cvs commit: fptools/libraries/base package.conf.in
fptools/libraries/base/Data IntMap.hs IntSet.hs Map.hs FiniteMap.hs Set.hs
ketil+haskell at ii.uib.no
Mon Jan 17 03:48:16 EST 2005
Tomasz Zielonka <tomasz.zielonka at gmail.com> writes:
>> Hmmm...I have perhaps a rather shallow reason. When using a FiniteMap
>> to collect lists of values, I think it will be more efficient to use
>> (flip (++)), prepending instead of appending each new element.
> If (flip (++)) is efficient for one interface, shouldn't (++) be as efficient
> for the other?
Yes. Sorry if that wasn't clear; my point was that the new interface
saves you the 'flip' -- or alternatively, the naive user not
considering these issues will likely just use (++), which may be more
efficient for the new interface.
> Why not use efficient catenable sequences or a ShowS trick, like here:
> groupFM :: Ord a => [(a, b)] -> FiniteMap a [b]
> groupFM l =
> mapFM (\_ -> ($ )) $
> addListToFM_C (.) emptyFM [ (a, (b:)) | (a, b) <- l ]
Because it is more complex? It's a neat trick, but it does takes me a
minute or two to see what's going on. Perhaps groupFM should be part
If I haven't seen further, it is by standing in the footprints of giants
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