> REPLs are not useful design tools (though, they are useful exploratory tools) I disagree with this. I’m a Clojure dev, and most of the time, I use the REPL to iterate on features, fix bugs, and refactor, thanks to the fast feedback loop. I used to be a Java dev—oh god, restarting the whole app after every change made me want to shoot myself in the head. Now, I use the REPL to build what I want and then move on. Thi…
The standard runtime didn't like some redefinition. But there were alternatives. Eclipse, for example, would purposely let you get otherwise broken code running so that you could breakpoint and replace as you went.