Multiple constraint classes - the alternative to superclass
This is alternative to SuperClasses - multiple constraint Classes
Now:
class Monoid a where ...
class Monad m => MonadPlus m where ...It could be:
class Monoid a where ...
class Monad m => Monoid m where ...
class Arrow c => Monoid c where ...
foo :: Monad m => Monoid m => m a
all classes must have same functions with same kind.
And if you wish to write superclass, it would be easy to write
class BeforeNum a where ....
class BeforeNum a => Num a where ...
foo :: BeforeNum a => Num a => aBackward compatibility
If class have single constraint, you could write without it.
If class have many constrains, you could write without it, if it is empty one.
bar :: MonadPlus m => m a <<==>> bar :: Monad m => MonadPlus m => m a
foo :: Monoid a => a <<==>> foo :: () => Monoid a => aTrac metadata
| Trac field | Value |
|---|---|
| Version | 7.6.3 |
| Type | FeatureRequest |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |