Prolog is one of the first logic programming languages, now seeing adoption in artificial intelligence applications and natural language processing. It is hard to learn because: It is an unconventional language, its data structures are unlike other programming languages. It requires an unreasonably competent compiler.

Why Prolog is so hard?

Prolog is harder to learn than many other programming languages. In part, this is due to inherent reasons: Prolog is simpler and more powerful than many other programming languages, and so it takes longer to get used to this if you are more familiar with low-level languages.

Is Prolog still used in 2020?

Trust me, Prolog is still being used — just not as extensively as some of the most commonly used languages in our industry, and there is a very good reason for that.