FileSystem

The @effect/platform/FileSystem module provides a set of operations for reading and writing from/to the file system.

Basic Usage

The module provides a single FileSystem tag, which acts as the gateway for interacting with the filesystem.

import { FileSystem } from "@effect/platform"
import { Effect } from "effect"

const program = Effect.gen(function* () {
  const fs = yield* FileSystem.FileSystem

  // use `fs` to operate on the file system
})

The FileSystem interface includes the following operations:

Operation	Description
access	Check if a file can be accessed. You can optionally specify the level of access to check for.
copy	Copy a file or directory from fromPath to toPath. Equivalent to cp -r.
copyFile	Copy a file from fromPath to toPath.
chmod	Change the permissions of a file.
chown	Change the owner and group of a file.
exists	Check if a path exists.
link	Create a hard link from fromPath to toPath.
makeDirectory	Create a directory at path. You can optionally specify the mode and whether to recursively create nested directories.
makeTempDirectory	Create a temporary directory. By default, the directory will be created inside the system’s default temporary directory.
makeTempDirectoryScoped	Create a temporary directory inside a scope. Functionally equivalent to makeTempDirectory, but the directory will be automatically deleted when the scope is closed.
makeTempFile	Create a temporary file. The directory creation is functionally equivalent to makeTempDirectory. The file name will be a randomly generated string.
makeTempFileScoped	Create a temporary file inside a scope. Functionally equivalent to makeTempFile, but the file will be automatically deleted when the scope is closed.
open	Open a file at path with the specified options. The file handle will be automatically closed when the scope is closed.
readDirectory	List the contents of a directory. You can recursively list the contents of nested directories by setting the recursive option.
readFile	Read the contents of a file.
readFileString	Read the contents of a file as a string.
readLink	Read the destination of a symbolic link.
realPath	Resolve a path to its canonicalized absolute pathname.
remove	Remove a file or directory. By setting the recursive option to true, you can recursively remove nested directories.
rename	Rename a file or directory.
sink	Create a writable Sink for the specified path.
stat	Get information about a file at path.
stream	Create a readable Stream for the specified path.
symlink	Create a symbolic link from fromPath to toPath.
truncate	Truncate a file to a specified length. If the length is not specified, the file will be truncated to length 0.
utimes	Change the file system timestamps of the file at path.
watch	Watch a directory or file for changes.
writeFile	Write data to a file at path.
writeFileString	Write a string to a file at path.

Example (Using readFileString)

import { FileSystem } from "@effect/platform"
import { NodeContext, NodeRuntime } from "@effect/platform-node"
import { Effect } from "effect"

const program = Effect.gen(function* () {
  const fs = yield* FileSystem.FileSystem

  // Reading the content of the same file where this code is written
  const content = yield* fs.readFileString("./index.ts", "utf8")
  console.log(content)
})

NodeRuntime.runMain(program.pipe(Effect.provide(NodeContext.layer)))