Context.Reference<boolean>Context reference that routes the built-in default logger and TTY pretty console logger to stderr.
When to use
Use to route built-in logger output to stderr while keeping stdout reserved for protocol messages or data output.
Details
The reference defaults to false. Providing true makes the affected
loggers call console.error instead of console.log.
export const const LogToStderr: Context.Reference<boolean>const LogToStderr: {
defaultValue: () => Shape;
of: (this: void, self: boolean) => boolean;
context: (self: boolean) => Context.Context<never>;
use: (f: (service: boolean) => Effect.Effect<A, E, R>) => Effect.Effect<A, E, R>;
useSync: (f: (service: boolean) => A) => Effect.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 that routes the built-in default logger and TTY pretty
console logger to stderr.
When to use
Use to route built-in logger output to stderr while keeping stdout reserved
for protocol messages or data output.
Details
The reference defaults to false. Providing true makes the affected
loggers call console.error instead of console.log.
LogToStderr: 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<boolean> = import effecteffect.const LogToStderr: Context.Reference<boolean>const LogToStderr: {
defaultValue: () => Shape;
of: (this: void, self: boolean) => boolean;
context: (self: boolean) => Context.Context<never>;
use: (f: (service: boolean) => Effect.Effect<A, E, R>) => Effect.Effect<A, E, R>;
useSync: (f: (service: boolean) => A) => Effect.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;
}