additions to Data.Map
lemming at henning-thielemann.de
Fri Aug 11 10:06:48 EDT 2006
On Fri, 11 Aug 2006, Ross Paterson wrote:
> On Fri, Aug 11, 2006 at 03:24:18PM +0200, Henning Thielemann wrote:
> > On Fri, 11 Aug 2006, Ross Paterson wrote:
> > > -- | /O(n)/. Map values and separate the 'Left' and 'Right' results.
> > > mapEither :: Ord k => (a -> Either b c) -> Map k a -> (Map k b, Map k c)
> > Looks more like 'partition' than 'map'.
> It's a bit of both, in the same way as mapMaybe (from Data.Maybe)
> combines map and filter.
How would you name a function with signature
??? :: Ord k => (a -> Maybe b) -> Map k a -> (Map k a, Map k b)
which returns the list of elements that resulted in Nothing and the list
of elements that could be translated to Just? It holds
mapMaybe f = snd . ??? f
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