Question: I totally agree that the second version is much cleaner. But, how does the performance of the two compare in Haskell? "Premature optimization is the

Question: I totally agree that the second version is much cleaner. But, how does the performance of the two compare in Haskell? "Premature optimization is the root of all evil" and all that. But, a sorting routine is something everyone would expect to be as efficient as possible, right? (Maybe it was just for the sake of the example?) I heard 1 or 2 things about Haskell being lazy, etc. Does it makes the second version less inefficient than it looks?