bound/c test

tests/bound contract/bound.rkt

@@ -0,0 +1,13 @@
+#lang racket
+
+(provide bound/c (rename-out (top~ #%top)))
+
+(define-syntax-rule (top~ . id)
+   (λ x `(id ,@x)))
+
+(define-syntax (bound/c stx)
+   (syntax-case stx ()
+     [(_ x)
+      (if (identifier-binding #'x )
+          #'x
+          #'(#%top . x))]))

tests/bound contract/test.rkt

@@ -0,0 +1,5 @@
+#lang racket
+(require "bound.rkt")
+
+(bar "hello") ; bar is unbound
+((bound/c bar) "hello")