module Qsort where
qsort _ [] = []
qsort f (x:xs) = before ++ (x : after)
　　where before = qsort f $ filter (not . (f x)) xs
　　　　after = qsort f $ filter (f x) xs

これを実行しようとしたら
ERROR file:.\Qsort.hs:5 - Syntax error in input (unexpected `=')

なにが悪いんですか