Writing a Hashmap-to-Struct Procedural Macro in Rust

A walkthrough of building a custom Rust procedural macro called `FromHashmap` that automatically generates boilerplate code to populate struct fields from a `HashMap<String, String>`. The post covers using the `syn` crate to parse a struct's AST, extracting field names as `Ident` values, and using the `quote!{}` macro to generate the `impl` block with repetition operators. The generated code uses `HashMap::entry` to match keys to struct fields and parse string values into the correct types, falling back to `Default` when a key is absent. Full macro crate source and a passing test are included.