io

A collection of utilities for working with the local filesystem.

Reference

• create
• current_dir
• exists
• open
• print
• read_to_string
• remove_file
• stderr
• stdin
• stdout
• temp_dir
• File
• File.flush
• File.path
• File.read_line
• File.read_to_string
• File.seek
• File.write
• File.write_line

create

|String| -> File

Returns an empty File at the provided path. If the file already exists it will be truncated.

Errors

A runtime error will be thrown if the file can't be created.

Example

f = io.create "foo.temp"
f.write_line "Hello"
f.read_to_string()
# Hello

current_dir

|| -> String

Returns the current working directory as a String, or Empty if the current directory can't be retrieved.

exists

|String| -> Bool

Returns true if a file exists at the provided path.

Example

path = "foo.temp"
io.exists path
# false

io.create path
io.exists path
# true

open

|String| -> File

Opens the file at the given path, and returns a corresponding File.

Errors

An error is thrown if a file can't be opened at the given path.

Example

f = io.open "path/to/existing.file"
f.exists()
# true

print

|Value| -> () |String, Value...| -> ()

Prints a formatted string to the active logger, by default this is the standard output.

Note

See string.format for the formatting syntax.

read_to_string

|String| -> String

Returns a string containing the contents of the file at the given path.

Errors

Errors are thrown:

• if the file doesn't contain valid UTF-8 data.
• if a file can't be opened at the given path.

Example

f = io.create "foo.temp"
f.write_line "Hello!"
io.read_to_string "foo.temp"
# Hello!

remove_file

|String| -> ()

Removes the file at the given path.

Errors

• An error is thrown if a file can't be removed at the given path.

Example

path "foo.temp"
io.create path
io.exists path
# true

io.remove_file path
io.exists path
# false

stderr

|| -> File

Returns the standard error output of the current process as a file.

Example

io.stderr().write_line "An error occurred!"

See Also

• io.stdin
• io.stdout

stdin

|| -> File

Returns the standard input of the current process as a file.

Example

io.stdin().read_to_string()
# "..."

See Also

• io.stderr
• io.stdout

stdout

|| -> File

Returns the standard output of the current process as a file.

Example

io.stdout().write_line "Hello, World!"

See Also

• io.stderr
• io.stdin

temp_dir

|| -> String

Returns the path to a temporary directory.

Note

This defers to Rust's std::env::temp_dir, for details see its documentation.

File

A map that wraps a file handle, returned from functions in io.

File.flush

|File| -> ()

Ensures that any buffered changes to the file have been written.

See Also

• file.write
• file.write_line

File.path

|File| -> String

Returns the file's path.

File.read_line

|File| -> String or Empty

Reads a line of output from the file as a string, not including the newline.

When the end of the file is reached, Empty will be returned.

Errors

An error is thrown if the line doesn't contain valid UTF-8 data.

File.read_to_string

|File| -> String

Reads the file's contents to a string.

Errors

An error is thrown if the file doesn't contain valid UTF-8 data.

File.seek

|File, Number| -> ()

Seeks within the file to the specified position in bytes.

File.write

|File, Value| -> ()

Writes the formatted value as a string to the file.

File.write_line

|File, Value| -> ()

Writes the formatted value as a string, with a newline, to the file.