Unit testing doesn't provide the level of interactivity a REPL does. A REPL lets you see the output of parts of an unfinished function based on the running program's state.
If you've already thought out the whole program before you start writing it, that may not be as valuable. In my experience, software often isn't that way and the ease of exploration a REPL and long-running process provide are unmatched.
If you've already thought out the whole program before you start writing it, that may not be as valuable. In my experience, software often isn't that way and the ease of exploration a REPL and long-running process provide are unmatched.