numbat/assets/reasons-for-rewriting-in-rust.md

Reasons why I rewrote Insect in Rust:

• Insect is written in PureScript, which is a niche programming language with a (fantastic but) small community. Rust is much more popular amongst developers, so it is much easier to find contributors in a Rust project than in a PureScript project. This has been an actual problem with Insect, since I got multiple comments over the years that people wanted to contribute, but couldn't.
• A redesign from scratch allowed me to focus on the following areas of improvement:
  • Introducing the concept of physical dimensions into the language (see https://numbat.dev/doc/dimension-definitions.html)
  • Adding a static type system (see https://numbat.dev/doc/type-system.html)
  • Allowing users to define their own units (https://numbat.dev/doc/unit-definitions.html)
  • Being able to define constants and the whole unit system in the language itself (https://numbat.dev/doc/prelude.html)
  • Much better error messages
  • Support for notepad-style computations (Mathematica/Jupyter style)
• The PureScript implementation is slow. Numbat's Rust-based parser & interpreter is orders of magnitude faster, not just on the command-line (startup speed!) but also on the Web (via WASM)
• I've always wanted to experiment with WASM and Numbat was a perfect excuse for this.