What is the difference between . (dot) and $ (dollar sign)?

Question

What is the difference between the dot (.) and the dollar sign ($)?

As I understand it, they are both syntactic sugar for not needing to us

Answer 1

All the other answers are pretty good. But there’s an important usability detail about how ghc treats $, that the ghc type checker allows for instatiarion with higher rank/ quantified types. If you look at the type of $ id for example you’ll find it’s gonna take a function whose argument is itself a polymorphic function. Little things like that aren’t given the same flexibility with an equivalent upset operator. (This actually makes me wonder if $! deserves the same treatment or not )