Joy is a programming language created by Manfred von Thun that is easy to use and understand and has many other nice properties. This Python package implements an interpreter for a dialect of Joy that attempts to stay very close to the spirit of Joy but does not precisely match the behaviour of the original version(s) written in C. The main difference between Thun and the originals, other than being written in Python, is that it works by the “Continuation-Passing Style”.

Abstract: Joy is a functional programming language which is not based on the application of functions to arguments but on the composition of functions. It does not use lambda-abstraction of expressions but instead it uses quotation of expressions. A large number of what are called combinators are used to perform dequotation, they have the effect of higher order functions. Several of them can be used to eliminate recursive definitions. Programs in Joy are compact and often look just like postfix notation. Writing programs and reasoning about them is made easy because there is no substitution of actual for formal parameters.

The language Joy is a purely functional programming language. Whereas all other functional programming languages are based on the application of functions to arguments, Joy is based on the composition of functions. All such functions take a stack as argument and produce a stack as value. Consequently much of Joy looks like ordinary postfix notation. However, in Joy a function can consume any number of parameters from the stack and leave any number of results on the stack