Jonathan Cast wrote:
I think surely you're using existential data types rather than rank-2 types.
You expect *me* to know?
Existential types: each application of Encoder2 is to arguments which require
a specific value of x.
Rank-2 types (polymorphic fields, actually): each application of Encoder2 is
to arguments which work with any value of x.
All I know is it didn't compile, so I added {-# LANGUAGE Rank2Types #-},
and now it works. *shrugs*
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