<A>(self: TxPriorityQueue<A>): Effect.Effect<Option<A>>Tries to take the smallest element. Returns None if the queue is empty.
Example (Taking without retrying)
import { Effect, Option, Order, TxPriorityQueue } from "effect"
const program = Effect.gen(function*() {
const pq = yield* TxPriorityQueue.empty<number>(Order.Number)
const result = yield* TxPriorityQueue.takeOption(pq)
console.log(Option.isNone(result)) // true
})export const const takeOption: <A>(
self: TxPriorityQueue<A>
) => Effect.Effect<Option<A>>
Tries to take the smallest element. Returns None if the queue is empty.
Example (Taking without retrying)
import { Effect, Option, Order, TxPriorityQueue } from "effect"
const program = Effect.gen(function*() {
const pq = yield* TxPriorityQueue.empty<number>(Order.Number)
const result = yield* TxPriorityQueue.takeOption(pq)
console.log(Option.isNone(result)) // true
})
takeOption = <function (type parameter) A in <A>(self: TxPriorityQueue<A>): Effect.Effect<Option<A>>A>(self: TxPriorityQueue<A>(parameter) self: {
ref: TxRef.TxRef<Chunk<A>>;
ord: Order<A>;
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 TxPriorityQueue<in out A>A transactional priority queue backed by a sorted Chunk.
Details
Elements are stored in ascending order according to the Order provided at
construction time. take returns the smallest element, peek observes it
without removing.
Example (Dequeuing values by priority)
import { Effect, Order, TxPriorityQueue } from "effect"
const program = Effect.gen(function*() {
const pq = yield* TxPriorityQueue.empty<number>(Order.Number)
yield* TxPriorityQueue.offer(pq, 3)
yield* TxPriorityQueue.offer(pq, 1)
yield* TxPriorityQueue.offer(pq, 2)
const first = yield* TxPriorityQueue.take(pq)
console.log(first) // 1
})
TxPriorityQueue<function (type parameter) A in <A>(self: TxPriorityQueue<A>): Effect.Effect<Option<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<type Option<A> = O.None<A> | O.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) A in <A>(self: TxPriorityQueue<A>): Effect.Effect<Option<A>>A>> =>
import TxRefTxRef.const modify: {
<A, R>(
f: (
current: NoInfer<A>
) => [returnValue: R, newValue: A]
): (self: TxRef<A>) => Effect.Effect<R>
<A, R>(
self: TxRef<A>,
f: (
current: A
) => [returnValue: R, newValue: A]
): Effect.Effect<R>
}
self: TxPriorityQueue<A>(parameter) self: {
ref: TxRef.TxRef<Chunk<A>>;
ord: Order<A>;
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; <…;
}
TxPriorityQueue<A>.ref: TxRef.TxRef<Chunk<A>>(property) TxPriorityQueue<A>.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; <…;
}
chunk: Chunk<A>(parameter) chunk: {
length: number;
right: Chunk<A>;
left: Chunk<A>;
backing: Backing<A>;
depth: number;
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 head: Option<A>head = import CC.const head: <A>(
self: Chunk<A>
) => Option<A>
Returns the first element of this chunk safely if it exists.
Example (Getting the first element)
import { Chunk } from "effect"
console.log(Chunk.head(Chunk.empty())) // { _tag: "None" }
console.log(Chunk.head(Chunk.make(1, 2, 3))) // { _tag: "Some", value: 1 }
head(chunk: Chunk<A>(parameter) chunk: {
length: number;
right: Chunk<A>;
left: Chunk<A>;
backing: Backing<A>;
depth: number;
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 OO.const isNone: <A>(
self: Option<A>
) => self is None<A>
Checks whether an Option is None (absent).
When to use
Use when you need to branch on an absent Option before accessing .value.
Details
- Acts as a type guard, narrowing to
None<A>
Example (Checking for None)
import { Option } from "effect"
console.log(Option.isNone(Option.some(1)))
// Output: false
console.log(Option.isNone(Option.none()))
// Output: true
isNone(const head: Option<A>head)) {
return [import OO.const none: <A = never>() => Option<A>Creates an Option representing the absence of a value.
When to use
Use to represent a missing or uninitialized value, such as returning "no
result" from a function.
Details
- Returns
Option<never>, which is a subtype of Option<A> for any A
- Always returns the same singleton instance
Example (Creating an empty Option)
import { Option } from "effect"
// ┌─── Option<never>
// ▼
const noValue = Option.none()
console.log(noValue)
// Output: { _id: 'Option', _tag: 'None' }
none<function (type parameter) A in <A>(self: TxPriorityQueue<A>): Effect.Effect<Option<A>>A>(), chunk: Chunk<A>(parameter) chunk: {
length: number;
right: Chunk<A>;
left: Chunk<A>;
backing: Backing<A>;
depth: number;
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 OO.const some: <A>(value: A) => Option<A>Wraps the given value into an Option to represent its presence.
When to use
Use to wrap a known present value as Option
- Returning a successful result from a partial function
Details
- Always returns
Some<A>
- Does not filter
null or undefined; use
fromNullishOr
for that
Example (Wrapping a value)
import { Option } from "effect"
// ┌─── Option<number>
// ▼
const value = Option.some(1)
console.log(value)
// Output: { _id: 'Option', _tag: 'Some', value: 1 }
some(const head: O.Some<A>const head: {
_tag: "Some";
_op: "Some";
value: A;
valueOrUndefined: 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; <…;
toString: () => string;
toJSON: () => unknown;
}
Some<A>.value: Avalue), import CC.const drop: {
(n: number): <A>(self: Chunk<A>) => Chunk<A>
<A>(self: Chunk<A>, n: number): Chunk<A>
}
chunk: Chunk<A>(parameter) chunk: {
length: number;
right: Chunk<A>;
left: Chunk<A>;
backing: Backing<A>;
depth: number;
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;
}