Prolog

Hello World in Prolog

Every programming journey starts with Hello World. Let’s write our first Prolog program and get our first taste of logic programming.

The Code

Create a file named hello.pl:

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:- write( …

Variables and Types in Prolog

Prolog’s data model is radically different from mainstream languages. There are no typed declarations, no assignment statements, and no primitive/object divide. Instead, everything is a term, …

Operators in Prolog

In most languages an operator like + quietly computes something. In Prolog, that assumption will trip you up. Prolog is a logic language, so 1 + 2 is not the number 3 — it is a term, a tree with the …

Control Flow in Prolog

Control flow in Prolog looks nothing like the if/for/while machinery of imperative languages — and that is the whole point. Prolog is a logic programming language, so the engine’s default …