Minor cleanup.

Author: RuedigerLunde

aima-core/src/main/java/aima/core/agent/AgentProgram.java

@@ -1,6 +1,7 @@
 package aima.core.agent;
 
 import java.util.Optional;
+import java.util.function.Function;
 
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): pg 35.<br>
@@ -13,14 +14,15 @@
  * @author Ravi Mohan
  * @author Ciaran O'Reilly
  */
-public interface AgentProgram<P, A> {
+public interface AgentProgram<P, A> extends Function<P, Optional<A>> {
 	/**
 	 * The Agent's program, which maps any given percept sequences to an action.
 	 * 
 	 * @param percept
 	 *            The current percept of a sequence perceived by the Agent.
 	 * @return the Action to be taken in response to the currently perceived
-	 *         percept. No action replaces NoOp in earlier implementations.
+	 *         percept. Empty replaces NoOp in earlier implementations.
 	 */
+	@Override
 	Optional<A> apply(P percept);
 }

aima-core/src/main/java/aima/core/environment/vacuum/VacuumPercept.java

@@ -45,11 +45,11 @@ public void setAttribute(String key, Object value) {
 	@Override
 	public String toString() {
 		StringBuilder result = new StringBuilder();
-		result.append("[ currLocation=").append(getCurrLocation()).append(" currState=").append(getCurrState());
+		result.append("[currLocation=").append(getCurrLocation()).append(", currState=").append(getCurrState());
 		if (!dynAttributes.isEmpty())
 			for (Map.Entry<String, Object> e : dynAttributes.entrySet())
-				result.append(" ").append(e.getKey()).append("=").append(e.getValue());
-		result.append(" ]");
+				result.append(", ").append(e.getKey()).append("=").append(e.getValue());
+		result.append("]");
 		return result.toString();
 	}