typed define/dataflow

racket/typed/roles.rkt

@@ -24,6 +24,7 @@
          define/query-value
          define/query-set
          define/query-hash
+         define/dataflow
          on-start on-stop
          ;; endpoints
          assert know on field
@@ -513,6 +514,22 @@
 (define-simple-macro (on-stop e ...)
   (on stop e ...))
 
+(define-typed-syntax define/dataflow
+  [(define/dataflow x:id τ:type e) ≫
+  [⊢ e ≫ e- (⇐ : τ)]
+  #:fail-unless (pure? #'e-) "expression must be pure"
+  ;; because the begin/dataflow body is scheduled to run at some later point,
+  ;; the initial value is visible e.g. immediately after the define/dataflow
+;; #:with place-holder (attach #'(#%datum- #f) ': #'τ.norm)
+  ----------------------------------------
+  [≻ (begin (field [x τ e-])
+            (begin/dataflow (set! x e-)))]]
+  [(define/dataflow x:id e) ≫
+   [⊢ e ≫ e- (⇒ : τ)]
+   #:fail-unless (pure? #'e-) "expression must be pure"
+   ----------------------------------------
+   [≻ (define/dataflow x τ e-)]])
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Expressions
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

racket/typed/tests/define-dataflow.rkt

@@ -0,0 +1,11 @@
+#lang typed/syndicate/roles
+
+(run-ground-dataspace (U)
+(spawn (U)
+       (start-facet x
+                    (field [y Int 0])
+                    (define/dataflow x (add1 (ref y)))
+                    (displayln (add1 (ref x)))
+                    ;; print 2
+                    #f))
+)