minihaskell/fib.mhs at master · foo/minihaskell · GitHub

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value fib = \ n -> case n of
      Zero -> Zero |
      Succ Zero -> Succ Zero |
      n -> add (fib (minus n (Succ Zero)))
               (fib (minus n (Succ (Succ Zero))))
value main = Dialog ( \ resp ->
		       	    Cons Read (case resp of
			    	       	     Cons (ReadOK a) rest ->
					     	  	    	Cons (Write (fib a)) Nil))

value minus = \ x y -> case Pair x y of
      Pair x Zero -> x |
      Pair (Succ x2) (Succ y2) -> minus x2 y2

value add = \ x y -> case Pair x y of
      Pair x (Succ y2) -> add (Succ x) y2 |
      Pair x Zero -> x

value mul = \ x y -> case Pair x y of
      Pair x (Succ y2) -> add x (mul x y2) |
      Pair x (Succ Zero) -> x |
      Pair x Zero -> Zero