Ticket #1267 (closed bug: duplicate)
Strictness of Integer's enumFrom
According to the Haskell report "For all four of these Prelude numeric types, all of the enumFrom family of functions are strict in all their arguments." (referring to Int, Integer, Float, Double). However, Integer's enumFrom and enumFromThen are lazy in their parameters.
main = print $ null [undefined :: Integer ..]
This yields "False", where it should yield _|_.