So I figured out how to fix this to do what I want. Basically, the
CallLambda Userfunction needs to check that the first argument is a
RU.BINDING in addtion to RU.LAMBDA. This this fix, things work as I
would like them to. Nice addition - and powerful, too.
public class CallLambda implements Userfunction {
private static final String NAME = "lcall";
/** Get the name of the Jess function.
* @see jess.Userfunction#getName()
*/
public String getName() {
return NAME;
}
/** Call the userfunction
* @see jess.Userfunction#call(jess.ValueVector, jess.Context)
*/
public Value call(ValueVector vv, Context context) throws
JessException {
int narg = vv.size() - 1;
// Check that we have at least one element.
if (narg < 1)
throw new JessException(NAME, "missing argument.", "");
// Evluate a variable or a function call.
Value valArg1 = vv.get(1);
if (valArg1.type() == RU.VARIABLE || valArg1.type() ==
RU.FUNCALL) {
valArg1 = valArg1.resolveValue(context);
}
// This must now be a lambda expression or a binding.
if (valArg1.type() != RU.LAMBDA && valArg1.type() !=
RU.BINDING) {
throw new JessException(
NAME,
"first argument is not a lambda
definition.",
Integer.toString(valArg1.type()));
}
// Get the function value,...
Deffunction d = (Deffunction) valArg1.functionValue(context);
// ...construct the argument list and...
ValueVector av = new ValueVector(narg);
av.add(d.getName());
for (int iArg = 2; iArg <= narg; iArg++) {
av.add(vv.get(iArg));
}
// ...call and return the result.
return d.call(av, context);
}
}
On Aug 14, 2008, at 9:04 AM, Hal Hildebrand wrote:
Have tried using the CallLambda Userfunction class from
http://herzberg.ca.sandia.gov/jesswiki/view?LambdaCallUserFunction
(load-function CallLambda)
(deftemplate functional-fact
(slot func)
)
(bind ?f (lambda (?x) (> 1 ?x)))
(assert (functional-fact (func ?f)))
(defrule test-me
(functional-fact (func ?f))
(test (lcall ?f 0))
=>
(printout t "1 > 0" crlf))
fails with:
Jess reported an error in routine lcall
while executing (lcall ?f 0)
while executing 'test' CE
while executing rule LHS (TECT).
Message: first argument is not a lambda definition. 4096.
Program text: ( defrule test-me ( functional-fact ( func ?f ) )
( test ( lcall ?f 0 ) ) = > ( printout t "1 > 0" crlf ) ) at line 17.
Seems as though nothing I can do with the slot value will turn it
into a function call.
On Aug 14, 2008, at 8:23 AM, Hal Hildebrand wrote:
I would like to have functions contained in the slot value of a
fact and then apply them. I can create and assign the function
values by using (lambda ...), which seems to be what I'm looking
for on that side of the equation:
(deftemplate functional-fact
(slot func)
)
(assert (functional-fact (func (lambda (?x) (> 1 ?x)))))
However, the question becomes how do I actually call this
function? What I would like to do is use these in test CE:
(deftemplate functional-fact
(slot func)
)
(assert (functional-fact (func (lambda (?x) (> 1 ?x)))))
(defrule test-me
(functional-fact (func ?function))
(test (?function 0))
=>
(printout t "1 > 0" crlf))
However, this does not work as I would expect instead failing with:
Jess reported an error in routine call
while executing (call ?function 0)
while executing 'test' CE
while executing rule LHS (TECT).
Message: No method named '0' found in class jess.Deffunction.
Program text: ( defrule test-me ( functional-fact ( func ?
function ) ) ( test ( ?function 0 ) ) = > ( printout t "1 > 0"
crlf ) ) at line 11.
Clearly, I'm not understanding this and would appreciate any help
from those on the list.
Thanks.
