Canadian Tax Calculations for 2003/2004 ------------------------------------------ This package performs tax calculations for Canadian income taxation, and has a variety of forms set up for calculations for the 2003 and 2004 tax year. The "main program" is the file taxreturn.pl; it starts by loading in all the forms, and then states a series of taxfact/3 and taxfact/4 rules that describe each individual's tax situation. There are, in addition, a set of "form" predicates, such as t4/15, used to present the values on one's T4 slips. (Presumably, additional similar "forms" will eventually be set up to support T3, T4A, and T5 slips...) Note that each of the facts begins with a taxpayer identifier; this means that if you are preparing returns for a family, you can put information about all of the family members together, and thus where the tax returns need to reference one another, they, well, do so. On Unix, you load this all up by visiting the directory where all the Prolog code is, thus: [cbbrowne@wolfe:canada2003] swipl Welcome to SWI-Prolog (Multi-threaded, Version 5.2.7) Copyright (c) 1990-2003 University of Amsterdam. SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under certain conditions. Please visit http://www.swi-prolog.org for details. For help, use ?- help(Topic). or ?- apropos(Word). ?- [taxreturn]. [Warnings elided] % taxreturn compiled 0.02 sec, 149,184 bytes Yes ?- At this point, you may interact with the system, querying values. In order to provide an organized way to collect values to copy onto a tax return, each tax form has an associated formatting/2 predicate that provides a schema for formatting the form's output. The predicate display_form/2 may be used to display the contents of a tax form. If you wish to display all of the forms for all of the taxpayers, you might enter the query: ?- display_form(TAXPAYER, YEAR, FORM). which will then display forms, pausing after each one. Press ";" to continue. At present, the set of forms supported is a bit limited, providing only calculations for residents of Ontario, for a set of tax forms that the initial author found useful or particularly interesting.