[Haskell-beginners] how to feel free of the Implementation of Data structure

[Markus Läll]

There's also ListLike: http://hackage.haskell.org/package/ListLike


--
Markus Läll

On Fri, Mar 25, 2011 at 6:32 AM, 吴兴博 <wuxb45 at gmail.com> wrote:

> :) Thanks.
>
> 2011/3/24 Brent Yorgey <byorgey at seas.upenn.edu>:
> > On Thu, Mar 24, 2011 at 06:34:57PM +0800, 吴兴博 wrote:
> >>
> >> 2.
> >> f1 :: (Integral a) => a -> String
> >> f2 :: (Integral a) => String -> a
> >>
> >> pipe = f1 . f2
> >> It is clear that pipe is String -> String,
> >
> > Actually, this code will give an "ambiguous type" error, since the
> > compiler cannot figure out what type 'a' should be.  And the type that
> > is chosen may make a difference for the behavior.
> >
> >> but.(1)How can I know what instance that 'a' is.
> >>     (2)How can I determine what instance of 'a' is.
> >
> > If you know what type you want to use for 'a' you can specify it with
> > a type annotation, like this:
> >
> >  pipe = f1 . (f2 :: String -> Int)
> >
> > -Brent
> >
> > _______________________________________________
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> > Beginners at haskell.org
> > http://www.haskell.org/mailman/listinfo/beginners
> >
>
>
>
> --
> ----------------
> 吴兴博
>
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