RPN Calculator Implementations
(currently in 56 languages)

The following links lead to implementations of the calculator in the respective languages. Each implementation is accompanied by an explanation.

In rare occasions there is more than one implementation in a language, but almost all of them are ‘hidden’ as HTML comments (you will have to read the page sources in order to find them).

The program text is displayed in colour, like good text editors do. This not only improves readability by making the lexical structure of a program more discernible, but also assists the reader in guessing the roles that the different tokens play in the language. The following classes of tokens are being discriminated between:

• constants;
• typenames and the like;
• command- or other names with a similar meaning;
• pseudo commands and others of the sort, e. g. the C pre-processor command names;
• built-in procedures, functions and other entities;
• library items;
• special characters, symbols or names, e. g. ‘escape’ character sequences;
• comments;
• section separators (see the C with Lex & Yacc implementation);
• everything else.

Colour coding lets one know, e. g., that PostScript, Refal, and Smalltalk have no commands, and that Pascal, Snobol, and Icon make extensive use of built-in procedures, while other languages have none, resorting to library procedures instead.

There are cases where classifying a certain token according to the above set can be decided in more than one way or not at all, or the choice made is disputable, but in general colouring helps a lot.

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