skeletons: implement assertion removal

src/syndicate/skeletons.nim

@@ -1,6 +1,8 @@
 # SPDX-FileCopyrightText: ☭ Emery Hemingway
 # SPDX-License-Identifier: Unlicense
 
+## https://git.syndicate-lang.org/syndicate-lang/syndicate-rkt/src/commit/90c4c60699069b496491b81ee63b5a45ffd638cb/syndicate/HOWITWORKS.md
+
 import std/[hashes, lists, options, sets, tables]
 import preserves
 import ./actors, ./bags, ./patterns
@@ -146,14 +148,21 @@ proc modify(node: Node; turn: var Turn; outerValue: Value; event: EventKind;
         of addedEvent, messageEvent:
           let leaf = constValMap.getLeaf(get constVals)
           modLeaf(leaf, outerValue)
-          assert not leaf.isEmpty
           for capturePaths, observerGroup in leaf.observerGroups.pairs:
             let captures = projectPaths(outerValue, capturePaths)
             if captures.isSome:
               modObs(turn, observerGroup, get captures)
-        else:
-          raiseAssert $event & " not handled"
-          # TODO: cleanup dead leaves
+        of removedEvent:
+          let leaf = constValMap.getOrDefault(get constVals)
+          if not leaf.isNil:
+            modLeaf(leaf, outerValue)
+            for capturePaths, observerGroup in leaf.observerGroups.pairs:
+              let captures = projectPaths(outerValue, capturePaths)
+              if captures.isSome:
+                modObs(turn, observerGroup, get captures)
+            if leaf.isEmpty:
+              constValMap.del(get constVals)
+
 
   proc walk(node: Node; turn: var Turn; termStack: TermStack) =
     walk(node.continuation, turn)
@@ -168,6 +177,8 @@ proc modify(node: Node; turn: var Turn; outerValue: Value; event: EventKind;
           let nextNode = table.getOrDefault(nextClass)
           if not nextNode.isNil:
             walk(nextNode, turn, push(nextStack, get nextValue))
+            if event == removedEvent and nextNode.isEmpty:
+              table.del(nextClass)
 
   walk(node, turn, @[@[outerValue].toPreserve(Ref)])
 

syndicate.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version = "20230723"
+version = "20230725"
 author        = "Emery Hemingway"
 description   = "Syndicated actors for conversational concurrency"
 license       = "Unlicense"