Fibonacci in Haskell

main = print (fibbs 100000)


fibbs :: Integer -> Integer
fibbs a = last (fibb [1,0,1,a,1])

fibb :: [Integer] -> [Integer]
fibb (a1:b1:e1:d:c1:_)
    |d > e1 = fibb [a,b,e,d,c]
    |otherwise = [a,b,e,d,c]
    where c = a1+b1
          a = b1
          b = c
          e = e1+1