Alas. No one's mentioned SNOBOL or SPITBOL. I'm sure modern coders would consider them esoteric, but for me they were kind of delightful back in the day.
I would not consider SPITBOL esoteric since it was not intended as such — but the original INTERCAL-72 interpreter was written in SPITBOL, so the language is quite important to esolang history (and deeply weird, besides).
Hmmm. GP listed three languages which are not esoteric, and you've patted them on the back and shared three more which are not esoteric. Oops. Esoteric language =/= any non-mainstream language. Here's the definition from the esoteric programming language wiki, which is a lovely resource for anyone interested https://esolangs.org/wiki/Esoteric_programming_language : > An esoteric programming language is a computer pro…
Ummm...APL, Prolog, and Rebol are extremely esoteric. Their share of total code out there has got to be like less than 0.0001% and their paradigms are considered extremely weird and not for general consumption . I don't agree with the definition of esoteric included above and by the original poster.