Re: [Haskell-cafe] Is there a nicer way to do this?

Don Stewart writes:

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splitAt n xs = (take n xs, drop n xs)

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Thanks. That is odd, though. It makes me wonder what to expect re optimization. Would the compiler/runtime know that splitAt could be done in a single pass?

Not with that definition. It would require some moderately unusual fusion combining the take and drop into a single fold with the (,) on the inside, rather than on the outside.

Uhm, but I'm quite sure I saw a paper about how the garbage collector could discover this, and update both thunks simultaneously. (Unfortunately, I can't seem to find it now.) -k -- If I haven't seen further, it is by standing in the footprints of giants