Difference between revisions of "Partible"
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(Initial content, loosely based on "Monad") |
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<haskell> |
<haskell> |
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| + | module Partible where |
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class Partible a where |
class Partible a where |
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| − | part :: a -> (a, a) |
+ | part :: a -> (a, a) |
| − | parts :: a -> [a] |
+ | parts :: a -> [a] |
| − | -- |
+ | -- Minimal complete definition: part or parts -- |
| − | part u = case parts u of u1:u2:_ -> (u1, u2) |
+ | part u = case parts u of u1:u2:_ -> (u1, u2) |
| − | parts u = case part u of (u1, u2) -> u1 : parts u2 |
+ | parts u = case part u of (u1, u2) -> u1 : parts u2 |
</haskell> |
</haskell> |
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Revision as of 22:21, 16 April 2021
Hint: if you're just looking for an introduction to partible types, see Plainly partible.
The Partible class
Partible types have an common (and austere) programming interface, this being captured by the Partible class:
module Partible where
class Partible a where
part :: a -> (a, a)
parts :: a -> [a]
-- Minimal complete definition: part or parts --
part u = case parts u of u1:u2:_ -> (u1, u2)
parts u = case part u of (u1, u2) -> u1 : parts u2
In addition to implementing the methods of the class, partible types should satisfy certain equations; for an explanation of them along with why they should be satisfied, see Partible laws.