Rust Programming Cookbook

Implementing matching with macros

When we created custom macros, we had already seen pattern matching at play: a command was only executed if particular words were present before compilation. In other words, the macro system compares raw text as patterns before they become expressions or types. Consequently, creating a DSL is really easy. Defining a web request handler? Use method names in the pattern: GET, POST, HEAD. There is an endless variety, however, so let's see how we can define some patterns in this recipe!