Alzint — An interpreter for AL(ℤ) programs

Source code: alzint.pl

You need Scryer Prolog to run it.

AL(ℤ) stands for Assignment Language over Integers. It is a Turing complete programming language supporting variable assignments, loops and conditions.

Alzint is an interpreter for AL(ℤ) programs, written in Prolog. Alzint lets you run AL(ℤ) programs. It also supports single-stepping and reverse execution of AL(ℤ) programs. This means that previous steps of the execution can be undone and later repeated.

To run an AL(ℤ) program with Alzint, use run(+File):

      ?- run("ex1.txt").

For single-stepping, use step(+File):

      ?- step("ex1.txt").

When single-stepping through an AL(ℤ) program, you press:

c to continue with the next statement
r to run the program without further interruption
u to undo the preceding step (reverse execution)
q to quit

Example files are ex1.txt, ex2.txt and ex3.txt.

A transcript of running ex3.txt: ex3.log

If you are interested in more interpreters and compilers in Prolog, also check out Thinking in States and Lisprolog.

Acknowledgments: Many thanks to Christian Fermüller for spawning my interest in AL(ℤ) and countless other topics in theoretical computer science.

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