clap is a fantastic Rust library for Command Line Argument Parsing. It's both easy to use and powerful - in the spirit of Rust philosophy - you get what you pay for. Simple CLI options are simple to define, while complex schemes (think git level of complex) are absolutely doable.

clap is also one of the best examples of what I would call developer marketing in the Rust community. It has a beautiful and informative homepage, an extensive README (including changelog - see note below), a bunch of good examples, even video tutorials! Hats off to Kevin and all clap contributors, you're doing a great job!

Note: Rust crate authors, please, please add changelogs/release notes to your libraries. Coming from Python where it's customary, it struck me that a lot of libraries do not document their changes aside from the commit log. (Oops, I'm guilty of this myself...)

We learned the basic concepts of nom yesterday when we wrote a parser for HTTP headers. HTTP is by its nature a text protocol. nom however always works on bytes (byte array slices, denoted in Rust with &[u8]). This makes it perfectly suitable for parsing binary data as well. There's already a selection of parsers using nom for binary formats such as Redis dump files, MySQL protocol or tar archives. Today we are going to build a simplified WebSocket frame parser.

Important note: this article is outdated! Go to http://zsiciarz.github.io/24daysofrust/ for a recent version of all of 24 days of Rust articles. The blogpost here is kept as it is for historical reasons.

One of the few chores when building a commandline program is argument parsing, so that myprogram --config=myfile.conf --verbose -o output.txt makes sense. Some arguments come in short and long variants, some are optional and some are positional only. There are a lot of libraries for argument parsing, some are even included in the respective languages' distributions. In Rust's case there's the getopts crate.

The first thing a moderately savvy user will do is... no, not read the documentation, but run myprogram -h (or --help) to discover available options. getopts and other libraries can derive such help summary for you, saving your time and reducing duplication. But what if it was the other way round? You'd write the usage message, listing possible options, and the tool would build an argument parser from that. Enter docopt.

Important note: this article is outdated! Go to http://zsiciarz.github.io/24daysofrust/ for a recent version of all of 24 days of Rust articles. The blogpost here is kept as it is for historical reasons.

Most of us programmers have encountered the CSV format at some point of our career. Whether you cooperate with financial people, analyze some scientific data or simply allow the users of your web app to download a record of their activities, chances are you'll use some variation of CSV as the data format. Note that I said some variation - CSV itself isn't standardized and there are lots of quirks in different implementations.

CSV libraries exist for lots of languages, making it a common format for interoperability (alongside XML or JSON) and sometimes preferred for data of a tabular nature. In the Rust ecosystem there is the csv crate which will be the focus of this blog post.