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 ...

Chicken 5 Eggs

anaphora

some anaphoric macros, some of them accompanied by equivalent named ones.

arrays

An implementation of functional arrays (of variable length) and - as an application - of sets.

biglists

an attempt to unify access to lists and lazy-lists, either finite or infinite.

bindings

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

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

callable-sequences

a common extendable functional interface to various flat and nested sequence types, including lists, pseudolists, vectors and strings.

checks

Procedures and macros that help to check pre- and postconditions

continuations

some additional interfaces to continuations

dotted-lambdas

a version of lambda, called lambda*, which accepts lists terminating with two, three or four dots referencing a list to its left of at most one, arbitrary many or at least one item respectively.

generics

an implementation of generic functions

holes

Transform expressions with holes into procedures with the holes as argument names. Here, a hole is symbol, consisting of zero or more digits enclosed in < and >.

iterators

a simple implementation of iterators and coroutines.

list-comprehensions

Some list creating procedures, in particular a variant of Clojure's for macro

locals

Three simple macros inspired by ML's local definitions

messages

An implementation of algebraic-types and abstract-types, based on messages, which are (functional) vectors tagged with a type keyword and a variant keyword.

pipes

piping partial combinations from left to right

premodules

creating a module-file, a tests-file and documentation automatically from one premodule file.

procedural-macros

Some macros to facilitate the writing of procedural macros, including define-macro and macro-rules, which mimics syntax-rules. All destructure the macro-code automatically behind the scene, using macros from the bindings egg. Renaming is simplified as well.

pseudolists

Routines to handle pseudolists as a generalisation of lists.

simple-cells

Another simple implementation of the cell datatype, a lightweight variant of boxes.

simple-contracts

design by contract for procedures.

simple-exceptions

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

simple-loops

some simple loop macros.

simple-sequences

common extensible interface to various sequence types, in particular lists, pairs, vectors, strings

simple-tests

Some simple macros and commands which help debugging and testing.

skiplists

an implementation of skiplists

tree-walkers

replacement of the nested car and cdr routines

Chicken 4 Eggs

These eggs will no longer be maintained. Most of them are ported to Chicken 5.

basic-macros

Some macros which help to write procedural macros. For example, define-er-macro does the renaming and bind the destructuring automatically. bind and bind-case are simplyfied versions of the equally named macros in the bindings egg, which are sufficient for macro-writing.

procedural-macros

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.

bindings

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.

datatypes

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.

locals

Implementation of a local macro inspired by the equally named operation in ML.

holes

Transform expressions with holes into procedures with the holes as argument names. Here, a hole is symbol, consisting of zero or more digits enclosed in bangs.

list-comprehensions

Some list creating procedures, in particular for and for*

anaphora

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

loops

Some simple loop macros.

tuples

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

simple-cells

Another simple implementation of the cell datatype, a lightweight variant of boxes.

typed-lists

a functor implementation of typed and immutable lists and sets.

arrays

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

basic-sequences

basic sequence-routines, which are used in bindings and can be used for a full-flegded sequence package

generics

an implementation of generic functions, using selectors for dispatching and insertion.

messages

implements messages as specialized generic functions of arity one, possibly parametrized.

lazy-lists

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.

treaps

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

skiplists

An alternative to balanced search-trees.

random-access-lists

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

simple-tests

Some simple macros and commands which help debugging and testing.

continuations

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

simple-exceptions

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

options

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

simple-contracts

Design by contract for procedures

yasos

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

Obsolete eggs

multi-methods

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. Deprecated, use generics instead.

cells

Simple implementation of the cell datatype, a lightweight variant of boxes. Deprecated, use simple-cells instead

list-bindings

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

er-macros

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

ir-macros

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

low-level-macros

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

dbc

An implementation of "Design by Contract", coined by Bertrand Meyer for his Eiffel language. Now obsolete, use simple-contracts instead

contracts

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

Tutorials

Explicit (and implicit) renaming macros made easy

The Iup GUI toolkit

Design by Contract

Object Orientation and SRFI-99 records