MutableHashSet.ts

MutableHashSet.ts overview

Stores unique values in a mutable hash set.

MutableHashSet updates the same collection in place and supports fast membership checks, insertion, removal, clearing, and iteration. It is built on MutableHashMap: each set value is stored as a map key, so uniqueness follows the same hashing and equality rules as the underlying mutable hash map.

Since v2.0.0

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Exports Grouped by Category

• constructors
  • empty
  • fromIterable
  • make
• elements
  • has
  • size
• models
  • MutableHashSet (interface)
• mutations
  • add
  • clear
  • remove
• refinements
  • isMutableHashSet

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constructors

empty

Creates an empty MutableHashSet.

When to use

Use to create a fresh mutable set before adding values over time.

Details

Each call returns a new empty set backed by an empty MutableHashMap.

Example (Creating an empty set)

import { MutableHashSet } from "effect"

const set = MutableHashSet.empty<string>()

// Add some values
MutableHashSet.add(set, "apple")
MutableHashSet.add(set, "banana")
MutableHashSet.add(set, "apple") // Duplicate, no effect

console.log(MutableHashSet.size(set)) // 2
console.log(Array.from(set)) // ["apple", "banana"]

See

• make for creating a set from explicit values
• fromIterable for creating a set from an iterable of values
• clear for emptying an existing mutable set

Signature

declare const empty: <K = never>() => MutableHashSet<K>

Source

Since v2.0.0

fromIterable

Creates a MutableHashSet from an iterable collection of values. Duplicates are automatically removed.

When to use

Use to build a mutable hash set from any iterable of values.

Example (Creating a set from an iterable)

import { MutableHashSet } from "effect"

const values = ["apple", "banana", "apple", "cherry", "banana"]
const set = MutableHashSet.fromIterable(values)

console.log(MutableHashSet.size(set)) // 3
console.log(Array.from(set)) // ["apple", "banana", "cherry"]

// Works with any iterable
const fromSet = MutableHashSet.fromIterable(new Set([1, 2, 3]))
console.log(MutableHashSet.size(fromSet)) // 3

// From string characters
const fromString = MutableHashSet.fromIterable("hello")
console.log(Array.from(fromString)) // ["h", "e", "l", "o"]

Signature

declare const fromIterable: <K = never>(keys: Iterable<K>) => MutableHashSet<K>

Source

Since v2.0.0

make

Creates a MutableHashSet from a variable number of values. Duplicates are automatically removed.

When to use

Use to build a mutable hash set from explicit values.

Example (Creating a set from values)

import { MutableHashSet } from "effect"

const set = MutableHashSet.make("apple", "banana", "apple", "cherry")

console.log(MutableHashSet.size(set)) // 3
console.log(Array.from(set)) // ["apple", "banana", "cherry"]

// With numbers
const numbers = MutableHashSet.make(1, 2, 3, 2, 1)
console.log(MutableHashSet.size(numbers)) // 3
console.log(Array.from(numbers)) // [1, 2, 3]

// Mixed types
const mixed = MutableHashSet.make("hello", 42, true, "hello")
console.log(MutableHashSet.size(mixed)) // 3

Signature

declare const make: <Keys extends ReadonlyArray<unknown>>(...keys: Keys) => MutableHashSet<Keys[number]>

Source

Since v2.0.0

elements

has

Checks whether the MutableHashSet contains the specified value.

When to use

Use to test whether a mutable set currently contains a value.

Details

Membership follows the same hashing and equality rules as the underlying MutableHashMap.

Example (Checking for a value)

import { MutableHashSet } from "effect"

const set = MutableHashSet.make("apple", "banana", "cherry")

console.log(MutableHashSet.has(set, "apple")) // true
console.log(MutableHashSet.has(set, "grape")) // false

// Pipe-able version
const hasApple = MutableHashSet.has("apple")
console.log(hasApple(set)) // true

// Check after adding
MutableHashSet.add(set, "grape")
console.log(MutableHashSet.has(set, "grape")) // true

See

• add for adding a value to the set
• remove for removing a value from the set

Signature

declare const has: { <V>(key: V): (self: MutableHashSet<V>) => boolean; <V>(self: MutableHashSet<V>, key: V): boolean }

Source

Since v2.0.0

size

Returns the number of unique values in the MutableHashSet.

When to use

Use to read how many unique values are currently stored in the set.

Example (Checking set size)

import { MutableHashSet } from "effect"

const set = MutableHashSet.empty<string>()
console.log(MutableHashSet.size(set)) // 0

MutableHashSet.add(set, "apple")
MutableHashSet.add(set, "banana")
MutableHashSet.add(set, "apple") // Duplicate
console.log(MutableHashSet.size(set)) // 2

MutableHashSet.remove(set, "apple")
console.log(MutableHashSet.size(set)) // 1

MutableHashSet.clear(set)
console.log(MutableHashSet.size(set)) // 0

Signature

declare const size: <V>(self: MutableHashSet<V>) => number

Source

Since v2.0.0

models

MutableHashSet (interface)

A mutable hash set for storing unique values with Effect structural equality support.

When to use

Use to store and mutate a collection of unique values with Effect hashing and equality semantics.

Details

Operations mutate the set in place. Values that implement Equal / Hash can be de-duplicated structurally; other values use normal JavaScript reference or primitive equality.

Example (Using a mutable hash set)

import { MutableHashSet } from "effect"

// Create a mutable hash set
const set: MutableHashSet.MutableHashSet<string> = MutableHashSet.make("apple", "banana")

// Add elements
MutableHashSet.add(set, "cherry")

// Check if elements exist
console.log(MutableHashSet.has(set, "apple")) // true
console.log(MutableHashSet.has(set, "grape")) // false

// Iterate over elements
for (const value of set) {
  console.log(value) // "apple", "banana", "cherry"
}

// Get size
console.log(MutableHashSet.size(set)) // 3

Signature

export interface MutableHashSet<out V> extends Iterable<V>, Pipeable, Inspectable {
  readonly [TypeId]: typeof TypeId
  readonly keyMap: MutableHashMap.MutableHashMap<V, boolean>
}

Source

Since v2.0.0

mutations

add

Adds a value to the MutableHashSet, mutating the set in place. If the value already exists, the set remains unchanged.

When to use

Use to insert a value into a mutable set while keeping uniqueness.

Example (Adding values)

import { MutableHashSet } from "effect"

const set = MutableHashSet.empty<string>()

// Add new values
MutableHashSet.add(set, "apple")
MutableHashSet.add(set, "banana")

console.log(MutableHashSet.size(set)) // 2
console.log(MutableHashSet.has(set, "apple")) // true

// Add duplicate (no effect)
MutableHashSet.add(set, "apple")
console.log(MutableHashSet.size(set)) // 2

// Pipe-able version
const addFruit = MutableHashSet.add("cherry")
addFruit(set)
console.log(MutableHashSet.size(set)) // 3

Signature

declare const add: {
  <V>(key: V): (self: MutableHashSet<V>) => MutableHashSet<V>
  <V>(self: MutableHashSet<V>, key: V): MutableHashSet<V>
}

Source

Since v2.0.0

clear

Removes all values from the MutableHashSet, mutating the set in place. The set becomes empty after this operation.

When to use

Use to empty a mutable set while keeping the same set instance.

Example (Clearing all values)

import { MutableHashSet } from "effect"

const set = MutableHashSet.make("apple", "banana", "cherry")

console.log(MutableHashSet.size(set)) // 3

// Clear all values
MutableHashSet.clear(set)

console.log(MutableHashSet.size(set)) // 0
console.log(MutableHashSet.has(set, "apple")) // false
console.log(Array.from(set)) // []

// Can still add new values after clearing
MutableHashSet.add(set, "new")
console.log(MutableHashSet.size(set)) // 1

Signature

declare const clear: <V>(self: MutableHashSet<V>) => MutableHashSet<V>

Source

Since v2.0.0

remove

Removes the specified value from the MutableHashSet, mutating the set in place. If the value doesn’t exist, the set remains unchanged.

When to use

Use to delete a value from a mutable set if it is present.

Example (Removing a value)

import { MutableHashSet } from "effect"

const set = MutableHashSet.make("apple", "banana", "cherry")

console.log(MutableHashSet.size(set)) // 3

// Remove existing value
MutableHashSet.remove(set, "banana")
console.log(MutableHashSet.size(set)) // 2
console.log(MutableHashSet.has(set, "banana")) // false

// Remove non-existent value (no effect)
MutableHashSet.remove(set, "grape")
console.log(MutableHashSet.size(set)) // 2

// Pipe-able version
const removeFruit = MutableHashSet.remove("apple")
removeFruit(set)
console.log(MutableHashSet.size(set)) // 1

Signature

declare const remove: {
  <V>(key: V): (self: MutableHashSet<V>) => MutableHashSet<V>
  <V>(self: MutableHashSet<V>, key: V): MutableHashSet<V>
}

Source

Since v2.0.0

refinements

isMutableHashSet

Checks whether the specified value is a MutableHashSet, false otherwise.

When to use

Use to narrow an unknown value before treating it as a mutable hash set.

Details

The check looks for the MutableHashSet runtime marker.

Gotchas

Native Set values do not satisfy this check.

See

• MutableHashSet for the mutable hash set interface

Signature

declare const isMutableHashSet: <V>(value: unknown) => value is MutableHashSet<V>

Source

Since v4.0.0