I have not been enjoying that => is not first-class. It works well for simple dict literals ([a=>b, c=>d]), but the other forms cause trouble. For example I defined

typealias AbstractValue Dict{Symbol,LatticeElement}

but one cannot make a Dict of this type using this definition. You have to write (Symbol=>LatticeElement)[...] every time.

In the near future it will be possible to write Dict( (a,b) for i in x ), which makes a pretty good dict comprehension syntax without any special code in the front end. For literals this would be Dict([(a,b), (c,d), ...]), which starts to suffer from too much punctuation. One way to solve this is to make => a type, so you could write Dict(a=>b, c=>d, ...). => would not be iterable, so this would not be ambiguous. This would eliminate all special dict syntax. It would also make it more obvious how to write a typed empty Dict: you just pass 0 arguments.