[Haskell-cafe] Non polymorphic numerals option -- avoiding type classes

[Kim-Ee Yeoh]

Hi David, it looks like Rustom's aware that haskell's not lisp. What he
really wants methinks is a way to suppress type classes altogether! That or
a NoOverloadedNumerals extension.

-- Kim-Ee


On Thu, Dec 27, 2012 at 4:03 PM, David Virebayre <dav.vire+haskell at gmail.com
> wrote:

> Prelude> :t [[1,2],3]
>
> you have a list with 2 elements:
> - [1,2]
> - 3
> the type of [1,2] is [Integer]
> the type of 3 is Integer
>
> But all elements in a list must have the same type.
>
>
>
>
>
> 2012/12/27 Rustom Mody <rustompmody at gmail.com>:
> >
> >
> > On Thu, Dec 27, 2012 at 1:48 AM, Roman Cheplyaka <roma at ro-che.info>
> wrote:
> >>
> >> * Rustom Mody <rustompmody at gmail.com> [2012-12-26 20:12:17+0530]
> >> > So is there any set of flags to make haskell literals less
> polymorphic?
> >>
> >> Yes, there is!
> >>
> >>   % ghci -XRebindableSyntax
> >>   GHCi, version 7.6.1: http://www.haskell.org/ghc/  :? for help
> >>   Loading package ghc-prim ... linking ... done.
> >>   Loading package integer-gmp ... linking ... done.
> >>   Loading package base ... linking ... done.
> >>   > import Prelude hiding (fromInteger)
> >>   Prelude> let fromInteger = id
> >>   Prelude> :t 3
> >>   3 :: Integer
> >>
> >> Roman
> >
> >
> >
> > Thanks Roman -- that helps.
> > And yet the ghci error is much more obscure than the gofer error:
> >
> > --- contents of .ghci ---
> > :set -XRebindableSyntax
> > let fromInteger = id
> > ------ ghci session -----
> > $ ghci
> > GHCi, version 7.4.1: 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> :t 5
> > 5 :: Integer
> > Prelude> :t [[1,2],3]
> >
> > <interactive>:1:8:
> >     Couldn't match expected type `[Integer]' with actual type `Integer'
> >     Expected type: Integer -> [Integer]
> >       Actual type: Integer -> Integer
> >     In the expression: 3
> >     In the expression: [[1, 2], 3]
> >
> >
> > ----- The same in gofer -----
> > Gofer session for:
> > pustd.pre
> > ? :t [[1,2],3]
> >
> >
> > ERROR: Type error in list
> > *** expression     : [[1,2],3]
> >
> > *** term           : 3
> > *** type           : Int
> > *** does not match : [Int]
> > --------------
> > So the error is occurring at the point of the fromInteger (= id) but the
> > message does not indicate that
> >
> > --
> > http://www.the-magus.in
> > http://blog.languager.org
> >
> >
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> > http://www.haskell.org/mailman/listinfo/haskell-cafe
> >
>
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