From 01baad11a057d53c77b2f350739f79327c40054b Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Fri, 25 Apr 2008 21:36:37 +0000
Subject: [PATCH] hack evcase to support old and new 'else' bindings

svn: r9481
---
 collects/mzlib/etc.ss                      |  4 +++-
 collects/mzlib/scribblings/etc.scrbl       | 13 +++++++++----
 collects/scribblings/reference/match.scrbl |  8 ++++----
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/collects/mzlib/etc.ss b/collects/mzlib/etc.ss
index 9125609b89..3f9c69703b 100644
--- a/collects/mzlib/etc.ss
+++ b/collects/mzlib/etc.ss
@@ -8,6 +8,7 @@
                build-list
                build-vector
                compose)
+         (rename scheme/base base-else else)
          "kw.ss")
 
 (require-for-syntax syntax/kerncase
@@ -136,8 +137,9 @@
      (let ([tests (syntax->list (syntax (test ...)))])
        (with-syntax ([(a-test ...)
                       (map (lambda (t)
-                             (syntax-case t (else)
+                             (syntax-case t (else base-else)
                                [else (syntax #t)]
+                               [base-else (syntax #t)]
                                [_else (with-syntax ([t t])
                                         (syntax (eqv? evcase-v t)))]))
                            tests)])
diff --git a/collects/mzlib/scribblings/etc.scrbl b/collects/mzlib/scribblings/etc.scrbl
index b272298a0c..28fcd5ee56 100644
--- a/collects/mzlib/scribblings/etc.scrbl
+++ b/collects/mzlib/scribblings/etc.scrbl
@@ -12,11 +12,12 @@
 @interaction-eval[#:eval etc-eval (require mzlib/etc)]
 
 @(begin
-  (define-syntax-rule (bind id)
+  (define-syntax-rule (bind id else-id)
     (begin
      (require (for-label scheme/base))
-     (define id (scheme lambda))))
-  (bind base-lambda))
+     (define id (scheme lambda))
+     (define else-id (scheme else))))
+  (bind base-lambda base-else))
 
 @mzlib[#:mode title etc]
 
@@ -108,7 +109,11 @@ data. After @scheme[key-expr] is evaluated, each @scheme[value-expr]
 is evaluated until a value is found that is @scheme[eqv?] to the key
 value; when a matching value is found, the corresponding
 @scheme[body-expr]s are evaluated and the value(s) for the last is the
-result of the entire @scheme[evcase] expression.}
+result of the entire @scheme[evcase] expression.
+
+The @scheme[else] literal is recognized either as unbound (like in the
+@schememodname[mzscheme] language) or bound as @|base-else| from
+@schememodname[scheme/base].}
 
 
 @defproc[(identity [v any/c]) any/c]{
diff --git a/collects/scribblings/reference/match.scrbl b/collects/scribblings/reference/match.scrbl
index 8c813ff355..728386f4f4 100644
--- a/collects/scribblings/reference/match.scrbl
+++ b/collects/scribblings/reference/match.scrbl
@@ -44,10 +44,10 @@ In more detail, patterns match as follows:
 
 @itemize{
 
- @item{@scheme[_id], excluding the reserved names @schemeidfont{"_"},
-       @schemeidfont{"..."}, @schemeidfont{".._"},
-       @schemeidfont{".."}@scheme[_k], and
-       @schemeidfont{".."}@scheme[_k] for non-negative integers
+ @item{@scheme[_id], excluding the reserved names @schemeidfont{_},
+       @schemeidfont{...}, @schemeidfont{.._},
+       @schemeidfont{..}@scheme[_k], and
+       @schemeidfont{..}@scheme[_k] for non-negative integers
        @scheme[_k] --- matches anything, and binds @scheme[id] to the
        matching values. If an @scheme[_id] is used multiple times
        within a pattern, the corresponding matches must be the same