Allow specifying that (some) dictionary fields should be strict
The type-class dictionary is a record, there should be a way to specify the strictness of the fields.
I don't know what the syntax would look like though.
class Foo a where
foo1 :: !a
foo2 :: !a
foo3 :: a -> a
is one idea. There can be bangs in record field definitions, so this is not completely "new". UNPACKing would make sense too. TL;DR Allow specifying data layout of dictionaries as well, they are "just" records in GHC implementation.