Factor has been a good source of inspiration when designing Kitten, and I would recommend it to people who want to try a concatenative language now. Kitten is not usable for real-world stuff yet—but it’s getting close, and eventually it should be a good alternative to Factor for those of us in the static-types camp.
I’m working on an updated tutorial, and I’ll definitely include some comparisons to other languages that people are likely to know, say JavaScript and C. But I still need to find the right balance between illustrative comparisons and standalone descriptions.
I like the concept of Factor and talked to the author awhile back who isn't actively involved anymore. My problem comes from the confusing doc and lack of beginner materials. Just because I can write a simple app in an imperative or OO context doesn't mean I can write functional nevermind efficient concatenative code without help.
I do hang out with Slava occasionally, and he’s been helpful even if he’s not that into concatenative programming anymore. For better or worse, the current Factor maintainers are focused more on language internals than onboarding new users. Concatenative/compositional programming does require a different way of thinking, which I think is easy to learn but hard to teach.
I’m working on an updated tutorial, and I’ll definitely include some comparisons to other languages that people are likely to know, say JavaScript and C. But I still need to find the right balance between illustrative comparisons and standalone descriptions.