From 1b1dc9cfb8b111c7603d6fe1901d8fd1f374d62e Mon Sep 17 00:00:00 2001
From: Max New <maxsnew@gmail.com>
Date: Mon, 10 Feb 2014 06:15:20 -0600
Subject: [PATCH] Redex Enumerator support for mismatch patterns

---
 .../redex-lib/redex/private/enum.rkt          |  4 +---
 .../redex/private/preprocess-pat.rkt          |  1 -
 .../redex-test/redex/tests/enum-test.rkt      | 21 ++++++++++++-------
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/pkgs/redex-pkgs/redex-lib/redex/private/enum.rkt b/pkgs/redex-pkgs/redex-lib/redex/private/enum.rkt
index 2680292973..53560eedae 100644
--- a/pkgs/redex-pkgs/redex-lib/redex/private/enum.rkt
+++ b/pkgs/redex-pkgs/redex-lib/redex/private/enum.rkt
@@ -135,9 +135,7 @@
      [`(name ,n ,pat)
       (const/e (name-ref n))]
      [`(mismatch-name ,n ,tag)
-      (unsupported "mismatch patterns")
-      ;; (const/e (misname-ref n tag))
-      ]
+      (const/e (misname-ref n tag))]
      [`(in-hole ,p1 ,p2)
       (map/e decomp
              (match-lambda
diff --git a/pkgs/redex-pkgs/redex-lib/redex/private/preprocess-pat.rkt b/pkgs/redex-pkgs/redex-lib/redex/private/preprocess-pat.rkt
index 5036ae5b31..d815369c0d 100644
--- a/pkgs/redex-pkgs/redex-lib/redex/private/preprocess-pat.rkt
+++ b/pkgs/redex-pkgs/redex-lib/redex/private/preprocess-pat.rkt
@@ -28,7 +28,6 @@
        (ann-pat (add-name subenv n subpat)
                 `(name ,n ,new-subpat))]
       [`(mismatch-name ,n ,subpat)
-       (unimplemented "mismatch")
        (match-define (ann-pat subenv new-subpat) (walk subpat))
        (define tag (get-and-inc!))
        (ann-pat (add-mismatch subenv n subpat tag)
diff --git a/pkgs/redex-pkgs/redex-test/redex/tests/enum-test.rkt b/pkgs/redex-pkgs/redex-test/redex/tests/enum-test.rkt
index b8b44ea76f..11843be174 100644
--- a/pkgs/redex-pkgs/redex-test/redex/tests/enum-test.rkt
+++ b/pkgs/redex-pkgs/redex-test/redex/tests/enum-test.rkt
@@ -98,15 +98,20 @@
 (try-it 25 λv x)
 
 ;; No longer supported
-;; (define-language M
-;;   (m (x_!_1 x_!_1))
-;;   (p (number_!_1 number_!_1))
-;;   (n (p_!_1 p_!_1))
-;;   (x number))
+(define-language M
+  (m (x_!_1 x_!_1))
+  (p (number_!_1 number_!_1))
+  (n (p_!_1 p_!_1))
+  (x number)
 
-;; (try-it 100 M m)
-;; (try-it 100 M n)
-;; (try-it 100 M p)
+  ;; Example of poorly behaved mismatch
+  (ambig (x ... x ...)))
+
+(try-it 100 M m)
+(try-it 100 M n)
+(try-it 100 M p)
+;; Ambiguity kills us here
+;; (try-it 5 M (ambig_!_1 ambig_!_1))
 
 ;; test variable filtering
 (define-language Vars