While experienced lispers already know this, it may not be clear to everyone that in Common Lisp "compile time" routinely happens repeatedly in a running image.

While experienced lispers already know this, it may not be clear to everyone that in Common Lisp "compile time" routinely happens repeatedly in a running image. cl-ppcre[1] relies heavily on this. It can take a regexp pattern as a runtime input and compile a recognizer down to machine code on the fly. This technique gets used routinely. Edit: In fact, I strongly suspect that this resulting unsuitability of Lisp for proprietary code played a major role in its commercial failure before the widespread advent of services. [1] https://edicl.github.io/cl-ppcre/ https://edicl.github.io/cl-ppcre/