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core

Ordering overview

Added in v1.0.0

Table of contents

instances

Monoid

Monoid instance for Ordering, returns the left-most non-zero Ordering.

The empty value is 0.

Signature

export declare const Monoid: monoid.Monoid<0 | 1 | -1>

Example

import { Monoid } from '@fp-ts/core/Ordering'

assert.deepStrictEqual(Monoid.combine(Monoid.empty, -1), -1)
assert.deepStrictEqual(Monoid.combine(Monoid.empty, 1), 1)
assert.deepStrictEqual(Monoid.combine(1, -1), 1)

Added in v1.0.0

Semigroup

Semigroup instance for Ordering, returns the left-most non-zero Ordering.

Signature

export declare const Semigroup: semigroup.Semigroup<0 | 1 | -1>

Example

import { Semigroup } from '@fp-ts/core/Ordering'

assert.deepStrictEqual(Semigroup.combine(0, -1), -1)
assert.deepStrictEqual(Semigroup.combine(0, 1), 1)
assert.deepStrictEqual(Semigroup.combine(1, -1), 1)

Added in v1.0.0

model

Ordering (type alias)

Signature

export type Ordering = -1 | 0 | 1

Added in v1.0.0

pattern matching

match

Depending on the Ordering parameter given to it, returns a value produced by one of the 3 functions provided as parameters.

Signature

export declare const match: {
  <A, B, C = B>(onLessThan: LazyArg<A>, onEqual: LazyArg<B>, onGreaterThan: LazyArg<C>): (self: Ordering) => A | B | C
  <A, B, C = B>(o: Ordering, onLessThan: LazyArg<A>, onEqual: LazyArg<B>, onGreaterThan: LazyArg<C>): A | B | C
}

Example

import { match } from '@fp-ts/core/Ordering'
import { constant } from '@fp-ts/core/Function'

const toMessage = match(constant('less than'), constant('equal'), constant('greater than'))

assert.deepStrictEqual(toMessage(-1), 'less than')
assert.deepStrictEqual(toMessage(0), 'equal')
assert.deepStrictEqual(toMessage(1), 'greater than')

Added in v1.0.0

utils

reverse

Inverts the ordering of the input Ordering.

Signature

export declare const reverse: (o: Ordering) => Ordering

Example

import { reverse } from '@fp-ts/core/Ordering'

assert.deepStrictEqual(reverse(1), -1)
assert.deepStrictEqual(reverse(-1), 1)
assert.deepStrictEqual(reverse(0), 0)

Added in v1.0.0