Copyright | (C) 2016 Edward Kmett and Eric Mertens |
---|---|

License | BSD-style (see the file LICENSE) |

Maintainer | Edward Kmett <ekmett@gmail.com> |

Stability | experimental |

Portability | non-portable |

Safe Haskell | Trustworthy |

Language | Haskell2010 |

## Synopsis

- coerce :: forall (k :: RuntimeRep) (a :: TYPE k) (b :: TYPE k). Coercible a b => a -> b
- coerce' :: forall a b. Coercible a b => b -> a
- (#..) :: (Profunctor p, Coercible c b) => (b -> c) -> p a b -> p a c

# Documentation

coerce :: forall (k :: RuntimeRep) (a :: TYPE k) (b :: TYPE k). Coercible a b => a -> b #

The function `coerce`

allows you to safely convert between values of
types that have the same representation with no run-time overhead. In the
simplest case you can use it instead of a newtype constructor, to go from
the newtype's concrete type to the abstract type. But it also works in
more complicated settings, e.g. converting a list of newtypes to a list of
concrete types.

This function is runtime-representation polymorphic, but the
`RuntimeRep`

type argument is marked as `Inferred`

, meaning
that it is not available for visible type application. This means
the typechecker will accept `coerce @Int @Age 42`

.

(#..) :: (Profunctor p, Coercible c b) => (b -> c) -> p a b -> p a c Source #