How to best display type variables with the same name

Christopher Done chrisdone at
Wed Oct 19 11:45:58 UTC 2016

We've encountered a problem in Intero which is that when inspecting types
of expressions and patterns, sometimes it happens that the type, when
pretty printing, yields variables of the same name but which have different

Here's a summary of the issue:

And a strawman proposal of how it could be solved:

What do you think?

Also, if I were to implement the strawman proposal, is it possible to
recover from a `tyvar :: Type` its original quantification/its "forall"?
I've had a look through the API briefly and it looks like a _maybe_.

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