[Haskell-beginners] Haskell laziness and data structures.

Hello, Why is there no default O(1) random access list data structure in haskell (for example clojure has [] vector). I would expect that this kind of data structure is used very often, so you shouldn't need to import one yourself. Is it safe to assume that ' reverse [1, 2, 3, 4, 5] ' is O(1) ? Is it safe to assume that main = x = [1, 2, 3, 4, 5] x = reverse reverse x won't use more space than for the initial [1, 2, 3, 4, 5] list? (No copy of x) Why is array indexeded by ! and list by !!. Shouldn't they be both instances of something like Indexable? King regards, Ford