module Plutarch.Docs.BasicExample (fib) where 

import Plutarch.Prelude

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Fibonacci number at given index

fib :: Term s (PInteger :--> PInteger)
fib = phoistAcyclic $
  pfix #$ plam $ \self n ->
    pif
      (n #== 0)
      0
      $ pif
        (n #== 1)
        1
        $ self # (n - 1) + self # (n - 2)

Execution:

> evalT $ fib # 2
Right (Program () (Version () 1 0 0) (Constant () (Some (ValueOf integer 2))))