[Haskell-cafe] lists with mixed types

[Lennart Augustsson]

Well, in this example I don't see how this would even be close to possible.
How would it know that 1 is supposed to be an Int a2.0 a Float?  1 has type
'Num a => a'  and 2.0 has type 'Fractional a => a' so how the compiler know
you want Int and Float?

  -- Lennart

On 6/16/07, Anatoly Yakovenko <aeyakovenko at gmail.com> wrote:
>
> If I define something like this:
>
> data Bar = Bi Int
>          | Bf String
>          deriving Show
>
> data Foo = Fi Int
>          | Fs Float
>          deriving Show
>
> func::Foo -> Bar
> func (Fi xx) = Bi xx
> func (Fs ff) = Bf (show ff)
>
> I can do:
> > map func [(Fi 1), (Fs 2.0)]
> [Bi 1,Bf "2.0"]
>
> but what i really want to do is just do
> map func [1, 2.0]
> [1, "2.0"]
>
> I understand that this is impossible in haskell, but why cant the
> compiler generate the Foo and Bar data types for me and just require
> that i have a func defined for Int -> Int and Float -> String?
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe at haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.haskell.org/pipermail/haskell-cafe/attachments/20070617/965819fc/attachment.htm