dpt at lotus.bostoncoop.net
Sat Nov 20 08:40:37 EST 2004
On Sat, Nov 20, 2004 at 12:47:58PM +0300, Serge D. Mechveliani wrote:
> Is such a function familia to the Haskell users?
> foldlWhile :: (a -> b -> a) -> (a -> Bool) -> a -> [b] -> a
> foldlWhile f p a bs =
> (bs, p a)
> (, _ ) -> a
> (_, False) -> a
> (b:bs', _ ) -> foldlWhile f p (f a b) bs'
> foldl does not seem to cover this.
Why not just
foldlWhile f p a bs = takeWhile p $ foldl f a bs
> More `generic' variant:
> foldlWhileJust :: (a -> b -> Maybe a) -> a -> [b] -> a
> foldlWhileJust f a bs = case bs of
>  -> a
> b:bs' -> case f a b of Just a' -> foldlWhileJust f a' bs'
> _ -> a
I don't know a short way to rewrite this one yet.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Size: 189 bytes
Desc: Digital signature
Url : http://www.haskell.org//pipermail/haskell-cafe/attachments/20041120/a5249de7/attachment.bin
More information about the Haskell-Cafe