The language definition process first began in a meeting in 1985 in Paris and took several years. The complete specification and a first implementation (interpreted-only) were made available in 1990.
Its main traits are that it is a Lisp-1 (no separate function and variable namespaces), has a Common Lisp Object System (CLOS) style generic-function type object-oriented system named The EuLisp Object System (TELOS) integrated from the ground up, has a built-in module system, and is defined in layers to promote the use of the Lisp on small, embedded hardware and educational machines. It supports continuations, though not as powerfully as Scheme. It has a simple lightweight process mechanism (threads).
Summary
A definition in levels, currently Level-0 and Level-1
An early implementation of EuLisp was Free and Eventually Eulisp (FEEL). The successor to FEEL was Youtoo (interpreted and compiled versions), by University of Bath in the United Kingdom.[3] An interpreter for the basic level of EuLisp, level-0, was written by Russell Bradford in XScheme, an implementation of Scheme by David Michael Betz, originally named EuScheme EuScheme but the most recent version is renamed EuXLisp [1] to avoid confusion. Also Eu2C [2], a EuLisp optimizing compiler, was created by Fraunhofer ISST under the APPLY project in Germany [3].
A dialect of EuLisp was developed, named Plural EuLisp. It was EuLisp with parallel computing programming extensions.
Example
Example use of classes in the algorithm to solve the "Towers of Hanoi" problem.
(defmodulehanoi(syntax(syntax-0)import(level-0)export(hanoi));;;-------------------------------------------------;;; Tower definition;;;-------------------------------------------------(defconstant*max-tower-height*10)(defclass<tower>()((idreader:tower-idkeyword:id:)(blocksaccessor:tower-blocks)))(defunbuild-tower(xn)(labels((loop(ires)(if(=i0)res(loop(-i1)(consires)))))((settertower-blocks)x(loopn()))x))(defmethodgeneric-print((x<tower>)(s<stream>))(sformats"#<tower ~a: ~a>"(tower-idx)(tower-blocksx)));;;-------------------------------------------------;;; Access to tower blocks;;;-------------------------------------------------(defgenericpush(xy))(defmethodpush((x<tower>)(y<fpi>))(let((blocks(tower-blocksx)))(if(or(null?blocks)(<y(carblocks)))((settertower-blocks)x(consyblocks))(error<condition>(fmt"cannot push block of size ~a on tower ~a"yx)))))(defgenericpop(x))(defmethodpop((x<tower>))(let((blocks(tower-blocksx)))(ifblocks(progn((settertower-blocks)x(cdrblocks))(carblocks))(error<condition>(fmt"cannot pop block from empty tower ~a"x)))));;;-------------------------------------------------;;; Move n blocks from tower x1 to tower x2 using x3 as buffer;;;-------------------------------------------------(defgenericmove(nx1x2x3))(defmethodmove((n<fpi>)(x1<tower>)(x2<tower>)(x3<tower>))(if(=n1)(progn(pushx2(popx1))(printx1nlx2nlx3nlnl))(progn(move(-n1)x1x3x2)(move1x1x2x3)(move(-n1)x3x2x1))));;;-------------------------------------------------;;; Initialize and run the 'Towers of Hanoi';;;-------------------------------------------------(defunhanoi()(let((x1(make<tower>id:0))(x2(make<tower>id:1))(x3(make<tower>id:2)))(build-towerx1*max-tower-height*)(build-towerx20)(build-towerx30)(printx1nlx2nlx3nlnl)(move*max-tower-height*x1x2x3)))(hanoi);;;-------------------------------------------------);; End of module hanoi;;;-------------------------------------------------
References
^"Eulisp"(PDF). GitHub. Archived from the original(PDF) on 2012-03-06. Retrieved 2017-09-20.
^Kind, Andreas. "Youtoo". School of Mathematical Sciences. University of Bath. England. Retrieved 2018-10-28.
"An Overview of EuLisp", Julian Padget, Greg Nuyens, and Harry Bretthauer, editors. LISP and Symbolic Computation, Volume 6, Number 1-2, 1993, pages 9–98.
"Balancing the EuLisp Metaobject Protocol", Harry Bretthauer, Jürgen Kopp, Harley Davis, and Keith Playford. LISP and Symbolic Computation, Volume 6, Issue 1–2, August 1993, pages 119–138.
"EuLisp in Education", R. Bradford and D.C. DeRoure. LISP and Symbolic Computation, Volume 6, Number 1-2, pages 99–118.
"Applications of Telos", Peter Broadbery, Christopher Burdorf. LISP and Symbolic Computation, Volume 6, Issue 1–2, August 1993, pages 139–158.
"EuLisp Threads: A Concurrency Toolbox", Neil Berrington, Peter Broadbery, David DeRoure, and Julian Padget. LISP and Symbolic Computation, Volume 6, Issue 1–2, August 1993, pages 177–200.