Topic summary
REPL
Extracted from the Wikipedia article Read–eval–print loop.
Combining source files and REPL development
Developers of Lisp applications typically do not write or copy-paste code to a REPL. They use the REPL for quick tests, for debugging and to explore a running system. They write their application in a source file under version control, they use commands or keyboard shortcuts to compile their code interactively. The Lisp process is running and connected to their editor, and it compiles new code "on the fly", without restarting.