =
  spawnActor(turn, name, bootProc, initialAssertions)

 type StopOnRetract = ref object of Entity

-method retract*(e: StopOnRetract; turn: var Turn; h: Handle) =
+method retract*(e: StopOnRetract; turn: Turn; h: Handle) =
  stop(turn)

 proc halfLink(facet, other: Facet) =
@ -595,7 +602,7 @@ proc halfLink(facet, other: Facet) =
      established: true,
    )

-proc linkActor*(turn: var Turn; name: string; bootProc: TurnAction; initialAssertions = initHashSet[Handle]()): Actor {.discardable.} =
+proc linkActor*(turn: Turn; name: string; bootProc: TurnAction; initialAssertions = initHashSet[Handle]()): Actor {.discardable.} =
  result = spawnActor(turn, name, bootProc, initialAssertions)
  halfLink(turn.facet, result.root)
  halfLink(result.root, turn.facet)
@ -604,7 +611,7 @@ var inertActor {.threadvar.}: Actor

 proc newInertCap*(): Cap =
  if inertActor.isNil:
-    inertActor = bootActor("inert") do (turn: var Turn): turn.stop()
+    inertActor = bootActor("inert") do (turn: Turn): turn.stop()
  Cap(relay: inertActor.root)

 proc atExit*(actor; action) = actor.exitHooks.add action
@ -627,7 +634,7 @@ proc terminateActor(turn; reason: ref Exception) =
        if reason.isNil:
          terminateActor(turn, err)
          return
-    proc finish(turn: var Turn) =
+    proc finish(turn: Turn) =
      assert not actor.root.isNil, actor.name
      terminateFacet(turn)
      actor.root = nil
@ -635,14 +642,14 @@ proc terminateActor(turn; reason: ref Exception) =
    queueTurn(actor.root, finish)

 proc terminateFacet*(facet; e: ref Exception) =
-  run(facet.actor.root) do (turn: var Turn):
+  run(facet.actor.root) do (turn: Turn):
    terminateActor(turn, e)

-proc terminate*(turn: var Turn; e: ref Exception) =
+proc terminate*(turn: Turn; e: ref Exception) =
    terminateActor(turn, e)

-proc stop*(turn: var Turn, facet: Facet) =
-  queueEffect(turn, facet) do (turn: var Turn):
+proc stop*(turn: Turn, facet: Facet) =
+  queueEffect(turn, facet) do (turn: Turn):
    when tracing:
      var act = ActionDescription(orKind: ActionDescriptionKind.facetStop)
      act.facetstop.path = facet.path
@ -650,17 +657,17 @@ proc stop*(turn: var Turn, facet: Facet) =
      turn.desc.actions.add act
    terminateFacet(turn)

-proc stop*(turn: var Turn) =
+proc stop*(turn: Turn) =
  stop(turn, turn.facet)

 proc stop*(facet: Facet) =
  run(facet, stop)

 proc onStop*(facet: Facet; act: TurnAction) =
-  ## Add a `proc (turn: var Turn)` action to `facet` to be called as it stops.
+  ## Add a `proc (turn: Turn)` action to `facet` to be called as it stops.
  add(facet.shutdownActions, act)

-proc onStop*(turn: var Turn; act: TurnAction) =
+proc onStop*(turn: Turn; act: TurnAction) =
  onStop(turn.facet, act)

 proc isAlive(actor): bool =
@ -668,7 +675,7 @@ proc isAlive(actor): bool =

 proc stop*(actor: Actor) =
  if actor.isAlive:
-    queueTurn(actor.root) do (turn: var Turn):
+    queueTurn(actor.root) do (turn: Turn):
      assert(not turn.facet.isNil)
      when tracing:
        var act = ActionDescription(orKind: ActionDescriptionKind.facetStop)
@ -680,10 +687,10 @@ proc stop*(actor: Actor) =
 proc stopActor*(facet: Facet) =
  stop(facet.actor)

-proc stopActor*(turn: var Turn) =
+proc stopActor*(turn: Turn) =
  stop(turn, turn.facet.actor.root)

-proc freshen*(turn: var Turn, act: TurnAction) {.deprecated.} =
+proc freshen*(turn: Turn, act: TurnAction) {.deprecated.} =
  run(turn.facet, act)

 proc newCap*(relay: Facet; entity: Entity): Cap =
@ -700,10 +707,10 @@ proc newCap*(e: Entity; turn): Cap =
 type SyncContinuation {.final.} = ref object of Entity
  action: TurnAction

-method message(entity: SyncContinuation; turn: var Turn; v: AssertionRef) =
+method message(entity: SyncContinuation; turn: Turn; v: AssertionRef) =
  entity.action(turn)

-proc sync*(turn: var Turn; refer: Cap; act: TurnAction) =
+proc sync*(turn: Turn; refer: Cap; act: TurnAction) =
  sync(turn, refer, newCap(turn, SyncContinuation(action: act)))

 proc running*(actor): bool =
@ -711,7 +718,7 @@ proc running*(actor): bool =
  if not (result or actor.exitReason.isNil):
    raise actor.exitReason

-proc run(turn: var Turn) =
+proc run(turn: Turn) =
  while turn.work.len > 0:
    var (facet, act) = turn.work.popFirst()
    assert not act.isNil
@ -736,8 +743,24 @@ proc runPendingTurns* =
      terminateActor(turn, err)
      raise err

+proc runOnce*: bool {.discardable.} =
+  ## Run pending turns if there are any, otherwise
+  ## poll for external events and run any resulting turns.
+  ## Return true if any turns have been processed.
+  if turnQueue.len == 0:
+    when defined(solo5):
+      discard solo5_dispatcher.runOnce()
+    else:
+      var ready: seq[Continuation]
+      ioqueue.poll(ready)
+      while ready.len > 0:
+        discard trampoline:
+          ready.pop()
+  result = turnQueue.len > 0
+  runPendingTurns()
+
 proc run* =
-  ## Run actors to completion
+  ## Run actors to completion.
  when defined(solo5):
    while turnQueue.len > 0 or solo5_dispatcher.runOnce():
      runPendingTurns()
--- a/src/syndicate/dataspaces.nim
+++ b/src/syndicate/dataspaces.nim
@ -16,14 +16,14 @@ type
    index: Index
    handleMap: Table[Handle, Assertion]

-method publish(ds: Dataspace; turn: var Turn; a: AssertionRef; h: Handle) =
+method publish(ds: Dataspace; turn: Turn; a: AssertionRef; h: Handle) =
  if add(ds.index, turn, a.value):
    var obs = a.value.preservesTo(Observe)
    if obs.isSome and obs.get.observer of Cap:
      ds.index.add(turn, obs.get.pattern, Cap(obs.get.observer))
  ds.handleMap[h] = a.value

-method retract(ds: Dataspace; turn: var Turn; h: Handle) =
+method retract(ds: Dataspace; turn: Turn; h: Handle) =
  let v = ds.handleMap[h]
  if remove(ds.index, turn, v):
    ds.handleMap.del h
@ -31,20 +31,20 @@ method retract(ds: Dataspace; turn: var Turn; h: Handle) =
    if obs.isSome and obs.get.observer of Cap:
      ds.index.remove(turn, obs.get.pattern, Cap(obs.get.observer))

-method message(ds: Dataspace; turn: var Turn; a: AssertionRef) =
+method message(ds: Dataspace; turn: Turn; a: AssertionRef) =
  ds.index.deliverMessage(turn, a.value)

-proc newDataspace*(turn: var Turn): Cap =
+proc newDataspace*(turn: Turn): Cap =
  newCap(turn, Dataspace(index: initIndex()))

-type BootProc = proc (turn: var Turn; ds: Cap) {.closure.}
-type DeprecatedBootProc = proc (ds: Cap; turn: var Turn) {.closure.}
+type BootProc = proc (turn: Turn; ds: Cap) {.closure.}
+type DeprecatedBootProc = proc (ds: Cap; turn: Turn) {.closure.}

 proc bootDataspace*(name: string; bootProc: BootProc): Actor =
-  bootActor(name) do (turn: var Turn):
+  bootActor(name) do (turn: Turn):
    turn.preventInertCheck()
    bootProc(turn, newDataspace(turn))

 proc bootDataspace*(name: string; bootProc: DeprecatedBootProc): Actor {.deprecated.} =
-  bootDataspace(name) do (turn: var Turn, ds: Cap):
+  bootDataspace(name) do (turn: Turn, ds: Cap):
    bootProc(ds, turn)
--- a/src/syndicate/drivers/http_driver.nim
+++ b/src/syndicate/drivers/http_driver.nim
@ -2,7 +2,7 @@
 # SPDX-License-Identifier: Unlicense

 import std/[httpcore, options, parseutils, sets, streams, strutils, tables, times, uri]
-import preserves, ../../syndicate, ../bags
+import preserves, ../../syndicate, ../bags, ./timers
 import ../protocols/http
 import taps

@ -16,8 +16,6 @@ when defined(posix):
  proc echo(args: varargs[string, `$`]) {.used.} =
    stderr.writeLine(args)

-proc `$`(b: seq[byte]): string = cast[string](b)
-
 proc badRequest(conn: Connection; msg: string) =
  conn.send(SupportedVersion & " 400 " & msg, endOfMessage = true)

@ -25,7 +23,7 @@ proc extractQuery(s: var string): Table[Symbol, seq[QueryValue]] =
  let start = succ skipUntil(s, '?')
  if start < s.len:
    var query = s[start..s.high]
-    s.setLen(start)
+    s.setLen(pred start)
    for key, val in uri.decodeQuery(query):
      var list = result.getOrDefault(Symbol key)
      list.add QueryValue(orKind: QueryValueKind.string, string: val)
@ -33,6 +31,9 @@ proc extractQuery(s: var string): Table[Symbol, seq[QueryValue]] =

 proc parseRequest(conn: Connection; text: string): (int, HttpRequest) =
  ## Parse an `HttpRequest` request out of a `text` from a `Connection`.
+  result[1].host = RequestHost(orKind: RequestHostKind.absent)
+  result[1].body = RequestBody(orKind: RequestBodyKind.absent)
+
  var
    token: string
    off: int
@ -91,13 +92,13 @@ proc parseRequest(conn: Connection; text: string): (int, HttpRequest) =
    for e in vals.mitems:
      e = e.toLowerAscii
      if k == Symbol"host":
-        result[1].host = e
+        result[1].host = RequestHost(orKind: RequestHostKind.`present`, present: e)
      if v == "": v = move e
      else:
        v.add ", "
        v.add e
      if k == Symbol"host":
-        result[1].host = v
+        result[1].host = RequestHost(orKind: RequestHostKind.`present`, present: v)
      result[1].headers[k] = v

  result[0] = off
@ -114,9 +115,10 @@ proc lenLine(chunk: Chunk): string =
 type
  Driver = ref object
    facet: Facet
-    ds: Cap
+    ds, timers: Cap
    bindings: Bag[Value]
      # cannot make a bag of HttpBinding, no `==` operator
+    sequenceNumber: BiggestInt
  Session = ref object
    facet: Facet
    driver: Driver
@ -127,6 +129,7 @@ type
    req: HttpRequest
    stream: StringStream
    mode: HttpResponseKind
+    active: bool

 proc send[T: byte|char](ses: Session; data: openarray[T]) =
  ses.conn.send(addr data[0], data.len, endOfMessage = false)
@ -138,6 +141,9 @@ proc send(ses: Session; chunk: Chunk) =
  of ChunkKind.bytes:
    ses.send(chunk.bytes)

+func `==`(s: string; rh: RequestHost): bool =
+  rh.orKind == RequestHostKind.present and rh.present == s
+
 proc match(b: HttpBinding, r: HttpRequest): bool =
  ## Check if `HttpBinding` `b` matches `HttpRequest` `r`.
  result =
@ -178,7 +184,7 @@ proc match(driver: Driver; req: HttpRequest): Option[HttpBinding] =
      if result.isNone or b.strongerThan(result.get):
        result = some b

-method message(e: Exchange; turn: var Turn; a: AssertionRef) =
+method message(e: Exchange; turn: Turn; a: AssertionRef) =
  # Send responses back into a connection.
  var res: HttpResponse
  if e.mode != HttpResponseKind.done and res.fromPreserves a.value:
@ -186,6 +192,7 @@ method message(e: Exchange; turn: var Turn; a: AssertionRef) =

    of HttpResponseKind.status:
      if e.mode == res.orKind:
+        e.active = true
        e.ses.conn.startBatch()
        e.stream.write(
            SupportedVersion, " ", res.status.code, " ", res.status.message, CRLF,
@ -198,24 +205,27 @@ method message(e: Exchange; turn: var Turn; a: AssertionRef) =
        e.stream.write(res.header.name, ": ", res.header.value, CRLF)

    of HttpResponseKind.chunk:
-      if e.mode == HttpResponseKind.header:
-        e.stream.write("transfer-encoding: chunked" & CRLF & CRLF)
-        e.ses.send(move e.stream.data)
-        e.mode = res.orKind
-      if e.mode == res.orKind:
-        e.ses.send(res.chunk.chunk.lenLine)
-        e.ses.send(res.chunk.chunk)
-        e.ses.send(CRLF)
+      if res.chunk.chunk.len > 0:
+        if e.mode == HttpResponseKind.header:
+          e.stream.write("transfer-encoding: chunked" & CRLF & CRLF)
+          e.ses.send(move e.stream.data)
+          e.mode = res.orKind
+        if e.mode == res.orKind:
+          e.ses.send(res.chunk.chunk.lenLine)
+          e.ses.send(res.chunk.chunk)
+          e.ses.send(CRLF)

    of HttpResponseKind.done:
      if e.mode in {HttpResponseKind.header, HttpResponseKind.chunk}:
        if e.mode == HttpResponseKind.header:
          e.stream.write("content-length: ", $res.done.chunk.len & CRLF & CRLF)
          e.ses.send(move e.stream.data)
-          e.ses.send(res.done.chunk)
+          if res.done.chunk.len > 0:
+            e.ses.send(res.done.chunk)
        elif e.mode == HttpResponseKind.chunk:
          e.ses.send(res.done.chunk.lenLine)
-          e.ses.send(res.done.chunk)
+          if res.done.chunk.len > 0:
+            e.ses.send(res.done.chunk)
          e.ses.send(CRLF & "0" & CRLF & CRLF)
        e.mode = res.orKind
        e.ses.conn.endBatch()
@ -225,7 +235,7 @@ method message(e: Exchange; turn: var Turn; a: AssertionRef) =
          # stop the facet scoped to the exchange
          # so that the response capability is withdrawn

-proc service(turn: var Turn; exch: Exchange) =
+proc service(turn: Turn; exch: Exchange) =
  ## Service an HTTP message exchange.
  var binding = exch.ses.driver.match exch.req
  if binding.isNone:
@ -235,23 +245,35 @@ proc service(turn: var Turn; exch: Exchange) =
    if handler.isNone:
      stop(turn)
    else:
+      let cap =  newCap(turn, exch)
      publish(turn, handler.get, HttpContext(
          req: exch.req,
-          res: embed newCap(turn, exch),
+          res: embed cap,
        ))
+      const timeout = initDuration(seconds = 4)
+      after(turn, exch.ses.driver.timers, timeout) do (turn: Turn):
+        if not exch.active:
+          var res = HttpResponse(orKind: HttpResponseKind.status)
+          res.status.code = 504
+          res.status.message = "Binding timeout"
+          message(turn, cap, res)
+          res = HttpResponse(orKind: HttpResponseKind.done)
+          message(turn, cap, res)

 proc service(ses: Session) =
  ## Service a connection to an HTTP client.
-  ses.facet.onStop do (turn: var Turn):
+  ses.facet.onStop do (turn: Turn):
    close ses.conn
  ses.conn.onClosed do ():
    stop ses.facet
  ses.conn.onReceivedPartial do (data: seq[byte]; ctx: MessageContext; eom: bool):
-    ses.facet.run do (turn: var Turn):
+    ses.facet.run do (turn: Turn):
      var (n, req) = parseRequest(ses.conn, cast[string](data))
      if n > 0:
+        inc(ses.driver.sequenceNumber)
+        req.sequenceNumber = ses.driver.sequenceNumber
        req.port = BiggestInt ses.port
-        inFacet(turn) do (turn: var Turn):
+        inFacet(turn) do (turn: Turn):
          preventInertCheck(turn)
          # start a new facet for this message exchange
          turn.service Exchange(
@ -269,18 +291,18 @@ proc newListener(port: Port): Listener =
  lp.with port
  listen newPreconnection(local=[lp])

-proc httpListen(turn: var Turn; driver: Driver; port: Port): Listener =
+proc httpListen(turn: Turn; driver: Driver; port: Port): Listener =
  let facet = turn.facet
  var listener = newListener(port)
  preventInertCheck(turn)
  listener.onListenError do (err: ref Exception):
    terminateFacet(facet, err)
-  facet.onStop do (turn: var Turn):
+  facet.onStop do (turn: Turn):
    stop listener
  listener.onConnectionReceived do (conn: Connection):
-    driver.facet.run do (turn: var Turn):
+    driver.facet.run do (turn: Turn):
      # start a new turn
-      linkActor(turn, "http-conn") do (turn: var Turn):
+      linkActor(turn, "http-conn") do (turn: Turn):
        preventInertCheck(turn)
        let facet = turn.facet
        conn.onConnectionError do (err: ref Exception):
@ -295,8 +317,9 @@ proc httpListen(turn: var Turn; driver: Driver; port: Port): Listener =
          )
  listener

-proc httpDriver(turn: var Turn; ds: Cap) =
-  let driver = Driver(facet: turn.facet, ds: ds)
+proc httpDriver(turn: Turn; ds: Cap) =
+  let driver = Driver(facet: turn.facet, ds: ds, timers: turn.newDataspace)
+  spawnTimerDriver(turn, driver.timers)

  during(turn, ds, HttpBinding?:{
        1: grab(),
@ -315,6 +338,6 @@ proc httpDriver(turn: var Turn; ds: Cap) =
  do:
    stop(l)

-proc spawnHttpDriver*(turn: var Turn; ds: Cap): Actor {.discardable.} =
-  spawnActor(turn, "http-driver") do (turn: var Turn):
+proc spawnHttpDriver*(turn: Turn; ds: Cap): Actor {.discardable.} =
+  spawnActor(turn, "http-driver") do (turn: Turn):
    httpDriver(turn, ds)
--- a/src/syndicate/drivers/timers.nim
+++ b/src/syndicate/drivers/timers.nim
@ -1,9 +1,9 @@
 # SPDX-FileCopyrightText: ☭ Emery Hemingway
 # SPDX-License-Identifier: Unlicense

-import std/times
+import std/[tables, times]
 import preserves
-import ../../syndicate, ../bags, ../protocols/[timer, dataspace]
+import ../../syndicate, ../protocols/[timer, dataspace]

 when defined(solo5):
  import solo5_dispatcher
@ -27,7 +27,7 @@ when defined(solo5):
        ## Owning facet of driver.
      target: Cap
        ## Destination for LaterThan assertions.
-      deadlines: Bag[float]
+      deadlines: Table[float, Facet]
        ## Deadlines that other actors are observing.

  proc spawnTimerDriver(facet: Facet; cap: Cap): TimerDriver =
@ -35,11 +35,12 @@ when defined(solo5):

  proc await(driver: TimerDriver; deadline: float) {.solo5dispatch.} =
    yieldUntil(deadline)
-    if deadline in driver.deadlines:
+    let facet = driver.deadlines.getOrDefault(deadline)
+    if not facet.isNil:
      # check if the deadline is still observed
-      proc turnWork(turn: var Turn) =
+      proc turnWork(turn: Turn) =
        discard publish(turn, driver.target, LaterThan(seconds: deadline))
-      run(driver.facet, turnWork)
+      run(facet, turnWork)

 else:
  import std/[oserrors, posix, sets]
@ -84,14 +85,14 @@ else:
        ## Owning facet of driver.
      target: Cap
        ## Destination for LaterThan assertions.
-      deadlines: Bag[float]
+      deadlines: Table[float, Facet]
        ## Deadlines that other actors are observing.
      timers: HashSet[cint]
        # TODO: use a single timer descriptor

  proc spawnTimerDriver(facet: Facet; cap: Cap): TimerDriver =
    let driver = TimerDriver(facet: facet, target: cap)
-    facet.onStop do (turn: var Turn):
+    facet.onStop do (turn: Turn):
      for fd in driver.timers:
        unregister(FD fd)
        discard close(fd)
@ -100,7 +101,7 @@ else:
  proc earliestFloat(driver: TimerDriver): float =
    assert driver.deadlines.len > 0
    result = high float
-    for deadline in driver.deadlines:
+    for deadline in driver.deadlines.keys:
      if deadline < result:
        result = deadline

@ -119,29 +120,29 @@ else:
      # Check if the timer is expired which
      # could happen before waiting.
      wait(FD fd, Read)
-    if deadline in driver.deadlines:
+    let facet = driver.deadlines.getOrDefault(deadline)
+    if not facet.isNil:
      # Check if the deadline is still observed.
-      proc turnWork(turn: var Turn) =
+      proc turnWork(turn: Turn) =
        discard publish(turn, driver.target, LaterThan(seconds: deadline))
-      run(driver.facet, turnWork)
+      run(facet, turnWork)
    discard close(fd)
    driver.timers.excl(fd)

-proc spawnTimerDriver*(turn: var Turn; ds: Cap): Actor {.discardable.} =
+proc spawnTimerDriver*(turn: Turn; ds: Cap): Actor {.discardable.} =
  ## Spawn a timer actor that responds to
  ## dataspace observations of timeouts on `ds`.
-  linkActor(turn, "timers") do (turn: var Turn):
+  linkActor(turn, "timers") do (turn: Turn):
    let driver = spawnTimerDriver(turn.facet, ds)
-    let pat = inject(grab Observe(pattern: dropType LaterThan), {0: grabLit()})
+    let pat = observePattern(!LaterThan, {@[0.toPreserves]: grabLit()})
    during(turn, ds, pat) do (deadline: float):
-      if change(driver.deadlines, deadline, +1) == cdAbsentToPresent:
-        discard trampoline(whelp await(driver, deadline))
+      driver.deadlines[deadline] = turn.facet
+      discard trampoline(whelp await(driver, deadline))
    do:
-      discard change(driver.deadlines, deadline, -1, clamp = true)
-        # TODO: retract assertions that are unobserved.
+      driver.deadlines.del deadline

-proc after*(turn: var Turn; ds: Cap; dur: Duration; act: TurnAction) =
+proc after*(turn: Turn; ds: Cap; dur: Duration; act: TurnAction) =
  ## Execute `act` after some duration of time.
  var later = wallFloat() + dur.inMilliseconds.float / 1_000.0
-  onPublish(turn, ds, grab LaterThan(seconds: later)):
+  onPublish(turn, ds, ?LaterThan(seconds: later)):
    act(turn)
--- a/src/syndicate/durings.nim
+++ b/src/syndicate/durings.nim
@ -6,7 +6,7 @@ import preserves
 import ./actors, ./patterns, ./protocols/dataspace

 type
-  DuringProc* = proc (turn: var Turn; a: Value; h: Handle): TurnAction
+  DuringProc* = proc (turn: Turn; a: Value; h: Handle): TurnAction
  DuringActionKind = enum null, dead, act
  DuringAction = object
    case kind: DuringActionKind
@ -17,8 +17,8 @@ type
    cb: DuringProc
    assertionMap: Table[Handle, DuringAction]

-method publish(de: DuringEntity; turn: var Turn; a: AssertionRef; h: Handle) =
-  discard inFacet(turn) do (turn: var Turn):
+method publish(de: DuringEntity; turn: Turn; a: AssertionRef; h: Handle) =
+  discard inFacet(turn) do (turn: Turn):
    let action =  de.cb(turn, a.value, h)
    # assert(not action.isNil "should have put in a no-op action")
    let g = de.assertionMap.getOrDefault h
@ -31,7 +31,7 @@ method publish(de: DuringEntity; turn: var Turn; a: AssertionRef; h: Handle) =
    of act:
      raiseAssert("during: duplicate handle in publish: " & $h)

-method retract(de: DuringEntity; turn: var Turn; h: Handle) =
+method retract(de: DuringEntity; turn: Turn; h: Handle) =
  let g = de.assertionMap.getOrDefault h
  case g.kind
  of null:
@ -45,5 +45,5 @@ method retract(de: DuringEntity; turn: var Turn; h: Handle) =

 proc during*(cb: DuringProc): DuringEntity = DuringEntity(cb: cb)

-proc observe*(turn: var Turn; ds: Cap; pat: Pattern; e: Entity): Handle =
+proc observe*(turn: Turn; ds: Cap; pat: Pattern; e: Entity): Handle =
  publish(turn, ds, Observe(pattern: pat, observer: newCap(turn, e)))
--- a/src/syndicate/patterns.nim
+++ b/src/syndicate/patterns.nim
@ -1,70 +1,46 @@
 # SPDX-FileCopyrightText: ☭ Emery Hemingway
 # SPDX-License-Identifier: Unlicense

-import std/[algorithm, assertions, options, sequtils, tables, typetraits]
+import std/[assertions, options, tables, typetraits]

 import preserves
-import ./protocols/dataspacePatterns
+import ./protocols/[dataspacePatterns, dataspace]
 from ./actors import Cap

-export dataspacePatterns.`$`, PatternKind, DCompoundKind, AnyAtomKind
+export dataspacePatterns.`$`, AnyAtomKind, GroupTypeKind, PatternKind

 type
-  AnyAtom = dataspacePatterns.AnyAtom
-  DBind = dataspacePatterns.DBind
-  DCompound = dataspacePatterns.DCompound
-  DCompoundArr = dataspacePatterns.DCompoundArr
-  DCompoundDict = dataspacePatterns.DCompoundDict
-  DCompoundRec = dataspacePatterns.DCompoundRec
-  DLit = dataspacePatterns.DLit
  Pattern* = dataspacePatterns.Pattern

-iterator orderedEntries*(dict: DCompoundDict): (Value, Pattern) =
-  ## Iterate a `DCompoundDict` in Preserves order.
-  ## Values captured from a dictionary are represented as an
-  ## array of values ordered by their former key, so using an
-  ## ordered iterator is sometimes essential.
-  var keys = dict.entries.keys.toSeq
-  sort(keys, preserves.cmp)
-  for k in keys:
-    yield(k, dict.entries.getOrDefault(k))
-      # getOrDefault doesn't raise and we know the keys will match
+proc toPattern(b: sink PatternBind): Pattern =
+  Pattern(orKind: PatternKind.`bind`, `bind`: b)

-proc toPattern(d: sink DBind): Pattern =
-  Pattern(orKind: PatternKind.DBind, dbind: d)
+proc toPattern(l: sink PatternLit): Pattern =
+  Pattern(orKind: PatternKind.`lit`, lit: l)

-proc toPattern(d: sink DLit): Pattern =
-  Pattern(orKind: PatternKind.DLit, dlit: d)
+proc toPattern(g: sink PatternGroup): Pattern =
+  Pattern(orKind: PatternKind.`group`, group: g)

-proc toPattern(aa: sink AnyAtom): Pattern =
-  DLit(value: aa).toPattern
+proc toPattern(a: sink AnyAtom): Pattern =
+  PatternLit(value: a).toPattern

-proc toPattern(d: sink DCompound): Pattern =
-  Pattern(orKind: PatternKind.DCompound, dcompound: d)
+proc grab*(p: sink Pattern): Pattern =
+  PatternBind(pattern: p).toPattern

-proc toPattern(d: sink DCompoundRec): Pattern =
-  DCompound(orKind: DCompoundKind.rec, rec: d).toPattern
-
-proc toPattern(d: sink DCompoundArr): Pattern =
-  DCompound(orKind: DCompoundKind.arr, arr: d).toPattern
-
-proc toPattern(d: sink DCompoundDict): Pattern =
-  DCompound(orKind: DCompoundKind.dict, dict: d).toPattern
-
-proc drop*(): Pattern {.inline.} = Pattern(orKind: PatternKind.DDiscard)
+proc drop*(): Pattern = Pattern(orKind: PatternKind.`discard`)
  ## Create a pattern to match any value without capture.

-proc grab*(): Pattern {.inline.} = DBind(pattern: drop()).toPattern
+proc grab*(): Pattern = drop().grab()
  ## Create a pattern to capture any value.

-proc grab*(pr: Value): Pattern =
+proc drop*(pr: Value): Pattern =
  ## Convert a `Preserve` value to a `Pattern`.
  runnableExamples:
    from std/unittest import check
    import preserves
    check:
-      $(grab parsePreserves"""<foo "bar" #"00" [0 1 2.0] {maybe: #t} <_>>""") ==
-        """<rec foo [<lit "bar"> <lit #"00"> <arr [<lit 0> <lit 1> <lit 2.0>]> <dict {maybe: <lit #t>}> <_>]>"""
+      $("""<foo "bar" #"00" [0 1 2.0] {maybe: #t} <_>>""".parsePreserves.drop) ==
+        """<group <rec foo> {0: <lit "bar"> 1: <lit #"00"> 2: <group <arr> {0: <lit 0> 1: <lit 1> 2: <lit 2.0>}> 3: <group <dict> {maybe: <lit #t>}> 4: <_>}>"""

  case pr.kind
  of pkBoolean:
@ -73,45 +49,67 @@ proc grab*(pr: Value): Pattern =
    AnyAtom(orKind: AnyAtomKind.`double`, double: pr.float).toPattern
  of pkRegister:
    AnyAtom(orKind: AnyAtomKind.`int`, int: pr.register).toPattern
+  of pkBigInt:
+    raiseAssert "cannot make a pattern over a big integer"
  of pkString:
    AnyAtom(orKind: AnyAtomKind.`string`, string: pr.string).toPattern
  of pkByteString:
    AnyAtom(orKind: AnyAtomKind.`bytes`, bytes: pr.bytes).toPattern
  of pkSymbol:
    AnyAtom(orKind: AnyAtomKind.`symbol`, symbol: pr.symbol).toPattern
+
  of pkRecord:
-    if (pr.isRecord("_") and pr.arity == 0) or (pr.isRecord("bind") and pr.arity == 1):
+    if pr.isRecord("_", 0):
      drop()
+    elif pr.isRecord("bind", 1):
+      pr.fields[0].drop
    else:
-      DCompoundRec(
-        label: pr.label,
-        fields: map[Value, Pattern](pr.fields, grab)).toPattern
+      var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.rec))
+      group.`type`.rec.label = pr.label
+      var i: int
+      for v in pr.fields:
+        group.entries[toPreserves i] = drop v
+        inc i
+      group.toPattern
+
  of pkSequence:
-    DCompoundArr(items: map(pr.sequence, grab)).toPattern
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.arr))
+    for i, v in pr.sequence:
+      group.entries[toPreserves i] = drop v
+    group.toPattern
+
  of pkSet:
    raiseAssert "cannot construct a pattern over a set literal"
+
  of pkDictionary:
-    var dict = DCompoundDict()
-    for key, val in pr.pairs: dict.entries[key] = grab val
-    dict.toPattern
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.dict))
+    for key, val in pr.pairs:
+      group.entries[key] = drop val
+    group.toPattern
+
  of pkEmbedded:
    if pr.embeddedRef.isNil: drop()
    else:
      AnyAtom(orKind: AnyAtomKind.`embedded`, embedded: pr.embeddedRef).toPattern
-  else:
-    raise newException(ValueError, "cannot generate a pattern for unhandled Value type")
+  #else:
+  #  raise newException(ValueError, "cannot generate a pattern for unhandled Value type")

-proc grab*[T](x: T): Pattern =
+proc drop*[T](x: T): Pattern =
  ## Construct a `Pattern` from value of type `T`.
+  ## This proc is called `drop` because the value `x` is matched but discarded.
  runnableExamples:
    from std/unittest import check
    check:
-      $grab(true) == "<lit #t>"
-      $grab(3.14) == "<lit 3.14>"
-      $grab([0, 1, 2, 3]) == "<arr [<lit 0> <lit 1> <lit 2> <lit 3>]>"
-  grab(x.toPreserves)
+      $drop(true) == "<lit #t>"
+      $drop(3.14) == "<lit 3.14>"
+      $drop([0, 1, 2, 3]) == "<group <arr> {0: <lit 0> 1: <lit 1> 2: <lit 2> 3: <lit 3>}>"
+  drop(x.toPreserves)

-proc grabType*(typ: static typedesc): Pattern =
+proc grab*[T](x: T): Pattern {.
+    deprecated: "use drop unless you wish to capture the provided value".} =
+  PatternBind(pattern: drop x).toPattern
+
+proc grabTypeFlat*(typ: static typedesc): Pattern =
  ## Derive a `Pattern` from type `typ`.
  ## This works for `tuple` and `object` types but in the
  ## general case will return a wildcard binding.
@ -119,41 +117,42 @@ proc grabType*(typ: static typedesc): Pattern =
    import preserves
    from std/unittest import check
    check:
-      $grabType(array[3, int]) ==
-        """<arr [<bind <_>> <bind <_>> <bind <_>>]>"""
+      $grabTypeFlat(array[3, int]) ==
+        """<group <arr> {0: <bind <_>> 1: <bind <_>> 2: <bind <_>> 3: <bind <_>>}>"""
    type
      Point = tuple[x: int; y: int]
      Rect {.preservesRecord: "rect".} = tuple[a: Point; B: Point]
      ColoredRect {.preservesDictionary.} = tuple[color: string; rect: Rect]
    check:
-      $(grabType Point) ==
-        "<arr [<bind <_>> <bind <_>>]>"
-      $(grabType Rect) ==
-        "<rec rect [<arr [<bind <_>> <bind <_>>]> <arr [<bind <_>> <bind <_>>]>]>"
-      $(grabType ColoredRect) ==
-        "<dict {color: <bind <_>> rect: <rec rect [<arr [<bind <_>> <bind <_>>]> <arr [<bind <_>> <bind <_>>]>]>}>"
+      $(grabTypeFlat Point) ==
+        "<group <arr> {0: <bind <_>> 1: <bind <_>>}>"
+      $(grabTypeFlat Rect) ==
+        "<group <rec rect> {0: <group <arr> {0: <bind <_>> 1: <bind <_>>}> 1: <group <arr> {0: <bind <_>> 1: <bind <_>>}>}>"
+      $(grabTypeFlat ColoredRect) ==
+        "<group <dict> {color: <bind <_>> rect: <group <rec rect> {0: <group <arr> {0: <bind <_>> 1: <bind <_>>}> 1: <group <arr> {0: <bind <_>> 1: <bind <_>>}>}>}>"
  when typ is ref:
-    grabType(pointerBase(typ))
+    grabTypeFlat(pointerBase(typ))
  elif typ.hasPreservesRecordPragma:
-    var rec = DCompoundRec(label: typ.recordLabel.toSymbol)
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`rec`))
+    group.`type`.rec.label = typ.recordLabel.toSymbol
    for _, f in fieldPairs(default typ):
-      add(rec.fields, grabType(typeof f))
-    result = rec.toPattern
+      group.entries[group.entries.len.toPreserves] = grabTypeFlat(typeof f)
+    group.toPattern
  elif typ.hasPreservesDictionaryPragma:
-    var dict = DCompoundDict()
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`dict`))
    for key, val in fieldPairs(default typ):
-      dict.entries[key.toSymbol] = grabType(typeof val)
-    dict.toPattern
+      group.entries[key.toSymbol] = grabTypeFlat(typeof val)
+    group.toPattern
  elif typ is tuple:
-    var arr = DCompoundArr()
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`arr`))
    for _, f in fieldPairs(default typ):
-      add(arr.items, grabType(typeof f))
-    arr.toPattern
+      group.entries[group.entries.len.toPreserves] = grabTypeFlat(typeof f)
+    group.toPattern
  elif typ is array:
-    var arr = DCompoundArr()
-    arr.items.setLen(len(typ))
-    for e in arr.items.mitems: e = grab()
-    arr.toPattern
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`arr`))
+    for i in 0..len(typ):
+      group.entries[toPreserves i] = grab()
+    group.toPattern
  else:
    grab()

@ -166,59 +165,50 @@ proc dropType*(typ: static typedesc): Pattern =
  when typ is ref:
    dropType(pointerBase(typ))
  elif typ.hasPreservesRecordPragma:
-    var rec = DCompoundRec(label: typ.recordLabel.toSymbol)
-    rec.fields.setLen(fieldCount typ)
-    for i, _ in rec.fields:
-      rec.fields[i] = drop()
-    result = rec.toPattern
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`rec`))
+    group.`type`.rec.label = typ.recordLabel.toSymbol
+    let high = typ.fieldCount.pred
+    if high >= 0: group.entries[high.toPreserves] = drop()
+    group.toPattern
  elif typ.hasPreservesDictionaryPragma:
-    DCompoundDict().toPattern
-  elif typ is tuple:
-    var arr = DCompoundArr()
-    arr.items.setLen(len typ)
-    for i, _ in arr.items:
-      arr.items[i] = drop()
-    arr.toPattern
-  elif typ is array:
-    var arr = DCompoundArr()
-    arr.items.setLen(len(typ))
-    for e in arr.items.mitems: e = drop()
-    arr.toPattern
+    PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`dict`)).toPattern
+  elif typ is tuple or typ is array:
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`arr`))
+    let high = typ.fieldCount.pred
+    if high >= 0: group.entries[high.toPreserves] = drop()
+    group.toPattern
  else:
    drop()

-proc lookup(bindings: openArray[(int, Pattern)]; i: int): Pattern =
-  for (j, b) in bindings:
-    if i == j: return b
-  return drop()
+proc grabType*(typ: static typedesc): Pattern =
+  PatternBind(pattern: typ.dropType).toPattern
+
+proc bindEntries(group: var PatternGroup; bindings: openArray[(int, Pattern)]) =
+  ## Set `bindings` for a `group`.
+  for (i, pat) in bindings: group.entries[toPreserves i] = pat

 proc grab*(typ: static typedesc; bindings: sink openArray[(int, Pattern)]): Pattern =
  ## Construct a `Pattern` from type `typ` with pattern `bindings` by integer offset.
  when typ is ptr | ref:
    grab(pointerBase(typ), bindings)
  elif typ.hasPreservesRecordPragma:
-    var rec = DCompoundRec(label: typ.recordLabel.toSymbol)
-    rec.fields.setLen(fieldCount typ)
-    var i: int
-    for _, f in fieldPairs(default typ):
-      rec.fields[i] = lookup(bindings, i)
-      inc i
-    result = rec.toPattern
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`rec`))
+    group.`type`.rec.label = typ.recordLabel.toSymbol
+    bindEntries(group, bindings)
+    group.toPattern
  elif typ is tuple:
-    var arr = DCompoundArr()
-    arr.items.setLen(fieldCount typ)
-    var i: int
-    for _, f in fieldPairs(default typ):
-      arr.items[i] = lookup(bindings, i)
-      inc i
-    result = arr.toPattern
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`arr`))
+    bindEntries(group, bindings)
+    group.toPattern
  else:
    {.error: "grab with indexed bindings not implemented for " & $typ.}

 proc grab*(typ: static typedesc; bindings: sink openArray[(Value, Pattern)]): Pattern =
  ## Construct a `Pattern` from type `typ` with dictionary field `bindings`.
  when typ.hasPreservesDictionaryPragma:
-    DCompoundDict(entries: bindings.toTable).toPattern
+    var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`dict`))
+    for key, val in bindinds: group.entries[key] = val
+    group.toPattern
  else:
    {.error: "grab with dictionary bindings not implemented for " & $typ.}

@ -226,11 +216,11 @@ proc grabLit*(): Pattern =
  runnableExamples:
    from std/unittest import check
    check:
-      $grabLit() == """<rec lit [<bind <_>>]>"""
-  grabType(dataspacePatterns.DLit)
+      $grabLit() == """<group <rec lit> {0: <bind <_>>}>"""
+  grabTypeFlat(dataspacePatterns.PatternLit)

 proc grabDict*(): Pattern =
-  grabType(dataspacePatterns.DCompoundDict)
+  grabTypeFlat(dataspacePatterns.GroupTypeDict)

 proc unpackLiterals*(pr: Value): Value =
  result = pr
@ -238,64 +228,42 @@ proc unpackLiterals*(pr: Value): Value =
    if pr.isRecord("lit", 1) or pr.isRecord("dict", 1) or pr.isRecord("arr", 1) or pr.isRecord("set", 1):
      pr = pr.record[0]

-proc inject*(pat: Pattern; bindings: openArray[(int, Pattern)]): Pattern =
-  ## Construct a `Pattern` from `pat` with injected overrides from `bindings`.
+proc inject*(pattern: sink Pattern; p: Pattern; path: varargs[Value, toPreserves]): Pattern =
+  ## Inject `p` inside `pattern` at `path`.
  ## Injects are made at offsets indexed by the discard (`<_>`) patterns in `pat`.
-  proc inject(pat: Pattern; bindings: openArray[(int, Pattern)]; offset: var int): Pattern =
-    case pat.orKind
-    of PatternKind.DDiscard:
-      result = pat
-      for (off, injection) in bindings:
-        if off == offset:
-          result = injection
-          break
-      inc offset
-    of PatternKind.DBind:
-      let bindOff = offset
-      result = pat
-      result.dbind.pattern = inject(pat.dbind.pattern, bindings, offset)
-      if result.orKind == PatternKind.DBind:
-        for (off, injection) in bindings:
-          if (off == bindOff) and (result.dbind.pattern == injection):
-            result = result.dbind.pattern
-            break # promote the injected pattern over the bind
-    of PatternKind.DLit:
-      result = pat
-    of PatternKind.DCompound:
-      result = pat
-      case pat.dcompound.orKind
-      of DCompoundKind.rec:
-        var fields = mapIt(pat.dcompound.rec.fields):
-          inject(it, bindings, offset)
-        result = DCompoundRec(label: result.dcompound.rec.label, fields: fields).toPattern
-      of DCompoundKind.arr:
-        var items = mapIt(pat.dcompound.arr.items):
-          inject(it, bindings, offset)
-        result = DCompoundArr(items: items).toPattern
-      of DCompoundKind.dict:
-        var dict = DCompoundDict()
-        for key, val in pat.dcompound.dict.entries:
-          dict.entries[key] = inject(val, bindings, offset)
-        result = toPattern(dict)
-  var offset = 0
-  inject(pat, bindings, offset)
-
-proc inject*(pat: Pattern; bindings: openArray[(Value, Pattern)]): Pattern =
-  ## Inject `bindings` into a dictionary pattern.
-  assert pat.orKind == PatternKind.DCompound
-  assert pat.dcompound.orKind == DCompoundKind.dict
-  result = pat
-  for (key, val) in bindings:
-    result.dcompound.dict.entries[key] = val
+  proc inject(pat: var Pattern; path: openarray[Value]) =
+    if len(path) == 0:
+      pat = p
+    elif pat.orKind != PatternKind.`group`:
+      raise newException(ValueError, "cannot inject along specified path")
+    else:
+      inject(pat.group.entries[path[0]], path[1..path.high])
+  result = pattern
+  inject(result, path)

 proc grabRecord*(label: Value, fields: varargs[Pattern]): Pattern =
  runnableExamples:
    from std/unittest import check
-    import syndicate/actors, preserves
+    import preserves
    check:
      $grabRecord("Says".toSymbol, grab(), grab()) ==
-        """<rec Says [<bind <_>> <bind <_>>]>"""
-  DCompoundRec(label: label, fields: fields.toSeq).toPattern
+        """<group <rec Says> {0: <bind <_>> 1: <bind <_>>}>"""
+  var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`rec`))
+  group.`type`.rec.label = label
+  for i, f in fields: group.entries[toPreserves i] = f
+  group.toPattern
+
+proc grabRecord*(label: Value, fields: sink openArray[(int, Pattern)]): Pattern =
+  runnableExamples:
+    from std/unittest import check
+    import preserves
+    check:
+      $grabRecord("Says".toSymbol, {3: grab(), 4: grab()}) ==
+        """<group <rec Says> {3: <bind <_>> 4: <bind <_>>}>"""
+  var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`rec`))
+  group.`type`.rec.label = label
+  for (i, p) in fields: group.entries[toPreserves i] = p
+  group.toPattern

 proc grabRecord*(label: string, fields: varargs[Pattern]): Pattern =
  ## Sugar for creating record patterns.
@ -304,47 +272,61 @@ proc grabRecord*(label: string, fields: varargs[Pattern]): Pattern =

 proc grabDictionary*(bindings: sink openArray[(Value, Pattern)]): Pattern =
  ## Construct a pattern that grabs some dictionary pairs.
-  DCompoundDict(entries: bindings.toTable).toPattern
+  var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`dict`))
+  for (key, val) in bindings: group.entries[key] = val
+  group.toPattern

 proc grabDictionary*(bindings: sink openArray[(string, Pattern)]): Pattern =
  ## Construct a pattern that grabs some dictionary pairs.
  ## Keys are converted from strings to symbols.
-  result = DCompoundDict().toPattern
-  for (key, val) in bindings.items:
-    result.dcompound.dict.entries[key.toSymbol] = val
+  var group = PatternGroup(`type`: GroupType(orKind: GroupTypeKind.`dict`))
+  for (key, val) in bindings: group.entries[toSymbol key] = val
+  group.toPattern

-proc depattern(comp: DCompound; values: var seq[Value]; index: var int): Value
+proc depattern(group: PatternGroup; values: var seq[Value]; index: var int): Value

 proc depattern(pat: Pattern; values: var seq[Value]; index: var int): Value =
  case pat.orKind
-  of PatternKind.DDiscard:
+  of PatternKind.`discard`:
    discard
-  of PatternKind.DBind:
+  of PatternKind.`bind`:
    if index < values.len:
      result = move values[index]
      inc index
-  of PatternKind.DLit:
-    result = pat.dlit.value.toPreserves
-  of PatternKind.DCompound:
-    result = depattern(pat.dcompound, values, index)
+  of PatternKind.`lit`:
+    result = pat.`lit`.value.toPreserves
+  of PatternKind.`group`:
+    result = depattern(pat.group, values, index)

-proc depattern(comp: DCompound; values: var seq[Value]; index: var int): Value =
-  case comp.orKind
-  of DCompoundKind.rec:
-    result = initRecord(comp.rec.label, comp.rec.fields.len)
-    for i, f in comp.rec.fields:
-      result[i] = depattern(f, values, index)
-  of DCompoundKind.arr:
-    result = initSequence(comp.arr.items.len)
-    for i, e in comp.arr.items:
-      result[i] = depattern(e, values, index)
-  of DCompoundKind.dict:
+proc depattern(group: PatternGroup; values: var seq[Value]; index: var int): Value =
+  case group.`type`.orKind
+  of GroupTypeKind.rec:
+    result = initRecord(group.`type`.rec.label, group.entries.len)
+    var i: int
+    for key, val in group.entries:
+      if i.fromPreserves key:
+        result[i] = depattern(val, values, index)
+  of GroupTypeKind.arr:
+    result = initSequence(group.entries.len)
+    var i: int
+    for key, val in group.entries:
+      if i.fromPreserves key:
+        result[i] = depattern(val, values, index)
+  of GroupTypeKind.dict:
    result = initDictionary(Cap)
-    for key, val in comp.dict.entries:
+    for key, val in group.entries:
      result[key] = depattern(val, values, index)

 proc depattern*(pat: Pattern; values: sink seq[Value]): Value =
  ## Convert a `Pattern` to a `Value` while replacing binds with `values`.
+  runnableExamples:
+    from std/unittest import check
+    import preserves
+    type Foo {.preservesRecord: "foo".} = object
+      a, b: int
+    let pat = grabTypeFlat Foo
+    let val = depattern(pat, @[1.toPreserves, 5.toPreserves])
+    check $val == "<foo 1 5>"
  var index: int
  depattern(pat, values, index)

@ -359,44 +341,73 @@ proc fromPreservesHook*[T](lit: var Literal[T]; pr: Value): bool =
 proc toPreservesHook*[T](lit: Literal[T]): Value =
  lit.value.grab.toPreserves

+func isGroup(pat: Pattern): bool =
+  pat.orKind == PatternKind.`group`
+
+func isMetaDict(pat: Pattern): bool =
+  pat.orKind == PatternKind.`group` and
+    pat.group.type.orKind == GroupTypeKind.dict
+
+proc metaApply(result: var Pattern; pat: Pattern; path: openarray[Value], offset: int) =
+  if offset == path.len:
+    result = pat
+  elif result.isGroup and result.group.entries[1.toPreserves].isMetaDict:
+    if offset == path.high:
+      result.group.entries[1.toPreserves].group.entries[path[offset]] = pat
+    else:
+      metaApply(result.group.entries[1.toPreserves].group.entries[path[offset]], pat, path, succ offset)
+  else:
+    assert result.isGroup, "non-group: " & $result
+    assert result.group.entries[1.toPreserves].isMetaDict, "non-meta-dict: " & $result.group.entries[1.toPreserves]
+    raise newException(ValueError, "cannot inject into non-group pattern " & $result)
+
+proc observePattern*(pat: Pattern; injects: openarray[(seq[Value], Pattern)]): Pattern =
+  result = dropType Observe
+  var meta = pat.toPreserves.drop
+  for (path, pat) in injects:
+    metaApply(meta, pat, path, 0)
+  result.group.entries[0.toPreserves] = meta
+
 type
  Path* = seq[Value]
  Paths* = seq[Path]
  Captures* = seq[Value]
  Analysis* = tuple
+    presentPaths: Paths
    constPaths: Paths
    constValues: seq[Value]
    capturePaths: Paths

 func walk(result: var Analysis; path: var Path; p: Pattern)

-func walk(result: var Analysis; path: var Path; key: int|Value; pat: Pattern) =
-  path.add(key.toPreserves)
+func walk(result: var Analysis; path: var Path; key: Value; pat: Pattern) =
+  path.add(key)
  walk(result, path, pat)
  discard path.pop

 func walk(result: var Analysis; path: var Path; p: Pattern) =
  case p.orKind
-  of PatternKind.DCompound:
-    case p.dcompound.orKind
-    of DCompoundKind.rec:
-      for k, e in p.dcompound.rec.fields: walk(result, path, k, e)
-    of DCompoundKind.arr:
-       for k, e in p.dcompound.arr.items: walk(result, path, k, e)
-    of DCompoundKind.dict:
-      for k, e in p.dcompound.dict.orderedEntries: walk(result, path, k, e)
-  of PatternKind.DBind:
+  of PatternKind.group:
+    for k, v in p.group.entries: walk(result, path, k, v)
+  of PatternKind.`bind`:
    result.capturePaths.add(path)
-    walk(result, path, p.dbind.pattern)
-  of PatternKind.DDiscard: discard
-  of PatternKind.DLit:
+    walk(result, path, p.`bind`.pattern)
+  of PatternKind.`discard`:
+    result.presentPaths.add(path)
+  of PatternKind.`lit`:
    result.constPaths.add(path)
-    result.constValues.add(p.dlit.value.toPreserves)
+    result.constValues.add(p.`lit`.value.toPreserves)

 func analyse*(p: Pattern): Analysis =
  var path: Path
  walk(result, path, p)

+func checkPresence*(v: Value; present: Paths): bool =
+  result = true
+  for path in present:
+    if not result: break
+    result = step(v, path).isSome
+
 func projectPaths*(v: Value; paths: Paths): Option[Captures] =
  var res = newSeq[Value](paths.len)
  for i, path in paths:
@ -408,30 +419,27 @@ func projectPaths*(v: Value; paths: Paths): Option[Captures] =
 proc matches*(pat: Pattern; pr: Value): bool =
  let analysis = analyse(pat)
  assert analysis.constPaths.len == analysis.constValues.len
-  for i, path in analysis.constPaths:
-    let v = step(pr, path)
-    if v.isNone: return false
-    if analysis.constValues[i] != v.get: return false
-  for path in analysis.capturePaths:
-    if isNone step(pr, path): return false
-  true
+  result = checkPresence(pr, analysis.presentPaths)
+  if result:
+    for i, path in analysis.constPaths:
+      let v = step(pr, path)
+      if v.isNone: return false
+      if analysis.constValues[i] != v.get: return false
+    for path in analysis.capturePaths:
+      if step(pr, path).isNone: return false

-func capture*(pat: Pattern; pr: Value): seq[Value] =
+proc capture*(pat: Pattern; pr: Value): seq[Value] =
  let analysis = analyse(pat)
  assert analysis.constPaths.len == analysis.constValues.len
-  for i, path in analysis.constPaths:
-    let v = step(pr, path)
-    if v.isNone : return @[]
-    if analysis.constValues[i] != v.get: return @[]
-  for path in analysis.capturePaths:
-    let v = step(pr, path)
-    if v.isNone: return @[]
-    result.add(get v)
+  if checkPresence(pr, analysis.presentPaths):
+    for i, path in analysis.constPaths:
+      let v = step(pr, path)
+      if v.isNone : return @[]
+      if analysis.constValues[i] != v.get: return @[]
+    for path in analysis.capturePaths:
+      let v = step(pr, path)
+      if v.isNone: return @[]
+      result.add(get v)

 when isMainModule:
-  let txt = readAll stdin
-  if txt != "":
-    let
-      v = parsePreserves(txt)
-      pat = grab v
-    stdout.writeLine(pat)
+  stdout.writeLine stdin.readAll.parsePreserves.grab
--- a/src/syndicate/protocols/dataspacePatterns.nim
+++ b/src/syndicate/protocols/dataspacePatterns.nim
@ -29,58 +29,58 @@ type
        `embedded`* {.preservesEmbedded.}: EmbeddedRef

  
-  DLit* {.preservesRecord: "lit".} = object
-    `value`*: AnyAtom
-
-  DBind* {.preservesRecord: "bind".} = object
-    `pattern`*: Pattern
-
-  DDiscard* {.preservesRecord: "_".} = object
-  
-  DCompoundKind* {.pure.} = enum
+  GroupTypeKind* {.pure.} = enum
    `rec`, `arr`, `dict`
-  DCompoundRec* {.preservesRecord: "rec".} = object
+  GroupTypeRec* {.preservesRecord: "rec".} = object
    `label`*: Value
-    `fields`*: seq[Pattern]

-  DCompoundArr* {.preservesRecord: "arr".} = object
-    `items`*: seq[Pattern]
+  GroupTypeArr* {.preservesRecord: "arr".} = object
+  
+  GroupTypeDict* {.preservesRecord: "dict".} = object
+  
+  `GroupType`* {.preservesOr.} = object
+    case orKind*: GroupTypeKind
+    of GroupTypeKind.`rec`:
+        `rec`*: GroupTypeRec

-  DCompoundDict* {.preservesRecord: "dict".} = object
-    `entries`*: Table[Value, Pattern]
+    of GroupTypeKind.`arr`:
+        `arr`*: GroupTypeArr

-  `DCompound`* {.preservesOr.} = object
-    case orKind*: DCompoundKind
-    of DCompoundKind.`rec`:
-        `rec`* {.preservesEmbedded.}: DCompoundRec
-
-    of DCompoundKind.`arr`:
-        `arr`* {.preservesEmbedded.}: DCompoundArr
-
-    of DCompoundKind.`dict`:
-        `dict`* {.preservesEmbedded.}: DCompoundDict
+    of GroupTypeKind.`dict`:
+        `dict`*: GroupTypeDict

  
  PatternKind* {.pure.} = enum
-    `DDiscard`, `DBind`, `DLit`, `DCompound`
+    `discard`, `bind`, `lit`, `group`
+  PatternDiscard* {.preservesRecord: "_".} = object
+  
+  PatternBind* {.preservesRecord: "bind".} = object
+    `pattern`*: Pattern
+
+  PatternLit* {.preservesRecord: "lit".} = object
+    `value`*: AnyAtom
+
+  PatternGroup* {.preservesRecord: "group".} = object
+    `type`*: GroupType
+    `entries`*: Table[Value, Pattern]
+
  `Pattern`* {.acyclic, preservesOr.} = ref object
    case orKind*: PatternKind
-    of PatternKind.`DDiscard`:
-        `ddiscard`*: DDiscard
+    of PatternKind.`discard`:
+        `discard`*: PatternDiscard

-    of PatternKind.`DBind`:
-        `dbind`* {.preservesEmbedded.}: DBind
+    of PatternKind.`bind`:
+        `bind`* {.preservesEmbedded.}: PatternBind

-    of PatternKind.`DLit`:
-        `dlit`* {.preservesEmbedded.}: DLit
+    of PatternKind.`lit`:
+        `lit`* {.preservesEmbedded.}: PatternLit

-    of PatternKind.`DCompound`:
-        `dcompound`* {.preservesEmbedded.}: DCompound
+    of PatternKind.`group`:
+        `group`* {.preservesEmbedded.}: PatternGroup

  
-proc `$`*(x: AnyAtom | DLit | DBind | DDiscard | DCompound | Pattern): string =
+proc `$`*(x: AnyAtom | GroupType | Pattern): string =
  `$`(toPreserves(x))

-proc encode*(x: AnyAtom | DLit | DBind | DDiscard | DCompound | Pattern): seq[
-    byte] =
+proc encode*(x: AnyAtom | GroupType | Pattern): seq[byte] =
  encode(toPreserves(x))
--- a/src/syndicate/protocols/http.nim
+++ b/src/syndicate/protocols/http.nim
@ -47,7 +47,7 @@ type
  
  HttpRequest* {.preservesRecord: "http-request".} = object
    `sequenceNumber`*: BiggestInt
-    `host`*: string
+    `host`*: RequestHost
    `port`*: BiggestInt
    `method`*: Symbol
    `path`*: seq[string]
@ -115,6 +115,17 @@ type
    `req`*: HttpRequest
    `res`* {.preservesEmbedded.}: Value

+  RequestHostKind* {.pure.} = enum
+    `present`, `absent`
+  `RequestHost`* {.preservesOr.} = object
+    case orKind*: RequestHostKind
+    of RequestHostKind.`present`:
+        `present`*: string
+
+    of RequestHostKind.`absent`:
+        `absent`* {.preservesLiteral: "#f".}: bool
+
+  
  PathPatternElementKind* {.pure.} = enum
    `label`, `wildcard`, `rest`
  `PathPatternElement`* {.preservesOr.} = object
@ -149,6 +160,7 @@ proc `$`*(x: HostPattern | HttpListener | MethodPattern | MimeType | QueryValue
    HttpService |
    HttpBinding |
    HttpContext |
+    RequestHost |
    PathPatternElement |
    Chunk |
    PathPattern): string =
@ -163,6 +175,7 @@ proc encode*(x: HostPattern | HttpListener | MethodPattern | MimeType |
    HttpService |
    HttpBinding |
    HttpContext |
+    RequestHost |
    PathPatternElement |
    Chunk |
    PathPattern): seq[byte] =
--- a/src/syndicate/protocols/noise.nim
+++ b/src/syndicate/protocols/noise.nim
@ -48,6 +48,17 @@ type
        `absent`*: SecretKeyFieldAbsent

  
+  SessionItemKind* {.pure.} = enum
+    `Initiator`, `Packet`
+  `SessionItem`* {.preservesOr.} = object
+    case orKind*: SessionItemKind
+    of SessionItemKind.`Initiator`:
+        `initiator`* {.preservesEmbedded.}: Initiator
+
+    of SessionItemKind.`Packet`:
+        `packet`*: Packet
+
+  
  NoiseProtocolKind* {.pure.} = enum
    `present`, `invalid`, `absent`
  NoiseProtocolPresent* {.preservesDictionary.} = object
@ -83,6 +94,9 @@ type
    `service`*: ServiceSelector

  ServiceSelector* = Value
+  Initiator* {.preservesRecord: "initiator".} = object
+    `initiatorSession`* {.preservesEmbedded.}: EmbeddedRef
+
  NoiseStepDetail* = ServiceSelector
  NoiseSpecKey* = seq[byte]
  NoiseSpecPreSharedKeys* = Option[Value]
@ -105,17 +119,21 @@ type

  
 proc `$`*(x: NoiseDescriptionDetail | NoisePreSharedKeys | SecretKeyField |
+    SessionItem |
    NoiseProtocol |
    NoisePathStepDetail |
    NoiseServiceSpec |
+    Initiator |
    NoiseSpec |
    Packet): string =
  `$`(toPreserves(x))

 proc encode*(x: NoiseDescriptionDetail | NoisePreSharedKeys | SecretKeyField |
+    SessionItem |
    NoiseProtocol |
    NoisePathStepDetail |
    NoiseServiceSpec |
+    Initiator |
    NoiseSpec |
    Packet): seq[byte] =
  encode(toPreserves(x))
--- a/src/syndicate/relays.nim
+++ b/src/syndicate/relays.nim
@ -29,8 +29,8 @@ type
  Turn = syndicate.Turn
  WireRef = sturdy.WireRef

-  PacketWriter = proc (turn: var Turn; buf: seq[byte]) {.closure.}
-  RelaySetup = proc (turn: var Turn; relay: Relay) {.closure.}
+  PacketWriter = proc (turn: Turn; buf: seq[byte]) {.closure.}
+  RelaySetup = proc (turn: Turn; relay: Relay) {.closure.}

  Relay* = ref object
    facet: Facet
@ -59,20 +59,20 @@ type
 proc releaseCapOut(r: Relay; e: WireSymbol) =
  r.exported.drop e

-method publish(spe: SyncPeerEntity; t: var Turn; a: AssertionRef; h: Handle) =
+method publish(spe: SyncPeerEntity; t: Turn; a: AssertionRef; h: Handle) =
  spe.handleMap[h] = publish(t, spe.peer, a.value)

-method retract(se: SyncPeerEntity; t: var Turn; h: Handle) =
+method retract(se: SyncPeerEntity; t: Turn; h: Handle) =
  var other: Handle
  if se.handleMap.pop(h, other):
    retract(t, other)

-method message(se: SyncPeerEntity; t: var Turn; a: AssertionRef) =
+method message(se: SyncPeerEntity; t: Turn; a: AssertionRef) =
  if not se.e.isNil:
    se.relay.releaseCapOut(se.e)
  message(t, se.peer, a.value)

-method sync(se: SyncPeerEntity; t: var Turn; peer: Cap) =
+method sync(se: SyncPeerEntity; t: Turn; peer: Cap) =
  sync(t, se.peer, peer)

 proc newSyncPeerEntity(r: Relay; p: Cap): SyncPeerEntity =
@ -109,10 +109,10 @@ proc deregister(relay: Relay; h: Handle) =
  if relay.outboundAssertions.pop(h, outbound):
    for e in outbound: releaseCapOut(relay, e)

-proc send(relay: Relay; turn: var Turn; rOid: protocol.Oid; m: Event) =
+proc send(relay: Relay; turn: Turn; rOid: protocol.Oid; m: Event) =
  # TODO: don't send right away.
  relay.pendingTurn.add TurnEvent(oid: rOid, event: m)
-  queueEffect(turn, relay.facet) do (turn: var Turn):
+  queueEffect(turn, relay.facet) do (turn: Turn):
    if relay.pendingTurn.len > 0:
      var pkt = Packet(
        orKind: PacketKind.Turn,
@ -120,29 +120,29 @@ proc send(relay: Relay; turn: var Turn; rOid: protocol.Oid; m: Event) =
      trace "C: ", pkt
      relay.packetWriter(turn, encode pkt)

-proc send(re: RelayEntity; turn: var Turn; ev: Event) =
+proc send(re: RelayEntity; turn: Turn; ev: Event) =
  send(re.relay, turn, protocol.Oid re.oid, ev)

-method publish(re: RelayEntity; t: var Turn; a: AssertionRef; h: Handle) =
+method publish(re: RelayEntity; t: Turn; a: AssertionRef; h: Handle) =
  re.send(t, Event(
      orKind: EventKind.Assert,
      `assert`: protocol.Assert(
        assertion: re.relay.register(a.value, h).rewritten,
        handle: h)))

-method retract(re: RelayEntity; t: var Turn; h: Handle) =
+method retract(re: RelayEntity; t: Turn; h: Handle) =
  re.relay.deregister h
  re.send(t, Event(
    orKind: EventKind.Retract,
    retract: Retract(handle: h)))

-method message(re: RelayEntity; turn: var Turn; msg: AssertionRef) =
+method message(re: RelayEntity; turn: Turn; msg: AssertionRef) =
  var (value, exported) = rewriteOut(re.relay, msg.value)
  assert(len(exported) == 0, "cannot send a reference in a message")
  if len(exported) == 0:
    re.send(turn, Event(orKind: EventKind.Message, message: Message(body: value)))

-method sync(re: RelayEntity; turn: var Turn; peer: Cap) =
+method sync(re: RelayEntity; turn: Turn; peer: Cap) =
  var
    peerEntity = newSyncPeerEntity(re.relay, peer)
    exported: seq[WireSymbol]
@ -195,7 +195,7 @@ proc rewriteIn(relay; facet; v: Value):

 proc close(r: Relay) = discard

-proc dispatch(relay: Relay; turn: var Turn; cap: Cap; event: Event) =
+proc dispatch(relay: Relay; turn: Turn; cap: Cap; event: Event) =
  case event.orKind
  of EventKind.Assert:
    let (a, imported) = rewriteIn(relay, turn.facet, event.assert.assertion)
@ -214,7 +214,7 @@ proc dispatch(relay: Relay; turn: var Turn; cap: Cap; event: Event) =
    turn.message(cap, a)

  of EventKind.Sync:
-    turn.sync(cap) do (turn: var Turn):
+    turn.sync(cap) do (turn: Turn):
      var
        (v, imported) = rewriteIn(relay, turn.facet, event.sync.peer)
        peer = unembed(v, Cap)
@ -224,7 +224,7 @@ proc dispatch(relay: Relay; turn: var Turn; cap: Cap; event: Event) =

 proc dispatch(relay: Relay; v: Value) =
  trace "S: ", v
-  run(relay.facet) do (t: var Turn):
+  run(relay.facet) do (t: Turn):
    var pkt: Packet
    if pkt.fromPreserves(v):
      case pkt.orKind
@ -251,7 +251,7 @@ proc recv(relay: Relay; buf: openarray[byte]; slice: Slice[int]) =
  var pr = decode(relay.wireBuf)
  if pr.isSome: dispatch(relay, pr.get)

-proc recv(relay: Relay; buf: openarray[byte]) =
+proc recv(relay: Relay; buf: openarray[byte]) {.used.} =
  feed(relay.wireBuf, buf)
  var pr = decode(relay.wireBuf)
  if pr.isSome: dispatch(relay, pr.get)
@ -265,8 +265,8 @@ type
    initialCap*: Cap
    nextLocalOid*: Option[Oid]

-proc spawnRelay(name: string; turn: var Turn; opts: RelayActorOptions; setup: RelaySetup) =
-  linkActor(turn, name) do (turn: var Turn):
+proc spawnRelay(name: string; turn: Turn; opts: RelayActorOptions; setup: RelaySetup) =
+  linkActor(turn, name) do (turn: Turn):
    turn.preventInertCheck()
    let relay = Relay(
        facet: turn.facet,
@ -300,7 +300,7 @@ proc accepted(cap: Cap): Resolved =
  result.accepted.responderSession = cap

 type ShutdownEntity = ref object of Entity
-method retract(e: ShutdownEntity; turn: var Turn; h: Handle) =
+method retract(e: ShutdownEntity; turn: Turn; h: Handle) =
  stopActor(e.facet)

 when defined(posix):
@ -314,7 +314,7 @@ when defined(posix):
    stdin: AsyncFile
    alive: bool

-  method message(entity: StdioEntity; turn: var Turn; ass: AssertionRef) =
+  method message(entity: StdioEntity; turn: Turn; ass: AssertionRef) =
    if ass.value.preservesTo(ForceDisconnect).isSome:
      entity.alive = false

@ -324,15 +324,17 @@ when defined(posix):
    while entity.alive:
      buf[].setLen(0x1000)
      let n = read(entity.stdin, buf)
-      if n == 0:
-        stopActor(entity.facet)
-      else:
+      if n > 0:
        entity.relay.recv(buf[], 0..<n)
+      else:
+        entity.alive = false
+        if n < 0: raiseOSError(osLastError())
+    stopActor(entity.facet)

-  proc connectTransport(turn: var Turn; ds: Cap; ta: transportAddress.Stdio) =
+  proc connectTransport(turn: Turn; ds: Cap; ta: transportAddress.Stdio) =
    ## Connect to an external dataspace over stdio.
    let localDataspace = newDataspace(turn)
-    proc stdoutWriter(turn: var Turn; buf: seq[byte]) =
+    proc stdoutWriter(turn: Turn; buf: seq[byte]) =
      ## Blocking write to stdout.
      let n = writeBytes(stdout, buf, 0, buf.len)
      flushFile(stdout)
@ -343,7 +345,7 @@ when defined(posix):
        initialCap: localDataspace,
        initialOid: 0.Oid.some,
      )
-    spawnRelay("stdio", turn, opts) do (turn: var Turn; relay: Relay):
+    spawnRelay("stdio", turn, opts) do (turn: Turn; relay: Relay):
      let
        facet = turn.facet
        fd = stdin.getOsFileHandle()
@ -353,7 +355,7 @@ when defined(posix):
        raiseOSError(osLastError())
      let entity = StdioEntity(
          facet: turn.facet, relay: relay, stdin: newAsyncFile(FD fd))
-      onStop(entity.facet) do (turn: var Turn):
+      onStop(entity.facet) do (turn: Turn):
        entity.alive = false
        close(entity.stdin)
          # Close stdin to remove it from the ioqueue
@ -365,7 +367,7 @@ when defined(posix):
          resolved: localDataspace.accepted,
        ))

-  proc connectStdio*(turn: var Turn; ds: Cap) =
+  proc connectStdio*(turn: Turn; ds: Cap) =
    ## Connect to an external dataspace over stdin and stdout.
    connectTransport(turn, ds, transportAddress.Stdio())

@ -382,33 +384,35 @@ when defined(posix):

    SocketEntity = TcpEntity | UnixEntity

-  method message(entity: SocketEntity; turn: var Turn; ass: AssertionRef) =
+  method message(entity: SocketEntity; turn: Turn; ass: AssertionRef) =
    if ass.value.preservesTo(ForceDisconnect).isSome:
      entity.alive = false

  template bootSocketEntity() {.dirty.} =
-    proc setup(turn: var Turn) {.closure.} =
-      proc kill(turn: var Turn) =
+    proc setup(turn: Turn) {.closure.} =
+      proc kill(turn: Turn) =
        if entity.alive:
          entity.alive = false
          close(entity.sock)
      onStop(turn, kill)
-      publish(turn, ds, TransportConnection(
+      var ass = TransportConnection(
          `addr`: ta.toPreserves,
          control: newCap(entity, turn),
          resolved: entity.relay.peer.accepted,
-        ))
+        )
+      publish(turn, ds, ass)
    run(entity.relay.facet, setup)
    let buf = new seq[byte]
    entity.alive = true
    while entity.alive:
      buf[].setLen(0x1000)
      let n = read(entity.sock, buf)
-      if n < 0: raiseOSError(osLastError())
-      elif n == 0:
-        stopActor(entity.facet)
-      else:
+      if n > 0:
        entity.relay.recv(buf[], 0..<n)
+      else:
+        entity.alive = false
+        if n < 0: raiseOSError(osLastError())
+    stopActor(entity.facet)
    # the socket closes when the actor is stopped

  proc boot(entity: TcpEntity; ta: transportAddress.Tcp; ds: Cap) {.asyncio.} =
@ -420,24 +424,25 @@ when defined(posix):
    bootSocketEntity()

  template spawnSocketRelay() {.dirty.} =
-    proc writeConn(turn: var Turn; buf: seq[byte]) =
-      discard trampoline:
-        whelp write(entity.sock, buf)
+    proc writeConn(turn: Turn; buf: seq[byte]) =
+      if entity.alive:
+        discard trampoline:
+          whelp write(entity.sock, buf)
    var ops = RelayActorOptions(
        packetWriter: writeConn,
        initialOid: 0.Oid.some,
      )
-    spawnRelay("socket", turn, ops) do (turn: var Turn; relay: Relay):
+    spawnRelay("socket", turn, ops) do (turn: Turn; relay: Relay):
      entity.facet = turn.facet
      entity.relay = relay
      discard trampoline:
        whelp boot(entity, ta, ds)

-  proc connectTransport(turn: var Turn; ds: Cap; ta: transportAddress.Tcp) =
+  proc connectTransport(turn: Turn; ds: Cap; ta: transportAddress.Tcp) =
    let entity =  TcpEntity()
    spawnSocketRelay()

-  proc connectTransport(turn: var Turn; ds: Cap; ta: transportAddress.Unix) =
+  proc connectTransport(turn: Turn; ds: Cap; ta: transportAddress.Unix) =
    let entity =  UnixEntity()
    spawnSocketRelay()

@ -452,14 +457,14 @@ elif defined(solo5):
      conn: Connection
      decoder: BufferedDecoder

-  method message(entity: TcpEntity; turn: var Turn; ass: AssertionRef) =
+  method message(entity: TcpEntity; turn: Turn; ass: AssertionRef) =
    if ass.value.preservesTo(ForceDisconnect).isSome:
      entity.conn.abort()

-  proc connectTransport(turn: var Turn; ds: Cap; ta: transportAddress.Tcp) =
+  proc connectTransport(turn: Turn; ds: Cap; ta: transportAddress.Tcp) =
    let entity =  TcpEntity(facet: turn.facet)

-    proc writeConn(turn: var Turn; buf: seq[byte]) =
+    proc writeConn(turn: Turn; buf: seq[byte]) =
      assert not entity.conn.isNil
      entity.conn.batch:
        entity.conn.send(buf)
@ -467,7 +472,7 @@ elif defined(solo5):
        packetWriter: writeConn,
        initialOid: 0.Oid.some,
      )
-    spawnRelay("socket", turn, ops) do (turn: var Turn; relay: Relay):
+    spawnRelay("socket", turn, ops) do (turn: Turn; relay: Relay):
      entity.facet = turn.facet
      entity.relay = relay

@ -486,10 +491,10 @@ elif defined(solo5):
      var preconn = newPreconnection(
        remote=[ep], transport=tp.some)
      entity.conn = preconn.initiate()
-      entity.facet.onStop do (turn: var Turn):
+      entity.facet.onStop do (turn: Turn):
        entity.conn.close()
      entity.conn.onConnectionError do (err: ref Exception):
-        run(entity.facet) do (turn: var Turn):
+        run(entity.facet) do (turn: Turn):
          terminate(turn, err)
      entity.conn.onClosed():
        stop(entity.facet)
@ -500,7 +505,7 @@ elif defined(solo5):
        else:
          entity.conn.receive()
      entity.conn.onReady do ():
-        entity.facet.run do (turn: var Turn):
+        entity.facet.run do (turn: Turn):
          publish(turn, ds, TransportConnection(
              `addr`: ta.toPreserves,
              control: newCap(entity, turn),
@ -508,7 +513,7 @@ elif defined(solo5):
            ))
          entity.conn.receive()

-proc walk(turn: var Turn; ds, origin: Cap; route: Route; transOff, stepOff: int) =
+proc walk(turn: Turn; ds, origin: Cap; route: Route; transOff, stepOff: int) =
  if stepOff < route.pathSteps.len:
    let
      step = route.pathSteps[stepOff]
@ -531,7 +536,7 @@ proc walk(turn: var Turn; ds, origin: Cap; route: Route; transOff, stepOff: int)
        resolved: origin.accepted,
      ))

-proc connectRoute(turn: var Turn; ds: Cap; route: Route; transOff: int) =
+proc connectRoute(turn: Turn; ds: Cap; route: Route; transOff: int) =
  let rejectPat = TransportConnection ?: {
      0: ?route.transports[transOff],
      2: ?:Rejected,
@ -547,33 +552,32 @@ proc connectRoute(turn: var Turn; ds: Cap; route: Route; transOff: int) =
      2: ?:ResolvedAccepted,
    }
  onPublish(turn, ds, acceptPat) do (origin: Cap):
-    walk(turn, ds, origin, route, transOff, 0)
+    origin.relay.run do (turn: Turn):
+      # walk using the facet that manages the transport connection
+      walk(turn, ds, origin, route, transOff, 0)

-type StepCallback = proc (turn: var Turn; step: Value; origin, next: Cap) {.closure.}
+type StepCallback = proc (turn: Turn; step: Value; origin: Cap; res: Resolved) {.closure.}

-proc spawnStepResolver(turn: var Turn; ds: Cap; stepType: Value; cb: StepCallback) =
-  let stepPat = grabRecord(stepType, grab())
-  let pat = ?Observe(pattern: ResolvedPathStep?:{1: stepPat}) ?? {0: grabLit(), 1: grab()}
+proc spawnStepResolver(turn: Turn; ds: Cap; stepType: Value; cb: StepCallback) =
+  let pat = observePattern(
+      ResolvedPathStep?:{1: grabRecord(stepType)},
+      { @[0.toPreserve]: grabLit(), @[1.toPreserve]: grab() },
+    )
  during(turn, ds, pat) do (origin: Cap; stepDetail: Literal[Value]):
-    let step = toRecord(stepType, stepDetail.value)
-    proc duringCallback(turn: var Turn; ass: Value; h: Handle): TurnAction =
-      var res = ass.preservesTo Resolved
-      if res.isSome:
-        if res.get.orKind == ResolvedKind.accepted and
-            res.get.accepted.responderSession of Cap:
-          cb(turn, step, origin, res.get.accepted.responderSession.Cap)
-      else:
-        publish(turn, ds, ResolvedPathStep(
-            origin: origin, pathStep: step, resolved: res.get))
-      proc action(turn: var Turn) =
+    proc duringCallback(turn: Turn; ass: Value; h: Handle): TurnAction =
+      var res: Resolved
+      if res.fromPreserves ass:
+        cb(turn, stepDetail.value, origin, res)
+      proc action(turn: Turn) =
        stop(turn)
      result = action
    publish(turn, origin, Resolve(
-        step: step, observer: newCap(turn, during(duringCallback))))
+        step: stepDetail.value, observer: newCap(turn, during(duringCallback))))

-proc spawnRelays*(turn: var Turn; ds: Cap) =
-  ## Spawn actors that manage routes and appeasing gatekeepers.
-  let transPat = ?Observe(pattern: !TransportConnection) ?? { 0: grab() }
+proc spawnRelays*(turn: Turn; ds: Cap) =
+  ## Spawn actors that manage routes and appease gatekeepers.
+
+  let transPat = observePattern(!TransportConnection, { @[0.toPreserves]: grab() })
    # Use a generic pattern and type matching
    # in the during handler because it is easy.

@ -600,20 +604,21 @@ proc spawnRelays*(turn: var Turn; ds: Cap) =
          resolved: rejected(embed e),
        ))

-  let resolvePat = ?Observe(pattern: !ResolvePath) ?? {0: grab()}
+  let resolvePat = observePattern(!ResolvePath, {@[0.toPreserves]: grab()})
  during(turn, ds, resolvePat) do (route: Literal[Route]):
    for i, transAddr in route.value.transports:
      connectRoute(turn, ds, route.value, i)

  spawnStepResolver(turn, ds, "ref".toSymbol) do (
-      turn: var Turn, step: Value, origin: Cap, next: Cap):
+      turn: Turn, step: Value, origin: Cap, res: Resolved):
    publish(turn, ds, ResolvedPathStep(
-        origin: origin, pathStep: step, resolved: next.accepted))
+        origin: origin, pathStep: step, resolved: res))

-type BootProc* = proc (turn: var Turn; ds: Cap) {.closure.}
+type BootProc* = proc (turn: Turn; ds: Cap) {.closure.}

-proc resolve*(turn: var Turn; ds: Cap; route: Route; bootProc: BootProc) =
+proc resolve*(turn: Turn; ds: Cap; route: Route; bootProc: BootProc) =
  ## Resolve `route` within `ds` and call `bootProc` with resolved capabilities.
+  let pat = ResolvePath ?: {0: ?route, 3: ?:ResolvedAccepted}
  during(turn, ds, ResolvePath ?: {0: ?route, 3: ?:ResolvedAccepted}) do (dst: Cap):
    bootProc(turn, dst)

@ -635,7 +640,7 @@ when defined(posix):
      if not result.fromPreserves(pr):
        raise newException(ValueError, "failed to parse $SYNDICATE_ROUTE " & $pr)

-  proc resolveEnvironment*(turn: var Turn; bootProc: BootProc) =
+  proc resolveEnvironment*(turn: Turn; bootProc: BootProc) =
    ## Resolve a capability from the calling environment
    ## and call `bootProc`. See envRoute_.
    var resolved = false
--- a/src/syndicate/skeletons.nim
+++ b/src/syndicate/skeletons.nim
@ -9,32 +9,28 @@ import ./actors, ./bags, ./patterns
 import ./protocols/dataspacePatterns

 type
-  DCompound = dataspacePatterns.DCompound
  Pattern = dataspacePatterns.Pattern
  Path = seq[Value]
  ClassKind = enum classNone, classRecord, classSequence, classDictionary
  Class = object
    kind: ClassKind
    label: Value
-    arity: int

 func classOf(v: Value): Class =
  case v.kind
-  of pkRecord: Class(kind: classRecord, label: v.label, arity: v.arity)
-  of pkSequence: Class(kind: classSequence, arity: v.len)
+  of pkRecord: Class(kind: classRecord, label: v.label)
+  of pkSequence: Class(kind: classSequence)
  of pkDictionary: Class(kind: classDictionary)
  else: Class(kind: classNone)

 proc classOf(p: Pattern): Class =
-  if p.orKind == PatternKind.DCompound:
-    case p.dcompound.orKind
-    of DCompoundKind.rec:
-      Class(kind: classRecord,
-        label: p.dcompound.rec.label,
-        arity: p.dcompound.rec.fields.len)
-    of DCompoundKind.arr:
-      Class(kind: classSequence, arity: p.dcompound.arr.items.len)
-    of DCompoundKind.dict:
+  if p.orKind == PatternKind.group:
+    case p.group.type.orKind
+    of GroupTypeKind.rec:
+      Class(kind: classRecord, label: p.group.`type`.rec.label)
+    of GroupTypeKind.arr:
+      Class(kind: classSequence)
+    of GroupTypeKind.dict:
      Class(kind: classDictionary)
  else:
    Class(kind: classNone)
@ -67,15 +63,16 @@ func isEmpty(cont: Continuation): bool =
 type
  ContinuationProc = proc (c: Continuation; v: Value) {.closure.}
  LeafProc = proc (l: Leaf; v: Value) {.closure.}
-  ObserverProc = proc (turn: var Turn; group: ObserverGroup; vs: seq[Value]) {.closure.}
+  ObserverProc = proc (turn: Turn; group: ObserverGroup; vs: seq[Value]) {.closure.}

-proc getLeaves(cont: Continuation; constPaths: Paths): LeafMap =
+proc getLeaves(cont: Continuation; presentPaths, constPaths: Paths): LeafMap =
  result = cont.leafMap.getOrDefault(constPaths)
  if result.isNil:
    new result
    cont.leafMap[constPaths] = result
    assert not cont.isEmpty
    for ass in cont.cache:
+      # TODO: check presence
      let key = projectPaths(ass, constPaths)
      if key.isSome:
        var leaf = result.getOrDefault(get key)
@ -114,10 +111,10 @@ proc top(stack: TermStack): Value =
  assert stack.len > 0
  stack[stack.high]

-proc modify(node: Node; turn: var Turn; outerValue: Value; event: EventKind;
+proc modify(node: Node; turn: Turn; outerValue: Value; event: EventKind;
    modCont: ContinuationProc; modLeaf: LeafProc; modObs: ObserverProc) =

-  proc walk(cont: Continuation; turn: var Turn) =
+  proc walk(cont: Continuation; turn: Turn) =
    modCont(cont, outerValue)
    for constPaths, constValMap in cont.leafMap.pairs:
      let constVals = projectPaths(outerValue, constPaths)
@ -142,7 +139,7 @@ proc modify(node: Node; turn: var Turn; outerValue: Value; event: EventKind;
              constValMap.del(get constVals)


-  proc walk(node: Node; turn: var Turn; termStack: TermStack) =
+  proc walk(node: Node; turn: Turn; termStack: TermStack) =
    walk(node.continuation, turn)
    for selector, table in node.edges:
      let
@ -165,25 +162,13 @@ proc getOrNew[A, B, C](t: var Table[A, TableRef[B, C]], k: A): TableRef[B, C] =
    result = newTable[B, C]()
    t[k] = result

-iterator pairs(dc: DCompound): (Value, Pattern) =
-  case dc.orKind
-  of DCompoundKind.rec:
-    for i, p in dc.rec.fields:
-      yield (i.toPreserves, p,)
-  of DCompoundKind.arr:
-    for i, p in dc.arr.items:
-      yield (i.toPreserves, p,)
-  of DCompoundKind.dict:
-    for pair in dc.dict.entries.pairs:
-      yield pair
-
 proc extendWalk(node: Node; popCount: Natural; stepIndex: Value; pat: Pattern; path: var Path): tuple[popCount: Natural, nextNode: Node] =
  case pat.orKind
-  of PatternKind.DDiscard, PatternKind.DLit:
+  of PatternKind.`discard`, PatternKind.lit:
    result = (popCount, node)
-  of PatternKind.DBind:
-    result = extendWalk(node, popCount, stepIndex, pat.dbind.pattern, path)
-  of PatternKind.DCompound:
+  of PatternKind.`bind`:
+    result = extendWalk(node, popCount, stepIndex, pat.`bind`.pattern, path)
+  of PatternKind.`group`:
    let
      selector: Selector = (popCount, stepIndex,)
      table = node.edges.getOrNew(selector)
@ -198,7 +183,7 @@ proc extendWalk(node: Node; popCount: Natural; stepIndex: Value; pat: Pattern; p
        if v.isSome and class == classOf(get v):
          result.nextNode.continuation.cache.incl a
    result.popCount = 0
-    for step, p in pat.dcompound.pairs:
+    for step, p in pat.group.entries:
      add(path, step)
      result = extendWalk(result.nextNode, result.popCount, step, p, path)
      discard pop(path)
@ -227,11 +212,11 @@ proc getEndpoints(leaf: Leaf; capturePaths: Paths): ObserverGroup =
      if captures.isSome:
        discard result.cachedCaptures.change(get captures, +1)

-proc add*(index: var Index; turn: var Turn; pattern: Pattern; observer: Cap) =
+proc add*(index: var Index; turn: Turn; pattern: Pattern; observer: Cap) =
  let
    cont = index.root.extend(pattern)
    analysis = analyse pattern
-    constValMap = cont.getLeaves(analysis.constPaths)
+    constValMap = cont.getLeaves(analysis.presentPaths, analysis.constPaths)
    leaf = constValMap.getLeaf(analysis.constValues)
    endpoints = leaf.getEndpoints(analysis.capturePaths)
  # TODO if endpoints.cachedCaptures.len > 0:
@ -240,7 +225,7 @@ proc add*(index: var Index; turn: var Turn; pattern: Pattern; observer: Cap) =
    captureMap[capture] = publish(turn, observer, capture)
  endpoints.observers[observer] = captureMap

-proc remove*(index: var Index; turn: var Turn; pattern: Pattern; observer: Cap) =
+proc remove*(index: var Index; turn: Turn; pattern: Pattern; observer: Cap) =
  let
    cont = index.root.extend(pattern)
    analysis = analyse pattern
@ -260,7 +245,7 @@ proc remove*(index: var Index; turn: var Turn; pattern: Pattern; observer: Cap)
    if constValMap.len == 0:
      cont.leafMap.del(analysis.constPaths)

-proc adjustAssertion(index: var Index; turn: var Turn; outerValue: Value; delta: int): bool =
+proc adjustAssertion(index: var Index; turn: Turn; outerValue: Value; delta: int): bool =
  case index.allAssertions.change(outerValue, delta)
  of cdAbsentToPresent:
    result = true
@ -268,7 +253,7 @@ proc adjustAssertion(index: var Index; turn: var Turn; outerValue: Value; delta:
      c.cache.incl(v)
    proc modLeaf(l: Leaf; v: Value) =
      l.cache.incl(v)
-    proc modObserver(turn: var Turn; group: ObserverGroup; vs: seq[Value]) =
+    proc modObserver(turn: Turn; group: ObserverGroup; vs: seq[Value]) =
      let change = group.cachedCaptures.change(vs, +1)
      if change == cdAbsentToPresent:
        for (observer, captureMap) in group.observers.pairs:
@ -281,7 +266,7 @@ proc adjustAssertion(index: var Index; turn: var Turn; outerValue: Value; delta:
      c.cache.excl(v)
    proc modLeaf(l: Leaf; v: Value) =
      l.cache.excl(v)
-    proc modObserver(turn: var Turn; group: ObserverGroup; vs: seq[Value]) =
+    proc modObserver(turn: Turn; group: ObserverGroup; vs: seq[Value]) =
      if group.cachedCaptures.change(vs, -1) == cdPresentToAbsent:
        for (observer, captureMap) in group.observers.pairs:
          var h: Handle
@ -293,12 +278,12 @@ proc adjustAssertion(index: var Index; turn: var Turn; outerValue: Value; delta:
 proc continuationNoop(c: Continuation; v: Value) = discard
 proc leafNoop(l: Leaf; v: Value) = discard

-proc add*(index: var Index; turn: var Turn; v: Value): bool =
+proc add*(index: var Index; turn: Turn; v: Value): bool =
  adjustAssertion(index, turn, v, +1)
-proc remove*(index: var Index; turn: var Turn; v: Value): bool =
+proc remove*(index: var Index; turn: Turn; v: Value): bool =
  adjustAssertion(index, turn, v, -1)

-proc deliverMessage*(index: var Index; turn: var Turn; v: Value) =
-  proc observersCb(turn: var Turn; group: ObserverGroup; vs: seq[Value]) =
+proc deliverMessage*(index: var Index; turn: Turn; v: Value) =
+  proc observersCb(turn: Turn; group: ObserverGroup; vs: seq[Value]) =
    for observer in group.observers.keys: message(turn, observer, vs)
  index.root.modify(turn, v, messageEvent, continuationNoop, leafNoop, observersCb)
--- a/syndicate.nimble
+++ b/syndicate.nimble
@ -1,6 +1,6 @@
 # Package

-version = "20240405"
+version = "20240507"
 author        = "Emery Hemingway"
 description   = "Syndicated actors for conversational concurrency"
 license       = "Unlicense"
@ -9,4 +9,4 @@ srcDir        = "src"

 # Dependencies

-requires "https://github.com/ehmry/hashlib.git >= 20231130", "nim >= 2.0.0", "https://git.syndicate-lang.org/ehmry/preserves-nim.git >= 20240312", "https://github.com/ehmry/nim-sys.git#4ef3b624db86e331ba334e705c1aa235d55b05e1", "https://git.sr.ht/~ehmry/nim_taps >= 20240405"
+requires "https://github.com/ehmry/hashlib.git >= 20231130", "nim >= 2.0.0", "https://git.syndicate-lang.org/ehmry/preserves-nim.git >= 20240422", "https://github.com/ehmry/nim-sys.git#4ef3b624db86e331ba334e705c1aa235d55b05e1", "https://git.sr.ht/~ehmry/nim_taps >= 20240405"
--- a/tests/solo5_relays_test.nim
+++ b/tests/solo5_relays_test.nim
@ -11,17 +11,17 @@ acquireDevices([("relay", netBasic)], netAcquireHook)
 type Netif {.preservesRecord: "netif"} = object
  device, ipAddr: string

-proc spawnNetifActor(turn: var Turn; ds: Cap) =
-  spawnActor(turn, "netif") do (turn: var Turn):
+proc spawnNetifActor(turn: Turn; ds: Cap) =
+  spawnActor(turn, "netif") do (turn: Turn):
    let facet = turn.facet
    onInterfaceUp do (device: string; ip: IpAddress):
-      run(facet) do (turn: var Turn):
+      run(facet) do (turn: Turn):
        if not ip.isLinkLocal:
          discard publish(turn, ds, Netif(device: device, ipAddr: $ip))

-runActor("relay-test") do (turn: var Turn):
+runActor("relay-test") do (turn: Turn):
  let root = turn.facet
-  onStop(turn) do (turn: var Turn):
+  onStop(turn) do (turn: Turn):
    quit()
  let ds = newDataspace(turn)
  spawnNetifActor(turn, ds)
@ -33,7 +33,7 @@ runActor("relay-test") do (turn: var Turn):
    echo "parsed route ", route.toPreserves
    during(turn, ds, Netif?:{1: grab()}) do (ip: string):
      echo "Acquired address ", ip
-      resolve(turn, ds, route) do (turn: var Turn; ds: Cap):
+      resolve(turn, ds, route) do (turn: Turn; ds: Cap):
        echo "route resolved!"
        echo "stopping root facet"
        stop(turn, root)
--- a/tests/solo5_test.nim
+++ b/tests/solo5_test.nim
@ -7,19 +7,19 @@ import syndicate, syndicate/drivers/timers

 acquireDevices()

-runActor("timer-test") do (turn: var Turn):
+runActor("timer-test") do (turn: Turn):
  let timers = newDataspace(turn)
  spawnTimerDriver(turn, timers)

  onPublish(turn, timers, ?LaterThan(seconds: 1356100000)):
    echo "now in 13th bʼakʼtun"

-  after(turn, timers, initDuration(seconds = 3)) do (turn: var Turn):
+  after(turn, timers, initDuration(seconds = 3)) do (turn: Turn):
    echo "third timer expired"
    stopActor(turn)

-  after(turn, timers, initDuration(seconds = 1)) do (turn: var Turn):
+  after(turn, timers, initDuration(seconds = 1)) do (turn: Turn):
    echo "first timer expired"

-  after(turn, timers, initDuration(seconds = 2)) do (turn: var Turn):
+  after(turn, timers, initDuration(seconds = 2)) do (turn: Turn):
    echo "second timer expired"
--- a/tests/test_chat.nim
+++ b/tests/test_chat.nim
@ -14,7 +14,7 @@ type
 proc syncAndStop(facet: Facet; cap: Cap) =
  ## Stop the actor responsible for `facet` after
  ## synchronizing with `cap`.
-  run(facet) do (turn: var Turn):
+  run(facet) do (turn: Turn):
    sync(turn, cap, stopActor)

 proc readStdin(facet: Facet; ds: Cap; username: string) {.asyncio.} =
@ -37,11 +37,11 @@ proc readStdin(facet: Facet; ds: Cap; username: string) {.asyncio.} =
      return
    else:
      var msg = buf[][0..<n].strip
-      proc send(turn: var Turn) =
+      proc send(turn: Turn) =
        message(turn, ds, Says(who: username, what: msg))
      run(facet, send)

-proc chat(turn: var Turn; ds: Cap; username: string) =
+proc chat(turn: Turn; ds: Cap; username: string) =
  during(turn, ds, ?:Present) do (who: string):
    echo who, " joined"
  do:
@ -67,8 +67,8 @@ proc main =
  if username == "":
      stderr.writeLine "--user: unspecified"
  else:
-    runActor("chat") do (turn: var Turn):
-      resolveEnvironment(turn) do (turn: var Turn; ds: Cap):
+    runActor("chat") do (turn: Turn):
+      resolveEnvironment(turn) do (turn: Turn; ds: Cap):
        chat(turn, ds, username)

 main()
--- a/tests/test_patterns.nim
+++ b/tests/test_patterns.nim
@ -1,103 +1,87 @@
 # SPDX-FileCopyrightText: ☭ Emery Hemingway
 # SPDX-License-Identifier: Unlicense

-import std/[options, tables, unittest]
+import std/[options, sequtils, tables, unittest]

-import preserves, syndicate, syndicate/protocols/gatekeeper
+import preserves, syndicate, syndicate/protocols/[gatekeeper, timer]

 import ./test_schema

-test "patterns":
-  let
-    pat = ?Observe(pattern: !Foo) ?? {0: grab()}
-    text = """<rec Observe [<rec rec [<lit foo> <arr [<bind <_>> <_> <_>]>]> <_>]>"""
-  check($pat == text)
+suite "example":
+  var pat: Pattern
+  check pat.fromPreserves parsePreserves"""
+      <group <arr> {
+        0: <lit 1>
+        1: <bind <group <arr> {
+          0: <bind <_>>
+          1: <_>
+        }>>
+        2: <_>
+      }>
+    """

-  let
-    worte = @["alles", "in", "ordnung"]
-    observer = Observe(pattern: inject(?:Foo, { 0: ?worte })).toPreserves
-    have = capture(pat, observer).toPreserves.unpackLiterals
-    want = [worte.toPreserves].toPreserves
-  check(have ==  want)
+  const A = "[1 2 3]"
+  test A:
+    let v = parsePreserves A
+    check:
+      not pat.matches(v)

-type Obj {.preservesDictionary.} = object
-  a, b, c: int
-
-test "dictionaries":
-  let pat = ?:Obj
-  var source = initDictionary(Cap)
-  source["b".toSymbol] = 2.toPreserves
-  source["c".toSymbol] = 3.toPreserves
-  source["a".toSymbol] = 1.toPreserves
-
-  let values = capture(pat, source)
-  check values.len == 3
-  check values[0] == 1.toPreserves
-  check values[1] == 2.toPreserves
-  check values[2] == 3.toPreserves
-
-type
-  File {.preservesDictionary.} = object
-    name: string
-    path: string
-    size: BiggestInt
-    `type`: string
-  Files = Table[Symbol, File]
-  Fields = Table[Symbol, string]
-
-  Request {.preservesRecord: "request".} = object
-    seq: BiggestInt
-    fields: Fields
-    files: Files
-
-test "literals":
-  const txt = """<rec request [<lit 3> <dict {artists: <lit "kyyyyym"> date: <lit "2023-10-14"> notes: <lit "Lots of stuff"> title: <lit "Domes show">}> <dict {front-cover: <dict {name: <lit "ADULT_TIME_Glielmi.jpg"> path: <lit "/tmp/652adad1b3d2b666dcc8d857.jpg"> size: <lit 255614> type: <lit "image/jpeg">}>}>]>"""
-  var pr = parsePreserves(txt)
-
-  var capture: Literal[Request]
-  check capture.fromPreserves(pr)
-
-suite "captures":
-  for txt in [
-      "#f",
-      "#t",
-      "0",
-      "-1",
-      "foo",
-      "<foo>",
-      "[0, 1, 2]",
-      ]:
-    test txt:
-      let
-        pr = parsePreserves txt
-        pat = grab pr
-      checkpoint $pat
-      check pat.matches pr
-
-suite "protocol":
-  test "Observe":
-    let pat = ?:Observe
-    const text = """<rec Observe [<bind <_>> <bind <_>>]>"""
-    check $pat == text
-
-  test "later-than":
+  const B = "[1 [2 3] 4]"
+  test B:
    let
-      obsA = parsePreserves"""<Observe <rec later-than [<lit 1704113731.419243>]> #f>"""
-      obsB = parsePreserves"""<Observe <rec Observe [<rec rec [<lit later-than> <arr [<rec lit [<bind <_>>]>]>]> <_>]> #f>"""
-      patA = """<rec later-than [<lit 1704113731.419243>]>""".parsePreserves.preservesTo(Pattern).get
-      patB = """<rec Observe [<rec rec [<lit later-than> <arr [<rec lit [<bind <_>>]>]>]> <_>]>""".parsePreserves.preservesTo(Pattern).get
+      v = parsePreserves B
+      c = parsePreserves "[[2 3] 2]"
+    check pat.matches(v)
+    check pat.capture(v).toPreserves == c

-      patC = grab obsA
+  const C = "[1 [2] 5]"
+  test C:
+    let v = parsePreserves C
+    check:
+      not pat.matches(v)

-    test $patC:
-      check patC.matches obsA
-
-    test $patB:
-      checkpoint $obsA
-      check patB.matches obsA
-
-  test "TransportConnection":
+  const D = "[1 [2 3 4] 5]"
+  test D:
    let
-      pat = TransportConnection ?: { 2: ?:Rejected}
-      text = """<rec connect-transport [<_> <_> <rec rejected [<bind <_>>]>]>"""
-    check $pat == text
+      v = parsePreserves D
+      c = parsePreserves "[[2 3 4] 2]"
+    check pat.matches(v)
+    check pat.capture(v).toPreserves == c
+
+  const E = "[1 [<x> <y>] []]"
+  test E:
+    let
+      v = parsePreserves E
+      c = parsePreserves "[[<x> <y>] <x>]"
+    check pat.matches(v)
+    check pat.capture(v).toPreserves == c
+
+suite "meta":
+
+  test "pattern-of-pattern":
+    let
+      pat = grabRecord("foo".toSymbol, {666: drop()})
+      meta = pat.toPreserves.drop()
+    check $meta == "<group <rec group> {0: <group <rec rec> {0: <lit foo>}> 1: <group <dict> {666: <_>}>}>"
+
+  test "observe":
+    let
+      val = Observe(pattern: LaterThan ?: {0: drop 12.24}).toPreserves
+      pat = grab(val)
+    check pat.matches(val)
+    check pat.capture(val) == @[val]
+    let
+      meta = observePattern(!LaterThan, {@[0.toPreserves]: grabLit()})
+      res = parsePreserves "[12.24]"
+    check meta.matches(val)
+    check meta.capture(val).toPreserves == res
+
+  test "connect-transport":
+    let pat = parsePreserves"""
+        <group <rec connect-transport> {0: <group <rec unix> {0: <lit "/run/user/1000/dataspace">}> 2: <group <rec accepted> {0: <bind <_>>}>}>
+      """.preservesTo(Pattern).get
+    let val = parsePreserves"""
+        <connect-transport <unix "/run/user/1000/dataspace"> #:#f <accepted #:#f>>
+      """
+    check pat.matches(val)
+    check pat.capture(val).toPreserves == parsePreserves "[#:#f]"
--- a/tests/test_timers.nim
+++ b/tests/test_timers.nim
@ -2,21 +2,31 @@
 # SPDX-License-Identifier: Unlicense

 import std/times
-import syndicate, syndicate/drivers/timers
+import syndicate, syndicate/drivers/timers, preserves

-runActor("timer-test") do (turn: var Turn):
+var passCount = 0
+
+runActor("timer-test") do (turn: Turn):
  let timers = newDataspace(turn)
  spawnTimerDriver(turn, timers)

  onPublish(turn, timers, ?LaterThan(seconds: 1356100000)):
    echo "now in 13th bʼakʼtun"
+    inc passCount

-  after(turn, timers, initDuration(seconds = 3)) do (turn: var Turn):
+  after(turn, timers, initDuration(seconds = 3)) do (turn: Turn):
    echo "third timer expired"
-    stopActor(turn)
+    assert passCount == 3
+    inc passCount

-  after(turn, timers, initDuration(seconds = 1)) do (turn: var Turn):
+  after(turn, timers, initDuration(seconds = 1)) do (turn: Turn):
    echo "first timer expired"
+    assert passCount == 1
+    inc passCount

-  after(turn, timers, initDuration(seconds = 2)) do (turn: var Turn):
+  after(turn, timers, initDuration(seconds = 2)) do (turn: Turn):
    echo "second timer expired"
+    assert passCount == 2
+    inc passCount
+
+doAssert passCount == 4, $passCount
Author	SHA1	Message	Date
Emery Hemingway	3a4dc1f133	Change behavior of grabType Make grabType grab a single composite value that can be converted to the type being grabbed instead of just the fields of the type. The old behavior is available in grabTypeFlat and the alias `?:` still points there.	2024-05-07 15:44:53 +02:00
Emery Hemingway	4fb0285190	relays: fix runnaway closed connection loop	2024-05-04 00:31:00 +02:00
Emery Hemingway	81792ac4ce	Replace "var Turn" with "Turn"	2024-04-30 12:52:40 +02:00
Emery Hemingway	7e15b37f44	Implement base method of sync	2024-04-24 20:28:28 +02:00
Emery Hemingway	c99f0a60ab	Add runOnce proc This is useful for forcing progress when embedding Syndicate in contexts that don't expose turn semantics.	2024-04-24 16:11:17 +02:00
Emery Hemingway	5fc371d187	Require newer Preserves	2024-04-24 16:10:34 +02:00
Emery Hemingway	06898e4ec1	Update dataspace patterns protocol Skeletons do not check for the presence of ignored entries in pattern matches, this will cause bugs!	2024-04-22 10:54:44 +02:00
Emery Hemingway	2aaa588f6a	drivers/timers: map deadlines to facets	2024-04-19 17:36:07 +02:00
Emery Hemingway	e0b569e465	Update noise schema	2024-04-19 17:36:07 +02:00
Emery Hemingway	13d3995507	Update http driver to latest schema	2024-04-19 17:36:07 +02:00
Emery Hemingway	6487ef65d0	http_driver: add 504 binding timeouts	2024-04-08 20:44:23 +01:00
Emery Hemingway	6a4854110c	http_driver: don't send empty chunks	2024-04-08 20:37:17 +01:00
Emery Hemingway	464043c8bf	http_driver: set sequenceNumber	2024-04-08 17:01:35 +01:00
Emery Hemingway	15637620f0	http_driver: strip query ? from URL path	2024-04-08 16:59:32 +01:00
Emery Hemingway	c2dce8a274	Update README	2024-04-08 14:50:36 +01:00
Emery Hemingway	1a3fdf2a5a	Update Taps dependency	2024-04-08 14:43:37 +01:00