Braces - compiler and virtual machine for a scheme dialect

  Inactive         Rust         certainty/braces

Braces started when I worked with the wonderful book crafting interpreters, and I took that as an opportunity to:

  1. learn rust
  2. dive deeper into compilers and virtual machine implementations

I achieved both of these objectives and had a lot of fun working on this project. It implements a subset of r7rs small of the scheme programming language. I chose a scheme mostly because its evaluation semantics are very simple, as is its syntax. I came, however to discover, that the meta-syntactic ability, macros, twist your compiler-builder-brain quite a bit. The implementation is incomplete, and I will probably not finish it, but I’m content with its current state as it works for quite some scenarios and implements non-trivial language features. Among them:

  • Procedural macro expander
  • Automatic tail call optimization
  • Efficient implementation of closures

I’m sure there are also plenty of bugs in there, but that doesn’t bother me at the moment.


  • Learn how to build a bigger project using the Rust programming language
  • Learn how to build a compiler and virtual machine


  • Build a full implementation of r7rs


  • Implement a subset of r7rs
  • Implement the virtual machine as a stack machine
  • Don’t implement continuations
  • Implement procedural macros with explicit renaming


The following screenshot shows the braces REPL. It uses readline for completion and provides a way to tweak the level of introspection via flags. This example also shows the disassembler in action.

braces replbraces repl

December 31, 2023