It's not exactly a question of Haskell's behaviour. The list [ (a,b) | a <-
[0..], b <- [0..] ]
is such that apart from pairs starting with zero, no other pair is
associated with a finite index. In other words, [ (a,b) | a <- [0..], b <-
[0..] ] is not a correct 'enumeration' of all pairs of nonnegative integers.
You need to reorder them if you need a finite index associated with every
pair.
On Fri, May 16, 2008 at 5:12 PM, leledumbo
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. -- View this message in context: http://www.nabble.com/elem-of-infinite-set-of-tuple-tp17272802p17272802.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.
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