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original commit: 1e66762202bc42766ae64dac137ace0c89d878db
2005-04-16 18:59:42 +00:00 · 2005-04-16 18:59:42 +00:00 · d462a25bd1
commit d462a25bd1
parent b2399cae60
1 changed files with 5 additions and 0 deletions
--- a/collects/mzlib/foreign.ss
+++ b/collects/mzlib/foreign.ss
@ -464,6 +464,11 @@
 ;; `-> expr'               specify different output, can use previous names
 ;; Also, see below for custom function types.

+(provide ->) ; to signal better errors when trying to use this with contracts
+(define-syntax ->
+  (syntax-id-rules ()
+    [_ (raise-syntax-error '-> "should be used only in a _fun context")]))
+
 (provide _fun)
 (define-syntax (_fun stx)
  (define (err msg . sub) (apply raise-syntax-error '_fun msg stx sub))