Copyright | (c) Sergey Vinokurov 2019 |
---|---|

License | BSD-2 (see LICENSE) |

Maintainer | sergey@debian |

Safe Haskell | None |

Language | Haskell2010 |

## Synopsis

- class (CFunctor f, CFoldable f) => CTraversable f where
- ctraverse :: (Constraints f a, Constraints f b, Monad m) => (a -> m b) -> f a -> m (f b)
- csequence :: (Constraints f a, Constraints f (m a), Monad m) => f (m a) -> m (f a)

- cfor :: (CTraversable f, Constraints f a, Constraints f b, Monad m) => f a -> (a -> m b) -> m (f b)
- class Constrained (f :: k2 -> k1) where
- type Constraints (f :: k2 -> k1) :: k2 -> Constraint

# Documentation

class (CFunctor f, CFoldable f) => CTraversable f where Source #

Like `Traversable`

but allows elements to have constraints on them.
Laws are the same:

ctraverse pure == pure ctraverse (f <=< g) == ctraverse f <=< ctraverse g

NB There's no aplicative version because Vectors from the
http://hackage.haskell.org/package/vector package only support
monadic traversals. Since they're one of the main motivation for
this package, `Applicative`

version of traversals will not exist.

Nothing

ctraverse :: (Constraints f a, Constraints f b, Monad m) => (a -> m b) -> f a -> m (f b) Source #

csequence :: (Constraints f a, Constraints f (m a), Monad m) => f (m a) -> m (f a) Source #

ctraverse :: (Constraints f a, Constraints f b, Monad m, Traversable f) => (a -> m b) -> f a -> m (f b) Source #

## Instances

cfor :: (CTraversable f, Constraints f a, Constraints f b, Monad m) => f a -> (a -> m b) -> m (f b) Source #

`ctraverse`

with araguments flipped.

class Constrained (f :: k2 -> k1) Source #

Specification of constrains that a functor might impose on its elements. For example, sets typically require that their elements are ordered and unboxed vectors require elements to have an instance of special class that allows them to be packed in memory.

NB The `Constraints`

type family is associated with a typeclass in
order to improve type inference. Whenever a typeclass constraint
will be present, instance is guaranteed to exist and typechecker is
going to take advantage of that.

type Constraints (f :: k2 -> k1) :: k2 -> Constraint Source #