REPLdriven

REPLdriven is a software development approach that centers the interactive Read-Eval-Print Loop (REPL) as the primary tool for building software. In REPLdriven workflows, developers prototype, experiment, and refine ideas by live evaluation of code fragments, gradually expanding them into well-structured modules. The emphasis is on immediate feedback, iterative exploration, and incremental design rather than upfront specification in static files.

Practices include starting from small, runnable expressions in a shell or notebook, exploring APIs, data structures, and algorithms, then shifting successful experiments into source files and tests as the design stabilizes. The REPL often serves as a continuous testing ground, with workflows bridging exploratory coding and formal development, sometimes aided by tooling that saves sessions or exports reproducible scripts.

Advantages include faster feedback, better intuition about API design, and natural support for prototyping and debugging. Limitations include risks of brittle sessions, challenges with reproducibility, and potential gaps in documentation or maintainability for large projects. REPL-driven workflows are often complemented by tests and version control to ensure reliability, and may require discipline to integrate exploratory work into production-ready code.

Historically, REPLs originated with Lisp and have remained central in languages with interactive shells. Modern ecosystems such as Clojure, Python, Ruby, and JavaScript support REPL-driven workflows, often integrated with editors or notebook-like environments to streamline iterative development.