include support for working_directory/2 as a system predicate.

docs/yap.tex

@@ -6895,6 +6895,13 @@ atoms.
 Execute a new shell.
 @end table
 
+@item working_directory(-@var{CurDir},?@var{NextDir})
+@findex  working_directory/2
+@syindex working_directory/2
+@cnindex working_directory/2    @c 
+Fetch the current directory at @var{CurDir}. If @var{NextDir} is bound
+to an atom, make its value the current working directory.
+
 @item alarm(+@var{Seconds},+@var{Callable},+@var{OldAlarm})
 @findex alarm/3
 @snindex alarm/3
@@ -11594,13 +11601,6 @@ The streams may be one of standard stream, @code{std}, null stream,
 @code{null}, or @code{pipe(S)}, where @var{S} is a pipe stream. Note
 that it is up to the user to close the pipe.
 
-@item working_directory(-@var{CurDir},?@var{NextDir})
-@findex  working_directory/2
-@syindex working_directory/2
-@cnindex working_directory/2    @c 
-Fetch the current directory at @var{CurDir}. If @var{NextDir} is bound
-to an atom, make its value the current working directory.
-
 @item popen(+@var{Command}, +@var{TYPE}, -@var{Stream})
 @findex  popen/3
 @syindex popen/3

library/system.yap

@@ -269,10 +269,6 @@ environ_split([61|SVal], [], SVal) :- !.
 environ_split([C|S],[C|SNa],SVal) :-
 	environ_split(S,SNa,SVal).
 
-working_directory(OLD, NEW) :-
-	getcwd(OLD),
-	cd(NEW).
-
 %
 % process execution
 %

packages/PLStream/pl-incl.h

@@ -862,7 +862,13 @@ typedef double			real;
 #define false(s, a)		(!true((s), (a)))
 #define set(s, a)		((s)->flags |= (a))
 #define clear(s, a)		((s)->flags &= ~(a))
+#ifdef  DEBUG
+/* should have messages here */
+#undef DEBUG
 #define DEBUG(LEVEL, COMMAND)
+#else
+#define DEBUG(LEVEL, COMMAND)
+#endif
 
 #define forwards static		/* forwards function declarations */
 

packages/PLStream/pl-yap.h

@@ -27,7 +27,7 @@
 typedef YAP_Term	        Module;
 typedef YAP_Term	       *Word;		/* Anonymous 4 byte object */
 typedef YAP_Atom		Atom;
-typedef YAP_Term		(*Func)();	/* foreign functions */
+typedef YAP_Term		(*Func)(term_t);	/* foreign functions */
 
 const char *Yap_GetCurrentPredName(void);
 YAP_Int     Yap_GetCurrentPredArity(void);

pl/utils.yap

@@ -247,6 +247,9 @@ pwd :-
 	getcwd(X),
 	write(X), nl.
 
+working_directory(OLD, NEW) :-
+	swi_working_directory(OLD, NEW).
+
 unix(V) :- var(V), !,
 	'$do_error'(instantiation_error,unix(V)).
 unix(argv(L)) :- '$is_list_of_atoms'(L,L), !, '$argv'(L).