From 327c55a28bc20403962f20a58cce445bff261706 Mon Sep 17 00:00:00 2001
From: Vincent St-Amour <stamourv@racket-lang.org>
Date: Mon, 4 Feb 2013 13:03:58 -0500
Subject: [PATCH] Don't special case typechecking of =.

Its type is more useful than the special typing rule.

original commit: 568f401bdcea778acfa8c1b80f18b23e9e9c9345
---
 collects/tests/typed-racket/succeed/num-equal-filter.rkt | 6 ++++++
 collects/typed-racket/typecheck/tc-app/tc-app-eq.rkt     | 7 ++++---
 2 files changed, 10 insertions(+), 3 deletions(-)
 create mode 100644 collects/tests/typed-racket/succeed/num-equal-filter.rkt

diff --git a/collects/tests/typed-racket/succeed/num-equal-filter.rkt b/collects/tests/typed-racket/succeed/num-equal-filter.rkt
new file mode 100644
index 00000000..f1e9f33a
--- /dev/null
+++ b/collects/tests/typed-racket/succeed/num-equal-filter.rkt
@@ -0,0 +1,6 @@
+#lang typed/racket
+
+(: f : Nonnegative-Integer -> Boolean)
+(define (f x)
+  (cond [(= 0 x) #t]
+        [else (f (sub1 x))])) ; here, x is Positive-Integer
diff --git a/collects/typed-racket/typecheck/tc-app/tc-app-eq.rkt b/collects/typed-racket/typecheck/tc-app/tc-app-eq.rkt
index 97302903..6791fd12 100644
--- a/collects/typed-racket/typecheck/tc-app/tc-app-eq.rkt
+++ b/collects/typed-racket/typecheck/tc-app/tc-app-eq.rkt
@@ -19,9 +19,10 @@
 (export tc-app-eq^)
 
 ;; comparators that inform the type system
+;; `=' is not included. Its type is more useful than this typing rule.
 (define-syntax-class comparator
-  #:literals (eq? equal? eqv? = string=? symbol=? memq member memv)
-  (pattern eq?) (pattern equal?) (pattern eqv?) (pattern =) (pattern string=?) (pattern symbol=?)
+  #:literals (eq? equal? eqv? string=? symbol=? memq member memv)
+  (pattern eq?) (pattern equal?) (pattern eqv?) (pattern string=?) (pattern symbol=?)
   (pattern member) (pattern memq) (pattern memv))
 
 
@@ -46,7 +47,7 @@
     (define-syntax-rule (alt nm pred ...)
       (and (free-identifier=? #'nm comparator) (or (pred val) ...)))
     (or (alt symbol=? symbol?)
-        (alt string=? string?)        
+        (alt string=? string?)
         (alt eq? eq?-able)
         (alt eqv? eqv?-able)
         (alt equal? equal?-able)))