Path

Path provides Effect's platform-specific path service to Effeck. Use it to join, split, normalize, and convert paths without hard-coding host separators or importing a native path module.

Requesting the path service

function pathSeparator() {
  const path = Effect.service(Path.Path)
  return path.sep
}
// string!!Path.Path

Path is the module and Path.Path is its service key. Effect.service obtains the implementation from the current environment. Reading sep returns that implementation's path separator.

Manipulating paths portably

function describeReport() {
  const path = Effect.service(Path.Path)
  const joined = path.join("reports", "weekly.txt")
  const normalized = path.normalize("reports/./draft/../weekly.txt")
  const parsed = path.parse(joined)
  return {
    joined,
    normalized,
    base: path.basename(joined),
    directory: path.dirname(joined),
    extension: path.extname(joined),
    absolute: path.isAbsolute(joined),
    rebuilt: path.format(parsed)
  }
}

Most Path methods are plain synchronous TypeScript functions. Effect's own packages are trusted, so call these methods directly; any exceptions are defects, which ordinary catch does not handle. Calling a member through the key, such as Path.Path.join("reports", "weekly.txt"), looks up the service and adds Path.Path to R even though the member returns a string.

function asFileUrl(file: string) {
  const path = Effect.service(Path.Path)
  const absolute = path.resolve(file)
  const url = path.toFileUrl(absolute)
  return path.fromFileUrl(url)
}

URL conversions return Effects and run directly when called, reporting BadArgument on invalid input. Path string operations are lexical: normalizing or resolving a path does not check that a file exists. Use FileSystem when filesystem state matters.

Supplying a platform path implementation

// main.effeck
import { NodeRuntime, NodeServices } from "@effect/platform-node"

function main() {
  const output = Path.Path.join("reports", "weekly.txt")
  log(output)
}

NodeRuntime.runMain(() => Effect.provide(() => main(), NodeServices.layer))

The Node service bundle supplies host path behavior. Path.layer supplies the built-in POSIX implementation for programs that intentionally use POSIX paths, including deterministic tests. Use Bun's service bundle when the rest of the application runs against Bun platform services.

Coming from Effect

Effect-returning methods run directly; synchronous methods from Effect's trusted packages return plain values. Both forms look up the service when called through its key, so both add the service to R. Value members are read from the implementation, for example Path.Path().sep.