<V, K>(f: (value: V, key: K) => void): (self: HashMap<K, V>) => void
<V, K>(self: HashMap<K, V>, f: (value: V, key: K) => void): voidApplies the specified function to the entries of the HashMap.
Example (Iterating with side effects)
import { HashMap } from "effect"
const map = HashMap.make(["a", 1], ["b", 2])
const collected: Array<[string, number]> = []
HashMap.forEach(map, (value, key) => {
collected.push([key, value])
})
console.log(collected.sort()) // [["a", 1], ["b", 2]]traversing
Source effect/HashMap.ts:10664 lines
export const const forEach: {
<V, K>(f: (value: V, key: K) => void): (
self: HashMap<K, V>
) => void
<V, K>(
self: HashMap<K, V>,
f: (value: V, key: K) => void
): void
}
Applies the specified function to the entries of the HashMap.
Example (Iterating with side effects)
import { HashMap } from "effect"
const map = HashMap.make(["a", 1], ["b", 2])
const collected: Array<[string, number]> = []
HashMap.forEach(map, (value, key) => {
collected.push([key, value])
})
console.log(collected.sort()) // [["a", 1], ["b", 2]]
forEach: {
<function (type parameter) V in <V, K>(f: (value: V, key: K) => void): (self: HashMap<K, V>) => voidV, function (type parameter) K in <V, K>(f: (value: V, key: K) => void): (self: HashMap<K, V>) => voidK>(f: (value: V, key: K) => voidf: (value: Vvalue: function (type parameter) V in <V, K>(f: (value: V, key: K) => void): (self: HashMap<K, V>) => voidV, key: Kkey: function (type parameter) K in <V, K>(f: (value: V, key: K) => void): (self: HashMap<K, V>) => voidK) => void): (self: HashMap<K, V>(parameter) self: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
interface HashMap<out Key, out Value>A HashMap is an immutable key-value data structure that provides efficient lookup,
insertion, and deletion operations. It uses a Hash Array Mapped Trie (HAMT) internally
for structural sharing and optimal performance.
Example (Using basic HashMap operations)
import { HashMap } from "effect"
// Create a HashMap
const map = HashMap.make(["a", 1], ["b", 2], ["c", 3])
// Access values
const valueA = HashMap.get(map, "a") // Option.some(1)
const valueD = HashMap.get(map, "d") // Option.none()
// Check if key exists
console.log(HashMap.has(map, "b")) // true
// Add/update values (returns new HashMap)
const updated = HashMap.set(map, "d", 4)
console.log(HashMap.size(updated)) // 4
The HashMap namespace contains type-level utilities and helper types
for working with HashMap instances.
Example (Extracting HashMap types)
import { HashMap } from "effect"
// Create a concrete HashMap for type extraction
const inventory = HashMap.make(
["laptop", { quantity: 5, price: 999 }],
["mouse", { quantity: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = HashMap.HashMap.Key<typeof inventory> // string
type Product = HashMap.HashMap.Value<typeof inventory> // { quantity: number, price: number }
type InventoryEntry = HashMap.HashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateInventory = (id: ProductId, product: Product) =>
HashMap.set(inventory, id, product)
const processEntry = ([id, product]: InventoryEntry) =>
`${id}: ${product.quantity} @ $${product.price}`
// Example of extracted types in action
const newProduct: Product = { quantity: 10, price: 199 }
const updatedInventory = updateInventory("tablet", newProduct)
HashMap<function (type parameter) K in <V, K>(f: (value: V, key: K) => void): (self: HashMap<K, V>) => voidK, function (type parameter) V in <V, K>(f: (value: V, key: K) => void): (self: HashMap<K, V>) => voidV>) => void
<function (type parameter) V in <V, K>(self: HashMap<K, V>, f: (value: V, key: K) => void): voidV, function (type parameter) K in <V, K>(self: HashMap<K, V>, f: (value: V, key: K) => void): voidK>(self: HashMap<K, V>(parameter) self: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
interface HashMap<out Key, out Value>A HashMap is an immutable key-value data structure that provides efficient lookup,
insertion, and deletion operations. It uses a Hash Array Mapped Trie (HAMT) internally
for structural sharing and optimal performance.
Example (Using basic HashMap operations)
import { HashMap } from "effect"
// Create a HashMap
const map = HashMap.make(["a", 1], ["b", 2], ["c", 3])
// Access values
const valueA = HashMap.get(map, "a") // Option.some(1)
const valueD = HashMap.get(map, "d") // Option.none()
// Check if key exists
console.log(HashMap.has(map, "b")) // true
// Add/update values (returns new HashMap)
const updated = HashMap.set(map, "d", 4)
console.log(HashMap.size(updated)) // 4
The HashMap namespace contains type-level utilities and helper types
for working with HashMap instances.
Example (Extracting HashMap types)
import { HashMap } from "effect"
// Create a concrete HashMap for type extraction
const inventory = HashMap.make(
["laptop", { quantity: 5, price: 999 }],
["mouse", { quantity: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = HashMap.HashMap.Key<typeof inventory> // string
type Product = HashMap.HashMap.Value<typeof inventory> // { quantity: number, price: number }
type InventoryEntry = HashMap.HashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateInventory = (id: ProductId, product: Product) =>
HashMap.set(inventory, id, product)
const processEntry = ([id, product]: InventoryEntry) =>
`${id}: ${product.quantity} @ $${product.price}`
// Example of extracted types in action
const newProduct: Product = { quantity: 10, price: 199 }
const updatedInventory = updateInventory("tablet", newProduct)
HashMap<function (type parameter) K in <V, K>(self: HashMap<K, V>, f: (value: V, key: K) => void): voidK, function (type parameter) V in <V, K>(self: HashMap<K, V>, f: (value: V, key: K) => void): voidV>, f: (value: V, key: K) => voidf: (value: Vvalue: function (type parameter) V in <V, K>(self: HashMap<K, V>, f: (value: V, key: K) => void): voidV, key: Kkey: function (type parameter) K in <V, K>(self: HashMap<K, V>, f: (value: V, key: K) => void): voidK) => void): void
} = import internalinternal.const forEach: anyforEach