fix openpsi example error opencog#3032

examples/openpsi/basic.scm

@@ -14,9 +14,9 @@
 ; applicable, and the action is taken, then the goal is fulfilled.
 ;
 ; The context is meant to be one or more EvaluationLinks (or boolean
-; combinations thereof).  If these evaluate to true, then the action
+; combinations thereof).  If these evaluate to ture, then the action
 ; will be taken.  The action must also be of the form of a predicate,
-; (that is, myst be an EvaluationLink, or a boolean combination
+; (that is, myst be an EvaluationLink, or a b oolean combination
 ; thereof).  If the action also evaluates to true, then the goal is
 ; considered to be fulfilled.
 
@@ -42,20 +42,35 @@
 	(stv 0.1 1)
 )
 
-(define demand-foo (psi-demand "foo"))
-(define demand-bar (psi-demand "bar"))
+;(define demand-foo (psi-component "foo"))
+(define (demand-foo) (psi-component  "foo"))
+;(define demand-bar (psi-component "bar"))
+(define (demand-bar) (psi-component  "bar"))
+
+(define context-foo (list
+    (Evaluation 
+        (GroundedPredicate "scm: check-situation")
+        (List (Concept "foo"))
+    )
+))
+
+(define action-foo    (Evaluation 
+    (GroundedPredicate "scm: action-doit")
+    (List (Concept "foo-action"))
+))
+
+(define goal-foo   (Evaluation 
+    (GroundedPredicate "scm: goal-update")
+    (List (Concept "foo-goal"))
+))
 
 (Member
 	(psi-rule
-		(list
-			(Evaluation (GroundedPredicate "scm: check-situation")
-				(List (Concept "foo"))))
-		(Evaluation (GroundedPredicate "scm: action-doit")
-				(List (Concept "foo-action")))
-		(Evaluation (GroundedPredicate "scm: goal-update")
-				(List (Concept "foo-goal")))
+		context-foo
+		action-foo
+		goal-foo
 		(stv 0.9 1)
-		demand-foo
+		(demand-foo)
 	)
 	(Concept "demo rule")
 )
@@ -70,26 +85,22 @@
 		(Evaluation (GroundedPredicate "scm: goal-update")
 				(List (Concept "bar-goal")))
 		(stv 0.9 1)
-		demand-bar
+		(demand-bar)
 	)
 	(Concept "demo rule")
 )
 
 
-; Single-step the psi rule-selection engine `n` times.
+; Single-step the psi rule-selection engine.
 ; This will print a message, single-step the psi rule engine, and
 ; then sleep for three seconds.  The loop repeats until the loop count
 ; reaches zero.
 (define (step-psi n)
 	(display "\n=================== Stepping psi one step\n")
-	(psi-step-per-demand)
+	(psi-step (demand-foo))
+    (psi-step (demand-bar))
 	(sleep 3)
 	(if (< 0 n) (step-psi (- n 1))))
 
 (step-psi 4)
-(display "Done running psi")
-
-; Alternately, one can run the psi engine as fast as possible. This
-; is not recommended for this demo, because it will clog the output
-; with print statements.
-; (psi-run-per-demand)
+(display "Done running psi\n")