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    Charity is a categorical programming language currently being developed by The Charity Development Group in The Department of Computer Science at The University of Calgary, Canada.

    [A darn pretty picture.]
    (Click here to see a larger picture!)

    Charity is functional in style. That is, programmers familiar with declarative paradigms (functional and logic programmers) should find Charity easy to grasp.

    Charity is based on the theory of strong categorical datatypes. These are divided into two subclasses: the inductive datatypes (built up by constructors in the familiar way) and the coinductive datatypes (broken down by destructors). Programs over these datatypes are expressed by folds (catamorphisms) and by unfolds (anamorphisms), respectively.

    We list some, but not all, of Charity's features below:

    It is our belief that Charity provides a very elegant, pure framework for software development, teaching, and language research. This framework supports straightforward reasoning about programs and is highly amenable to program specification, transformation, and verification.

    This page © The Charity Development Group 1996 (
    Last revised December 1998.