[Haskell-cafe] elem of infinite set of tuple

leledumbo leledumbo_cool at yahoo.co.id
Fri May 16 07:42:31 EDT 2008


I don't know how Haskell should behave on this. Consider this function:
elemOf (x,y) = (x,y) `elem` [ (a,b) | a <- [0..], b <- [0..] ]

If I try to query elemOf (1,1), the program keeps searching and searching
but it never makes it. But if I query elemOf (0,1) (or anything as long as
the first element is 0), it can find it easily. I wonder how it's handled.

>From my point of view, instead of starting from (1,0), the program starts
from (0,0), which will never finish since the limit of the second element is
infinite.
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