[Haskell-beginners] Different behaviors between GHC 7.6.3 and 7.8.3

[Hamid]

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 at 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
>
>
>
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://www.haskell.org/mailman/listinfo/beginners
>
>


-- 
Cheers,
Hamid.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/beginners/attachments/20141001/609b5571/attachment.html>