[Haskell-cafe] Re: Reinvention

[J. Garrett Morris]

More generally, that's unfoldr:

Prelude> :t Data.List.unfoldr
Data.List.unfoldr :: (b -> Maybe (a, b)) -> b -> [a]

unfoldr represents the end of the unfold explicitly (using Nothing)
instead of implicitly (using the empty list).

 /g

On 27 Jun 2007 20:26:56 +0100, Jon Fairbairn <jon.fairbairn at cl.cam.ac.uk> wrote:
> Andrew Coppin <andrewcoppin at btinternet.com> writes:
>
> > I seem to be forever writing code that looks like this:
> >
> > decode :: String -> (SKI,String)
> > decode (c:cs) = case c of
> >   'S' -> (S,cs)
> >   'K' -> (K,cs)
> >   'I' -> (I,cs)
> >   '*' -> let (e0,cs0) = decode cs; (e1,cs1) = decode cs1 in (e0 :@: e1, cs1)
>
> This looks like parsing to me.
>
> --
> Jón Fairbairn                                 Jon.Fairbairn at cl.cam.ac.uk
>
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