What makes this confusing for me is that this is backwards from the way expressions work pretty much anywhere else. It should be possible to know the type of a

What makes this confusing for me is that this is backwards from the way expressions work pretty much anywhere else. It should be possible to know the type of a sub-expression without knowing anything about the expression that contains it. That is, start at the leaves, and work your way up. In Haskell, sometimes you have to go the other way. It's like trying to read a novel where some chapters randomly assume you know what happens several chapters later.