(that: number): (self: number) => number
(self: number, that: number): numberProvides a subtraction operation on numbers.
When to use
Use to subtract one number from another.
Example (Subtracting numbers)
import { Number } from "effect"
import * as assert from "node:assert"
assert.deepStrictEqual(Number.subtract(2, 3), -1)export const const subtract: {
(that: number): (self: number) => number
(self: number, that: number): number
}
Provides a subtraction operation on numbers.
When to use
Use to subtract one number from another.
Example (Subtracting numbers)
import { Number } from "effect"
import * as assert from "node:assert"
assert.deepStrictEqual(Number.subtract(2, 3), -1)
subtract: {
(that: numberthat: number): (self: numberself: number) => number
(self: numberself: number, that: numberthat: number): number
} = dual<(...args: Array<any>) => any, (self: number, that: number) => number>(arity: 2, body: (self: number, that: number) => number): ((...args: Array<any>) => any) & ((self: number, that: number) => number) (+1 overload)Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual(2, (self: numberself: number, that: numberthat: number): number => self: numberself - that: numberthat)