From f7fd6ee68996564d73ed71055182c4c425c240d1 Mon Sep 17 00:00:00 2001
From: Casey Klein <clklein@racket-lang.org>
Date: Mon, 31 Jan 2011 12:32:12 -0600
Subject: [PATCH] Changes the term generator to produce shorter sequences

It now uses the (local) size bound instead of the (global) attempt count.
---
 collects/redex/private/rg.rkt    | 6 +++---
 collects/redex/redex.scrbl       | 5 +++--
 collects/redex/tests/rg-test.rkt | 2 +-
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/collects/redex/private/rg.rkt b/collects/redex/private/rg.rkt
index 86b67f962e..88f3e53ce5 100644
--- a/collects/redex/private/rg.rkt
+++ b/collects/redex/private/rg.rkt
@@ -141,8 +141,8 @@
 (define (pick-real attempt [random generator-random])
   (pick-number attempt #:top-threshold real-threshold random))
 
-(define (pick-sequence-length attempt)
-  (random-natural (expected-value->p ((attempt->size) attempt))))
+(define (pick-sequence-length size)
+  (random-natural (expected-value->p size)))
 
 (define (min-prods nt prods base-table)
   (let* ([sizes (hash-ref base-table nt)]
@@ -371,7 +371,7 @@
                                             (let ([prior (hash-ref e class #f)])
                                               (if prior
                                                   prior
-                                                  (if (zero? s) 0 ((next-sequence-decision) a))))]
+                                                  (if (zero? s) 0 ((next-sequence-decision) s))))]
                                            [(seq env)
                                             (generate-sequence (λ (e) (elemg r s a e f)) e vars len)]
                                            [(tail env) 
diff --git a/collects/redex/redex.scrbl b/collects/redex/redex.scrbl
index fba853226a..27c0792a82 100644
--- a/collects/redex/redex.scrbl
+++ b/collects/redex/redex.scrbl
@@ -1278,8 +1278,9 @@ The argument @racket[size-expr] bounds the height of the generated term
 The optional keyword argument @racket[attempt-num-expr] 
 (default @racket[1]) provides coarse grained control over the random
 decisions made during generation; increasing @racket[attempt-num-expr]
-tends to increase the complexity of the result. For example, the expected
-length of @pattech[pattern-sequence]s increases with @racket[attempt-num-expr].
+tends to increase the complexity of the result. For example, the absolute
+values of numbers chosen for @pattech[integer] patterns increase with
+@racket[attempt-num-expr].
 
 The random generation process does not actively consider the constraints
 imposed by @pattech[side-condition] or @tt{_!_} @|pattern|s; instead, 
diff --git a/collects/redex/tests/rg-test.rkt b/collects/redex/tests/rg-test.rkt
index 81bf0c722a..f73c48da4f 100644
--- a/collects/redex/tests/rg-test.rkt
+++ b/collects/redex/tests/rg-test.rkt
@@ -1272,7 +1272,7 @@
 (let ([seed 0])
   (define-language L)
   (define (generate)
-    (generate-term L (number ...) 10000000 #:attempt-num 10000000))
+    (generate-term L (number ...) 100 #:attempt-num 10000000))
   (test (begin (random-seed seed) (generate))
         (begin (random-seed seed) (generate)))
   (let ([prg (make-pseudo-random-generator)])