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.