/Prolog-Interpreter

Prolog interpreter univeristy project

Primary LanguageHaskell

Haskellog

Simple Prolog interpreter written in Haskell

Hello!

This is an university project made in Haskell for Functional programming course.

Supported:

  • Constants*
  • Rules and facts**
  • Infinite generation

*Only atom constants are supported. Lists, numbers and aritmetic operations and not yet implemented.

**Rules only support logical AND via "," in their body.

How to use:

  • Load Main module into GHCi and run main function by typing "main" in *Main> prompt
  • Load .pl file with valid Prolog code by entering its full path when prompted
    • You are now inside a Read Evaluate Print Loop (REPL) made for this version of Prolog.
    • The prompt of this REPL is *Haskellog>
  • Enter commands inside *Haskellog> prompt.

Supported commands

  • *Haskellog> :help

    • Get a list of supported commands.

  • *Haskellog> ??

    • Get a list of all rules and facts. Prints the current state of the knowledge base.

  • *Haskellog> blue(sky).

    • Adds fact "blue(sky)." to knowledge base.

  • *Haskellog> p(X, Y) :- q(X, Z), r(Z, Y).

    • Adds rule "p(X,Y):-q(X,Z),r(Z,Y)." to knowledge base.

  • *Haskellog> ?- p(X, Y).

    • Make a query. To get more answers enter ";". Enter anything else (for example ".") to stop.

  • *Haskellog> ?- q1(X, Y, Z), q2(Y), q3(T).

    • Make multiple queries at once connected with logical AND similar to a rules body.

  • *Haskellog> :q

    • Quit interactive loop (exits out of *Haskellog> prompt).

Please reload Main module (*Main> :r) before running main function again after *Haskellog> :q

Sources and inspirations for code and approach