io

bufio.Scanner is great until it isn’t: by default it refuses tokens larger than 64K, which makes it a bad fit for long log lines or large JSON records. The failure mode is subtle—scan stops and Err() returns a token-too-long error. For production log

Rust's std::fs module provides file I/O. fs::read_to_string() reads a file into a String, fs::write() writes bytes. For larger files or streaming, use File::open() and BufReader/BufWriter for buffered I/O. Always handle errors with Result and ?. For p

BufReader and BufWriter wrap readers/writers with an in-memory buffer, reducing system calls. For example, reading a file line-by-line with BufReader::new(file).lines() is much faster than unbuffered reads. I use them for parsing large files, log proc