From e6e7222d5a730368ed4e84c2e0f55427460e5230 Mon Sep 17 00:00:00 2001
From: Bradley Smith
Date: Mon, 21 Jan 2008 00:16:45 +0000
Subject: Imported GNU robots from CVS.

Signed-off-by: Bradley Smith <brad@brad-smith.co.uk>---
 scheme/greedy.scm | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 scheme/greedy.scm

(limited to 'scheme/greedy.scm')

diff --git a/scheme/greedy.scm b/scheme/greedy.scm
new file mode 100644
index 0000000..79a57f8
--- /dev/null
+++ b/scheme/greedy.scm
@@ -0,0 +1,112 @@
+;;;
+;;; Greedy robot for GNU Robots 0.77
+;;; 1998-08-15 by Kyle Hasselbacher <kyle@toehold.com>
+;;;
+
+;;; Greedy Robot wanders around looking for food and valuable prizes.
+;;; The definitions for thing-one and thing-two determine which it thinks
+;;; is more important (thing-one is).
+;;; It's not always very efficient in its gathering and can easily walk in
+;;; a circle if it can't see anything worth grabbing.  It also assumes that
+;;; there is nothing interesting behind it, and that's not always true.
+;;; It treats baddies and walls the same way in that they are not
+;;; food, prizes, or open space.  It just avoids running into them.
+
+(define thing-one "food")
+(define thing-two "prize")
+
+;;; If something interesting has been spotted, in-sights holds the name
+;;; of the thing we're headed for.  Once it's grabbed, we set! in-sights
+;;; back to #f.  Using the variable saves us a little energy since we don't
+;;; have to keep looking at the same thing over and over.
+(define in-sights #f)
+
+;;; grab a single prize (and move onto the space that had it)
+(define (grab)
+  (if (robot-grab)
+      (robot-move 1))
+  (set! in-sights #f))
+
+;;; Look around!
+(define (look-left-right thing)
+  (if (not (equal? in-sights thing))
+      (robot-turn 1))
+  (if (and (not (equal? in-sights thing)) (robot-look thing))
+      (set! in-sights thing))
+  (if (not (equal? in-sights thing))
+      (robot-turn 2))
+  (if (and (not (equal? in-sights thing)) (robot-look thing))
+      (set! in-sights thing)))
+
+(define (seek-thing thing)
+  (if (and (not (equal? in-sights thing)) (robot-look thing))
+      (set! in-sights thing))
+  (look-left-right thing)
+  (if (not (equal? in-sights thing))
+      (robot-turn 1))
+  (equal? in-sights thing))
+
+;;; Book it for a priority-one item.  We don't look around for anything
+;;; else, but we do sniff the air for items of the same type we might pass
+;;; on the way.
+(define (get-thing thing)
+  (if (robot-feel thing)
+      (grab)
+      (begin (smell-test thing)
+	     (if (robot-move 1)
+		 (get-thing thing)))))
+
+;;; This doesn't do any smelling.  It's called by smell-test when it thinks
+;;; there might be something to the left (it's already checked to the right).
+(define (smell-behind thing)
+  (robot-turn 2)
+  (if (robot-feel thing)
+      (robot-grab))
+  (robot-turn 1))
+
+;;; This feels to the right and left if it smells the thing its asked about.
+;;; Do the smell test after (robot-feel thing) fails.
+;;; Otherwise you spin around from smelling what's in front of you.
+;;; smell-test does a lot of turning but leaves you facing the same way.
+(define (smell-test thing)
+  (if (robot-smell thing)
+      (begin
+	(robot-turn 1)
+	(if (robot-feel thing)
+	    (begin
+	      (robot-grab)
+	      (if (robot-smell thing)
+		  (smell-behind thing)
+		  (robot-turn -1)))
+	    (smell-behind thing)))))
+
+;;; The drunkard's walk isn't too drunk.
+;;; Without obstructions, it only turns once in a while (1/10 steps).
+(define (drunkard-walk)
+  (if (and (not (= (random 10) 0)) (robot-feel "space"))
+      (robot-move 1)
+      (begin (robot-turn (+ 1 (random 2))) (drunkard-walk))))
+
+;;; The main loop!  We go for our thing-one if we can see it.  If we can see
+;;; thing-two, we go for that while checking for thing-one.  If we can see
+;;; neither, we drunkards-walk one step.
+(define (main-loop)
+  (cond ((seek-thing thing-one)
+	 (get-thing thing-one)
+	 (set! in-sights #f))
+
+	((seek-thing thing-two) 
+	 (if (robot-feel thing-two)
+	     (grab)
+	     (begin
+	       (smell-test thing-two)
+	       (robot-move 1))))
+
+	(#t (drunkard-walk)))
+  (main-loop))
+
+;;; Be random
+;(randomize)
+
+;;; Go to it.
+(main-loop)
-- 
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