List comprehensions: Difference between revisions
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(→{{header|Haskell}}: (pure and empty in lieu of return and mzero)) |
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and both of the above could be de-sugared to: |
and both of the above could be de-sugared to: |
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<lang haskell>import Control. |
<lang haskell>import Control.Applicative (empty) |
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pyth :: Int -> [(Int, Int, Int)] |
pyth :: Int -> [(Int, Int, Int)] |
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[y .. n] >>= |
[y .. n] >>= |
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\z -> |
\z -> |
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case x ^ 2 + y ^ 2 == z ^ 2 of |
case (((x ^ 2) + (y ^ 2)) == (z ^ 2)) of |
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True -> |
True -> pure (x, y, z) |
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False -> |
False -> empty</lang> |
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which can be further specialised (given the particular context of the list monad, in which >>= is concatMap) to: |
which can be further specialised (given the particular context of the list monad, in which >>= is concatMap, pure is flip (:) [], and empty is []) to: |
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<lang haskell>pyth :: Int -> [(Int, Int, Int)] |
<lang haskell>pyth :: Int -> [(Int, Int, Int)] |
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