The first one looks like you're chaining functions together, while the second one looks like you're taking multiple bitwise or operations over the result of each function.

I think it's fascinating to see how the language can be extended. On the other hand I would not want to be the poor bastard stuck maintaining either construct after discovering some compiler edge case. If I've learned anything it's that just because you can do something doesn't mean you should.

The issue with extending operators in this fashion is that you're violating the principle of least surprise. | is an operator that should only really do exactly what it always does--bitwise or. If composition of functions is fundamentally analogous to taking the bitwise or of two values then I would concede that your second syntax is a bit clearer.

Personally I feel that this is not the case.