Proposal: Strict scanl, scanl1 and mapAccumL
lemming at henning-thielemann.de
Mon Nov 12 11:17:09 CET 2012
On Mon, 12 Nov 2012, Bas van Dijk wrote:
> On 12 November 2012 10:41, Henning Thielemann
> <lemming at henning-thielemann.de> wrote:
>> There was already a discussion some weeks ago
> Thanks, I missed that one. It seems it didn't reach a conclusion yet.
> Maybe we can continue the discussion here.
My impression is that making 'seq' available as function without a
typeclass constraint was a step in the wrong direction. Then foldl' and
friends were the second step in the wrong direction and scanl' would be
the third step. For 'seq' I would propose we first start with a cleanly
typed 'seq' and base foldl' functions on this function instead of the
built-in 'seq'. But I assume that most of the time where foldl' is used,
actually a deepseq-foldl' is meant. I have often seen foldl' in Haskell
library code that had not the intended effect since the accumulator was a
lazy pair or a Map.
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