[eclipse-users] bug in lib(hash), compile_term/1 and/or handling of arguments

From: Stephan Schiffel <stephan.schiffel_at_...69...>
Date: Tue, 10 Jul 2007 19:29:00 +0200
Hello ECLiPSe users,

I ran into a problem with a project of mine and managed to reduce it to a 
fairly small program (see below). It just puts two values in a hash table, 
makes facts from the hash table and compiles the facts.
If the facts are then called with instantiated first argument (e.g., f([a],_)) 
they fail, but f(A,_),A=[a] succeeds.

Can anyone confirm this as a bug or am I doing something stupid here?

Best regards,
Stephan

===============
% the program:

:- lib(hash).

test :-
  make_facts(Facts),
  compile_term(Facts),
  testf([a]),
  testf([b]).

testf(Key) :-
  (f(Key, _) ->
    printf("f(%w, _) succeeds\n",[Key])
  ;
    printf("f(%w, _) fails\n",[Key]),
    (f(Key2, _), Key2=Key ->
      printf("  but f(Key2, _), Key2=%w succeeds!\n",[Key])
    ;
      true
    )
  ).

make_facts(Facts) :-
  % add two entries in a hash table
  hash_create(Hash),
  my_hash_set(Hash, p([a], 1)),   % line x
% hash_set(Hash, [a], 1),         % line y
  hash_set(Hash, [b], 1),

  hash_list(Hash, Keys, Values),
  (foreach(Key, Keys), foreach(Value, Values), foreach(Fact, Facts) do (
    Fact=f(Key, Value),
	writeq(Fact), writeln(".")
  )),
  nl.

my_hash_set(Hash1, p(X, Y)) :-
  hash_set(Hash1, X, Y).

% The expected output is
% f([a], 1).
% f([b], 1).
% f([a], _) succeeds
% f([b], _) succeeds

% The output I get:
% f([a], 1).
% f([b], 1).
% f([a], _) fails
%   but f(Key2, _), Key2=[a] succeeds!
% f([b], _) fails
%   but f(Key2, _), Key2=[b] succeeds!

% If "line x" is replaced by "line y" it works.
% If [a] and [b] are replaced by 'a' and 'b' 
%  respectively, it also works.

============
Received on Tue Jul 10 2007 - 18:29:16 CEST

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