Module

pooka/order

src/pooka/order.pooka

A comparison needs three signposts, not an arbitrary magic number.

Represent Less, Equal and Greater, and define the Comparator interface used by object-based comparisons. from_int uses only the sign of its input.

import pooka/order.{Order}

assert order.from_int(0) == Order.Equal

API reference

enum

src/pooka/order.pooka:17

enum Order

The three possible comparison directions. Equal reverses to itself.

variant

src/pooka/order.pooka:18

Order.Less

variant

src/pooka/order.pooka:19

Order.Equal

variant

src/pooka/order.pooka:20

Order.Greater

interface

src/pooka/order.pooka:24

interface Comparator(a)

A comparison contract for values with an explicit ordering policy.

method

src/pooka/order.pooka:26

compare(left: a, right: a) -> Order

Compare left to right and return Less, Equal or Greater.

function

src/pooka/order.pooka:36

reverse(value: Order) -> Order

INFERREDfn(pooka/order.Order) -> pooka/order.Order

Turn Less into Greater and Greater into Less. Equal stays where it is.

import pooka/order.{Order}

assert order.reverse(Order.Less) == Order.Greater

function

src/pooka/order.pooka:51

from_int(value: Int) -> Order

INFERREDfn(Int) -> pooka/order.Order

Use only the sign: negative is Less, zero is Equal and positive is Greater.

import pooka/order.{Order}

assert order.from_int(0) == Order.Equal