<A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (
self: HashMap<K, A>
) => HashMap<K, B>
<K, A, B, X>(
self: HashMap<K, A>,
f: (input: A, key: K) => Result<B, X>
): HashMap<K, B>Maps over the entries of the HashMap using the specified filter and keeps
only successful results.
Example (Filtering and mapping Results)
import { HashMap, Result } from "effect"
const map1 = HashMap.make(["a", 1], ["b", 2], ["c", 3], ["d", 4])
const map2 = HashMap.filterMap(
map1,
(value) => value % 2 === 0 ? Result.succeed(value * 2) : Result.failVoid
)
console.log(HashMap.size(map2)) // 2
console.log(HashMap.get(map2, "b")) // Option.some(4)
console.log(HashMap.get(map2, "d")) // Option.some(8)filtering
Source effect/HashMap.ts:11664 lines
export const const filterMap: {
<A, K, B, X>(
f: (input: A, key: K) => Result<B, X>
): (self: HashMap<K, A>) => HashMap<K, B>
<K, A, B, X>(
self: HashMap<K, A>,
f: (input: A, key: K) => Result<B, X>
): HashMap<K, B>
}
Maps over the entries of the HashMap using the specified filter and keeps
only successful results.
Example (Filtering and mapping Results)
import { HashMap, Result } from "effect"
const map1 = HashMap.make(["a", 1], ["b", 2], ["c", 3], ["d", 4])
const map2 = HashMap.filterMap(
map1,
(value) => value % 2 === 0 ? Result.succeed(value * 2) : Result.failVoid
)
console.log(HashMap.size(map2)) // 2
console.log(HashMap.get(map2, "b")) // Option.some(4)
console.log(HashMap.get(map2, "d")) // Option.some(8)
filterMap: {
<function (type parameter) A in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>A, function (type parameter) K in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>K, function (type parameter) B in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>B, function (type parameter) X in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>X>(f: (input: A, key: K) => Result<B, X>f: (input: Ainput: function (type parameter) A in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>A, key: Kkey: function (type parameter) K in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>K) => type Result<A, E = never> = Success<A, E> | Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) B in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>B, function (type parameter) X in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>X>): (self: HashMap<K, A>(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} @ $${product.price}`
// Example of extracted types in action
const newProduct: Product = { quantity: 10, price: 199 }
const updatedInventory = updateInventory("tablet", newProduct)
HashMap<function (type parameter) K in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>K, function (type parameter) A in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>A>) => interface HashMap<out Key, out Value>A HashMap is an immutable key-value data structure that provides efficient lookup,
insertion, and deletion operations. It uses a Hash Array Mapped Trie (HAMT) internally
for structural sharing and optimal performance.
Example (Using basic HashMap operations)
import { HashMap } from "effect"
// Create a HashMap
const map = HashMap.make(["a", 1], ["b", 2], ["c", 3])
// Access values
const valueA = HashMap.get(map, "a") // Option.some(1)
const valueD = HashMap.get(map, "d") // Option.none()
// Check if key exists
console.log(HashMap.has(map, "b")) // true
// Add/update values (returns new HashMap)
const updated = HashMap.set(map, "d", 4)
console.log(HashMap.size(updated)) // 4
The HashMap namespace contains type-level utilities and helper types
for working with HashMap instances.
Example (Extracting HashMap types)
import { HashMap } from "effect"
// Create a concrete HashMap for type extraction
const inventory = HashMap.make(
["laptop", { quantity: 5, price: 999 }],
["mouse", { quantity: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = HashMap.HashMap.Key<typeof inventory> // string
type Product = HashMap.HashMap.Value<typeof inventory> // { quantity: number, price: number }
type InventoryEntry = HashMap.HashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateInventory = (id: ProductId, product: Product) =>
HashMap.set(inventory, id, product)
const processEntry = ([id, product]: InventoryEntry) =>
`${id}: ${product.quantity} @ $${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 <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>K, function (type parameter) B in <A, K, B, X>(f: (input: A, key: K) => Result<B, X>): (self: HashMap<K, A>) => HashMap<K, B>B>
<function (type parameter) K in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>K, function (type parameter) A in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>A, function (type parameter) B in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>B, function (type parameter) X in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>X>(self: HashMap<K, A>(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, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>K, function (type parameter) A in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>A>, f: (input: A, key: K) => Result<B, X>f: (input: Ainput: function (type parameter) A in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>A, key: Kkey: function (type parameter) K in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>K) => type Result<A, E = never> = Success<A, E> | Failure<A, E>A value that is either Success<A, E> or Failure<A, E>.
When to use
Use when both success and failure should remain available as data and
Option would lose failure information.
Details
- Use
succeed
/
fail
to construct
- Use
match
to fold both branches
- Use
isSuccess
/
isFailure
to narrow the type
E defaults to never, so Result<number> means a result that cannot fail.
Example (Creating and matching a Result)
import { Result } from "effect"
const success = Result.succeed(42)
const failure = Result.fail("something went wrong")
const message = Result.match(success, {
onSuccess: (value) => `Success: ${value}`,
onFailure: (error) => `Error: ${error}`
})
console.log(message)
// Output: "Success: 42"
Namespace containing type-level utilities for extracting the inner types
of a Result.
Example (Extracting inner types)
import type { Result } from "effect"
type R = Result.Result<number, string>
// number
type A = Result.Result.Success<R>
// string
type E = Result.Result.Failure<R>
Result<function (type parameter) B in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>B, function (type parameter) X in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>X>): 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, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>K, function (type parameter) B in <K, A, B, X>(self: HashMap<K, A>, f: (input: A, key: K) => Result<B, X>): HashMap<K, B>B>
} = import internalinternal.const filterMap: anyfilterMapReferenced by 1 symbols