It got mingled without newlines (and "λ:" prompt doesn't help readability). In one line: let fibs = 0 : 1 : zipWith (+) fibs (tail fibs) in fibs !! 47 Shorter

It got mingled without newlines (and "λ:" prompt doesn't help readability). In one line: let fibs = 0 : 1 : zipWith (+) fibs (tail fibs) in fibs !! 47 Shorter but less readable: fix (scanl (+) 0 . (1:)) !! 47