Proposal: Add strict versions of foldlWithKey and
insertLookupWithKey to Data.Map
nominolo at googlemail.com
Thu Sep 2 21:00:13 EDT 2010
On 29 August 2010 14:34, Johan Tibell <johan.tibell at gmail.com> wrote:
> Proposal: Add strict versions of foldlWithKey and insertLookupWithKey to
> This proposal depends on #4277 .
> The current Data.Map API lacks two important functions:
> * A strict left (pre-order) fold -- needed to e.g. sum all the values in
> a map efficiently.
> * A strict insertLookupWithKey' -- needed to e.g. update an integer
> counter and retrieve the previous value in a single traversal.
> The benchmark we ran indicates that foldlWithKey' is 95% faster than its
> lazy counter part.insertLookupWithKey' is only 6% faster, but the speedup is
> highly dependent on how many times each element is update. Each element was
> only updated once in our benchmark so real speedups should be larger.
> The consideration period is 3 weeks.
> 1. http://hackage.haskell.org/trac/ghc/ticket/4277
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