From 1f1d1a38aae9f4994f76f69948f1feaca73ba57f Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Wed, 21 May 2014 12:10:00 -0500
Subject: [PATCH] minor cleanups to contract-random-generate's API

---
 .../racket-doc/scribblings/reference/contracts.scrbl |  4 ++--
 racket/collects/racket/contract/private/generate.rkt | 12 ++++++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/pkgs/racket-pkgs/racket-doc/scribblings/reference/contracts.scrbl b/pkgs/racket-pkgs/racket-doc/scribblings/reference/contracts.scrbl
index f3b1356890..e8cf1653e0 100644
--- a/pkgs/racket-pkgs/racket-doc/scribblings/reference/contracts.scrbl
+++ b/pkgs/racket-pkgs/racket-doc/scribblings/reference/contracts.scrbl
@@ -2766,8 +2766,8 @@ parts of the contract system.
 @section{Random generation}
 
 @defproc[(contract-random-generate [ctc contract?]
-                                   [fuel int?]
-                                   [fail (-> any/c) (λ () (error ...))])
+                                   [fuel 5 exact-nonnegative-integer?]
+                                   [fail (or/c #f (-> any)) #f])
          any/c]{
 Attempts to randomly generate a value which will match the contract. The fuel
 argument limits how hard the generator tries to generate a value matching the
diff --git a/racket/collects/racket/contract/private/generate.rkt b/racket/collects/racket/contract/private/generate.rkt
index c52b208abe..77b16cc22f 100644
--- a/racket/collects/racket/contract/private/generate.rkt
+++ b/racket/collects/racket/contract/private/generate.rkt
@@ -107,9 +107,17 @@
                    (append ctcs (definitely-available-contracts))])
     (thunk)))
 
-; generate : contract int -> ctc value or error
-(define (contract-random-generate ctc fuel [_fail #f])
+(define (contract-random-generate ctc [fuel 5] [_fail #f])
   (define def-ctc (coerce-contract 'contract-random-generate ctc))
+  (unless (exact-nonnegative-integer? fuel)
+    (raise-argument-error 'contract-random-generate
+                          "exact-nonnegative-integer?"
+                          fuel))
+  (unless (or (not _fail) (and (procedure? _fail) (procedure-arity-includes? _fail 0)))
+    (raise-argument-error 'contract-random-generate
+                          (format "~s" '(or/c #f (-> any)))
+                          3
+                          ctc fuel _fail))
   (define proc
     (parameterize ([generate-env (make-hash)]) 
       (generate/choose def-ctc fuel)))