Comments on current TypeHoles implementation

[Simon Peyton-Jones]

| Sounds cool. I would also expect that if you have several occurences of
| the same unbound identifier, then it gets a unified type.

I thought about this, but I think not. Consider

f x1 = _y
g x2 = _y

Do you want _y and _y to be unified, so that f and g are no longer polymorphic?  I think not.  Any more than the "_" holes we have now are unified.

| I guess this is something you can get currently by creating a top-level
| declaration
|   foo = _
| and then using foo in several places.

Yes. Or even _foo = _!

Simon