diff --git a/racket/typed/core-expressions.rkt b/racket/typed/core-expressions.rkt
index 6480f4f..9039f00 100644
--- a/racket/typed/core-expressions.rkt
+++ b/racket/typed/core-expressions.rkt
@@ -29,12 +29,12 @@
 
 (define-typed-syntax (bind x:id τ:type) ≫
   ----------------------------------------
-  [⊢ (error- 'bind "escaped") (⇒ : (Bind τ))])
+  [⊢ (#%app- error- 'bind "escaped") (⇒ : (Bind τ))])
 
 (define-typed-syntax discard
   [_ ≫
    --------------------
-   [⊢ (error- 'discard "escaped") (⇒ : Discard)]])
+   [⊢ (#%app- error- 'discard "escaped") (⇒ : Discard)]])
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Core-ish forms
@@ -84,12 +84,13 @@
   ------------------------------------
   [≻ (if e #f (let () s ...))])
 
+
 ;; copied from ext-stlc
 (define-typed-syntax let
   [(_ ([x e] ...) e_body ...) ⇐ τ_expected ≫
    [⊢ e ≫ e- ⇒ : τ_x] ...
    #:fail-unless (stx-andmap pure? #'(e- ...)) "expressions must be pure"
-   [[x ≫ x- : τ_x] ... ⊢ (begin e_body ...) ≫ e_body- (⇐ : τ_expected)
+   [[x ≫ x- : τ_x] ... ⊢ (block e_body ...) ≫ e_body- (⇐ : τ_expected)
                    (⇒ ν-ep (~effs eps ...))
                    (⇒ ν-f (~effs fs ...))
                    (⇒ ν-s (~effs ss ...))]
@@ -101,7 +102,7 @@
   [(_ ([x e] ...) e_body ...) ≫
    [⊢ e ≫ e- ⇒ : τ_x] ...
    #:fail-unless (stx-andmap pure? #'(e- ...)) "expressions must be pure"
-   [[x ≫ x- : τ_x] ... ⊢ (begin e_body ...) ≫ e_body- (⇒ : τ_body)
+   [[x ≫ x- : τ_x] ... ⊢ (block e_body ...) ≫ e_body- (⇒ : τ_body)
                    (⇒ ν-ep (~effs eps ...))
                    (⇒ ν-f (~effs fs ...))
                    (⇒ ν-s (~effs ss ...))]
@@ -115,7 +116,7 @@
 (define-typed-syntax let*
   [(_ () e_body ...) ≫
    --------
-   [≻ (begin e_body ...)]]
+   [≻ (block e_body ...)]]
   [(_ ([x e] [x_rst e_rst] ...) e_body ...) ≫
    --------
    [≻ (let ([x e]) (let* ([x_rst e_rst] ...) e_body ...))]])
@@ -123,7 +124,7 @@
 (define-typed-syntax (cond [pred:expr s ...+] ...+) ≫
   [⊢ pred ≫ pred- (⇐ : Bool)] ...
   #:fail-unless (stx-andmap pure? #'(pred- ...)) "predicates must be pure"
-  [⊢ (begin s ...) ≫ s- (⇒ : τ-s)
+  [⊢ (block s ...) ≫ s- (⇒ : τ-s)
                    (⇒ ν-ep (~effs eps ...))
                    (⇒ ν-f (~effs fs ...))
                    (⇒ ν-s (~effs ss ...))] ...
@@ -141,7 +142,7 @@
   #:with (p/e ...) (for/list ([pat (in-syntax #'(p ...))])
                      (elaborate-pattern/with-type pat #'τ-e))
   #:with (([x τ:type] ...) ...) (stx-map pat-bindings #'(p/e ...))
-  [[x ≫ x- : τ.norm] ... ⊢ (begin s ...) ≫ s- (⇒ : τ-s)
+  [[x ≫ x- : τ.norm] ... ⊢ (block s ...) ≫ s- (⇒ : τ-s)
                 (⇒ ν-ep (~effs eps ...))
                 (⇒ ν-f (~effs fs ...))
                 (⇒ ν-s (~effs ss ...))] ...
diff --git a/racket/typed/core-types.rkt b/racket/typed/core-types.rkt
index 756c58a..1775dce 100644
--- a/racket/typed/core-types.rkt
+++ b/racket/typed/core-types.rkt
@@ -26,6 +26,9 @@
   (require rackunit)
   (require rackunit/turnstile))
 
+(begin-for-syntax
+  (current-use-stop-list? #f))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Type Checking Conventions
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -1079,7 +1082,7 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define-typed-syntax (lambda ([x:id (~optional (~datum :)) τ:type] ...) body ...+) ≫
-  [[x ≫ x- : τ] ... ⊢ (begin body ...) ≫ body- (⇒ : τ-e)
+  [[x ≫ x- : τ] ... ⊢ (block body ...) ≫ body- (⇒ : τ-e)
                 (⇒ ν-ep (~effs τ-ep ...))
                 (⇒ ν-s (~effs τ-s ...))
                 (⇒ ν-f (~effs τ-f ...))]
@@ -1265,7 +1268,7 @@
    #:with x- (generate-temporary #'x)
    #:with x+ (syntax-local-identifier-as-binding #'x)
    --------
-   [⊢ (define/intermediate x+ x- τ.norm e-)
+   [⊢ (erased (define/intermediate x+ x- τ.norm e-))
       (⇒ : ★/t)
       (⇒ ν-ep (τ-ep ...))
       (⇒ ν-f (τ-f ...))
@@ -1276,7 +1279,7 @@
    #:with x- (generate-temporary #'x)
    #:with x+ (syntax-local-identifier-as-binding #'x)
    --------
-   [⊢ (define/intermediate x+ x- τ e-)
+   [⊢ (erased (define/intermediate x+ x- τ e-))
       (⇒ : ★/t)
       (⇒ ν-ep (τ-ep ...))
       (⇒ ν-f (τ-f ...))
@@ -1284,7 +1287,7 @@
   [(_ (f [x (~optional (~datum :)) ty:type] ...
          (~or (~datum →) (~datum ->)) ty_out:type)
          e ...+) ≫
-   [⊢ (lambda ([x : ty] ...) (begin e ...)) ≫ e- (⇒ : (~and fun-ty
+   [⊢ (lambda ([x : ty] ...) (block e ...)) ≫ e- (⇒ : (~and fun-ty
                                                             (~→ (~not (~Computation _ ...)) ...
                                                                 (~Computation (~Value τ-v)
                                                                               _ ...))))]
@@ -1295,7 +1298,7 @@
        #;(type->str #'ty_out))
    #:with f- (add-orig (generate-temporary #'f) #'f)
    --------
-   [⊢ (define/intermediate f f- fun-ty e-) (⇒ : ★/t)]]
+   [⊢ (erased (define/intermediate f f- fun-ty e-)) (⇒ : ★/t)]]
   [(_ (f [x (~optional (~datum :)) ty] ...)
          e ...+) ≫
    ----------------------------
@@ -1307,7 +1310,7 @@
       e ...+) ≫
    #:with e+ #'(Λ (X ...)
                   (lambda ([x : ty] ...)
-                    (begin e ...)))
+                    (block e ...)))
    [[X ≫ X- :: #%type] ... ⊢ e+ ≫ e-
                        (⇒ : (~and res-ty
                                   (~∀ (Y ...)
@@ -1320,13 +1323,24 @@
                          #'τ-v #'ty_out)
    #:with f- (add-orig (generate-temporary #'f) #'f)
    -------------------------------------------------------
-   [⊢ (define/intermediate f f- res-ty e-) (⇒ : ★/t)]]
+   [⊢ (erased (define/intermediate f f- res-ty e-)) (⇒ : ★/t)]]
   [(_ ((~datum ∀) (X:id ...)
                   (f [x (~optional (~datum :)) ty] ...))
       e ...+) ≫
    --------------------------------------------------
    [≻ (define (∀ (X ...) (f [x ty] ... -> ★/t)) e ...)]])
 
+(define-typed-syntax block
+  [(_ e_unit ... e) ≫
+   #:do [(define-values (e-... τ... ep-effs f-effs s-effs) (walk/bind #'(e_unit ... e)))]
+   #:with τ (last τ...)
+   --------
+   [⊢ (let- () #,@e-...) (⇒ : τ)
+      (⇒ ν-ep (#,@ep-effs))
+      (⇒ ν-f (#,@f-effs))
+      (⇒ ν-s (#,@s-effs))]])
+
+
 (define-typed-syntax begin
   [(_ e_unit ... e) ≫
    #:do [(define-values (e-... τ... ep-effs f-effs s-effs) (walk/bind #'(e_unit ... e)))]
diff --git a/racket/typed/for-loops.rkt b/racket/typed/for-loops.rkt
index 9b7a103..b3d5d29 100644
--- a/racket/typed/for-loops.rkt
+++ b/racket/typed/for-loops.rkt
@@ -115,6 +115,14 @@
      (type-error #:src e
                  #:msg "not an iterable type: ~a" τ)]))
 
+(define-for-syntax (bind-renames renames body)
+  (syntax-parse renames
+    [([x:id x-:id] ...)
+     #:with (x-- ...) (map syntax-local-identifier-as-binding (syntax->list #'(x- ...)))
+     (quasisyntax/loc body
+       (let- ()
+             (define-syntax x (make-variable-like-transformer #'x--)) ...
+             #,body))]))
 
 (define-typed-syntax for/fold
   [(for/fold ([acc:id (~optional (~datum :)) τ-acc init])
@@ -125,16 +133,15 @@
   #:fail-unless (pure? #'init-) "expression must be pure"
   #:with (clauses- ([x x- τ] ...)) (analyze-for-clauses #'(clause.parend ...))
   [[x ≫ x-- : τ] ...
-   [acc ≫ acc- : τ-acc] ⊢ (begin e-body ...) ≫ e-body-
+   [acc ≫ acc- : τ-acc] ⊢ (block e-body ...) ≫ e-body-
                            (⇐ : τ-acc)
                            (⇒ ν-ep (~effs τ-ep ...))
                            (⇒ ν-s (~effs τ-s ...))
                            (⇒ ν-f (~effs τ-f ...))]
-  #:with e-body-- (substs #'(x- ...) #'(x-- ...) #'e-body- free-identifier=?)
   -------------------------------------------------------
   [⊢ (for/fold- ([acc- init-])
                 clauses-
-                e-body--)
+                #,(bind-renames #'([x-- x-] ...) #'e-body-))
      (⇒ : τ-acc)
      (⇒ ν-ep (τ-ep ...))
      (⇒ ν-s (τ-s ...))
@@ -151,34 +158,34 @@
 (define-typed-syntax (for/list (clause:iter-clause ...)
                        e-body ...+) ≫
   #:with (clauses- ([x x- τ] ...)) (analyze-for-clauses #'(clause.parend ...))
-  [[x ≫ x-- : τ] ... ⊢ (begin e-body ...) ≫ e-body-
+  [[x ≫ x-- : τ] ... ⊢ (block e-body ...) ≫ e-body-
                            (⇒ : τ-body)
                            (⇒ ν-ep (~effs τ-ep ...))
                            (⇒ ν-s (~effs τ-s ...))
                            (⇒ ν-f (~effs τ-f ...))]
-  #:with e-body-- (substs #'(x- ...) #'(x-- ...) #'e-body- free-identifier=?)
   ----------------------------------------------------------------------
   [⊢ (for/list- clauses-
-                e-body--) (⇒ : (List τ-body))
-                          (⇒ ν-ep (τ-ep ...))
-                          (⇒ ν-s (τ-s ...))
-                          (⇒ ν-f (τ-f ...))])
+       #,(bind-renames #'([x-- x-] ...) #'e-body-))
+                (⇒ : (List τ-body))
+                (⇒ ν-ep (τ-ep ...))
+                (⇒ ν-s (τ-s ...))
+                (⇒ ν-f (τ-f ...))])
 
 (define-typed-syntax (for/set (clause:iter-clause ...)
                        e-body ...+) ≫
   #:with (clauses- ([x x- τ] ...)) (analyze-for-clauses #'(clause.parend ...))
-  [[x ≫ x-- : τ] ... ⊢ (begin e-body ...) ≫ e-body-
+  [[x ≫ x-- : τ] ... ⊢ (block e-body ...) ≫ e-body-
                            (⇒ : τ-body)
                            (⇒ ν-ep (~effs τ-ep ...))
                            (⇒ ν-s (~effs τ-s ...))
                            (⇒ ν-f (~effs τ-f ...))]
-  #:with e-body-- (substs #'(x- ...) #'(x-- ...) #'e-body- free-identifier=?)
   ----------------------------------------------------------------------
   [⊢ (for/set- clauses-
-                e-body--) (⇒ : (Set τ-body))
-                          (⇒ ν-ep (τ-ep ...))
-                          (⇒ ν-s (τ-s ...))
-                          (⇒ ν-f (τ-f ...))])
+       #,(bind-renames #'([x-- x-] ...) #'e-body-))
+              (⇒ : (Set τ-body))
+              (⇒ ν-ep (τ-ep ...))
+              (⇒ ν-s (τ-s ...))
+              (⇒ ν-f (τ-f ...))])
 
 (define-typed-syntax (for/sum (clause ...)
                        e-body ...+) ≫
@@ -198,18 +205,17 @@
 (define-typed-syntax (for/first (clause:iter-clause ...)
                        e-body ...+) ≫
   #:with (clauses- ([x x- τ] ...)) (analyze-for-clauses #'(clause.parend ...))
-  [[x ≫ x-- : τ] ... ⊢ (begin e-body ...) ≫ e-body-
+  [[x ≫ x-- : τ] ... ⊢ (block e-body ...) ≫ e-body-
                  (⇒ : τ-body)
                  (⇒ ν-ep (~effs τ-ep ...))
                  (⇒ ν-s (~effs τ-s ...))
                  (⇒ ν-f (~effs τ-f ...))]
-  #:with e-body-- (substs #'(x- ...) #'(x-- ...) #'e-body- free-identifier=?)
   [[res ≫ _ : τ-body] ⊢ res  ≫ res- (⇒ : _)]
   ----------------------------------------------------------------------
   [⊢ (let- ()
        (define- res-
          (for/first- clauses-
-                     e-body--))
+                     #,(bind-renames #'([x-- x-] ...) #'e-body-)))
        (if- res-
             (some res-)
             none))
diff --git a/racket/typed/roles.rkt b/racket/typed/roles.rkt
index f238cab..b3c2531 100644
--- a/racket/typed/roles.rkt
+++ b/racket/typed/roles.rkt
@@ -162,7 +162,7 @@
   #:with (τ ...) (stx-map type-eval #'((Field τ-f.norm) ...))
   #:with MF (type-eval #'MakesField)
   ----------------------------------------------------------------------
-  [⊢ (field/intermediate [x x- τ e-] ...)
+  [⊢ (erased (field/intermediate [x x- τ e-] ...))
      (⇒ : ★/t)
      (⇒ ν-ep (MF))])
 
@@ -200,7 +200,7 @@
 
 (define-typed-syntax (stop facet-name:id cont ...) ≫
   [⊢ facet-name ≫ facet-name- (⇐ : FacetName)]
-  [⊢ (begin #f cont ...) ≫ cont-
+  [⊢ (block #f cont ...) ≫ cont-
                          (⇒ ν-ep (~effs))
                          (⇒ ν-s (~effs))
                          (⇒ ν-f (~effs τ-f ...))]
@@ -256,7 +256,7 @@
 (define-typed-syntax on
   #:datum-literals (start stop)
   [(on start s ...) ≫
-   [⊢ (begin s ...) ≫ s- (⇒ ν-ep (~effs))
+   [⊢ (block s ...) ≫ s- (⇒ ν-ep (~effs))
                           (⇒ ν-f (~effs τ-f ...))
                           (⇒ ν-s (~effs τ-s ...))]
    #:with τ-r (type-eval #'(Reacts OnStart τ-f ... τ-s ...))
@@ -264,7 +264,7 @@
    [⊢ (syndicate:on-start s-) (⇒ : ★/t)
       (⇒ ν-ep (τ-r))]]
   [(on stop s ...) ≫
-   [⊢ (begin s ...) ≫ s- (⇒ ν-ep (~effs))
+   [⊢ (block s ...) ≫ s- (⇒ ν-ep (~effs))
                           (⇒ ν-f (~effs τ-f ...))
                           (⇒ ν-s (~effs τ-s ...))]
    #:with τ-r (type-eval #'(Reacts OnStop τ-f ... τ-s ...))
@@ -281,7 +281,7 @@
    [⊢ p/e ≫ p-- (⇒ : τp)]
    #:fail-unless (pure? #'p--) "pattern not allowed to have effects"
    #:with ([x:id τ:type] ...) (pat-bindings #'p/e)
-   [[x ≫ x- : τ] ... ⊢ (begin s ...) ≫ s-
+   [[x ≫ x- : τ] ... ⊢ (block s ...) ≫ s-
                  (⇒ ν-ep (~effs))
                  (⇒ ν-f (~effs τ-f ...))
                  (⇒ ν-s (~effs τ-s ...))]
@@ -295,7 +295,7 @@
       (⇒ ν-ep (τ-r))]])
 
 (define-typed-syntax (begin/dataflow s ...+) ≫
-  [⊢ (begin s ...) ≫ s-
+  [⊢ (block s ...) ≫ s-
      (⇒ : _)
      (⇒ ν-ep (~effs))
      (⇒ ν-f (~effs τ-f ...))
@@ -319,7 +319,7 @@
   ;; TODO: check that each τ-f is a Role
   #:mode (communication-type-mode #'τ-c.norm)
     [
-     [⊢ s ≫ s- (⇒ ν-ep (~effs)) (⇒ ν-s (~effs)) (⇒ ν-f (~effs τ-f ...))]
+     [⊢ (block s) ≫ s- (⇒ ν-ep (~effs)) (⇒ ν-s (~effs)) (⇒ ν-f (~effs τ-f ...))]
     ]
   ;; TODO: s shouldn't refer to facets or fields!
   #:with (τ-i τ-o τ-i/i τ-o/i τ-a) (analyze-roles #'(τ-f ...))
@@ -570,11 +570,15 @@
 ;; n.b. this is a blocking operation, so an actor that uses this internally
 ;; won't necessarily terminate.
 (define-typed-syntax (run-ground-dataspace τ-c:type s ...) ≫
-  [⊢ (dataspace τ-c s ...) ≫ ((~literal erased) ((~literal syndicate:dataspace) s- ...)) (⇒ : t)]
+  ;;#:fail-unless (flat-type? #'τ-c.norm) "Communication type must be first-order"
+  #:mode (communication-type-mode #'τ-c.norm)
+  [
+   [⊢ s ≫ s- (⇒ : t1)] ...
+   [⊢ (dataspace τ-c.norm s- ...) ≫ _ (⇒ : t2)]
+  ]
   -----------------------------------------------------------------------------------
   [⊢ (#%app- syndicate:run-ground s- ...) (⇒ : (AssertionSet τ-c))])
 
-
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Utilities
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
diff --git a/racket/typed/tests/for-loop-regression.rkt b/racket/typed/tests/for-loop-regression.rkt
new file mode 100644
index 0000000..3a29747
--- /dev/null
+++ b/racket/typed/tests/for-loop-regression.rkt
@@ -0,0 +1,9 @@
+#lang typed/syndicate/roles
+
+(require rackunit/turnstile)
+
+(check-type (for/list ([x (for/list ([y (list 1 2 3)])
+                            y)])
+              x)
+            : (List Int)
+            ⇒ (list 1 2 3))
diff --git a/racket/typed/tests/regression-define-with-effects.rkt b/racket/typed/tests/regression-define-with-effects.rkt
index 92537e1..1ac74e1 100644
--- a/racket/typed/tests/regression-define-with-effects.rkt
+++ b/racket/typed/tests/regression-define-with-effects.rkt
@@ -3,7 +3,7 @@
 (require rackunit/turnstile)
 
 (check-type
- (begin
+ (let ()
   (field [boo Int 0])
   (define x (begin (send! "hi") 5))
   ;; relying on `set` not allowing effects for this to be a good test