I wrote a somewhat related response at the time the "Who Killed Prolog" article this one is responding to came out: http://www.kmjn.org/notes/prolog_lost_steam.

I wrote a somewhat related response at the time the "Who Killed Prolog" article this one is responding to came out: http://www.kmjn.org/notes/prolog_lost_steam.html http://www.kmjn.org/notes/prolog_lost_steam.html I agree that "easier to understand" could've helped. But things that are hard to understand can get uptake if they're big wins. The bigger problem in my opinion is that the number of cases where Prolog was a big win significantly decreased over time. When it appeared in the '70s, Prolog's declarative-programming approach based on logic had very few peers where you could do even simple textbook examples in as nice a way. But now even SQL (with features like recursive queries) can do a lot of the intro-level Prolog examples. It doesn't have the full logic semantics with unification, but a lot of problems don't need them. SMT solvers, LINQ, and rules engines like Jess/Drools are a few other declarative paradigms that ended up eating into some of what Prolog proponents once saw as its space. If Prolog were up exclusively against FORTRAN77 or K&R C, there would be many problems where it's a big win, but that's not the competition anymore.