A common approach would be that the code you're testing / playing with is defined in a file somewhere, and reloading that file resets the REPL state sufficientl

A common approach would be that the code you're testing / playing with is defined in a file somewhere, and reloading that file resets the REPL state sufficiently to iterate on your tests. e.g. if it does rely on external state, the reload will re-initialize that state. Morally similar to the setup instructions in a unit test.