Pipes the value of an expression into a pipeline of functions.
Details
The pipe function is a utility that allows us to compose functions in a
readable and sequential manner. It takes the output of one function and
passes it as the input to the next function in the pipeline. This enables us
to build complex transformations by chaining multiple functions together.
import { pipe } from"effect"
constresult=pipe(input, func1, func2, ..., funcN)
In this syntax, input is the initial value, and func1, func2, ...,
funcN are the functions to be applied in sequence. The result of each
function becomes the input for the next function, and the final result is
returned.
Runs an effect and returns a Promise that resolves to an Exit,
representing the outcome.
Details
This function executes an effect and resolves to an Exit object. The Exit
type provides detailed information about the result of the effect:
If the effect succeeds, the Exit will be of type Success and include
the value produced by the effect.
If the effect fails, the Exit will be of type Failure and contain a
Cause object, detailing the failure.
Using this function allows you to examine both successful results and failure
cases in a unified way, while still leveraging Promise for handling the
asynchronous behavior of the effect.
When to Use
Use this function when you need to understand the outcome of an effect,
whether it succeeded or failed, and want to work with this result using
Promise syntax. This is particularly useful when integrating with systems
that rely on promises but need more detailed error handling than a simple
rejection.
Example (Handling Results as Exit)
import { Effect } from"effect"
// Execute a successful effect and get the Exit result as a Promise
Provides a way to write effectful code using generator functions, simplifying
control flow and error handling.
When to Use
Effect.gen allows you to write code that looks and behaves like synchronous
code, but it can handle asynchronous tasks, errors, and complex control flow
(like loops and conditions). It helps make asynchronous code more readable
and easier to manage.
The generator functions work similarly to async/await but with more
explicit control over the execution of effects. You can yield* values from
effects and return the final result at the end.
Example
import { Effect } from"effect"
constaddServiceCharge= (amount:number) =>amount+1
constapplyDiscount= (
total:number,
discountRate:number
):Effect.Effect<number, Error> =>
discountRate===0
?Effect.fail(newError("Discount rate cannot be zero"))
Pipes the value of an expression into a pipeline of functions.
Details
The pipe function is a utility that allows us to compose functions in a
readable and sequential manner. It takes the output of one function and
passes it as the input to the next function in the pipeline. This enables us
to build complex transformations by chaining multiple functions together.
import { pipe } from"effect"
constresult=pipe(input, func1, func2, ..., funcN)
In this syntax, input is the initial value, and func1, func2, ...,
funcN are the functions to be applied in sequence. The result of each
function becomes the input for the next function, and the final result is
returned.
Provides necessary dependencies to an effect, removing its environmental
requirements.
Details
This function allows you to supply the required environment for an effect.
The environment can be provided in the form of one or more Layers, a
Context, a Runtime, or a ManagedRuntime. Once the environment is
provided, the effect can run without requiring external dependencies.
You can compose layers to create a modular and reusable way of setting up the
environment for effects. For example, layers can be used to configure
databases, logging services, or any other required dependencies.
constprovideService: <Sui.ChannelDestination, Sui.Sui.Channel>(tag:Tag<Sui.ChannelDestination, Sui.Sui.Channel>, service:Sui.Sui.Channel) => <A, E, R>(self:Effect.Effect<A, E, R>) =>Effect.Effect<...> (+1overload)
Provides an implementation for a service in the context of an effect.
Details
This function allows you to supply a specific implementation for a service
required by an effect. Services are typically defined using Context.Tag,
which acts as a unique identifier for the service. By using this function,
you link the service to its concrete implementation, enabling the effect to
execute successfully without additional requirements.
For example, you can use this function to provide a random number generator,
a logger, or any other service your effect depends on. Once the service is
provided, all parts of the effect that rely on the service will automatically
use the implementation you supplied.
Example
import { Effect, Context } from"effect"
// Declaring a tag for a service that generates random numbers
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.
The module exports two specific components:
A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.
Warning: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.
Example using the global console:
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(newError('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
// Error: Whoops, something bad happened
// at [eval]:5:15
// at Script.runInThisContext (node:vm:132:18)
// at Object.runInThisContext (node:vm:309:38)
// at node:internal/process/execution:77:19
// at [eval]-wrapper:6:22
// at evalScript (node:internal/process/execution:76:60)
// at node:internal/main/eval_string:23:3
constname='Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:
constout=getStreamSomehow();
consterr=getStreamSomehow();
constmyConsole=newconsole.Console(out, err);
myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(newError('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err
Prints to stdout with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).