-- where F is a type function and (F a ~ [a])
-- Then unification might succeed with a coercion. But it's much
-- much simpler to require that such signatures have identical contexts
- checkTc (all isIdentityCoercion cois)
+ checkTc (all isIdentityCoI cois)
(ptext (sLit "Mutually dependent functions have syntactically distinct contexts"))
}