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User:Zzo38/Proposal for additional kinds

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It also means a type of kind <tt>+ -> + -> +</tt> can be a type of adding numbers or other stuff like that, too.
 
It also means a type of kind <tt>+ -> + -> +</tt> can be a type of adding numbers or other stuff like that, too.
  +
  +
A natural number type would be a type with the number of values being that number, for example <tt>4</tt> is <tt>Maybe (Maybe (Maybe (Maybe Zero)))</tt>, and <tt>(-&gt;)</tt> would be the type for a array with a specific number of elements fixed by the type.
   
 
==See also==
 
==See also==

Latest revision as of 20:18, 12 January 2012

This document is proposal about additional kinds.

Contents

[edit] 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

[edit] 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.

[edit] 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.

A natural number type would be a type with the number of values being that number, for example 4 is Maybe (Maybe (Maybe (Maybe Zero))), and (->) would be the type for a array with a specific number of elements fixed by the type.

[edit] 4 See also