Quackery is a lightweight, open-source language for recreational and educational programming, inspired by Forth and Lisp.
Sample Quackery Shell dialogue; defining and testing an insertion sort.
/O> [ [] swap witheach ... [ swap 2dup ... findwith [ over > ] [ ] ... nip stuff ] ] is i-sort ( [ --> [ ) ... Stack empty. /O> [] 10 times [ i join ] ... shuffle dup echo ... say " --> " ... i-sort echo ... [ 6 7 5 8 3 4 2 1 0 9 ] --> [ 0 1 2 3 4 5 6 7 8 9 ] Stack empty. /O>
The Quackery language is an extensible assembler for a Quackery Engine. The Quackery Engine has a memory model based on dynamic arrays and bignums, so presumes comprehensive hardware support for these features.
Program execution consists of the Quackery Processor traversing directed tree-like graphs built from dynamic arrays ("Nests" in the Quackery nomenclature) containing Operators (op-codes), Numbers (pointers to bignums) and pointers to Nests. The Quackery processor is stack-based rather than register-based.
Programming in Quackery consists of extending the predefined graphs that constitute the Quackery environment.
This implementation of a virtual Quackery Engine uses Python lists as Nests, Python functions as Operators and Python ints as Numbers.
The Quackery processor and a basic Quackery compiler are coded in Python 3, and the Python Quackery compiler is used to compile the Quackery environment, which is written in Quackery and includes a more fully featured (and extensible) Quackery compiler, which is available to the Quackery programmer.
That the Quackery language has similarities to Forth (also an extensible assembler for a stack processor), that it leans on Python for support for dynamic arrays and bignums, and that the majority of Quackery is written in Quackery all make for a very compact implementation, under 48k of source code. The downsides are that it is rather slow by modern standards, and that it is by no means "fully featured".
In its defence it is possible to understand the entirety of Quackery in short order, and, once the hurdle of Reverse Polish Notation has been passed, program development with the interactive environment (the Quackery Shell) is quick and rewarding. Quackery is intended primarily for recreational and educational programming, and is a relatively painless introduction to the concatenative programming paradigm.