Inferred type appears to detect an infinite loop, but what's really happening?

This is indeed a remarkable example; an infinite loop being detected, essentially, at compile time! There is nothing special about the Hindley–Milner inference in this example; it just proceeds as usual.

That type can be inferred because it sees that you pass the result of mergesort to merge, which in turn compares the heads of the lists with.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.