[Haskell-cafe] how to break foldl' ?

Henning Thielemann lemming at henning-thielemann.de
Fri Sep 30 06:52:58 EDT 2005

On Fri, 30 Sep 2005, gary ng wrote:

> Hi,
> say if I want to sum a list of numbers but only until
> it hits a max limit.
> Currently, I control it through the function and
> basically do nothing when the max is hit. However, if
> the list is very long, would this mean the same
> function would be called for the rest of the list
> which can be a waste of cycle ?

Depends on how you implemented it. If your implementation ignores the
result of the rest of the list, then it won't be computed.

This should work as expected:
  takeWhile (<maxX) (scanl (+) 0 xs)

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