Wado

Wado is a programming language that compiles exclusively to WebAssembly, targeting the Component Model and WASI platform. Its defining characteristic is that platform boundaries and language effects are unified at the type level, meaning WASI capabilities appear directly in function signatures rather than being implicit runtime behaviors. When a function uses standard output, network access, or filesystem operations, it declares those capabilities explicitly in its type signature with an effects annotation. This makes side effects visible in the code's structure rather than hidden in implementation details, producing programs where what you read is genuinely what executes.

The language produces remarkably small binaries because it targets WebAssembly GC where the host runtime provides garbage collection. No memory management runtime gets embedded in the compiled output, eliminating the bloat that most compiled languages add for automatic memory handling. This architectural decision shapes everything about how Wado code compiles and executes, making it particularly suited for embedded scenarios, edge computing, and environments where binary size directly impacts load time or resource constraints. The lean output means faster cold starts and lower memory overhead in production deployments.

Wado's type system mirrors the WebAssembly Component Model's structure precisely, distinguishing between variant, enum, and flags types in ways that map cleanly to the underlying platform. It includes static typing with generics including variadic type parameters for flexible data structures, closures and lambda expressions for functional programming patterns, pattern matching through match expressions for control flow, and trait based abstractions with associated types for extensible designs. Error handling works through Result and Option values rather than exceptions, following explicit error propagation that integrates naturally with the effects system.

The language deliberately avoids macros, implicit conversions, and any types that would obscure what code actually does. This explicit design philosophy means analyzing a Wado program requires no hidden knowledge about compile time transformations or surprising type coercions. The transparency benefits both human readers trying to understand unfamiliar code and AI agents or automated analysis tools that need to reason about program behavior reliably. Template literals exist for compile time execution when needed, but their behavior remains predictable within the language's explicit design constraints.

The standard library covers practical needs including JSON parsing and serialization, cryptographic digests, collections with standard data structures, temporal operations for date and time handling, HTTP routing primitives for web services, and CLI argument parsing for command line tools. These components ship as part of the language ecosystem rather than requiring external dependency management, simplifying the toolchain for new projects while ensuring consistent behavior across deployments.

Developers can write and run Wado code directly in the browser through the online playground, which compiles and executes entirely client side with no server requirements. The playground includes an editor with syntax highlighting and real time output visible alongside the code, making experimentation immediate. Language server features providing code intelligence require a JSPI capable browser like Chrome or Chromium 137 or newer, though basic editing and execution work more broadly. One file scripts support shebangs for quick execution in development workflows without project scaffolding.

Wado remains experimental but functional for its intended purpose of producing type safe, compact WebAssembly modules with explicit effects tracking. The full potential depends on three ecosystem developments still in progress across the broader WebAssembly community: browser Component Model support for running components in web contexts, WASI 1.0 standardization for stable system interfaces, and garbage collected type interoperability across Component boundaries for seamless language interoperation. Developers building for WebAssembly who care about binary size, explicit effects, deterministic behavior, and forward compatibility with the Component Model will find Wado worth exploring as these platform capabilities mature. The project is open source under MIT license, designed by FUJI Goro.