Juergen Lorenz

ju (at) jugilo (dot) de

I am a mathematician and a member of the "small is beautiful" crowd. And R5RS-Scheme is the definite example, that a small language is possible which allows one to do almost everything with it. And that in a clear syntax -- or should I better say -- with almost no syntax at all? And it is a programmable programming language! You can always add new syntax to it.

In my mind, Chicken is the best Scheme implementation. Its compiler compiles to C in the most ingenious way, it has the simplest interface to C, and it has a beautiful infrastructure, the eggs system, a helpful community and, and, and ...



Some macros which help to write procedural macros. For example, a hygienic version of define-macro and a procedural variant of syntax-rules, called macro-rules, which is as easy to use as the latter but much more powerfull.


A light-weight alternative to the matchable egg, with many enhancements.

A number of binding macros is provided, which can destructure arbitrary mixtures of lists, pseudolists, vectors and strings, as well as arbitrary sequence types, the client may add later. The most important one is bind, a variant of Common Lisp's destructuring-bind.


An implementation of concrete and abstract types, the former beeing discriminated variant records, as advocated by Friedman, Wand and Haynes in "Essentials of programming languages" and ported to Chicken by Felix Winkelmann. The latter are based on the former, but hide the variant constructors and export constructor and accessor procedures instead. A simple object system is also provided.


Implements a variant of generic functions, where arguments are checked against predicates to choose a matching procedure which is eventually invoked. A destinctive feature of this implementation is, that the client has complete control over the multi-methods state, a search tree, and can decide where to insert a procedure to be eventually invoked, so that more specific procedures are found before less specific ones. Hence, multi-methods can be used to implement OOP. But note, that dispatching is done on all arguments, not only the first one, as in traditional OOP-implementations.


Anaphoric macros, which are unhygienic by design. Most of them insert the special identifier "it" behind the scene.


Some simple loop macros.


Something like immutable random-access vectors, with empty, couples and triples as special cases, and mutable singles as a possible replacement of boxes.


Simple implementation of the cell datatype, a lightweight variant of boxes.


a functor implementation of typed and immutable lists and sets.


An implementation of functional arrays and - as an application - of sets.


lazy list implementation based on Moritz Heidkamp's lazy-seq. Contrary to Moritz' implementation, the lazy-list's length is stored in the datastructure, so that a distinction between finite and infinite lazy lists can be made.


A functional interface to Oleg Kiselyov's and Ivan Raikov's treap egg.


An alternative to balanced search-trees.


combine the advantages of linked lists (fast insert and remove) and vectors (fast access).


Some simple macros and commands which help debugging and testing.


Syntactic sugar for Marc Feeley's continuation interface providing i.a. catch and throw


An easy to use exception wrapper around chicken's condition system.


A variant of ML's option datatype, implemented as a functor producing typed modules and an untyped module.


An implementation of "Design by Contract", coined by Bertrand Meyer for his Eiffel language.


A Chicken port of Kenneth A. Dickey's "Yet another Scheme Object System".

Obsolete eggs


Restricting some macros of the bindings egg to nested list expressions and supplying define-macro as an application. Obsolete, use bindings instead!


Explicit renaming macros made easy. Obsolete, use bindings instead!


Implicit renaming macros made even easier. Obsolete, use bindings instead!


Low level macros made easy. A merger of the two eggs er-macros and ir-macros. Obsolete, use bindings instead!


My first implementation of "Design by Contract". Now obsolete, use dbc instead.


Explicit (and implicit) renaming macros made easy

The Iup GUI toolkit

Design by Contract

Object Orientation and SRFI-99 records