18 Sep
2021
18 Sep
'21
10:32 a.m.
On Saturday, September 18th, 2021 at 14:12, Anthony Clayden
The end of your error message:
| 63 | pattern Any a <- Some a | ^
Appears to have program text (a mono-directional pattern binding) that doesn't correspond to the program text you quote.
I just tried both ways of writing bidirectional pattern synonmys, neither worked with explicit `forall`.
I'm suspecting the explicit forall is not much to do with it.
With an implicit forall, the code does type check. Regards, Marcin