| Portability | portable |
|---|---|
| Stability | experimental |
| Maintainer | Edward Kmett <ekmett@gmail.com> |
| Safe Haskell | None |
Data.Proxy
Contents
Description
Tagged values
Constructors
| Proxy |
Instances
| Monad (Proxy *) | |
| Functor (Proxy *) | |
| Typeable1 (Proxy *) | |
| Applicative (Proxy *) | |
| Foldable (Proxy *) | |
| Traversable (Proxy *) | |
| Bounded (Proxy k s) | |
| Enum (Proxy k s) | |
| Eq (Proxy k s) | |
| (Typeable (Proxy * s), Data s) => Data (Proxy * s) | |
| Eq (Proxy k s) => Ord (Proxy k s) | |
| Read (Proxy k s) | |
| Show (Proxy k s) | |
| Ord (Proxy k s) => Ix (Proxy k s) | |
| Monoid (Proxy k s) |
reproxy :: Proxy s -> Proxy tSource
Some times you need to change the proxy you have lying around.
Idiomatic usage is to make a new combinator for the relationship
between the proxies that you want to enforce, and define that
combinator using reproxy.
data Succ n reproxySucc :: Proxy n -> Proxy (Succ n) reproxySucc = reproxy
asProxyTypeOf :: a -> Proxy a -> aSource
asProxyTypeOf is a type-restricted version of const.
It is usually used as an infix operator, and its typing forces its first
argument (which is usually overloaded) to have the same type as the tag
of the second.