However, that solution would require the same level of language-specific knowledge as the modification mentioned below "Limitations" in the blog post. That's also why I never implemented the idea, despite having carried it around in my head for a few years now. Hopefully someone else will eventually get around to implementing it.
It's an example of what you can do with "specific to a language", although it'd suffer the same limitation of "slower after a big computation".
IPython is fancier and can be used with expensive computations, so this might be a dead end, but I didn't want to have to think about whether the state of the examples was ever out of sync with a fresh reexecution of the code (and also I wrote this a long time ago). I thought I might get to cleverer incremental update methods eventually, but it hasn't been worth the trouble to try when the above workflow has worked well enough.
The trouble with tools like that is that they're pretty language specific, so it's my impression that it would require a fair bit of work to generalize to languages other than C++.
"This has obvious performance disadvantages if you're actually doing computation inside your REPL instance—for each new line, you'll have to redo all old computation. However, this technique has other distinct advantages that make it very desirable for certain use cases."
Are there any cleaver increment compile/run tricks that could speed this up?