File

1 min read

Import: import system.io;

Read the usage guide for examples and common tasks. This reference lists the public declarations for this part of the library. See Reading API signatures for parameter and result notation.

File

File - a small cross-runtime filesystem API.

public static class File

read

Reads the whole file at path as UTF-8 text.

public static async fun read(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<string, IoError>

write

Overwrites path with content; resolves with Ok(bytes_written) or Err on failure.

public static async fun write(
    borrow path: string,
    borrow content: string,
    token: Option<CancellationToken> = Option.None
): Result<long, IoError>

append

Appends content to the end of path; resolves with Ok(bytes_written) or Err.

public static async fun append(
    borrow path: string,
    borrow content: string,
    token: Option<CancellationToken> = Option.None
): Result<long, IoError>

read_bytes

Reads the whole file at path as raw bytes.

public static async fun read_bytes(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<byte[], IoError>

write_bytes

Writes raw bytes to path, replacing any existing contents.

public static async fun write_bytes(
    borrow path: string,
    borrow data: byte[],
    token: Option<CancellationToken> = Option.None
): Result<long, IoError>

delete

Deletes path; resolves Ok(Unit()) on success.

public static async fun delete(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<Unit, IoError>

copy

Copies a file from from to to, overwriting to when it already exists.

public static async fun copy(
    borrow from: string,
    borrow to: string,
    token: Option<CancellationToken> = Option.None
): Result<Unit, IoError>

rename

Renames or moves from to to (same-volume when the OS requires it).

public static async fun rename(
    borrow from: string,
    borrow to: string,
    token: Option<CancellationToken> = Option.None
): Result<Unit, IoError>

remove_dir

Removes an empty directory at path.

public static async fun remove_dir(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<Unit, IoError>

remove_dir_all

Recursively deletes path (file or directory tree).

public static async fun remove_dir_all(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<Unit, IoError>

create_dir

Creates a single directory at path; resolves Ok(Unit()) on success.

public static async fun create_dir(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<Unit, IoError>

create_dir_all

Creates path and any missing parents; resolves Ok(Unit()) on success.

public static async fun create_dir_all(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<Unit, IoError>

list

Lists the entries of directory path, or Err(IoError) when the path is missing or not a directory (an existing empty directory yields Ok([])).

public static async fun list(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<string[], IoError>

list_paths

Like list, but each name is joined onto path. Fails with the same IoError cases.

public static async fun list_paths(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<string[], IoError>

read_lines

Reads the whole file and splits on \n, dropping a trailing empty part from a final newline.

public static async fun read_lines(
    borrow path: string,
    token: Option<CancellationToken> = Option.None
): Result<string[], IoError>

write_lines

Writes lines joined by newlines, including a trailing newline when lines is non-empty.

public static async fun write_lines(
    borrow path: string,
    borrow lines: string[],
    token: Option<CancellationToken> = Option.None
): Result<long, IoError>

exists

Cheap synchronous predicates (no async overhead).

public static fun exists(borrow path: string): bool

size

Size of path in bytes, or None if it does not exist.

public static fun size(borrow path: string): Option<long>

is_dir

Returns whether the path refers to a directory.

public static fun is_dir(borrow path: string): bool

is_file

Returns whether path exists and is a regular file. Returns false when the path is missing or cannot be inspected; call stat to see why.

public static fun is_file(borrow path: string): bool

stat

One stat of path. Follows symlinks. Missing paths are Err.

public static fun stat(borrow path: string): Result<FileStats, IoError>