Async I/O API Reference

Asynchronous file operations with buffering support

Import

U std/async_io

Overview

The async_io module provides asynchronous file I/O with buffered reading and writing. It wraps POSIX file operations (open, read, write, close, lseek) and provides AsyncFile, AsyncFileReader, and AsyncFileWriter for structured file access.

Constants

Structs

AsyncFile

S AsyncFile {
    fd: i64,
    path: str,
    mode: i64,
    is_open: i64
}

Async file handle.

Methods:

• open(path: str, mode: i64) -> AsyncFile -- Open a file (0=read, 1=write, 2=append)
• read(@, buf: i64, len: i64) -> i64 -- Read data into buffer
• write(@, buf: i64, len: i64) -> i64 -- Write data from buffer
• close(@) -> i64 -- Close the file
• read_all(@) -> str -- Read entire file content as string
• write_all(@, data: str) -> i64 -- Write entire string to file

AsyncFileReader

S AsyncFileReader {
    file: AsyncFile,
    buffer: i64,
    buf_pos: i64,
    buf_len: i64
}

Buffered line reader for async files.

Methods:

• new(file: AsyncFile) -> AsyncFileReader -- Create a reader
• read_line(@) -> str -- Read next line (newline-delimited)
• has_next(@) -> i64 -- Check if more data is available
• close(@) -> i64 -- Clean up and close

AsyncFileWriter

S AsyncFileWriter {
    file: AsyncFile,
    buffer: i64,
    buf_pos: i64,
    capacity: i64
}

Buffered writer for async files.

Methods:

• new(file: AsyncFile) -> AsyncFileWriter -- Create a writer
• write(@, data: str) -> i64 -- Write data to buffer
• flush(@) -> i64 -- Flush buffer to file
• close(@) -> i64 -- Flush, clean up, and close

Helper Functions

async_read_file

F async_read_file(path: str) -> str

Read an entire file and return its content as a string. Returns "" on error.

async_write_file

F async_write_file(path: str, content: str) -> i64

Write a string to a file (creates/overwrites). Returns bytes written or -1 on error.

async_copy_file

F async_copy_file(src: str, dst: str) -> i64

Copy a file from src to dst. Returns total bytes copied or -1 on error.

Example

U std/async_io

F main() {
    # Write a file
    async_write_file("/tmp/hello.txt", "Hello, World!")

    # Read it back
    content := async_read_file("/tmp/hello.txt")

    # Buffered reading
    file := AsyncFile.open("/tmp/hello.txt", 0)
    reader := AsyncFileReader.new(file)
    line := reader.read_line()
    reader.close()
}