MiniLang

MiniLang is a from-scratch compiler, static analyzer, and bytecode interpreter for a small imperative programming language, built in C++17, with an in-browser playground powered by WebAssembly.

THE APP CAN BE ACCESED AND TEST AT: https://minilang.bhalla.info

What's here

• A hand-written lexer and recursive-descent parser (no parser generator in the shipped build — see docs/design-log.md)
• A type checker that catches type mismatches, undefined references, and argument/return errors with precise source locations
• A static analyzer that flags use-before-initialization, unreachable code, unused variables, and literal overflow risk as Clang-Tidy-style warnings
• A stack-based bytecode compiler and VM
• A WebAssembly build of the whole pipeline, driving a browser playground with a code editor, AST viewer, diagnostics panel, and bytecode disassembly view

Quick start

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build
./build/src/cli/minilangc examples/fibonacci.ml

Language at a glance

// Compute the nth Fibonacci number iteratively.
func fib(n: int) -> int {
    int a = 0;
    int b = 1;
    while (n > 0) {
        int next = a + b;
        a = b;
        b = next;
        n = n - 1;
    }
    return a;
}

func main() -> void {
    print(fib(10));
}

The full grammar is specified in docs/grammar.md.

Architecture

 source (.ml)
      |
      v
  +--------+     +--------+     +--------------+     +-----------------+
  | Lexer  | --> | Parser | --> | Type Checker | --> | Static Analyzer |
  +--------+     +--------+     +--------------+     +-----------------+
                       |                                      |
                       v                                      v
                 AST (shared)  ------------------------> diagnostics
                       |
                       v
               +------------------+     +----+
               | Bytecode Compiler| --> | VM | --> program output
               +------------------+     +----+

The CLI (minilangc), the GoogleTest suite, and the WebAssembly bridge all drive this same compiler core in include/minilang/ and src/minilang/ — the browser playground is a thin client, not a reimplementation.

Playground

The web/ directory contains a CodeMirror-based playground that compiles and runs MiniLang entirely client-side via WebAssembly — no server round trip. See web/README.md to run it locally.

Design decisions

Key trade-offs (hand-written parser vs. generator, stack-based vs. register-based bytecode, why type checking and static analysis are separate passes) are documented as they were made in docs/design-log.md.

License

MIT — see LICENSE.

Built With

• c++
• cmake
• css
• html
• javascript
• shell