WebAssembly (Wasm) has revolutionized the way developers create programs that run at near-native speed in browsers and other environments. While Wasm is not typically written directly, it can be compiled from other languages, including Rust, Go, JavaScript, C/C++, and Python. In this article, we'll explore the feasibility of deploying these languages onto Wasm runtimes, highlighting the level of effort required for each.

Rust is often considered the most suitable language for deployment on Wasm, requiring minimal modifications to existing code. The tooling automatically generates boilerplate JavaScript, allowing the compiled Wasm modules to work seamlessly with web pages. Rust's maintainers have even created a comprehensive guide to using Wasm from Rust, providing insights on keeping delivered binaries small and adding Wasm support to existing crates.

C and C++ were among the first languages to be compiled to Wasm, thanks to their lower-level behaviors mapping well to Wasm's instruction set. The Emscripten toolchain, developed early on, offers detailed instructions for porting code, including support for SIMD, networking, C++ exceptions, and asynchronous code. As of version 8, the Clang C/C++ compiler can also compile natively to Wasm with no additional tooling.

Go, or Golang, added support for WebAssembly as a compilation target in version 1.11. Most changes involve modifying the compilation process rather than the program itself. The Wasm toolchain is included with the Go compiler, making it easy to deploy. However, interacting with the DOM can be awkward, and the generated binary artifacts are relatively large, often exceeding 2MB. Compression or using a different Go runtime, like TinyGo, can help mitigate this issue.

JavaScript, being a common destination for Wasm, can also be compiled to Wasm using tools like Javy, created by the Bytecode Alliance. Javy executes JavaScript code in a Wasm-based JavaScript runtime, using dynamic linking to keep module sizes reasonable.

Python's situation is more complex, as it requires the Python runtime and standard library to function. Pyodide, a port of the CPython runtime to Wasm via Emscripten, allows Python applications to run through a Wasm runtime. However, this approach comes with drawbacks, including the need to manually port packages with C extensions, limited support for PyPI packages, and a large Wasm package download for the Python runtime.

In conclusion, WebAssembly has opened up new possibilities for developers, enabling the deployment of a range of programming languages onto Wasm runtimes. While each language has its unique challenges and requirements, understanding these nuances can help developers make informed decisions about their technology stack and unlock the full potential of Wasm.