veykril/nom

nom is a Rust library that helps developers build parsers, code that reads structured data (like a file, a network message, or a line of text) and breaks it into meaningful pieces. Instead of hand-writing tedious and error-prone parsing logic, you assemble small, reusable functions that each handle one tiny task, and combine them to process complex formats. The approach is called "parser combinators." Rather than writing a grammar in a separate file and generating code from it, you write code that directly describes what you're looking for. You might say "take a #, then two hex digits, then two more, then two more", and that assembles into a parser for CSS color values. Because the building blocks are small and focused, they're easy to test and reuse across projects. The code ends up looking a lot like a description of the format itself. This library shines for binary formats (like video files or network packets), text formats (like JSON or CSV), and even programming language prototyping. Real projects using it include parsers for GIF, TLS, HTTP, Kerberos, SQL, Lua, and many others. It also handles streaming data, when data arrives in chunks rather than all at once, the parser can recognize that it needs more input rather than guessing and returning wrong results. Two things stand out. First, it's designed around Rust's safety guarantees, which means parsers built with it avoid common bugs like buffer overflows. Second, it's fast, benchmarks suggest it often outperforms comparable libraries and even some handwritten C parsers. It also supports zero-copy parsing, meaning it can reference parts of the input directly rather than copying data around. For anyone working in Rust who needs to read and understand a structured data format, this is a battle-tested starting point with a large ecosystem of existing parsers to learn from.