[Haskell-beginners] will GHC optimize pattern-matching on integers?

Suppose I am doing a pattern match on a large number of consecutive (or mostly-consecutive) integers: foo 0 = something foo 1 = somethingElse ... foo 1000 = anotherThing Will GHC optimize this to a table lookup, or is it going to test each integer in turn? Am I better off using a Vector or Map instead of pattern matching? Thanks, --Patrick