[timomaxgalvin]

These are true, but it's not the reason it's so successful.

It's the original agile, functional programming environment. Code iteration and basic testing is done in microseconds.

I remember laughing very hard when someone excitedly told me about REPL in python, like it was a new idea.

[Symbiote]

REPL is far older than Excel, it's from the 1960s.