GADT problems

[Simon Peyton-Jones]

| > So that's the story.  If you find situations in which it's very hard to give a signature for
| the result type, I'd like to see them.
|
| I find that usually when it becomes difficult is when I'm using
| existential types and lexically scoped type variables.
|
...
|
| I wish I had a concrete example to show you.  I guess the next time it
| shows up I should send it in.

Yes, please do!  I'm always interested in bad type error messages.

S