Context.Reference<number | "unbounded">Context reference for controlling the current concurrency limit. Can be set to "unbounded" for unlimited concurrency or a specific number to limit concurrent operations.
When to use
Use to configure the default concurrency limit for operations that read concurrency from the current context.
Example (Setting current concurrency)
import { Effect, References } from "effect"
const limitConcurrency = Effect.gen(function*() {
// Get current setting
const current = yield* References.CurrentConcurrency
console.log(current) // "unbounded" (default)
// Run with limited concurrency
yield* Effect.provideService(
Effect.gen(function*() {
const limited = yield* References.CurrentConcurrency
console.log(limited) // 10
}),
References.CurrentConcurrency,
10
)
// Run with unlimited concurrency
yield* Effect.provideService(
Effect.gen(function*() {
const unlimited = yield* References.CurrentConcurrency
console.log(unlimited) // "unbounded"
}),
References.CurrentConcurrency,
"unbounded"
)
})export const const CurrentConcurrency: Context.Reference<
number | "unbounded"
>
const CurrentConcurrency: {
defaultValue: () => Shape;
of: (this: void, self: number | 'unbounded') => number | 'unbounded';
context: (self: number | 'unbounded') => Context.Context<never>;
use: (f: (service: number | 'unbounded') => Effect<A, E, R>) => Effect<A, E, R>;
useSync: (f: (service: number | 'unbounded') => A) => Effect<A, never, never>;
Identifier: Identifier;
Service: Shape;
key: string;
stack: string | undefined;
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;
}
Context reference for controlling the current concurrency limit. Can be set to "unbounded"
for unlimited concurrency or a specific number to limit concurrent operations.
When to use
Use to configure the default concurrency limit for operations that read
concurrency from the current context.
Example (Setting current concurrency)
import { Effect, References } from "effect"
const limitConcurrency = Effect.gen(function*() {
// Get current setting
const current = yield* References.CurrentConcurrency
console.log(current) // "unbounded" (default)
// Run with limited concurrency
yield* Effect.provideService(
Effect.gen(function*() {
const limited = yield* References.CurrentConcurrency
console.log(limited) // 10
}),
References.CurrentConcurrency,
10
)
// Run with unlimited concurrency
yield* Effect.provideService(
Effect.gen(function*() {
const unlimited = yield* References.CurrentConcurrency
console.log(unlimited) // "unbounded"
}),
References.CurrentConcurrency,
"unbounded"
)
})
CurrentConcurrency: import ContextContext.interface Reference<in out Shape>Service key with a lazily computed default value.
Details
When a Reference is requested from a Context that does not contain an
override, Context getters that resolve references return the cached default
value instead of failing.
Example (Defining a reference with a default value)
import { Context } from "effect"
// Define a reference with a default value
const LoggerRef: Context.Reference<{ log: (msg: string) => void }> =
Context.Reference("Logger", {
defaultValue: () => ({ log: (msg: string) => console.log(msg) })
})
// The reference can be used without explicit provision
const context = Context.empty()
const logger = Context.get(context, LoggerRef) // Uses default value
Creates a context key with a default value.
When to use
Use when you need to define a context key with a lazily computed default
value.
Details
Context.Reference allows you to create a key that can hold a value. You
can provide a default value for the service, which will automatically be used
when the context is accessed, or override it with a custom implementation
when needed. The default value is computed lazily and cached on the
reference.
Example (Creating references with default values)
import { Context } from "effect"
// Create a reference with a default value
const LoggerRef = Context.Reference("Logger", {
defaultValue: () => ({ log: (msg: string) => console.log(msg) })
})
// The reference provides the default value when accessed from an empty context
const context = Context.empty()
const logger = Context.get(context, LoggerRef)
// You can also override the default value
const customContext = Context.make(LoggerRef, {
log: (msg: string) => `Custom: ${msg}`
})
const customLogger = Context.get(customContext, LoggerRef)
Reference<number | "unbounded"> = import referencesreferences.const CurrentConcurrency: Context.Reference<
number | "unbounded"
>
const CurrentConcurrency: {
defaultValue: () => Shape;
of: (this: void, self: number | 'unbounded') => number | 'unbounded';
context: (self: number | 'unbounded') => Context.Context<never>;
use: (f: (service: number | 'unbounded') => Effect<A, E, R>) => Effect<A, E, R>;
useSync: (f: (service: number | 'unbounded') => A) => Effect<A, never, never>;
Identifier: Identifier;
Service: Shape;
key: string;
stack: string | undefined;
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;
}