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[pure-lang-svn] SF.net SVN: pure-lang: [144] pure/trunk
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From: <ag...@us...> - 2008-05-27 09:28:37
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Revision: 144
http://pure-lang.svn.sourceforge.net/pure-lang/?rev=144&view=rev
Author: agraef
Date: 2008-05-27 02:28:46 -0700 (Tue, 27 May 2008)
Log Message:
-----------
Disable TCO of logical operators, it's broken by design.
Modified Paths:
--------------
pure/trunk/ChangeLog
pure/trunk/interpreter.cc
pure/trunk/interpreter.hh
pure/trunk/lib/prelude.pure
pure/trunk/test/prelude.log
Modified: pure/trunk/ChangeLog
===================================================================
--- pure/trunk/ChangeLog 2008-05-27 09:18:50 UTC (rev 143)
+++ pure/trunk/ChangeLog 2008-05-27 09:28:46 UTC (rev 144)
@@ -1,10 +1,10 @@
2008-05-27 Albert Graef <Dr....@t-...>
* interpreter.cc (toplevel_codegen): Experimental support for
- tail-recursive short-circuit logical operators (&& and ||). Note
- that this makes these operations behave slightly differently (more
- like if-then-else) if they form the right-hand side of an
- equation. But the advantages seem to outweigh the semantic quirks.
+ tail-recursive logical operators (&& and ||). This works but is
+ disabled, since it makes these operations behave in different ways
+ depending on the context, which is a really bad idea because it
+ violates referential transparency.
2008-05-26 Albert Graef <Dr....@t-...>
Modified: pure/trunk/interpreter.cc
===================================================================
--- pure/trunk/interpreter.cc 2008-05-27 09:18:50 UTC (rev 143)
+++ pure/trunk/interpreter.cc 2008-05-27 09:28:46 UTC (rev 144)
@@ -3224,6 +3224,11 @@
return 0;
}
+/* Experimental support for tail-recursive logical operators (&& and ||). This
+ works, but is inherently broken (e.g., 0||-1 might return either -1 or 1,
+ depending on whether the code is TCO'ed or not). Never use this. */
+#define TAILOPS 0
+
void interpreter::toplevel_codegen(expr x)
{
#if USE_FASTCC
Modified: pure/trunk/interpreter.hh
===================================================================
--- pure/trunk/interpreter.hh 2008-05-27 09:18:50 UTC (rev 143)
+++ pure/trunk/interpreter.hh 2008-05-27 09:28:46 UTC (rev 144)
@@ -28,11 +28,6 @@
/* Experimental support for the "fast" calling convention which is needed to
get tail call elimination. */
#define USE_FASTCC 1
-/* Experimental support for tail-recursive short-circuit logical operators (&&
- and ||). This will only have an effect if USE_FASTCC is enabled. Note that
- if you disable this option, && and || will still be short-curcuit, they
- just won't be tail-recursive in their second operand any more. */
-#define TAILOPS 1
using namespace std;
Modified: pure/trunk/lib/prelude.pure
===================================================================
--- pure/trunk/lib/prelude.pure 2008-05-27 09:18:50 UTC (rev 143)
+++ pure/trunk/lib/prelude.pure 2008-05-27 09:28:46 UTC (rev 144)
@@ -98,12 +98,12 @@
()==() = 1;
(x,xs)==() = 0;
()==(x,xs) = 0;
-(x,xs)==(y,ys) = x==y && xs==ys;
+(x,xs)==(y,ys) = if x==y then xs==ys else 0;
()!=() = 0;
(x,xs)!=() = 1;
()!=(x,xs) = 1;
-(x,xs)!=(y,ys) = x!=y || xs!=ys;
+(x,xs)!=(y,ys) = if x!=y then 1 else xs!=ys;
null () = 1;
null (x,xs) = 0;
@@ -136,12 +136,12 @@
[]==[] = 1;
(x:xs)==[] = 0;
[]==(x:xs) = 0;
-(x:xs)==(y:ys) = x==y && xs==ys;
+(x:xs)==(y:ys) = if x==y then xs==ys else 1;
[]!=[] = 0;
(x:xs)!=[] = 1;
[]!=(x:xs) = 1;
-(x:xs)!=(y:ys) = x!=y || xs!=ys;
+(x:xs)!=(y:ys) = if x!=y then 1 else xs!=ys;
null [] = 1;
null (x:xs) = 0;
@@ -214,10 +214,10 @@
to make them tail-recursive. */
all p [] = 1;
-all p (x:xs) = p x && all p xs;
+all p (x:xs) = if p x then all p xs else 0;
any p [] = 0;
-any p (x:xs) = p x || any p xs;
+any p (x:xs) = if p x then 1 else any p xs;
do f [] = ();
do f (x:xs) = do f xs when _ = f x end;
Modified: pure/trunk/test/prelude.log
===================================================================
--- pure/trunk/test/prelude.log 2008-05-27 09:18:50 UTC (rev 143)
+++ pure/trunk/test/prelude.log 2008-05-27 09:28:46 UTC (rev 144)
@@ -338,11 +338,11 @@
()==() = 1;
(x/*0:0101*/,xs/*0:011*/)==() = 0;
()==(x/*0:101*/,xs/*0:11*/) = 0;
-(x/*0:0101*/,xs/*0:011*/)==(y/*0:101*/,ys/*0:11*/) = x/*0:0101*/==y/*0:101*/&&xs/*0:011*/==ys/*0:11*/;
+(x/*0:0101*/,xs/*0:011*/)==(y/*0:101*/,ys/*0:11*/) = if x/*0:0101*/==y/*0:101*/ then xs/*0:011*/==ys/*0:11*/ else 0;
()!=() = 0;
(x/*0:0101*/,xs/*0:011*/)!=() = 1;
()!=(x/*0:101*/,xs/*0:11*/) = 1;
-(x/*0:0101*/,xs/*0:011*/)!=(y/*0:101*/,ys/*0:11*/) = x/*0:0101*/!=y/*0:101*/||xs/*0:011*/!=ys/*0:11*/;
+(x/*0:0101*/,xs/*0:011*/)!=(y/*0:101*/,ys/*0:11*/) = if x/*0:0101*/!=y/*0:101*/ then 1 else xs/*0:011*/!=ys/*0:11*/;
null () = 1;
null (x/*0:101*/,xs/*0:11*/) = 0;
#() = 0;
@@ -412,11 +412,11 @@
[]==[] = 1;
x/*0:0101*/:xs/*0:011*/==[] = 0;
[]==x/*0:101*/:xs/*0:11*/ = 0;
-x/*0:0101*/:xs/*0:011*/==y/*0:101*/:ys/*0:11*/ = x/*0:0101*/==y/*0:101*/&&xs/*0:011*/==ys/*0:11*/;
+x/*0:0101*/:xs/*0:011*/==y/*0:101*/:ys/*0:11*/ = if x/*0:0101*/==y/*0:101*/ then xs/*0:011*/==ys/*0:11*/ else 1;
[]!=[] = 0;
x/*0:0101*/:xs/*0:011*/!=[] = 1;
[]!=x/*0:101*/:xs/*0:11*/ = 1;
-x/*0:0101*/:xs/*0:011*/!=y/*0:101*/:ys/*0:11*/ = x/*0:0101*/!=y/*0:101*/||xs/*0:011*/!=ys/*0:11*/;
+x/*0:0101*/:xs/*0:011*/!=y/*0:101*/:ys/*0:11*/ = if x/*0:0101*/!=y/*0:101*/ then 1 else xs/*0:011*/!=ys/*0:11*/;
null [] = 1;
null (x/*0:101*/:xs/*0:11*/) = 0;
#[] = 0;
@@ -640,9 +640,9 @@
state 1: #0
}) n/*0:01*/;
all p/*0:01*/ [] = 1;
-all p/*0:01*/ (x/*0:101*/:xs/*0:11*/) = p/*0:01*/ x/*0:101*/&&all p/*0:01*/ xs/*0:11*/;
+all p/*0:01*/ (x/*0:101*/:xs/*0:11*/) = if p/*0:01*/ x/*0:101*/ then all p/*0:01*/ xs/*0:11*/ else 0;
any p/*0:01*/ [] = 0;
-any p/*0:01*/ (x/*0:101*/:xs/*0:11*/) = p/*0:01*/ x/*0:101*/||any p/*0:01*/ xs/*0:11*/;
+any p/*0:01*/ (x/*0:101*/:xs/*0:11*/) = if p/*0:01*/ x/*0:101*/ then 1 else any p/*0:01*/ xs/*0:11*/;
do f/*0:01*/ [] = ();
do f/*0:01*/ (x/*0:101*/:xs/*0:11*/) = do f/*1:01*/ xs/*1:11*/ when _/*0:*/ = f/*0:01*/ x/*0:101*/ {
rule #0: _ = f x
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