Safe Haskell | Safe |
---|---|

Language | Haskell2010 |

Standard representation of n-ary sums.

## Synopsis

- data NS :: (k -> *) -> [k] -> * where
- mapNS :: (f :-> g) -> NS f ks -> NS g ks
- mapNSM :: Monad m => (forall x. f x -> m (g x)) -> NS f ks -> m (NS g ks)
- elimNS :: (forall x. f x -> a) -> NS f ks -> a
- zipNS :: MonadPlus m => NS ki xs -> NS kj xs -> m (NS (ki :*: kj) xs)
- cataNS :: (forall x xs. f x -> r (x ': xs)) -> (forall x xs. r xs -> r (x ': xs)) -> NS f xs -> r xs
- eqNS :: (forall x. p x -> p x -> Bool) -> NS p xs -> NS p xs -> Bool

# Documentation

data NS :: (k -> *) -> [k] -> * where Source #

Indexed n-ary sums. This is analogous to the `Any`

datatype
in `Agda`

.
Combinations of `Here`

and `There`

s are also called injections.

# Map, Zip and Elim

mapNSM :: Monad m => (forall x. f x -> m (g x)) -> NS f ks -> m (NS g ks) Source #

Maps a monadic function over a sum

zipNS :: MonadPlus m => NS ki xs -> NS kj xs -> m (NS (ki :*: kj) xs) Source #

Combines two sums. Note that we have to fail if they are constructed from different injections.

# Catamorphism

cataNS :: (forall x xs. f x -> r (x ': xs)) -> (forall x xs. r xs -> r (x ': xs)) -> NS f xs -> r xs Source #

Consumes a value of type `NS`