ghc: panic! (the 'impossible' happened)

[Simon Peyton-Jones]

Thanks.  Certainly a bug. I've created a ticket http://hackage.haskell.org/trac/ghc/ticket/7372.

Turns out that it's fixed in HEAD already, and I *think* the fix is in http://hackage.haskell.org/trac/ghc/ticket/7312, which should get into 7.6.2.

Simon

|  -----Original Message-----
|  From: glasgow-haskell-users-bounces at haskell.org [mailto:glasgow-haskell-users-
|  bounces at haskell.org] On Behalf Of Sjoerd Visscher
|  Sent: 28 October 2012 11:46
|  To: José Romildo Malaquias
|  Cc: glasgow-haskell-users at haskell.org
|  Subject: Re: ghc: panic! (the 'impossible' happened)
|  
|  You can avoid the error by replacing
|  
|    eval :: Exp -> (->) Memory Integer
|  
|  with
|  
|    eval :: Exp -> Memory -> Integer
|  
|  which should be the same, but apparently isn't internally in GHC. This is definitely
|  a bug.
|  
|  Sjoerd
|  
|  On Oct 28, 2012, at 4:55 AM, José Romildo Malaquias <j.romildo at gmail.com>
|  wrote:
|  
|  > Hello.
|  >
|  > Today I wrote a small program to experiment with the Applicative
|  > class. The program is supposed to use an "applicative reader", similar
|  > to a "monad reader", to evaluate arithmetic expressions.
|  >
|  > But when compiling the program with ghc-7.6.1, I get the following message:
|  >
|  >  $ ghc --make applicative-eval
|  >  [1 of 1] Compiling Main             ( applicative-eval.hs, applicative-eval.o )
|  >  ghc: panic! (the 'impossible' happened)
|  >    (GHC version 7.6.1 for x86_64-unknown-linux):
|  >    expectJust cpeBody:collect_args
|  >
|  >  Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
|  >
|  > If the line
|  >
|  >  eval (Let s a b) = \m -> eval b ((s,eval a m):m)
|  >
|  > is commented out, the program compiles without problems.
|  >
|  > Is this a known issue with the compiler?
|  >
|  > The source code is attached.
|  >
|  > Romildo
|  > <applicative-
|  eval.hs>_______________________________________________
|  > Glasgow-haskell-users mailing list
|  > Glasgow-haskell-users at haskell.org
|  > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
|  
|  
|  _______________________________________________
|  Glasgow-haskell-users mailing list
|  Glasgow-haskell-users at haskell.org
|  http://www.haskell.org/mailman/listinfo/glasgow-haskell-users