new keyword: infixlr?

Bas van Dijk v.dijk.bas at gmail.com
Tue Sep 14 08:11:47 EDT 2010


Oops, I mixed up associative with commutative.

On Tue, Sep 14, 2010 at 1:27 PM, Bas van Dijk <v.dijk.bas at gmail.com> wrote:
> On Mon, Sep 13, 2010 at 4:23 PM, Nick Bowler <nbowler at elliptictech.com> wrote:
>> ... not all Num instances have an associative (+).
>
> Indeed:
>
> $ cabal install repr    # [1]
> ...
> $ ghci
> Prelude> :m Text.Repr
> Prelude Text.Repr> show (1 + 2 :: Repr Int) == show (2 + 1 :: Repr Int)
> False
>
> because:
> show (1 + 2 :: Repr Int) == "1 + 2"
> show (2 + 1 :: Repr Int) == "2 + 1"
>
> but note:
> Prelude Text.Repr> (1 + 2 :: Repr Int) == (2 + 1 :: Repr Int)
> True
>
> Bas
>
> [1] http://hackage.haskell.org/package/repr
>


More information about the Haskell-prime mailing list