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@haskell.org [mailto:glasgow-haskell-users- | bounces@haskell.org] On Behalf Of Sjoerd Visscher | Sent: 28 October 2012 11:46 | To: José Romildo Malaquias | Cc: glasgow-haskell-users@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 | 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 | > _______________________________________________ | > Glasgow-haskell-users mailing list | > Glasgow-haskell-users@haskell.org | > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users | | | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users@haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users