Data.Number.PartialOrd

The Prelude's Ord class for dealing with ordered types is often onerous to use because it requires Eq as well as a total ordering. While such total orderings are common, partial orderings are more so. This module presents a class for partially ordered types.

Partial Ordering

class PartialOrd a where

This class defines a partially ordered type. The method names were chosen so as not to conflict with Ord and Eq. We use Maybe instead of defining new types PartialOrdering and FuzzyBool because this way should make the class easier to use.

Minimum complete definition: cmp

Minimal complete definition

cmp

Methods

cmp :: a -> a -> Maybe Ordering

like compare

gt :: a -> a -> Maybe Bool infix 4

like (>)

ge :: a -> a -> Maybe Bool infix 4

like (>=)

eq :: a -> a -> Maybe Bool infix 4

like (==)

ne :: a -> a -> Maybe Bool infix 4

like (/=)

le :: a -> a -> Maybe Bool infix 4

like (<=)

lt :: a -> a -> Maybe Bool infix 4

like (<)

maxPO :: a -> a -> Maybe a infix 4

like max. The default instance returns the left argument when they're equal.

minPO :: a -> a -> Maybe a infix 4

like min. The default instance returns the left argument when they're equal.

Instances

PartialOrd Double

PartialOrd Float

Ord a => PartialOrd a

PartialOrd LogFloat

Functions

comparingPO :: PartialOrd b => (a -> b) -> a -> a -> Maybe Ordering

Like Data.Ord.comparing. Helpful in conjunction with the xxxBy family of functions from Data.List