<K, V>(self: HashMap<K, V>): HashMap<K, V>Creates a transient mutable HashMap for efficient batched updates.
Details
Apply updates to the returned map, then call endMutation to finish the
mutation window and use the result as an immutable HashMap.
Example (Beginning batch mutation)
import { HashMap } from "effect"
const map = HashMap.make(["a", 1])
// Begin mutation for efficient batch operations
const mutable = HashMap.beginMutation(map)
// Multiple operations are now more efficient
HashMap.set(mutable, "b", 2)
HashMap.set(mutable, "c", 3)
HashMap.remove(mutable, "a")
// End mutation to get final immutable result
const result = HashMap.endMutation(mutable)
console.log(HashMap.size(result)) // 2export const const beginMutation: <K, V>(
self: HashMap<K, V>
) => HashMap<K, V>
Creates a transient mutable HashMap for efficient batched updates.
Details
Apply updates to the returned map, then call endMutation to finish the
mutation window and use the result as an immutable HashMap.
Example (Beginning batch mutation)
import { HashMap } from "effect"
const map = HashMap.make(["a", 1])
// Begin mutation for efficient batch operations
const mutable = HashMap.beginMutation(map)
// Multiple operations are now more efficient
HashMap.set(mutable, "b", 2)
HashMap.set(mutable, "c", 3)
HashMap.remove(mutable, "a")
// End mutation to get final immutable result
const result = HashMap.endMutation(mutable)
console.log(HashMap.size(result)) // 2
beginMutation: <function (type parameter) K in <K, V>(self: HashMap<K, V>): HashMap<K, V>K, function (type parameter) V in <K, V>(self: HashMap<K, V>): HashMap<K, V>V>(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} @ $${product.price}`
// Example of extracted types in action
const newProduct: Product = { quantity: 10, price: 199 }
const updatedInventory = updateInventory("tablet", newProduct)
HashMap<function (type parameter) K in <K, V>(self: HashMap<K, V>): HashMap<K, V>K, function (type parameter) V in <K, V>(self: HashMap<K, V>): HashMap<K, V>V>) => interface HashMap<out Key, out Value>A HashMap is an immutable key-value data structure that provides efficient lookup,
insertion, and deletion operations. It uses a Hash Array Mapped Trie (HAMT) internally
for structural sharing and optimal performance.
Example (Using basic HashMap operations)
import { HashMap } from "effect"
// Create a HashMap
const map = HashMap.make(["a", 1], ["b", 2], ["c", 3])
// Access values
const valueA = HashMap.get(map, "a") // Option.some(1)
const valueD = HashMap.get(map, "d") // Option.none()
// Check if key exists
console.log(HashMap.has(map, "b")) // true
// Add/update values (returns new HashMap)
const updated = HashMap.set(map, "d", 4)
console.log(HashMap.size(updated)) // 4
The HashMap namespace contains type-level utilities and helper types
for working with HashMap instances.
Example (Extracting HashMap types)
import { HashMap } from "effect"
// Create a concrete HashMap for type extraction
const inventory = HashMap.make(
["laptop", { quantity: 5, price: 999 }],
["mouse", { quantity: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = HashMap.HashMap.Key<typeof inventory> // string
type Product = HashMap.HashMap.Value<typeof inventory> // { quantity: number, price: number }
type InventoryEntry = HashMap.HashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateInventory = (id: ProductId, product: Product) =>
HashMap.set(inventory, id, product)
const processEntry = ([id, product]: InventoryEntry) =>
`${id}: ${product.quantity} @ $${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 <K, V>(self: HashMap<K, V>): HashMap<K, V>K, function (type parameter) V in <K, V>(self: HashMap<K, V>): HashMap<K, V>V> = import internalinternal.const beginMutation: <K, V>(
self: internal.HashMap<K, V>
) => internal.HashMap<K, V>