The Icon Programming Language

Icon is a very high-level programming language based on the concept of "goal-directed execution" in which code returns a "success" along with valid values, or a "failure", indicating that there is no valid data to return.

Icon is a mature, general-purpose programming language which is available for free on many platforms. It has a rich set of types: integers (of arbitrary size), reals, strings, lists, sets, tables, and records, together with an interesting goal-directed evaluation mechanism. The book is clear and user-friendly. Some prior programming experience necessary.