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Scheme

 (define (fib n)
   (if *1 (fib (- n 2)))))

Python

 def fib1(n):
   return n <= 2 and 1 or fib1(n-1) + fib1(n-2)

 def fib2(n):
   if n <= 2: return 1
   else    : return fib2(n-1) + fib2(n-2)

Haskell でパターンマッチを利用しての関数宣言。

 fib :: Integer -> Integer
 fib 1 = 1
 fib 2 = 1
 fib n = fib(n-1) + fib(n-2)

Ocaml

 let rec fib n =
   match n with
   1 -> 1
 | 2 -> 1
 | _ -> fib(n-1) + fib(n-2);;

*1:<= n 2) 1) (+ (fib (- n 1