transpiler

A transpiler, also called a source-to-source compiler, is a type of compiler that translates code from one programming language into another at a similar level of abstraction. The aim is to preserve program behavior while adapting syntax, constructs, or platform requirements to the target language. Transpiled code is typically high-level and readable, and it may be further compiled or executed in the target environment. Transpilers differ from traditional compilers that produce machine code or bytecode; they bridge languages and enable cross-language interoperability or platform portability.

A typical transpilation pipeline involves parsing the source language into an abstract syntax tree, applying semantic or syntactic transformations, and emitting source code in the target language. Many transpilers also generate source maps to connect positions in the generated code with the original source for debugging.

Common use cases include converting statically typed languages like TypeScript or Kotlin into JavaScript, enabling developers to use modern language features while delivering code that runs in environments that do not natively support them. Tools such as TypeScript, Babel, CoffeeScript, Kotlin/JS, and Scala.js exemplify transpilation workflows. Some projects transpile between languages to improve interoperability or align with a chosen ecosystem.

Limitations exist: not all constructs map cleanly across languages, runtime semantics may differ, and debugging generated code can be challenging without source maps. Transpilers can introduce overhead, and generated code may be less optimized than hand-written code. Despite these caveats, transpilers support modernization and cross-platform development without changing the target runtime.