[Haskell-cafe] how to break foldl' ?

[Henning Thielemann]

On Fri, 30 Sep 2005, gary ng wrote:

> > This should work as expected:
> >   takeWhile (<maxX) (scanl (+) 0 xs)
>
> Thanks. But how would I think about using scanl
> instead of foldl(or foldl') when I want is the sum,
> but not the progressive result. Once again show me
> that I need to throw away all imperative stuff.

No problem:
  last (takeWhile (<maxX) (scanl (+) 0 xs))
    Convinced?

The first sum which exceeds the limit could be computed with
  head (dropWhile (<=maxX) (scanl (+) 0 xs))