>I've seen various attempts of this over the years, but quickly your code becomes more complex than the computer can run while you type and you fall back to running most of the tests after in some way.
That does not match my experience with lisp.
Mine, either.
My last experience with lisp was assignments in college which are too small to count as anything more than a toy problem.
For real world code in other languages I've worked with the complexity of the problems demands so much code that the REPL cannot keep up.