<K, V>(predicate: (value: V, key: K) => boolean): (
self: TxHashMap<K, V>
) => Effect.Effect<Option.Option<[K, V]>>
<K, V>(
self: TxHashMap<K, V>,
predicate: (value: V, key: K) => boolean
): Effect.Effect<Option.Option<[K, V]>>Finds the first entry in the TxHashMap that matches the given predicate. Returns the key-value pair as a tuple wrapped in an Option.
Example (Finding the first matching entry)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a task priority map
const tasks = yield* TxHashMap.make(
["task1", { priority: 1, assignee: "alice", completed: false }],
["task2", { priority: 3, assignee: "bob", completed: true }],
["task3", { priority: 2, assignee: "alice", completed: false }]
)
// Find first high-priority incomplete task
const highPriorityTask = yield* TxHashMap.findFirst(
tasks,
(task) => task.priority >= 2 && !task.completed
)
if (highPriorityTask._tag === "Some") {
const [taskId, task] = highPriorityTask.value
console.log(`Found task: ${taskId}, priority: ${task.priority}`)
// "Found task: task3, priority: 2"
}
// Find first task assigned to specific user
const aliceTask = yield* tasks.pipe(
TxHashMap.findFirst((task) => task.assignee === "alice")
)
if (aliceTask._tag === "Some") {
console.log(`Alice's task: ${aliceTask.value[0]}`)
}
})export const const findFirst: {
<K, V>(
predicate: (value: V, key: K) => boolean
): (
self: TxHashMap<K, V>
) => Effect.Effect<Option.Option<[K, V]>>
<K, V>(
self: TxHashMap<K, V>,
predicate: (value: V, key: K) => boolean
): Effect.Effect<Option.Option<[K, V]>>
}
Finds the first entry in the TxHashMap that matches the given predicate.
Returns the key-value pair as a tuple wrapped in an Option.
Example (Finding the first matching entry)
import { Effect, TxHashMap } from "effect"
const program = Effect.gen(function*() {
// Create a task priority map
const tasks = yield* TxHashMap.make(
["task1", { priority: 1, assignee: "alice", completed: false }],
["task2", { priority: 3, assignee: "bob", completed: true }],
["task3", { priority: 2, assignee: "alice", completed: false }]
)
// Find first high-priority incomplete task
const highPriorityTask = yield* TxHashMap.findFirst(
tasks,
(task) => task.priority >= 2 && !task.completed
)
if (highPriorityTask._tag === "Some") {
const [taskId, task] = highPriorityTask.value
console.log(`Found task: ${taskId}, priority: ${task.priority}`)
// "Found task: task3, priority: 2"
}
// Find first task assigned to specific user
const aliceTask = yield* tasks.pipe(
TxHashMap.findFirst((task) => task.assignee === "alice")
)
if (aliceTask._tag === "Some") {
console.log(`Alice's task: ${aliceTask.value[0]}`)
}
})
findFirst: {
<function (type parameter) K in <K, V>(predicate: (value: V, key: K) => boolean): (self: TxHashMap<K, V>) => Effect.Effect<Option.Option<[K, V]>>K, function (type parameter) V in <K, V>(predicate: (value: V, key: K) => boolean): (self: TxHashMap<K, V>) => Effect.Effect<Option.Option<[K, V]>>V>(
predicate: (value: V, key: K) => booleanpredicate: (value: Vvalue: function (type parameter) V in <K, V>(predicate: (value: V, key: K) => boolean): (self: TxHashMap<K, V>) => Effect.Effect<Option.Option<[K, V]>>V, key: Kkey: function (type parameter) K in <K, V>(predicate: (value: V, key: K) => boolean): (self: TxHashMap<K, V>) => Effect.Effect<Option.Option<[K, V]>>K) => boolean
): (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>(predicate: (value: V, key: K) => boolean): (self: TxHashMap<K, V>) => Effect.Effect<Option.Option<[K, V]>>K, function (type parameter) V in <K, V>(predicate: (value: V, key: K) => boolean): (self: TxHashMap<K, V>) => Effect.Effect<Option.Option<[K, V]>>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<import OptionOption.type Option<A> = Option.None<A> | Option.Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<[function (type parameter) K in <K, V>(predicate: (value: V, key: K) => boolean): (self: TxHashMap<K, V>) => Effect.Effect<Option.Option<[K, V]>>K, function (type parameter) V in <K, V>(predicate: (value: V, key: K) => boolean): (self: TxHashMap<K, V>) => Effect.Effect<Option.Option<[K, V]>>V]>>
<function (type parameter) K in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>K, function (type parameter) V in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>V>(
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>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>K, function (type parameter) V in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>V>,
predicate: (value: V, key: K) => booleanpredicate: (value: Vvalue: function (type parameter) V in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>V, key: Kkey: function (type parameter) K in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>K) => boolean
): 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<import OptionOption.type Option<A> = Option.None<A> | Option.Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<[function (type parameter) K in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>K, function (type parameter) V in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>V]>>
} = dual<(...args: Array<any>) => any, <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean) => Effect.Effect<Option.Option<[K, V]>>>(arity: 2, body: <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean) => Effect.Effect<Option.Option<[K, V]>>): ((...args: Array<any>) => any) & (<K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean) => Effect.Effect<Option.Option<[K, V]>>) (+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>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>K, function (type parameter) V in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>V>(
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>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>K, function (type parameter) V in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>V>,
predicate: (value: V, key: K) => booleanpredicate: (value: Vvalue: function (type parameter) V in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>V, key: Kkey: function (type parameter) K in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>K) => boolean
): 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<import OptionOption.type Option<A> = Option.None<A> | Option.Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<[function (type parameter) K in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>K, function (type parameter) V in <K, V>(self: TxHashMap<K, V>, predicate: (value: V, key: K) => boolean): Effect.Effect<Option.Option<[K, V]>>V]>> =>
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; <…;
}
Pipeable.pipe<Effect.Effect<HashMap.HashMap<K, V>, never, never>, Effect.Effect<Option.Option<[K, V]>, never, never>>(this: Effect.Effect<HashMap.HashMap<K, V>, never, never>, ab: (_: Effect.Effect<HashMap.HashMap<K, V>, never, never>) => Effect.Effect<Option.Option<[K, V]>, never, never>): Effect.Effect<Option.Option<[K, V]>, never, never> (+21 overloads)pipe(import EffectEffect.const map: {
<A, B>(f: (a: A) => B): <E, R>(
self: Effect<A, E, R>
) => Effect<B, E, R>
<A, E, R, B>(
self: Effect<A, E, R>,
f: (a: A) => B
): Effect<B, E, R>
}
map: HashMap.HashMap<K, V>(parameter) map: {
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 HashMapHashMap.const findFirst: {
<K, A>(
predicate: (a: NoInfer<A>, k: K) => boolean
): (self: HashMap<K, A>) => Option<[K, A]>
<K, A>(
self: HashMap<K, A>,
predicate: (a: A, k: K) => boolean
): Option<[K, A]>
}
map: HashMap.HashMap<K, V>(parameter) map: {
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;
}
predicate: (value: V, key: K) => booleanpredicate)))
)