Re: [GHC] #10688: Incorrect program produced, different result with equivalent code

25 Jul 2015

      #10688: Incorrect program produced, different result with equivalent code
-------------------------------------+-------------------------------------
        Reporter:  Ideophage         |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  lowest            |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------
Changes (by Ideophage):

 * priority:  normal => lowest

Old description:
...
The program enters an infinite loop (100% cpu, not stopping) because it
fails to recognize the stopping condition of a takeWhile. If we make the
list finite, it takes all the elements while it should stop before.
I don't know how to simplify the code since if I change it a little (e.g.
by replacing the name of an object by its definition), sometimes it works
well, sometimes not.
When I enter the code in ghci, it works well but not when compiled.
I don't know if I should explain what the code was for initially, tell
me.
New description:

 The program enters an infinite loop (100% cpu, not stopping) because it
 fails to recognize the stopping condition of a `takeWhile`. If we make the
 list finite, it takes all the elements while it should stop before.

 I don't know how to simplify the code since if I change it a little (e.g.
 by replacing the name of an object by its definition), sometimes it works
 well, sometimes not.

 When I enter the code in ghci, it works well but not when compiled.

 I don't know if I should explain what the code was for initially, tell me.

 edit :
 Actually, I realized that this is not a bug. This is due to the lack of
 type signatures in my program. I thought that was a bug because sometimes
 the program used `Int`s, sometimes `Integer`s, and just expanding a
 definition can change this (see the code in attachment). I apologize for
 opening a ticket for that (I thought `Integer`s were used since it is the
 case in ghci).

--

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10688#comment:2
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler