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effect-extras

SetX overview

Generic, framework-agnostic extensions for working with Set.

Added in v0.0.0

Table of contents

combinators

add

Returns a new Set with value added, leaving the input set unchanged.

When value is already present the input set is returned as-is (no copy), making repeated adds of existing members allocation-free. Supports both data-first and data-last (pipeable) call styles.

Signature

export declare const add: (<A>(value: A) => (set: Set<A>) => Set<A>) & (<A>(set: Set<A>, value: A) => Set<A>)

Example

import { SetX } from "@nunofyobiz/effect-extras"
import { pipe } from "effect"

// Data-first — adds a new element into a fresh set
assert.deepStrictEqual(SetX.add(new Set(["a", "b"]), "c"), new Set(["a", "b", "c"]))

// Data-last — existing element leaves the set unchanged
assert.deepStrictEqual(pipe(new Set(["a", "b"]), SetX.add("b")), new Set(["a", "b"]))

Added in v0.0.0

remove

Returns a new Set with value removed, leaving the input set unchanged.

When value is absent the input set is returned as-is (no copy). Supports both data-first and data-last (pipeable) call styles.

Signature

export declare const remove: (<A>(value: A) => (set: Set<A>) => Set<A>) & (<A>(set: Set<A>, value: A) => Set<A>)

Example

import { SetX } from "@nunofyobiz/effect-extras"
import { pipe } from "effect"

// Data-first — removes an existing element into a fresh set
assert.deepStrictEqual(SetX.remove(new Set(["a", "b", "c"]), "c"), new Set(["a", "b"]))

// Data-last — absent element leaves the set unchanged
assert.deepStrictEqual(pipe(new Set(["a", "b"]), SetX.remove("z")), new Set(["a", "b"]))

Added in v0.0.0

safelyMutate

Runs a mutating function against a copy of set, leaving the original untouched, and returns the mutated copy.

Use it to reuse imperative Set mutation code (.add, .delete) without sacrificing immutability: the callback may freely mutate the set it receives because it operates on a fresh clone. Supports both data-first and data-last (pipeable) call styles.

Signature

export declare const safelyMutate: (<A>(mutate: (set: Set<A>) => Set<A>) => (set: Set<A>) => Set<A>) &
  (<A>(set: Set<A>, mutate: (set: Set<A>) => Set<A>) => Set<A>)

Example

import { SetX } from "@nunofyobiz/effect-extras"
import { pipe } from "effect"

const original = new Set(["a", "b"])

const result = pipe(
  original,
  SetX.safelyMutate((set) => {
    set.delete("a")
    return set.add("c")
  })
)

assert.deepStrictEqual(result, new Set(["b", "c"]))
// The original is left intact
assert.deepStrictEqual(original, new Set(["a", "b"]))

Added in v0.0.0

toggle

Returns a new Set with value added if it was absent or removed if it was present, leaving the input set unchanged.

Use it for membership toggles (selection state, feature flags by key) where a value’s presence should flip on each call. Supports both data-first and data-last (pipeable) call styles.

Signature

export declare const toggle: (<A>(value: A) => (set: Set<A>) => Set<A>) & (<A>(set: Set<A>, value: A) => Set<A>)

Example

import { SetX } from "@nunofyobiz/effect-extras"
import { pipe } from "effect"

// Data-first — absent value gets added
assert.deepStrictEqual(SetX.toggle(new Set(["a", "b"]), "c"), new Set(["a", "b", "c"]))

// Data-last — present value gets removed
assert.deepStrictEqual(pipe(new Set(["a", "b", "c"]), SetX.toggle("b")), new Set(["a", "c"]))

Added in v0.0.0