Haskell - parse error in pattern: n + 1

Should you get the following error from Haskell

Parse error in pattern: n + 1

this maybe because you are using the n+1 pattern, which is no longer included by default eg

> power :: Double -> Int -> Double
> power x 0         = 1
> power x (n + 1)   = x * power x n

the fix is to include

> {-# LANGUAGE NPlusKPatterns #-}

Hope this helps.