[Haskell-cafe] curious about sum
max.rabkin at gmail.com
Wed Jun 17 07:25:32 EDT 2009
On Wed, Jun 17, 2009 at 1:07 PM, Henk-Jan van Tuyl<hjgtuyl at chello.nl> wrote:
> On Wed, 17 Jun 2009 10:38:23 +0200, Yitzchak Gale <gale at sefer.org> wrote:
> An improved reverse function:
> reverse' = foldl' (flip (:)) 
> There is no need for reverse to be lazy, so this one could replace the
> original one.
> reverse' is not too strict:
> Data.List> let reverse' = foldl' (flip (:))  in head $ reverse'
> [undefined, 1]
Since reverse' is polymorphic in the type of list elements, the only
way it could be strict in the *elements* is if it applied seq to them.
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