[eclipse-clp-users] Questions about ECR

Hello Kish and all,

I have some questions and comments regarding the ECH library.

- The chr/1 predicate allows to clear out old CHR code before compiling new
  ones.  In ECH, this predicate looks really awkward because the argument
  has to be a file and is not really used.  In particular, the file is not
  compiled as in CHR.  I'd be happy if a new version of the library could
  provide a more intuitive predicate.

- Another question about chr/1 and ECH: Some time ago, this list gave me the
  following advice on how to remove old ECLiPSe code.  At those times, I did
  not use CHR or ECH.

    % [...] turn your file into a module, i.e., add a :- module(mymodule).
    % directive to it.  Then the module will be automatically erased before
    % every recompilation.  If you don't want to bother learning about
    % modules, you can choose 'eclipse' as the module name, then you should
    % see no further difference in behaviour.

  That trick doesn't seem to work in combination with chr/1 in ECH: There is
  an error on compiling the second time, see below.  So, what is the best
  way to erase the old clauses and to erase the CHR store?

Thank you,

Ulrich



test.ecl:
--
:- module(eclipse).

:- lib(ech).

% to clean out the constraint store
%
:- chr(empty).

:- handler typemodule.

% CHR constraints
:- constraints typeSameset/2.
--

empty.ecl

This is an empty file, i.e., a file with zero bytes length.



[scholzuh_at_...161...:ECH] >eclipse
ECLiPSe Constraint Logic Programming System [kernel]
Kernel and basic libraries copyright Cisco Systems, Inc.
and subject to the Cisco-style Mozilla Public Licence 1.1
(see legal/cmpl.txt or www.eclipse-clp.org/licence)
Source available at www.sourceforge.org/projects/eclipse-clp
GMP library copyright Free Software Foundation, see legal/lgpl.txt
For other libraries see their individual copyright notices
Version 6.0 #42 (i386_linux), Wed Sep 24 01:37 2008
[eclipse 1]: [test].
source_processor.eco loaded in 0.01 seconds
hash.eco   loaded in 0.00 seconds
compiler_common.eco loaded in 0.03 seconds
compiler_normalise.eco loaded in 0.02 seconds
compiler_map.eco loaded in 0.01 seconds
compiler_analysis.eco loaded in 0.02 seconds
compiler_peephole.eco loaded in 0.03 seconds
compiler_codegen.eco loaded in 0.04 seconds
compiler_varclass.eco loaded in 0.02 seconds
compiler_indexing.eco loaded in 0.01 seconds
compiler_regassign.eco loaded in 0.02 seconds
asm.eco    loaded in 0.05 seconds
module_options.eco loaded in 0.00 seconds
ecl_compiler.eco loaded in 0.28 seconds
lists.eco  loaded in 0.01 seconds
numbervars.eco loaded in 0.01 seconds
ech.eco    loaded in 0.07 seconds
empty.ecl  compiled 0 bytes in 0.00 seconds
Found CHR typeSameset/2 in module eclipse, generating transformed code
test.ecl   compiled 0 bytes in 0.09 seconds

Yes (0.38s cpu)
[eclipse 2]: -1.
[test].
record does not exist in abolish_record_body('CHRcode', eclipse)
ERROR: test.ecl:3:
  Query exited (abort): :- chr(empty)
Error(s) occurred while compiling /home/scholzuh/Forschung/Invarianten/ECH/test.ecl
Aborting execution ...
Abort
[eclipse 3]: