GitHub: https://github.com/webc-site/ulua Playground: https://webc-site.github.io/ulua crates.io: https://crates.io/crates/ulua

ulua is a pure-Rust implementation of the Luau language (Roblox's typed Lua derivative), covering the lexer, parser, bytecode compiler, register VM, garbage collector, bidirectional type inferencer, and A64/X64 native JIT code generation.

Current focus: We are actively refactoring transliteration artifacts from earlier C++ ports, eliminating raw pointers, removing warning suppressions, and shrinking unsafe boundaries. Systematic microarchitectural tuning will follow once idiomatic Rust patterns are stabilized.

In-Memory Benchmark Comparison: Tested 16 compute-heavy benchmarks in a single process on Apple Silicon (M2 Max, arm64), taking median runtimes in milliseconds (ms):

  Benchmark (ms)   ulua  Luau C++  ulua JIT  Luau JIT  LuaJIT   Lua5.4
  -----------------------------------------------------------------
  binarytrees     105.0     135.7      70.4      89.9    49.6    116.9
  coroutines       83.1     108.2      82.8     130.8    26.1    145.3
  fannkuch         33.1      28.8       7.9       7.8     3.6     22.6
  fib              83.7      92.6      35.2      34.8     8.4     74.9
  mandel           93.2      93.5      25.4      23.3    11.0     56.2
  matmul           51.8      45.8      12.2      12.5     4.3     38.3
  nbody            93.4      95.7      92.5      92.7     4.8     72.1
  spectralnorm     79.9      74.6      20.7      19.9     2.2     90.9
  tablesort        64.5      66.9      63.8      67.4   115.2    241.1
  -----------------------------------------------------------------
  GeoMean ratio    1.00      1.02      0.52      0.57    0.16     1.17

- Interpreter: ulua tracks upstream C++ Luau throughput (1.0 vs 1.02 GeoMean) and is ~17% faster than Lua 5.4. - JIT: native compilation cuts runtime by ~48% (0.52 GeoMean), matching C++ Luau JIT (0.57).

WebAssembly Playground: Without C/C++ build dependencies, ulua compiles directly to wasm32. A live browser playground is running client-side at https://webc-site.github.io/ulua

Quick example:

  use ulua::prelude::*;

  fn main() -> Result<()> {
      let lua = Lua::new();
      lua.load("print('Hello from ulua')").exec()?;

      #[cfg(feature = "jit")]
      {
          lua.enable_jit(true)?;
          let res: i64 = lua.load("local s = 0; for i = 1, 1000 do s += i end; return s").eval()?;
          assert_eq!(res, 500500);
      }
      Ok(())
  }

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