Implement operator sectioning

[benl]

Added by Jared.

The following function fails to compile.

example = (0 ==)

The error message is:

ddc: PANIC in Source.DefixApps
        makeXDefixApps: parse error at
        ./Test.ds:1:13   xx = []

[erikd]

It should be possible to fix this during the current Parser refactoring.

[erikd]

I was thinking about converting:

isZero = 0 ==

to a lambda expression:

isZero = \ x -> 0 == x

but that was problematic because there was no easy way to generate a variable name for 'x' without threading a State monad through DefixApps?. Mentioned this to Ben and he suggested converting it to:

isZero = flip (==) 0

This requires making Data.Function.flip available as a primitive in Shared.VarPrim?.