Monads/List monad: Difference between revisions
Realize in F#
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</lang>
=={{header|F_Sharp|F#}}==
<lang fsharp>
// Monads/List monad . Nigel Galloway: March 8th., 2021
List.iter ((+) 1>>(*) 2>>printf "%d ") [3;4;5]; printfn "";;
let pT n=[for i in 1..n do for g in i+1..n do for n in g+1..n do if i*i+g*g=n*n then yield(i,g,n)]
Seq.iter(printf "%A ")(pT 25)
let fN g=match g<10 with false->Error "is greater than 9"|_->Ok g
let fG n=match n>5 with false->Error "is less than 6" |_->Ok n
let valid n=n|>Result.bind fN|>Result.bind fG
let test n=match valid(Ok n) with Ok g->printfn "%d is valid" g|Error e->printfn "Error: %d %s" n e
[5..10]|>List.iter test
</lang>
{{out}}
<pre>
8 10 12
(3, 4, 5) (5, 12, 13) (6, 8, 10) (7, 24, 25) (8, 15, 17) (9, 12, 15) (12, 16, 20) (15, 20, 25)
Error: 5 is less than 6
6 is valid
7 is valid
8 is valid
9 is valid
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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