<Message, Output>(self: Logger<Message, Output>): Logger<Message, void>Returns a new Logger that writes all output of the specified Logger to
the console using console.error.
When to use
Use when logger output should be routed to console.error, such as error logs that
should appear on stderr instead of stdout.
Example (Writing logger output with console.error)
import { Effect, Logger } from "effect"
// Create an error-specific formatter
const errorFormatter = Logger.make((options) =>
`ERROR [${options.date.toISOString()}]: ${options.message}`
)
// Route to console.error
const errorLogger = Logger.withConsoleError(errorFormatter)
const program = Effect.logError("Database connection failed").pipe(
Effect.provide(Logger.layer([errorLogger]))
)logging
Source effect/Logger.ts:3067 lines
export const const withConsoleError: <Message, Output>(
self: Logger<Message, Output>
) => Logger<Message, void>
Returns a new Logger that writes all output of the specified Logger to
the console using console.error.
When to use
Use when logger output should be routed to console.error, such as error logs that
should appear on stderr instead of stdout.
Example (Writing logger output with console.error)
import { Effect, Logger } from "effect"
// Create an error-specific formatter
const errorFormatter = Logger.make((options) =>
`ERROR [${options.date.toISOString()}]: ${options.message}`
)
// Route to console.error
const errorLogger = Logger.withConsoleError(errorFormatter)
const program = Effect.logError("Database connection failed").pipe(
Effect.provide(Logger.layer([errorLogger]))
)
withConsoleError = <function (type parameter) Message in <Message, Output>(self: Logger<Message, Output>): Logger<Message, void>Message, function (type parameter) Output in <Message, Output>(self: Logger<Message, Output>): Logger<Message, void>Output>(
self: Logger<Message, Output>(parameter) self: {
log: (options: Options<Message>) => Output;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface Logger<in Message, out Output>A logger that transforms a runtime log event into an output value.
Details
The runtime calls log with the message, level, cause, fiber, and timestamp
for each log event. Use Logger.layer to install one or more loggers for an
effect.
Example (Creating custom loggers)
import { Effect, Logger } from "effect"
// Create a custom logger that accepts unknown messages and returns void
const stringLogger = Logger.make<unknown, void>((options) => {
console.log(`[${options.logLevel}] ${options.message}`)
})
// Create a logger that accepts any message type and returns a formatted string
const formattedLogger = Logger.make<unknown, string>((options) =>
`${options.date.toISOString()} [${options.logLevel}] ${options.message}`
)
// Use the logger in an Effect program
const program = Effect.log("Hello World").pipe(
Effect.provide(Logger.layer([stringLogger]))
)
Logger<function (type parameter) Message in <Message, Output>(self: Logger<Message, Output>): Logger<Message, void>Message, function (type parameter) Output in <Message, Output>(self: Logger<Message, Output>): Logger<Message, void>Output>
): interface Logger<in Message, out Output>A logger that transforms a runtime log event into an output value.
Details
The runtime calls log with the message, level, cause, fiber, and timestamp
for each log event. Use Logger.layer to install one or more loggers for an
effect.
Example (Creating custom loggers)
import { Effect, Logger } from "effect"
// Create a custom logger that accepts unknown messages and returns void
const stringLogger = Logger.make<unknown, void>((options) => {
console.log(`[${options.logLevel}] ${options.message}`)
})
// Create a logger that accepts any message type and returns a formatted string
const formattedLogger = Logger.make<unknown, string>((options) =>
`${options.date.toISOString()} [${options.logLevel}] ${options.message}`
)
// Use the logger in an Effect program
const program = Effect.log("Hello World").pipe(
Effect.provide(Logger.layer([stringLogger]))
)
Logger<function (type parameter) Message in <Message, Output>(self: Logger<Message, Output>): Logger<Message, void>Message, void> =>
import effecteffect.const loggerMake: <Message, Output>(
log: (
options: Logger.Options<Message>
) => Output
) => Logger.Logger<Message, Output>
options: Options<Message>(parameter) options: {
message: Message;
logLevel: LogLevel.LogLevel;
cause: Cause.Cause<unknown>;
fiber: Fiber.Fiber<unknown, unknown>;
date: Date;
}
const console: Consoleconst console: {
assert: (condition: boolean, ...args: ReadonlyArray<any>) => void;
clear: () => void;
count: (label?: string) => void;
countReset: (label?: string) => void;
debug: (...args: ReadonlyArray<any>) => void;
dir: (item: any, options?: any) => void;
dirxml: (...args: ReadonlyArray<any>) => void;
error: (...args: ReadonlyArray<any>) => void;
group: (...args: ReadonlyArray<any>) => void;
groupCollapsed: (...args: ReadonlyArray<any>) => void;
groupEnd: () => void;
info: (...args: ReadonlyArray<any>) => void;
log: (...args: ReadonlyArray<any>) => void;
table: (tabularData: any, properties?: ReadonlyArray<string>) => void;
time: (label?: string) => void;
timeEnd: (label?: string) => void;
timeLog: (label?: string, ...args: ReadonlyArray<any>) => void;
trace: (...args: ReadonlyArray<any>) => void;
warn: (...args: ReadonlyArray<any>) => void;
}
options: Options<Message>(parameter) options: {
message: Message;
logLevel: LogLevel.LogLevel;
cause: Cause.Cause<unknown>;
fiber: Fiber.Fiber<unknown, unknown>;
date: Date;
}
Options<out Message>.fiber: Fiber.Fiber<unknown, unknown>(property) Options<out Message>.fiber: {
id: number;
currentOpCount: number;
getRef: <A>(ref: Context.Reference<A>) => A;
context: Context.Context<never>;
setContext: (context: Context.Context<never>) => void;
currentScheduler: Scheduler;
currentDispatcher: SchedulerDispatcher;
currentSpan: AnySpan | undefined;
currentLogLevel: LogLevel;
minimumLogLevel: LogLevel;
currentStackFrame: StackFrame | undefined;
maxOpsBeforeYield: number;
currentPreventYield: boolean;
addObserver: (cb: (exit: Exit<A, E>) => void) => () => void;
interruptUnsafe: (fiberId?: number | undefined, annotations?: Context.Context<never> | undefined) => void;
pollUnsafe: () => Exit<A, E> | 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; <…;
}
import effecteffect.const ConsoleRef: Context.Reference<Console>const ConsoleRef: {
key: string;
Service: {
assert: (condition: boolean, ...args: ReadonlyArray<any>) => void;
clear: () => void;
count: (label?: string) => void;
countReset: (label?: string) => void;
debug: (...args: ReadonlyArray<any>) => void;
dir: (item: any, options?: any) => void;
dirxml: (...args: ReadonlyArray<any>) => void;
error: (...args: ReadonlyArray<any>) => void;
group: (...args: ReadonlyArray<any>) => void;
groupCollapsed: (...args: ReadonlyArray<any>) => void;
groupEnd: () => void;
info: (...args: ReadonlyArray<any>) => void;
log: (...args: ReadonlyArray<any>) => void;
table: (tabularData: any, properties?: ReadonlyArray<string>) => void;
time: (label?: string) => void;
timeEnd: (label?: string) => void;
timeLog: (label?: string, ...args: ReadonlyArray<any>) => void;
trace: (...args: ReadonlyArray<any>) => void;
warn: (...args: ReadonlyArray<any>) => void;
};
defaultValue: () => Shape;
of: (this: void, self: Console) => Console;
context: (self: Console) => Context.Context<never>;
use: (f: (service: Console) => Effect.Effect<A, E, R>) => Effect.Effect<A, E, R>;
useSync: (f: (service: Console) => A) => Effect.Effect<A, never, never>;
Identifier: Identifier;
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;
}
const console: Consoleconst console: {
assert: (condition: boolean, ...args: ReadonlyArray<any>) => void;
clear: () => void;
count: (label?: string) => void;
countReset: (label?: string) => void;
debug: (...args: ReadonlyArray<any>) => void;
dir: (item: any, options?: any) => void;
dirxml: (...args: ReadonlyArray<any>) => void;
error: (...args: ReadonlyArray<any>) => void;
group: (...args: ReadonlyArray<any>) => void;
groupCollapsed: (...args: ReadonlyArray<any>) => void;
groupEnd: () => void;
info: (...args: ReadonlyArray<any>) => void;
log: (...args: ReadonlyArray<any>) => void;
table: (tabularData: any, properties?: ReadonlyArray<string>) => void;
time: (label?: string) => void;
timeEnd: (label?: string) => void;
timeLog: (label?: string, ...args: ReadonlyArray<any>) => void;
trace: (...args: ReadonlyArray<any>) => void;
warn: (...args: ReadonlyArray<any>) => void;
}
self: Logger<Message, Output>(parameter) self: {
log: (options: Options<Message>) => Output;
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; <…;
}
Logger<Message, Output>.log(options: Options<Message>): Outputlog(options: Options<Message>(parameter) options: {
message: Message;
logLevel: LogLevel.LogLevel;
cause: Cause.Cause<unknown>;
fiber: Fiber.Fiber<unknown, unknown>;
date: Date;
}