[Haskell-cafe] How to write fast for loops
mail at nh2.me
Sat Apr 26 21:40:50 UTC 2014
As you probably now, `forM_ [1..n]` is incredibly slow in Haskell due to
lack of list fusion ; a manually written loop is 10x faster.
How do you people work around this?
I keep defining myself something like
loop :: (Monad m) => Int -> (Int -> m ()) -> m ()
loop bex f = go 0
go !n | n == bex = return ()
| otherwise = f n >> go (n+1)
Is there a function for this somewhere already?
Or do you have another way to deal with this problem?
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