You misunderstand me. By "repl-drive programming" I do not mean programming that is fixated on the "command-line repl". On the contrary, what I'm talking about

You misunderstand me. By "repl-drive programming" I do not mean programming that is fixated on the "command-line repl". On the contrary, what I'm talking about has much more in common with what you describe as "far more productive". It's not about a particular shell or window or buffer; it's about a runtime environment that is designed to support writing software by building and changing it as it runs. By "repl", I do not mean the window or the buffer or the shell program. I mean the loop of: read an expression, evaluate it, and present the results, in the context of a runtime that is designed to comprehensively support it. Moreover, you can have all of the tools that you listed and still not be working with a properly-designed repl-driven environment. For example, I built a 3D interactive environment on the JVM that worked quite well--it launched into the 3D environment ns no more than a second or two, and could build whole procedurally-generated scenes in a few seconds. It supported networked multiuser interactions. I could start it from a repl and dynamically alter scenes and objects and their behavior in the environment by talking to them. It still wasn't a proper repl-driven environment because the underlying runtime could not correctly handle dynamic redefinition of classes and methods. That meant that if I decided that I needed to change a representation or something, I had to kill the environment and rebuild it. It meant that there was always a gratuitous barrier that I might run into at any moment. It meant that some abitrary set of things I was working on was always on the other side of that barrier. Contrast that to working with, for example, SK8, where I could redefine absolutely everything in the environment (including, for example, the system-level procedures used to draw window frames) without ever restarting the code that was under development.