t (#) gives parse error

In GHC 6.0.1, using GHCi:

Prelude> let x # f = f x
Prelude> :t (#)
<interactive>:1: parse error on input `)'
Prelude> :t ( #)
<interactive>:1: parse error on input `#)'
Prelude> :t (# )
<interactive>:1: parse error on input `)'
Prelude> :t ( # )
( # ) :: forall t t1. t1 -> (t1 -> t) -> t
Prelude> zipWith (#) [1] [(+1)]
<interactive>:1: parse error on input `)'
Prelude> zipWith ( # ) [1] [(+1)]
[2]
Prelude> 

                                                                Juanma