RE: [Haskell-cafe] Are there performant mutable Arrays in Haskell?

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To make a long story short, here is the library code: elems arr = case bounds arr of (_l, _u) -> [unsafeAt arr i | i <- [0 .. numElements arr - 1]

And my version: boundedElems arr = case bounds arr of (_l, _u) -> [unsafeAt arr i | i <- [1737 .. 1752]]

Is there a reason, why the library version is 4 times faster, than mine?

There shouldn't be any reason. Try putting

{-# INLINE boundedElems #-}

to make it inline, it might be faster.

Ah, ok, did that, but no difference. :) If I got it right, for the library version exists a C-translation while for my version there isn't.