algol 68 and grenoble influence laurent trilling, lab. timc-imag, u. joseph fourier, grenoble,...

ALGOL 68 and Grenoble influence

Laurent Trilling, lab. TIMC-IMAG, U. Joseph Fourier, Grenoble,

Soft-EU ConferenceJan. 24th, 2008

Grenoble

Cv and Algol 68as an example of the Grenoble influence…

64 - 67, Grenoble:

Algol X (66), study of the language, garbage collection, compiler

67- 70, Montréal:

Design of a tool coupling system and langage with J.P. Verjus (later SAR, Système Algol 68 de Rennes), study of input/output.

70 - 87 Rennes

Implementations (ALGOL 68 and SERA, a subset) with a new

compiling method (compiling by events), extensions (prolators),

documentation (participation to the writing of a manual and a

primer), teaching (with SERA as a first language, ALGOL 68 with

the SAR compiler, later with the RRE implementation on

MULTICS)

77 - 78, Montréal

Teaching with the CDC compiler.

About Grenoble and ALGOL 68

Pionners in France (Louis Bolliet, Jean-Claude Boussard).

Study of the language (syntax, semantics, extension) and documentation: cooperation with Paris, Nancy, Paris, Rennes (same origin), Nice (same origin)

Implementation : main spot in France (with Rennes)

Teaching: Grenoble (grad. students), Nancy (id.), Paris-Nord(as a first language with SERA), Rennes(underg. students until 86-87)

About Grenoble and influence of ALGOL 68

What remains ?

Many, many papers and thesis…, also the use of terms like « orthogonality » or « coercions »…

Influences in compiling courses (Grenoble, Rennes).

Design and use of Prolog and derivatives by Alain Colmerauer (same origin, then Montréal and later Marseilles).

Why such an (apparent) failure ?« The minority Report »(1)

This term (failure) is used in this report, written by well-known scientists (Dijkstra,

Hoare, Randell…). It now can be criticized too. Two points are mentioned:

1. A very clear critics of the specification (W-grammars). These people could not

accept that «every word and every symbol matters ». Where were they ?

A personal anecdote which came again to my mind where at Santa Theresa where

IBM-type specification were presented. A very strange sentence had been

produced automatically by B. Houssais as a test from the W-grammar:

a of begin mode m = struct (int a, b), m x = …;…;x) end

Does it belong to the language ? Answer given in 0h. 30 (J.P. Banatre and I) by

consulting the Algol 68 Report.

Why such an (apparent) failure ?« The minority Report »(2)

2. A very confused attack on the language itself. May be on

its « complexity » due to the orthogonal design ?

Another anecdote. Simula 68 and the impossibility to

« compose » class and procedures as parameters (it is still

the case for JAVA).

Also orthogonal design leads naturally to fundamental

challenges, like infinite trees (see Prolog II) :

mode m = struct(int a, m b); m x = (1, x); ….

Correspondance with B. Mailloux in 1966.

Why such an (apparent) failure ?« Practical » reasons

Too few implementations which were produced too late, when people were « tired ». But around 1975 it was possible for main Universities to get good implementations (last revision was in 1973).

No industrial support. What would have happened if IBM has supported Algol 68 (as SUN for JAVA) ?

On the contrary, a very strong counter-publicity by well-known scientists !

Why such an (apparent) failure Real reasons

At least in Universities. Professors were not really conscious (are they

now ?) of the role that they are supposed to play (see La trahison des

clercs, Julien Benda, 1927), Grasset, ppalpant@uqac.ca ). The

« clerks » have to say the « truth » in their domain (judges for law, priests

for religion, …) by resisting if necessary to undue pressures. In our case:

- (mental) pressure of « industry ». Still well alive. See what languages

are used as a first language in Universities.

- pressure due to the time. A clerk must decided quietly.

- pressure due to the environment and specially to publicity and counter-

publicity.

A last point

As Algol 68 was produced by an international group, it was

difficult to introduce into it new basic constructions.

Certainly, some people could be disappointed.

But it was left to another steps. For example, SAR contained

the basic construction necessary to manipulate objects as in

SIMULA

A last last pointA recommendation.

Do like SIMULA has done with Algol 60 (and we with

Algol 68): include clearly the culture from which you are

second, do not digest it (see Europe, la voie romaine,

Rémi Brague, 1999, Gallimard).

Also, keep in touch with your students. If I knew the

reaction of P. Besnard to the teaching of SERA in 1975,

may be I would have fought better !