% ---------------------------------------------------------------------- % System: ECLiPSe Constraint Logic Programming System % Copyright (C) Imperial College London and ICL 1995-1999 % Version: $Id: cprolog.pl,v 1.13 2004/11/17 15:19:21 js10 Exp $ % ---------------------------------------------------------------------- /* * SEPIA PROLOG SOURCE MODULE */ /* * sccsid("%W% %E%"). * sccscr("%Z% Copyright 1989 ECRC GmbH "). */ /* * IDENTIFICATION: cprolog.pl * * DESCRIPTION: C-Prolog compatibility package. * This is also the basis for the * Quintus and SICStus packages. * * CONTENTS: * */ :- module(cprolog). :- comment(summary, 'C-Prolog compatibility package'). :- comment(author, 'Various, ECRC Munich'). :- comment(copyright, 'Imperial College London and ICL'). :- comment(date, '$Date: 2004/11/17 15:19:21 $'). :- comment(desc, html(' One of the requirements during the development of ECLiPSe has been the aim of minimising the work required to port traditional Prolog programs to ECLiPSe. A de-facto standard for many years was the C-Prolog dialect, often referred to as Edinburgh Prolog. Therefore, many of the non standard predicates in C-Prolog have also been included in ECLiPSe. It is of course impossible to achieve total compatibility between the two systems. To assist in making the changes necessary to run a C-Prolog program on the current version of ECLiPSe, we describve here the predicates available in the C-Prolog compatibility library and summarise the principal differences between ECLiPSe Prolog and C-Prolog.

Most of the C-Prolog predicates are also ECLiPSe built-in predicates and so they can be always accessed.

Please note that this text does not detail the functionality of C-Prolog, refer to the C-Prolog documentation for this information.

The effect of the compatibility library is local to the module where it is loaded. For maximum compatibility, a C-Prolog program should be wrapped in a separate module starting with a directive like 

    :- module(mymodule, [], cprolog).
In this case, Eclipse-specific language constructs will not be available.

If the compatibility package is loaded into a standard module, e.g. like 

    :- module(mymixedmdule).
    :- use_module(library(cprolog)).
then C-Prolog and Eclipse language features can be used together. However, ambiguities must be resolved explicitly and confusion may arise from the different meaning of quotes in Eclipse vs C-Prolog.

Note that the C-Prolog compatibility package includes the cio (for see/1, seeing/1, seen/0, skip/1, tab/1, tell/1, telling/1, told/0) and the scattered library.

The following C-Prolog predicates are not available in ECLiPSe, or the corresponding predicates have a different semantics:

assert/2, asserta/2, assertz/2, clause/3
ECLiPSe does not support database references for clauses.
expand_term/2
This is not supported. ECLiPSe provides the macro facility for transforming input terms (see chapter 13).
'LC'/0, 'NOLC'/0
These are not supported in ECLiPSe.

The following differences remain even with the compatibility package:

Database References
ECLiPSe provides database references only for terms in the indexed database, not for program clauses.
Numbers
C-Prolog has a tendency to "prefer" integers over real numbers. For instance, under C-Prolog when the call X is 4.0/2.0 is made, X is instantiated to an integer. This behaviour does not occur in ECLiPSe. The order of integers and reals in the standard order is different.
Operators
In C-Prolog there is a bug regarding the operator not -- it binds closer than its precedence declaration.
Strings
Strings are simulated in C-Prolog by lists. Under C-Prolog mode, ECLiPSe provides this functionality -- double-quoted strings are parsed as lists of integers. This can cause confusion when pure ECLiPSe predicates are used in C-Prolog mode, e.g. substring/3 will not accept double-quoted items, since they are lists, not ECLiPSe strings. The built-in string_list/2 converts between both representations.
consult/1, reconsult/1
These are implemented by simply calling the ECLiPSe predicate compile/1. By default all compiled procedures are static. Procedures on which assert/1 etc. will be applied, have to be declared as dynamic using dynamic/1. The notation [-File] for reconsult/1 is not supported.
get/1
This is similar to the ECLiPSe predicate get/1, but control characters and blank spaces are skipped.
put/1
This is similar to the ECLiPSe predicate put/1, but it first applies arithmetic evaluation to its argument.
heapused/1
Needed for evaluating heapused in arithmetic expressions. It returns the sum of code heap and general heap usage.
instance/2
Note that this compatibility predicate redefines the ECLiPSe builtin of the same name but different meaning (which is no longer available in C-Prolog mode). It is implemented using the ECLiPSe predicate referenced_record/2.
log/2, log10/2
These are not predicates in C-Prolog (arithmetic functors), but in ECLiPSe they are needed for evaluating log/1 and log10/1 in arithmetic expressions.
ttyput/1
corresponds to the DEC-10 Prolog predicate
The list below describes the syntax differences between ECLiPSe and C-Prolog. The following C-Prolog properties are simulated by the compatibility package: The following properties of original C-Prolog are not simulated by the compatibility package: ')). :- reexport cio. :- reexport eclipse_language except get/1, % redefined predicates put/1, instance/2, (abolish)/1, % op(_, xfx, (of)), % don't provide these % op(_, xfx, (with)), % op(_, xfy, (do)), % op(_, xfx, (@)), % op(_, fx, (-?->)), % macro((with)/2, _, _), % macro((of)/2, _, _), macro((if)/2,_,_). :- export % temporary, while op/macros still global op(0, xfx, (of)), op(0, xfx, (with)), op(0, xfy, (do)), op(0, xfx, (@)), op(0, fx, (-?->)), macro((with)/2, (=)/2, []), macro((of)/2, (=)/2, []). :- export syntax_option(nl_in_quotes), syntax_option(no_blanks), syntax_option(no_array_subscripts), syntax_option(limit_arg_precedence), syntax_option(doubled_quote_is_quote), syntax_option(bar_is_no_atom), syntax_option(no_attributes), syntax_option(no_curly_arguments), syntax_option(blanks_after_sign), chtab(0'$, lower_case), chtab(0'\, symbol), % disable escape sequences chtab(128, string_quote), % there must be some string_quote chtab(0'", list_quote), op(500, fx, (\)), op(900, fy, (spy)), op(900, fy, (nospy)). :- export (.)/3, % to evaluate lists in arithmetic expressions (abolish)/2, assertz/1, consult/1, current_functor/2, current_predicate/2, db_reference/1, erased/1, fileerrors/0, get/1, get0/1, heapused/1, instance/2, leash/1, log10/2, log/2, nofileerrors/0, primitive/1, prompt/2, put/1, reconsult/1, sh/0. :- skipped (abolish)/2, assertz/1, consult/1, current_functor/2, erased/1, fileerrors/0, get/1, get0/1, instance/2, log10/2, nofileerrors/0, primitive/1, prompt/2, put/1, reconsult/1. :- import assert_/2, current_predicate_body / 2, error_handler / 2, get_flag_body/4, set_default_error_handler/2, system_error_handler / 4, undef_dynamic_handler / 3 from sepia_kernel. :- use_module(library(scattered)). % handler settings only :- system. % compiler directive to add the SYSTEM flag /* * OTHER DIRECTIVES */ :- tool(assertz/1, assert_/2), tool((abolish)/2, abolish_body/3), tool(consult/1, compile/2), tool(reconsult/1, compile/2), tool(current_predicate/2, current_predicate_body/3). %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % EVENT HANDLERS % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% cp_inst_fault(_, arg(N, _, _)) :- integer(N), !, fail. cp_inst_fault(_, functor(_, _, _)) :- !, fail. cp_inst_fault(X, Y):- error_handler(X,Y). cp_range_error(_, arg(_, _, _)) :- !, fail. cp_range_error(X, Y) :- error_handler(X, Y). cp_type_error(_, arg(_, _, _)) :- !, fail. cp_type_error(X, Y) :- error_handler(X, Y). % This simulates Quintus' behaviour cp_undef_dynamic_handler(_, retract_all(_), _) :- !. cp_undef_dynamic_handler(_, listing(_), _) :- !. cp_undef_dynamic_handler(_, retract(_), _) :- !, fail. cp_undef_dynamic_handler(_, clause(_), _) :- !, fail. cp_undef_dynamic_handler(_, clause(_, _), _) :- !, fail. cp_undef_dynamic_handler(E, G, M) :- undef_dynamic_handler(E, G, M). cp_access_undefined(_, abolish(_)) :- !. cp_access_undefined(X,Y) :- error_handler(X,Y). nofileerrors_handler(_, open(_, _, _), _, _) :- !, fail. nofileerrors_handler(N, Goal, CM, LM) :- system_error_handler(N, Goal, CM, LM). fileerrors :- set_default_error_handler(170, system_error_handler/4), set_default_error_handler(171, error_handler/2), reset_event_handler(170), reset_event_handler(171). nofileerrors :- set_default_error_handler(170, nofileerrors_handler/4), set_default_error_handler(171, fail/0), reset_event_handler(170), reset_event_handler(171). :- % we may change the default handlers, because we can't switch back set_default_error_handler(4, cp_inst_fault/2), reset_event_handler(4), set_default_error_handler(5, cp_type_error/2), reset_event_handler(5), set_default_error_handler(6, cp_range_error/2), reset_event_handler(6), set_default_error_handler(60, cp_access_undefined/2), reset_event_handler(60), set_default_error_handler(70, cp_undef_dynamic_handler/3), reset_event_handler(70), set_default_error_handler(100, cp_undef_dynamic_handler/3), reset_event_handler(100). %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % NEW PREDICATES % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% sh :- getenv('SHELL', X), sh(X). primitive(X) :- atomic(X), fail_if(atom(X)). db_reference(X) :- type_of(X, db_reference). get0(X):- get(input, X). leash(Ports) :- set_leash(_, print), set_leash(Ports, stop). heapused(X) :- X is statistics(general_heap_used) + statistics(code_heap_used). prompt(Old, New) :- get_prompt(input, Old, Out), set_prompt(input, New, Out). ttyput(Char) :- N is Char, put(stdout, N). current_functor(F, T) :- current_functor(F/A), functor(T, F, A). abolish_body(N, A, M) :- @(:(sepia_kernel,abolish(N/A)),M). erased(Ref) :- fail_if(referenced_record(Ref, _)). % ARITHMETIC log10(Y,X):- X is ln(Y)/ln(10.0). log(Y,X) :- X is ln(Y). .(X,_,X). %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % REDEFINED PREDICATES % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% get(X):- repeat, get(input, X), X > 32, X < 127, !. put(X):- N is X, put(output,N). instance(Ref, Term) :- referenced_record(Ref, Term). current_predicate_body(F, T, M) :- current_predicate_body(F/A, M), functor(T, F, A), get_flag_body(F/A, definition_module, M, M).