6 lines
161 B
Forth
6 lines
161 B
Forth
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let rec fix f x = f (fix f) x
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let fib = function
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| n when n < 0 -> None
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| n -> Some (fix (fun f -> (function | 0 | 1 -> 1 | n -> f (n-1) + f (n-2))) n)
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