🚀 go-pugleaf

>There is a paper by Hansson, Haridi, and Tarnlund (all from Sweden)
>called ``Properties of a Logic Programming Language''.  They refer to
>a C implementation, but don't offer a name for their language.  
>
>Any pointers to the implementation?


The C-implementation in progress of LPL mentioned in the book seems to
be an early PDP-11 version of what later came to be the "pure" logic
programming language named LPL0 with a notion of handling first order
functions, co-written for unix-vaxen by Seif Haridi and Dan Sahlin.

Many of the language properties stated in the book, were not
implemented, but the ideas occur in later projects like the recent
attempts by Dan Sahlin to build a logic programming language based on
Sequent Calculus as a metainterpreter in SICStus Prolog.  Refer to
dan@sics.se or seif@sics.se for further references about that work.

There are some reports including Haridi's thesis from 1981 giving
some background material fyi. Whether Taernlund and Hansson pursued
the work in some other direction or went to work on other problems
I cannot tell. 

The recent works on the ANDORRA language are perhaps of interest here.
In one of its instances it is being implemented by Haridi as a
metainterpreter and compiler to SICStus prolog and contains
interesting and novel ideas about the computation rule. This language
is being developed jointly with David Warren's group in Bristol including
Rong Yang whose thesis contained some initial ideas, there named P-Prolog.

My conclusion would be that LPL had a fate similar to that of IC-prolog.
Nice ideas but not very efficiently implemented, yet. 

Refs:
[HaBr]	Seif Haridi and Per Brand,
	ANDORRA Prolog - An Integration of Prolog and Committed Choice
	Languages.
	In "Proc. Int. Conf. on 5th gen. Computer Systems 1988" p. 745
	[ACM and IEEE sponsored, ICOT hosted]

(more historical stuff)

[HaHaTa] Aake Hansson, Seif Haridi and Sten-Aake Taernlund
	Language Features of LPL, A Logic Programming Language.
	CSALAB TTDS/KTH Stockholm 1981 
	TRITA-CS-8103

[Ha81]	Seif Haridi,
	Logic Programming Based on A Natural Deduction System.
	Ph.D. thesis, 
	CSALAB TTDS/KTH Stockholm 1981 
	TRITA-CS-8104

[HaSa]	Seif Haridi & Dan Sahlin
	An Abstract Machine for LPL0.
	Report, CSALAB TTDS/KTH Stockholm 1984

[Sj1]	Thomas Sjoeland
	Transforming LPL0-programs using LPL0.
	Report, CSALAB TTDS/KTH Stockholm 1984
	TRITA-CS-8405

[Sj2]	Thomas Sjoeland
	Logic Programming with LPL0 - An Introduction.
	Report, CSALAB TTDS/KTH Stockholm 1984
	TRITA-CS-8404

The TRITA reports about LPL0 including Haridi's thesis could be ordered from:

	The Royal Institute of Technology
	Dept. of Telecommunication Systems - Computer Systems
	S-100 44 Stockholm, Sweden

--
Thomas Sj|land
SICS, PO Box 1263, S-164 28 KISTA, SWEDEN
Tel: +46 8 752 15 42	Ttx: 812 61 54 SICS S	Fax: +46 8 751 72 30
Internet: alf@sics.se or {mcvax,munnari,ukc,unido}!enea!sics.se!alf