[Haskell-cafe] Efficiency question

[Evil Bro]

> Counting can be done elegantly by 'filter' and 'length':
I figured out the following code after posting:

solve d = length [(y,x) | x <- [2..d], y <- [1..(x-1)], gcd x y == 1]
main = print (solve 1000000)

However when running it, it gave an answer of -1255316543. How on earth can
a length be negative?

> length $ filter (>1) $ Monad.liftM2 gcd [2..1000] [2..1000]
Thanks... now I'll just have to figure out what it does and why it does what
it does.


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