Mon Jul 16 14:11:21 EDT 2018

Rank N types

I think it had already clicked for me as I recently needed multiple
instantiations of the same function type in setting that made perfect
practical sense, but here is some more explanation:


   ... while you can write a function that takes different types of
   arguments without this extension, you can't write a function that
   uses its argument as different types in the same invocation.

It is about being able to instantiate the type multiple times.

The comment about System F is insightful.