[Haskell-beginners] fold over elem?
daniel.is.fischer at web.de
Fri Sep 19 14:04:03 EDT 2008
Am Freitag, 19. September 2008 19:32 schrieb Logesh Pillay:
> I want to check if all the numbers in a list A are elements of a bigger
> unordered list B.
> Is there some way to fold /A into elem /B?
I suppose what you want is an efficient way to check if all elements of A also
belong to B?
I think if the type of elements belongs to Ord, your best bet, if B is large
but not huge, is to sort B or build a Set from it and exploit the faster
membership tests. If B is huge (or even infinite), that could require too
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