>>16
http://book.realworldhaskell.org/read/getting-started.html
>It is sometimes better to leave at least some parentheses in place, even when Haskell allows us to omit them. Complex expressions that rely completely on operator precedence are notorious sources of bugs. A compiler and a human can easily end up with different notions of what even a short, parenthesis-free expression is supposed to do. There is no need to remember all of the precedence and associativity rules numbers: it is simpler to add parentheses if you are unsure.