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Monads/List monad: Difference between revisions
→{{header|F_Sharp|F#}}: Add true list monad implementation
(Added C++ implementation) |
(→{{header|F_Sharp|F#}}: Add true list monad implementation) |
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=={{header|F_Sharp|F#}}==
<lang fsharp>
type ListMonad() =
member o.Bind( (m:'a list), (f: 'a -> 'b list) ) = List.concat( List.map f m )
member o.Return(x) = [x]
member o.Zero() = []
let list = ListMonad()
let pyth_triples n = list { let! x = [1..n]
let! y = [x..n]
let! z = [y..n]
if x*x + y*y = z*z then return (x,y,z) }
printf "%A" (pyth_triples 100)
</lang>
(The original example, which follows, variously uses List.iter, a list comprehension and the Result type but doesn't define anything like a list monad.)
<lang fsharp>
// Monads/List monad . Nigel Galloway: March 8th., 2021
Line 408 ⟶ 426:
Error: 10 is greater than 9
</pre>
=={{header|Factor}}==
Factor comes with an implementation of Haskell-style monads in the <code>monads</code> vocabulary.
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