<A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (
self: TxHashMap<K, V>
) => Effect.Effect<TxHashMap<K, A>>
<K, V, A>(
self: TxHashMap<K, V>,
f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>
): Effect.Effect<TxHashMap<K, A>>Maps each entry effectfully to a TxHashMap and flattens the produced maps.
Details
This function returns a new TxHashMap reference with the flattened results. The original TxHashMap is not modified.
Example (Flat mapping entries)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a department-employee map
const departments = yield* TxHashMap.make(
["engineering", ["alice", "bob"]],
["marketing", ["charlie", "diana"]]
)
// Expand each department into individual employee entries with metadata
const employeeDetails = yield* TxHashMap.flatMap(
departments,
(employees, department) =>
Effect.gen(function*() {
const employeeMap = yield* TxHashMap.empty<
string,
{ department: string; role: string }
>()
for (let i = 0; i < employees.length; i++) {
const employee = employees[i]
const role = i === 0 ? "lead" : "member"
yield* TxHashMap.set(employeeMap, employee, { department, role })
}
return employeeMap
})
)
// Check the flattened result
const alice = yield* TxHashMap.get(employeeDetails, "alice")
console.log(alice) // Option.some({ department: "engineering", role: "lead" })
const charlie = yield* TxHashMap.get(employeeDetails, "charlie")
console.log(charlie) // Option.some({ department: "marketing", role: "lead" })
const size = yield* TxHashMap.size(employeeDetails)
console.log(size) // 4 (all employees)
})export const const flatMap: {
<A, V, K>(
f: (
value: V,
key: K
) => Effect.Effect<TxHashMap<K, A>>
): (
self: TxHashMap<K, V>
) => Effect.Effect<TxHashMap<K, A>>
<K, V, A>(
self: TxHashMap<K, V>,
f: (
value: V,
key: K
) => Effect.Effect<TxHashMap<K, A>>
): Effect.Effect<TxHashMap<K, A>>
}
Maps each entry effectfully to a TxHashMap and flattens the produced maps.
Details
This function returns a new TxHashMap reference with the flattened results.
The original TxHashMap is not modified.
Example (Flat mapping entries)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a department-employee map
const departments = yield* TxHashMap.make(
["engineering", ["alice", "bob"]],
["marketing", ["charlie", "diana"]]
)
// Expand each department into individual employee entries with metadata
const employeeDetails = yield* TxHashMap.flatMap(
departments,
(employees, department) =>
Effect.gen(function*() {
const employeeMap = yield* TxHashMap.empty<
string,
{ department: string; role: string }
>()
for (let i = 0; i < employees.length; i++) {
const employee = employees[i]
const role = i === 0 ? "lead" : "member"
yield* TxHashMap.set(employeeMap, employee, { department, role })
}
return employeeMap
})
)
// Check the flattened result
const alice = yield* TxHashMap.get(employeeDetails, "alice")
console.log(alice) // Option.some({ department: "engineering", role: "lead" })
const charlie = yield* TxHashMap.get(employeeDetails, "charlie")
console.log(charlie) // Option.some({ department: "marketing", role: "lead" })
const size = yield* TxHashMap.size(employeeDetails)
console.log(size) // 4 (all employees)
})
flatMap: {
<function (type parameter) A in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>A, function (type parameter) V in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>V, function (type parameter) K in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>K>(
f: (
value: V,
key: K
) => Effect.Effect<TxHashMap<K, A>>
value: Vvalue: function (type parameter) V in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>V, key: Kkey: function (type parameter) K in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>K) => import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<interface TxHashMap<in out K, in out V>A TxHashMap is a transactional hash map data structure that provides atomic operations
on key-value pairs within Effect transactions. It uses an immutable HashMap internally
with TxRef for transactional semantics, ensuring all operations are performed atomically.
Example (Using transactional hash maps)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional hash map
const txMap = yield* TxHashMap.make(["user1", "Alice"], ["user2", "Bob"])
// Single operations are automatically transactional
yield* TxHashMap.set(txMap, "user3", "Charlie")
const user = yield* TxHashMap.get(txMap, "user1")
console.log(user) // Option.some("Alice")
// Multi-step atomic operations
yield* Effect.tx(
Effect.gen(function*() {
const currentUser = yield* TxHashMap.get(txMap, "user1")
if (currentUser._tag === "Some") {
yield* TxHashMap.set(txMap, "user1", currentUser.value + "_updated")
yield* TxHashMap.remove(txMap, "user2")
}
})
)
const size = yield* TxHashMap.size(txMap)
console.log(size) // 2
})
The TxHashMap namespace contains type-level utilities and helper types
for working with TxHashMap instances.
Example (Reusing extracted TxHashMap types)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional inventory map
const inventory = yield* TxHashMap.make(
["laptop", { stock: 5, price: 999 }],
["mouse", { stock: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = TxHashMap.TxHashMap.Key<typeof inventory> // string
type Product = TxHashMap.TxHashMap.Value<typeof inventory> // { stock: number, price: number }
type InventoryEntry = TxHashMap.TxHashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateStock = (id: ProductId, newStock: number) =>
TxHashMap.modify(
inventory,
id,
(product) => ({ ...product, stock: newStock })
)
yield* updateStock("laptop", 3)
})
TxHashMap<function (type parameter) K in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>K, function (type parameter) A in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>A>>
): (self: TxHashMap<K, V>(parameter) self: {
ref: TxRef.TxRef<HashMap.HashMap<K, V>>;
toString: () => string;
toJSON: () => unknown;
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; <…;
}
interface TxHashMap<in out K, in out V>A TxHashMap is a transactional hash map data structure that provides atomic operations
on key-value pairs within Effect transactions. It uses an immutable HashMap internally
with TxRef for transactional semantics, ensuring all operations are performed atomically.
Example (Using transactional hash maps)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional hash map
const txMap = yield* TxHashMap.make(["user1", "Alice"], ["user2", "Bob"])
// Single operations are automatically transactional
yield* TxHashMap.set(txMap, "user3", "Charlie")
const user = yield* TxHashMap.get(txMap, "user1")
console.log(user) // Option.some("Alice")
// Multi-step atomic operations
yield* Effect.tx(
Effect.gen(function*() {
const currentUser = yield* TxHashMap.get(txMap, "user1")
if (currentUser._tag === "Some") {
yield* TxHashMap.set(txMap, "user1", currentUser.value + "_updated")
yield* TxHashMap.remove(txMap, "user2")
}
})
)
const size = yield* TxHashMap.size(txMap)
console.log(size) // 2
})
The TxHashMap namespace contains type-level utilities and helper types
for working with TxHashMap instances.
Example (Reusing extracted TxHashMap types)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional inventory map
const inventory = yield* TxHashMap.make(
["laptop", { stock: 5, price: 999 }],
["mouse", { stock: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = TxHashMap.TxHashMap.Key<typeof inventory> // string
type Product = TxHashMap.TxHashMap.Value<typeof inventory> // { stock: number, price: number }
type InventoryEntry = TxHashMap.TxHashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateStock = (id: ProductId, newStock: number) =>
TxHashMap.modify(
inventory,
id,
(product) => ({ ...product, stock: newStock })
)
yield* updateStock("laptop", 3)
})
TxHashMap<function (type parameter) K in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>K, function (type parameter) V in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>V>) => import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<interface TxHashMap<in out K, in out V>A TxHashMap is a transactional hash map data structure that provides atomic operations
on key-value pairs within Effect transactions. It uses an immutable HashMap internally
with TxRef for transactional semantics, ensuring all operations are performed atomically.
Example (Using transactional hash maps)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional hash map
const txMap = yield* TxHashMap.make(["user1", "Alice"], ["user2", "Bob"])
// Single operations are automatically transactional
yield* TxHashMap.set(txMap, "user3", "Charlie")
const user = yield* TxHashMap.get(txMap, "user1")
console.log(user) // Option.some("Alice")
// Multi-step atomic operations
yield* Effect.tx(
Effect.gen(function*() {
const currentUser = yield* TxHashMap.get(txMap, "user1")
if (currentUser._tag === "Some") {
yield* TxHashMap.set(txMap, "user1", currentUser.value + "_updated")
yield* TxHashMap.remove(txMap, "user2")
}
})
)
const size = yield* TxHashMap.size(txMap)
console.log(size) // 2
})
The TxHashMap namespace contains type-level utilities and helper types
for working with TxHashMap instances.
Example (Reusing extracted TxHashMap types)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional inventory map
const inventory = yield* TxHashMap.make(
["laptop", { stock: 5, price: 999 }],
["mouse", { stock: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = TxHashMap.TxHashMap.Key<typeof inventory> // string
type Product = TxHashMap.TxHashMap.Value<typeof inventory> // { stock: number, price: number }
type InventoryEntry = TxHashMap.TxHashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateStock = (id: ProductId, newStock: number) =>
TxHashMap.modify(
inventory,
id,
(product) => ({ ...product, stock: newStock })
)
yield* updateStock("laptop", 3)
})
TxHashMap<function (type parameter) K in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>K, function (type parameter) A in <A, V, K>(f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): (self: TxHashMap<K, V>) => Effect.Effect<TxHashMap<K, A>>A>>
<function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K, function (type parameter) V in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>V, function (type parameter) A in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>A>(
self: TxHashMap<K, V>(parameter) self: {
ref: TxRef.TxRef<HashMap.HashMap<K, V>>;
toString: () => string;
toJSON: () => unknown;
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; <…;
}
interface TxHashMap<in out K, in out V>A TxHashMap is a transactional hash map data structure that provides atomic operations
on key-value pairs within Effect transactions. It uses an immutable HashMap internally
with TxRef for transactional semantics, ensuring all operations are performed atomically.
Example (Using transactional hash maps)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional hash map
const txMap = yield* TxHashMap.make(["user1", "Alice"], ["user2", "Bob"])
// Single operations are automatically transactional
yield* TxHashMap.set(txMap, "user3", "Charlie")
const user = yield* TxHashMap.get(txMap, "user1")
console.log(user) // Option.some("Alice")
// Multi-step atomic operations
yield* Effect.tx(
Effect.gen(function*() {
const currentUser = yield* TxHashMap.get(txMap, "user1")
if (currentUser._tag === "Some") {
yield* TxHashMap.set(txMap, "user1", currentUser.value + "_updated")
yield* TxHashMap.remove(txMap, "user2")
}
})
)
const size = yield* TxHashMap.size(txMap)
console.log(size) // 2
})
The TxHashMap namespace contains type-level utilities and helper types
for working with TxHashMap instances.
Example (Reusing extracted TxHashMap types)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional inventory map
const inventory = yield* TxHashMap.make(
["laptop", { stock: 5, price: 999 }],
["mouse", { stock: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = TxHashMap.TxHashMap.Key<typeof inventory> // string
type Product = TxHashMap.TxHashMap.Value<typeof inventory> // { stock: number, price: number }
type InventoryEntry = TxHashMap.TxHashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateStock = (id: ProductId, newStock: number) =>
TxHashMap.modify(
inventory,
id,
(product) => ({ ...product, stock: newStock })
)
yield* updateStock("laptop", 3)
})
TxHashMap<function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K, function (type parameter) V in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>V>,
f: (
value: V,
key: K
) => Effect.Effect<TxHashMap<K, A>>
value: Vvalue: function (type parameter) V in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>V, key: Kkey: function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K) => import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<interface TxHashMap<in out K, in out V>A TxHashMap is a transactional hash map data structure that provides atomic operations
on key-value pairs within Effect transactions. It uses an immutable HashMap internally
with TxRef for transactional semantics, ensuring all operations are performed atomically.
Example (Using transactional hash maps)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional hash map
const txMap = yield* TxHashMap.make(["user1", "Alice"], ["user2", "Bob"])
// Single operations are automatically transactional
yield* TxHashMap.set(txMap, "user3", "Charlie")
const user = yield* TxHashMap.get(txMap, "user1")
console.log(user) // Option.some("Alice")
// Multi-step atomic operations
yield* Effect.tx(
Effect.gen(function*() {
const currentUser = yield* TxHashMap.get(txMap, "user1")
if (currentUser._tag === "Some") {
yield* TxHashMap.set(txMap, "user1", currentUser.value + "_updated")
yield* TxHashMap.remove(txMap, "user2")
}
})
)
const size = yield* TxHashMap.size(txMap)
console.log(size) // 2
})
The TxHashMap namespace contains type-level utilities and helper types
for working with TxHashMap instances.
Example (Reusing extracted TxHashMap types)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional inventory map
const inventory = yield* TxHashMap.make(
["laptop", { stock: 5, price: 999 }],
["mouse", { stock: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = TxHashMap.TxHashMap.Key<typeof inventory> // string
type Product = TxHashMap.TxHashMap.Value<typeof inventory> // { stock: number, price: number }
type InventoryEntry = TxHashMap.TxHashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateStock = (id: ProductId, newStock: number) =>
TxHashMap.modify(
inventory,
id,
(product) => ({ ...product, stock: newStock })
)
yield* updateStock("laptop", 3)
})
TxHashMap<function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K, function (type parameter) A in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>A>>
): import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<interface TxHashMap<in out K, in out V>A TxHashMap is a transactional hash map data structure that provides atomic operations
on key-value pairs within Effect transactions. It uses an immutable HashMap internally
with TxRef for transactional semantics, ensuring all operations are performed atomically.
Example (Using transactional hash maps)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional hash map
const txMap = yield* TxHashMap.make(["user1", "Alice"], ["user2", "Bob"])
// Single operations are automatically transactional
yield* TxHashMap.set(txMap, "user3", "Charlie")
const user = yield* TxHashMap.get(txMap, "user1")
console.log(user) // Option.some("Alice")
// Multi-step atomic operations
yield* Effect.tx(
Effect.gen(function*() {
const currentUser = yield* TxHashMap.get(txMap, "user1")
if (currentUser._tag === "Some") {
yield* TxHashMap.set(txMap, "user1", currentUser.value + "_updated")
yield* TxHashMap.remove(txMap, "user2")
}
})
)
const size = yield* TxHashMap.size(txMap)
console.log(size) // 2
})
The TxHashMap namespace contains type-level utilities and helper types
for working with TxHashMap instances.
Example (Reusing extracted TxHashMap types)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional inventory map
const inventory = yield* TxHashMap.make(
["laptop", { stock: 5, price: 999 }],
["mouse", { stock: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = TxHashMap.TxHashMap.Key<typeof inventory> // string
type Product = TxHashMap.TxHashMap.Value<typeof inventory> // { stock: number, price: number }
type InventoryEntry = TxHashMap.TxHashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateStock = (id: ProductId, newStock: number) =>
TxHashMap.modify(
inventory,
id,
(product) => ({ ...product, stock: newStock })
)
yield* updateStock("laptop", 3)
})
TxHashMap<function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K, function (type parameter) A in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>A>>
} = dual<(...args: Array<any>) => any, <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>) => Effect.Effect<TxHashMap<K, A>>>(arity: 2, body: <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>) => Effect.Effect<TxHashMap<K, A>>): ((...args: Array<any>) => any) & (<K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>) => Effect.Effect<TxHashMap<K, A>>) (+1 overload)Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual(
2,
<function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K, function (type parameter) V in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>V, function (type parameter) A in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>A>(
self: TxHashMap<K, V>(parameter) self: {
ref: TxRef.TxRef<HashMap.HashMap<K, V>>;
toString: () => string;
toJSON: () => unknown;
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; <…;
}
interface TxHashMap<in out K, in out V>A TxHashMap is a transactional hash map data structure that provides atomic operations
on key-value pairs within Effect transactions. It uses an immutable HashMap internally
with TxRef for transactional semantics, ensuring all operations are performed atomically.
Example (Using transactional hash maps)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional hash map
const txMap = yield* TxHashMap.make(["user1", "Alice"], ["user2", "Bob"])
// Single operations are automatically transactional
yield* TxHashMap.set(txMap, "user3", "Charlie")
const user = yield* TxHashMap.get(txMap, "user1")
console.log(user) // Option.some("Alice")
// Multi-step atomic operations
yield* Effect.tx(
Effect.gen(function*() {
const currentUser = yield* TxHashMap.get(txMap, "user1")
if (currentUser._tag === "Some") {
yield* TxHashMap.set(txMap, "user1", currentUser.value + "_updated")
yield* TxHashMap.remove(txMap, "user2")
}
})
)
const size = yield* TxHashMap.size(txMap)
console.log(size) // 2
})
The TxHashMap namespace contains type-level utilities and helper types
for working with TxHashMap instances.
Example (Reusing extracted TxHashMap types)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional inventory map
const inventory = yield* TxHashMap.make(
["laptop", { stock: 5, price: 999 }],
["mouse", { stock: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = TxHashMap.TxHashMap.Key<typeof inventory> // string
type Product = TxHashMap.TxHashMap.Value<typeof inventory> // { stock: number, price: number }
type InventoryEntry = TxHashMap.TxHashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateStock = (id: ProductId, newStock: number) =>
TxHashMap.modify(
inventory,
id,
(product) => ({ ...product, stock: newStock })
)
yield* updateStock("laptop", 3)
})
TxHashMap<function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K, function (type parameter) V in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>V>,
f: (
value: V,
key: K
) => Effect.Effect<TxHashMap<K, A>>
value: Vvalue: function (type parameter) V in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>V, key: Kkey: function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K) => import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<interface TxHashMap<in out K, in out V>A TxHashMap is a transactional hash map data structure that provides atomic operations
on key-value pairs within Effect transactions. It uses an immutable HashMap internally
with TxRef for transactional semantics, ensuring all operations are performed atomically.
Example (Using transactional hash maps)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional hash map
const txMap = yield* TxHashMap.make(["user1", "Alice"], ["user2", "Bob"])
// Single operations are automatically transactional
yield* TxHashMap.set(txMap, "user3", "Charlie")
const user = yield* TxHashMap.get(txMap, "user1")
console.log(user) // Option.some("Alice")
// Multi-step atomic operations
yield* Effect.tx(
Effect.gen(function*() {
const currentUser = yield* TxHashMap.get(txMap, "user1")
if (currentUser._tag === "Some") {
yield* TxHashMap.set(txMap, "user1", currentUser.value + "_updated")
yield* TxHashMap.remove(txMap, "user2")
}
})
)
const size = yield* TxHashMap.size(txMap)
console.log(size) // 2
})
The TxHashMap namespace contains type-level utilities and helper types
for working with TxHashMap instances.
Example (Reusing extracted TxHashMap types)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional inventory map
const inventory = yield* TxHashMap.make(
["laptop", { stock: 5, price: 999 }],
["mouse", { stock: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = TxHashMap.TxHashMap.Key<typeof inventory> // string
type Product = TxHashMap.TxHashMap.Value<typeof inventory> // { stock: number, price: number }
type InventoryEntry = TxHashMap.TxHashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateStock = (id: ProductId, newStock: number) =>
TxHashMap.modify(
inventory,
id,
(product) => ({ ...product, stock: newStock })
)
yield* updateStock("laptop", 3)
})
TxHashMap<function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K, function (type parameter) A in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>A>>
): import EffectEffect.interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<interface TxHashMap<in out K, in out V>A TxHashMap is a transactional hash map data structure that provides atomic operations
on key-value pairs within Effect transactions. It uses an immutable HashMap internally
with TxRef for transactional semantics, ensuring all operations are performed atomically.
Example (Using transactional hash maps)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional hash map
const txMap = yield* TxHashMap.make(["user1", "Alice"], ["user2", "Bob"])
// Single operations are automatically transactional
yield* TxHashMap.set(txMap, "user3", "Charlie")
const user = yield* TxHashMap.get(txMap, "user1")
console.log(user) // Option.some("Alice")
// Multi-step atomic operations
yield* Effect.tx(
Effect.gen(function*() {
const currentUser = yield* TxHashMap.get(txMap, "user1")
if (currentUser._tag === "Some") {
yield* TxHashMap.set(txMap, "user1", currentUser.value + "_updated")
yield* TxHashMap.remove(txMap, "user2")
}
})
)
const size = yield* TxHashMap.size(txMap)
console.log(size) // 2
})
The TxHashMap namespace contains type-level utilities and helper types
for working with TxHashMap instances.
Example (Reusing extracted TxHashMap types)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a transactional inventory map
const inventory = yield* TxHashMap.make(
["laptop", { stock: 5, price: 999 }],
["mouse", { stock: 20, price: 29 }]
)
// Extract types for reuse
type ProductId = TxHashMap.TxHashMap.Key<typeof inventory> // string
type Product = TxHashMap.TxHashMap.Value<typeof inventory> // { stock: number, price: number }
type InventoryEntry = TxHashMap.TxHashMap.Entry<typeof inventory> // [string, Product]
// Use extracted types in functions
const updateStock = (id: ProductId, newStock: number) =>
TxHashMap.modify(
inventory,
id,
(product) => ({ ...product, stock: newStock })
)
yield* updateStock("laptop", 3)
})
TxHashMap<function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K, function (type parameter) A in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>A>> =>
import EffectEffect.const gen: {
<Eff extends Effect<any, any, any>, AEff>(
f: () => Generator<Eff, AEff, never>
): Effect<
AEff,
[Eff] extends [never]
? never
: [Eff] extends [
Effect<infer _A, infer E, infer _R>
]
? E
: never,
[Eff] extends [never]
? never
: [Eff] extends [
Effect<infer _A, infer _E, infer R>
]
? R
: never
>
<Self, Eff extends Effect<any, any, any>, AEff>(
options: { readonly self: Self },
f: (this: Self) => Generator<Eff, AEff, never>
): Effect<
AEff,
[Eff] extends [never]
? never
: [Eff] extends [
Effect<infer _A, infer E, infer _R>
]
? E
: never,
[Eff] extends [never]
? never
: [Eff] extends [
Effect<infer _A, infer _E, infer R>
]
? R
: never
>
}
const currentMap: HashMap.HashMap<K, V>const currentMap: {
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;
}
import TxRefTxRef.const get: <A>(
self: TxRef<A>
) => Effect.Effect<A>
Reads the current value of the TxRef.
When to use
Use to read the current value of a TxRef.
Example (Reading transactional references)
import { Effect, TxRef } from "effect"
const program = Effect.gen(function*() {
const counter = yield* TxRef.make(42)
// Read the value within a transaction
const value = yield* Effect.tx(
TxRef.get(counter)
)
console.log(value) // 42
})
get(self: TxHashMap<K, V>(parameter) self: {
ref: TxRef.TxRef<HashMap.HashMap<K, V>>;
toString: () => string;
toJSON: () => unknown;
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; <…;
}
TxHashMap<K, V>.ref: TxRef.TxRef<HashMap.HashMap<K, V>>(property) TxHashMap<K, V>.ref: {
version: number;
pending: Map<unknown, () => void>;
value: A;
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; <…;
}
const result: TxHashMap<K, A>const result: {
ref: TxRef.TxRef<HashMap.HashMap<K, V>>;
toString: () => string;
toJSON: () => unknown;
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; <…;
}
const empty: <K, V>() => Effect.Effect<
TxHashMap<K, V>
>
Creates an empty TxHashMap.
Example (Creating an empty map)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create an empty transactional hash map
const emptyMap = yield* TxHashMap.empty<string, number>()
// Verify it's empty
const isEmpty = yield* TxHashMap.isEmpty(emptyMap)
console.log(isEmpty) // true
const size = yield* TxHashMap.size(emptyMap)
console.log(size) // 0
// Start adding elements
yield* TxHashMap.set(emptyMap, "first", 1)
const newSize = yield* TxHashMap.size(emptyMap)
console.log(newSize) // 1
})
empty<function (type parameter) K in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>K, function (type parameter) A in <K, V, A>(self: TxHashMap<K, V>, f: (value: V, key: K) => Effect.Effect<TxHashMap<K, A>>): Effect.Effect<TxHashMap<K, A>>A>()
const const mapEntries: [K, V][]mapEntries = import HashMapHashMap.const toEntries: <K, V>(
self: HashMap<K, V>
) => Array<[K, V]>
Returns an Array<[K, V]> of the entries within the HashMap.
Example (Converting entries to an array)
import { HashMap } from "effect"
const gameScores = HashMap.make(
["alice", 1250],
["bob", 980],
["charlie", 1100]
)
// Convert to entries for processing
const scoreEntries = HashMap.toEntries(gameScores)
// Sort by score (descending)
const leaderboard = scoreEntries
.sort(([, a], [, b]) => b - a)
.map(([player, score], rank) => `${rank + 1}. ${player}: ${score}`)
console.log(leaderboard)
// ["1. alice: 1250", "2. charlie: 1100", "3. bob: 980"]
// Convert back to HashMap if needed
const sortedMap = HashMap.fromIterable(scoreEntries)
toEntries(const currentMap: HashMap.HashMap<K, V>const currentMap: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
const key: Kkey, const value: Vvalue] of const mapEntries: [K, V][]mapEntries) {
const const newMap: TxHashMap<K, A>const newMap: {
ref: TxRef.TxRef<HashMap.HashMap<K, V>>;
toString: () => string;
toJSON: () => unknown;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
f: (
value: V,
key: K
) => Effect.Effect<TxHashMap<K, A>>
const value: Vvalue, const key: Kkey)
const const newEntries: (readonly [K, A])[]newEntries = yield* const entries: <K, V>(
self: TxHashMap<K, V>
) => Effect.Effect<Array<readonly [K, V]>>
Returns an array of all key-value pairs in the TxHashMap.
Example (Reading entries)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
const config = yield* TxHashMap.make(
["host", "localhost"],
["port", "3000"],
["ssl", "false"]
)
const allEntries = yield* TxHashMap.entries(config)
const sortedEntries = allEntries.toSorted(([left], [right]) => left.localeCompare(right))
console.log(sortedEntries)
// [["host", "localhost"], ["port", "3000"], ["ssl", "false"]]
// Process configuration entries
for (const [key, value] of sortedEntries) {
console.log(`${key}=${value}`)
}
// host=localhost
// port=3000
// ssl=false
})
entries(const newMap: TxHashMap<K, A>const newMap: {
ref: TxRef.TxRef<HashMap.HashMap<K, V>>;
toString: () => string;
toJSON: () => unknown;
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; <…;
}
const setMany: {
<K1 extends K, K, V1 extends V, V>(
entries: Iterable<readonly [K1, V1]>
): (
self: TxHashMap<K, V>
) => Effect.Effect<void>
<K1 extends K, K, V1 extends V, V>(
self: TxHashMap<K, V>,
entries: Iterable<readonly [K1, V1]>
): Effect.Effect<void>
}
const result: TxHashMap<K, A>const result: {
ref: TxRef.TxRef<HashMap.HashMap<K, V>>;
toString: () => string;
toJSON: () => unknown;
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; <…;
}
const newEntries: (readonly [K, A])[]newEntries)
}
return const result: TxHashMap<K, A>const result: {
ref: TxRef.TxRef<HashMap.HashMap<K, V>>;
toString: () => string;
toJSON: () => unknown;
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; <…;
}
Pipeable.pipe<Effect.Effect<TxHashMap<K, A>, never, never>, Effect.Effect<TxHashMap<K, A>, never, never>>(this: Effect.Effect<TxHashMap<K, A>, never, never>, ab: (_: Effect.Effect<TxHashMap<K, A>, never, never>) => Effect.Effect<TxHashMap<K, A>, never, never>): Effect.Effect<TxHashMap<K, A>, never, never> (+21 overloads)pipe(import EffectEffect.const tx: <A, E, R>(
effect: Effect<A, E, R>
) => Effect<A, E, Exclude<R, Transaction>>
Defines a transaction boundary. Transactions are "all or nothing" with respect to changes
made to transactional values (i.e. TxRef) that occur within the transaction body.
Details
If called inside an active transaction, tx composes with the current transaction and reuses
its journal and retry state instead of creating a nested boundary.
Effect transactions are optimistic with retry. A transaction is retried when
its body explicitly calls Effect.txRetry and any accessed transactional
value changes, or when any accessed transactional value changes because a
different transaction commits before the current one.
The outermost tx call creates the transaction boundary and commits or rolls back the full
composed transaction.
Example (Running a transaction)
import { Effect, TxRef } from "effect"
const program = Effect.gen(function*() {
const ref1 = yield* TxRef.make(0)
const ref2 = yield* TxRef.make(0)
// Nested tx calls compose into the same transaction
yield* Effect.tx(Effect.gen(function*() {
yield* TxRef.set(ref1, 10)
yield* Effect.tx(TxRef.set(ref2, 20))
const sum = (yield* TxRef.get(ref1)) + (yield* TxRef.get(ref2))
console.log(`Transaction sum: ${sum}`)
}))
console.log(`Final ref1: ${yield* TxRef.get(ref1)}`) // 10
console.log(`Final ref2: ${yield* TxRef.get(ref2)}`) // 20
})
tx)
)