Reason (programming language)

Reason is a syntax extension and toolchain built on top of the OCaml programming language. Developed by Facebook (now Meta), it offers a new syntax designed to be more accessible to JavaScript developers while retaining the power and performance of OCaml.

Reason's key goals are to provide a familiar and approachable syntax, excellent performance through OCaml's native compilation, and seamless interoperability with existing JavaScript code and libraries. The syntax is inspired by JavaScript and aims to reduce the learning curve for developers familiar with that language.

Reason code is typically compiled either to native machine code via OCaml's native compiler or to JavaScript via the BuckleScript compiler (now known as Rescript). This allows developers to target both server-side and client-side environments with a single codebase.

Reason provides static typing and type inference, leading to improved code reliability and maintainability compared to dynamically typed languages. Its strong type system helps catch errors at compile time, preventing runtime issues.

While sharing the same core language, Reason differs from OCaml in its syntax and tooling. Reason uses a more JavaScript-like syntax, while OCaml uses a more traditional ML-style syntax. Reason also has its own set of tools, such as a parser, a compiler, and a build system, which are designed to improve the developer experience.

Reason's interoperability with JavaScript is facilitated by its ability to compile to readable and performant JavaScript code and its Foreign Function Interface (FFI), which allows Reason code to call JavaScript functions and vice versa. This interoperability makes it easier for developers to integrate Reason into existing JavaScript projects or to gradually migrate from JavaScript to Reason.