module NFib where

instruction primadd "addint" :: Int! -> Int! -> Int!
instruction primsub "subint" :: Int! -> Int! -> Int!

(+) x y   = let! y = y in let! x = x in primadd x y
(-) x y   = let! y = y in let! x = x in primsub x y


main  = nfib 27

-- normal nfib
nfib n = case n of
          0  -> 1
          1  -> 1
          n  -> (+) 1 ((+) (nfib ((-) n 1)) (nfib ((-) n 2)))