io

import io

High-level path helpers

Signature	Description
io.read_text(path: str) -> str	Read entire file as string
io.write_text(path: str, data: str) -> None	Write string to file (overwrite)
io.append_text(path: str, data: str) -> None	Append string to file
io.exists(path: str) -> bool	Check if path exists

File handle operations

io.File is an opaque managed handle. It is not a normal value type and cannot be stored in unions.

Signature	Description
io.open(path: str, mode: str) -> io.File	Open a file ("r", "w", "a")
io.read(file: io.File) -> str	Read entire file
io.read_line(file: io.File) -> str	Read next line (without trailing newline, "" at EOF)
io.write(file: io.File, data: str) -> None	Write to file
io.flush(file: io.File) -> None	Flush buffers
io.close(file: io.File) -> None	Close file

Examples

import io

def main() -> None:
    path: str = "/tmp/example.txt"
    io.write_text(path, "hello")
    io.append_text(path, " world")
    print(io.exists(path))
    print(io.read_text(path))

import io

def main() -> None:
    path: str = "/tmp/example.txt"
    f: io.File = io.open(path, "w")
    io.write(f, "alpha\nbeta\n")
    io.flush(f)
    io.close(f)

    f = io.open(path, "r")
    print(io.read_line(f))
    print(io.read_line(f))
    io.close(f)

with statement

Use with to ensure the file is closed automatically:

import io

def main() -> None:
    path: str = "/tmp/example.txt"
    writer: io.File = io.open(path, "w")

    with writer as file:
        io.write(file, "first\n")
        io.write(file, "second\n")
        io.flush(file)
    io.close(writer)  # writer is still valid here

    with io.open(path, "r") as file:
        print(io.read_line(file))
        print(io.read_line(file))