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

Language | Haskell2010 |

Helpers for working with type-level lists.

## Synopsis

- type family AllAre a ts :: Constraint where ...
- type family ReplaceAll a xs where ...
- type family ReplaceAllSnd a (xs :: [(k1, k2)]) where ...

# Documentation

type family AllAre a ts :: Constraint where ... Source #

Constraint that every element of a promoted list is equal to a particular type. That is, the list of types is a single type repeated some number of times.

type family ReplaceAll a xs where ... Source #

`ReplaceAll x ys`

produces a type-level list of the same length
as `ys`

where each element is `x`

. In other words, it replaces each
element of `ys`

with `x`

. This would be `map (const x) ys`

in
value-level Haskell.

ReplaceAll a '[] = '[] | |

ReplaceAll a (x ': xs) = a ': ReplaceAll a xs |

type family ReplaceAllSnd a (xs :: [(k1, k2)]) where ... Source #

Replace the second component of every tuple in a type-level list with a constant.

ReplaceAllSnd a '[] = '[] | |

ReplaceAllSnd a ('(s, x) ': xs) = '(s, a) ': ReplaceAllSnd a xs |