Even among "pl", even a quick sampling shows that these aren't necessarily correctly categorized. For instance, "advice-taker" according to the site is "an actively used programming language created in 1958". But Wikipedia, which I would take to be more credible in this context, says it "was a hypothetical computer program" and explains the philosophical point put forth by the idea. So it was not a language, not even a real program, and certainly not actively used.

"open source" only appears in the editorialized HN title.