gleam/order

Types

Order

Represents the result of a single comparison to determine the precise ordering of two values.

pub type Order {
  Lt
  Eq
  Gt
}

Constructors

```
Lt
```
Less-than
```
Eq
```
Equal
```
Gt
```
Greater than

Functions

break_tie

</>

pub fn break_tie(in order: Order, with other: Order) -> Order

Return a fallback Order in case the first argument is Eq.

Examples

import gleam/int

break_tie(in: int.compare(1, 1), with: Lt)
// -> Lt

break_tie(in: int.compare(1, 0), with: Eq)
// -> Gt

compare

</>

pub fn compare(a: Order, with b: Order) -> Order

Compares two Order values to one another, producing a new Order.

Examples

compare(Eq, with: Lt)
// -> Gt

lazy_break_tie

</>

pub fn lazy_break_tie(
  in order: Order,
  with comparison: fn() -> Order,
) -> Order

Invokes a fallback function returning an Order in case the first argument is Eq.

This can be useful when the fallback comparison might be expensive and it needs to be delayed until strictly necessary.

Examples

import gleam/int

lazy_break_tie(in: int.compare(1, 1), with: fn() { Lt })
// -> Lt

lazy_break_tie(in: int.compare(1, 0), with: fn() { Eq })
// -> Gt

max

</>

pub fn max(a: Order, b: Order) -> Order

Returns the largest of two orders given that Gt > Eq > Lt.

Examples

max(Eq, Lt)
// -> Eq

min

</>

pub fn min(a: Order, b: Order) -> Order

Returns the smallest of two orders given that Gt > Eq > Lt.

Examples

min(Eq, Lt)
// -> Lt

negate

</>

pub fn negate(order: Order) -> Order

Inverts an order, so less-than becomes greater-than and greater-than becomes less-than.

Examples

negate(Lt)
// -> Gt

negate(Eq)
// -> Eq

negate(Lt)
// -> Gt

reverse

</>

pub fn reverse(orderer: fn(a, a) -> Order) -> fn(a, a) -> Order

Inverts an ordering function, so less-than becomes greater-than and greater-than becomes less-than.

Examples

import gleam/int
import gleam/list
list.sort([1, 5, 4], by: reverse(int.compare))
// -> [5, 4, 1]

to_int

</>

pub fn to_int(order: Order) -> Int

Produces a numeric representation of the order.

Examples

to_int(Lt)
// -> -1

to_int(Eq)
// -> 0

to_int(Gt)
// -> 1