# User:Zzo38/Proposal for additional kinds

### From HaskellWiki

< User:Zzo38(Difference between revisions)

Line 3: | Line 3: | ||

==New kinds== |
==New kinds== |
||

## -- New name for (#) kind (although (#) is available for compatibility) |
## -- New name for (#) kind (although (#) is available for compatibility) |
||

− | [x] -- If x is a kind, [x] is the kind of classes of types of kind x |
+ | & -- Kind for classes |

+ -- Kind for type-level natural numbers |
+ -- Kind for type-level natural numbers |
||

$ -- Means make up a kind from a Template Haskell code |
$ -- Means make up a kind from a Template Haskell code |
||

Line 9: | Line 9: | ||

==Kind of classes== |
==Kind of classes== |
||

Example: |
Example: |
||

− | [*] -- Kind of Eq class. |
+ | * -> & -- Kind of Eq class. |

− | [* -> *] -- Kind of Monad class. |
+ | (* -> *) -> & -- Kind of Monad class. |

− | * -> [*] -- A class that requires a type as a parameter to make a class. |
+ | (* -> &) -> & -- Class of classes. |

− | [<b></b>[*]] -- Class of classes. |
+ | + -> * -> & -- Infinite series of classes, selected by a natural number. |

− | + -> [*] -- Infinite series of classes, selected by a natural number. |
||

− | k -> [k] -- Polymorphic class that corresponds to any given kind. |
||

− | <!-- <b></b> means make it appear correctly on HTML view --> |
||

==Natural number kind== |
==Natural number kind== |

## Revision as of 01:48, 5 September 2011

This document is proposal about additional kinds.

## 1 New kinds

## -- New name for (#) kind (although (#) is available for compatibility) & -- Kind for classes + -- Kind for type-level natural numbers $ -- Means make up a kind from a Template Haskell code

## 2 Kind of classes

Example:

* -> & -- Kind of Eq class. (* -> *) -> & -- Kind of Monad class. (* -> &) -> & -- Class of classes. + -> * -> & -- Infinite series of classes, selected by a natural number.

## 3 Natural number kind

If a type requires a parameter, it can be a `+` kind, meaning numbers.

There should be some way to specify a type taking natural numbers by defining it for zero and them for a successor, so that it applies for all natural numbers.

It also means a type of kind `+ -> + -> +` can be a type of adding numbers or other stuff like that, too.