Summary

amb does not fail when there's no acceptable values

Metadata

• Id: 6f4e1a70793a7696f2822ca429b1ac7e86ced193
• Trac id: 303
• Type: defect
• Reporter: jeronimo
• Owner:
• Cc:
• Status: closed
• Component: extensions
• Estimated difficulty:
• Resolution: fixed
• Priority: minor
• Milestone:
• Version:
• Changetime: 2010-08-25 23:11:38 UTC
• Created: 2010-08-04 15:14:22 UTC
• Keywords: amb egg

Description

Hi,

It seems that amb will not fail at all when there are no acceptable values:

 (let ((a (amb 1 2 3))
       (b (amb -1 -2 -3)))
   (required (> (+ a b) 10))
   (print (list a b)))
 
 ==> (3 -1)

As I understand, it should have failed just like (amb) without arguments would...

This is version 2.1.2 of amb with Chicken 4.5.7 (experimental).

J.

Changes and comments

[2010-08-06 23:04:39 UTC] kon changed status from new to closed

[2010-08-06 23:04:39 UTC] kon set resolution to worksforme

[2010-08-06 23:04:39 UTC] kon wrote:

csi -n

CHICKEN (c)2008-2010 The Chicken Team (c)2000-2007 Felix L. Winkelmann Version 4.5.6 macosx-unix-gnu-ppc [[|symbolgc manyargs dload ptables gchooks ]] compiled 2010-07-10 on Nikko-2.local (Darwin) #;1> (use amb amb-extras)

#;2> (let ((a (amb 1 2 3))

     (b (amb -1 -2 -3)))
 (required (> (+ a b) 10))
 (print (list a b)))

Error: (amb) expression tree exhausted

Call history:

<eval>		(> (+ a b) 10)
<eval>		(+ a b)
<eval>		((amb#amb-failure-continuation))
<eval>		(amb#amb-failure-continuation)
<eval>		(> (+ a b) 10)
<eval>		(+ a b)
<eval>		((amb#amb-failure-continuation))
<eval>		(amb#amb-failure-continuation)	<--

[2010-08-25 20:10:11 UTC] jeronimo changed status from closed to reopened

[2010-08-25 20:10:11 UTC] jeronimo removed version 4.6.0

[2010-08-25 20:10:11 UTC] jeronimo removed resolution worksforme

[2010-08-25 20:10:11 UTC] jeronimo wrote:

Hi,

It seems that the bug is now reproducible with the master branch of Chicken also:

 $ csi
 
 CHICKEN
 (c)2008-2010 The Chicken Team
 (c)2000-2007 Felix L. Winkelmann
 Version 4.6.0rc1 
 linux-unix-gnu-x86-64 [ 64bit manyargs dload ptables ]
 compiled 2010-08-09 on newton (Linux)
 
 #;1> (use amb amb-extras)
 ...
 #;2> (let ((a (amb 1 2 3)) (b (amb -3 -2 -1))) (required (= (+ a b) 0)) (list a b))
 (1 -1)
 #;3> (let ((a (amb 1 2 3)) (b (amb -3 -2 -1))) (required (= (+ a b) 10)) (list a b))
 (2 -2)
 #;4> (let ((a (amb 1 2 3)) (b (amb -3 -2 -1))) (required (= (+ a b) 0)) (list a b))
 (1 -1)
 #;5> (let ((a (amb 1 2 3)) (b (amb -3 -2 -1))) (required (= (+ a b) 0)) (required (even? a)) (list a b))
 (2 -2)
 #;6> (let ((a (amb 1 2 3)) (b (amb -3 -2 -1))) (required (= (+ a b) 50)) (required (even? a)) (list a b))
 (2 -2)

This is fc8d57e897df9eefd638b9358250fbd3069c70f9 from git master; I have reinstalled amb before running these tests.

[2010-08-25 23:11:38 UTC] jeronimo changed status from reopened to closed

[2010-08-25 23:11:38 UTC] jeronimo set resolution to fixed

[2010-08-25 23:11:38 UTC] jeronimo wrote:

... and a couple of hours later, with aa5874e1fc35c8d343771ce9dd954b87dc3551a0, the bug is gone. Sorry for the noise!