Different behaviors between GHC 7.6.3 and 7.8.3
Hello everyone, I'm quite intrigued about these different behaviors between GHCs 7.6.3 and 7.8.3: GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let x = 3 + 4 Prelude> :print x x = (_t1::Integer) Prelude> :force x x = 7 Prelude> print _t1 7 Prelude> GHCi, version 7.8.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let x = 3 + 4 Prelude> :print x x = (_t1::Num a => a) Prelude> :force x x = _ Prelude> print _t1 ghc: panic! (the 'impossible' happened) (GHC version 7.8.3 for x86_64-unknown-linux): tcTyVarDetails a{tv atm} [tv] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Is it really a bug or is it something I really shouldn't be doing? I've found this (fixed) bug (https://ghc.haskell.org/trac/ghc/ticket/8557), with a similar error output, but it does not seem to be the same case. Thanks Emilio
Testing on 7.8.2: GHCi, version 7.8.2: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let x = 3 + 4 Prelude> :print x x = (_t1::Num a => a) Prelude> :force x x = _ Prelude> :print _t1 _t1 = (_t2::Num a => a) Prelude> On Tue, Sep 30, 2014 at 7:03 PM, Emilio De Camargo Francesquini < francesquini@gmail.com> wrote:
Hello everyone,
I'm quite intrigued about these different behaviors between GHCs 7.6.3 and 7.8.3:
GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let x = 3 + 4 Prelude> :print x x = (_t1::Integer) Prelude> :force x x = 7 Prelude> print _t1 7 Prelude>
GHCi, version 7.8.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let x = 3 + 4 Prelude> :print x x = (_t1::Num a => a) Prelude> :force x x = _ Prelude> print _t1 ghc: panic! (the 'impossible' happened) (GHC version 7.8.3 for x86_64-unknown-linux): tcTyVarDetails a{tv atm} [tv]
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Is it really a bug or is it something I really shouldn't be doing? I've found this (fixed) bug (https://ghc.haskell.org/trac/ghc/ticket/8557), with a similar error output, but it does not seem to be the same case.
Thanks
Emilio
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-- Cheers, Hamid.
On Tue, 30 Sep 2014 17:33:51 +0200, Emilio De Camargo Francesquini
GHCi, version 7.8.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let x = 3 + 4 Prelude> :print x x = (_t1::Num a => a) Prelude> :force x x = _ Prelude> print _t1 ghc: panic! (the 'impossible' happened) (GHC version 7.8.3 for x86_64-unknown-linux): tcTyVarDetails a{tv atm} [tv]
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Is it really a bug or is it something I really shouldn't be doing?
It seems to me that _t1 is a temporary name, therefore it is not meaningful to print _t1; GHCi should give a message telling that _t1 is not defined, not a panic message. It is best to write a bug report for this. Regards, Henk-Jan van Tuyl -- Folding@home What if you could share your unused computer power to help find a cure? In just 5 minutes you can join the world's biggest networked computer and get us closer sooner. Watch the video. http://folding.stanford.edu/ http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming --
Hello,
That, however, does not explain why
Prelude> :force x
x = _
did not evaluate "x". I finally found the related bug and apparently it is
indeed a known problem: https://ghc.haskell.org/trac/ghc/ticket/9046
Thanks!
Emilio
2014-10-01 9:02 GMT-03:00 Henk-Jan van Tuyl
On Tue, 30 Sep 2014 17:33:51 +0200, Emilio De Camargo Francesquini < francesquini@gmail.com> wrote:
:
GHCi, version 7.8.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let x = 3 + 4 Prelude> :print x x = (_t1::Num a => a) Prelude> :force x x = _ Prelude> print _t1 ghc: panic! (the 'impossible' happened) (GHC version 7.8.3 for x86_64-unknown-linux): tcTyVarDetails a{tv atm} [tv]
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Is it really a bug or is it something I really shouldn't be doing?
It seems to me that _t1 is a temporary name, therefore it is not meaningful to print _t1; GHCi should give a message telling that _t1 is not defined, not a panic message. It is best to write a bug report for this.
Regards, Henk-Jan van Tuyl
-- Folding@home What if you could share your unused computer power to help find a cure? In just 5 minutes you can join the world's biggest networked computer and get us closer sooner. Watch the video. http://folding.stanford.edu/
http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming --
participants (3)
-
Emilio De Camargo Francesquini -
Hamid -
Henk-Jan van Tuyl