Class restrictions on type instances
I'm using type families to implement bools and integers on type level.
There is a class BoolT with with two instances and type families representing usual boolean functions, e.g. NotT. By semantics of NotT, implication (BoolT a) => (BoolT (NotT a)) holds, but I cannot specify this to compiler, and using BoolT with NotT is painful.
So I think there must be syntactic construction to restrict type family instances to some class, something like
type family NotT a
with (BoolT a) => (BoolT (NotT a))
or
class BoolT a where
type NotT a
with BoolT (NotT a)
Trac metadata
Trac field | Value |
---|---|
Version | 6.10.4 |
Type | FeatureRequest |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |