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doc/llogo/demos.germ

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+
+
+GOBBLE 
+THE PURPOSE IN LIFE OF THE SIMPLEST GERMS IS JUST TO EAT. 
+WE SHALL CALL THIS SPECIES THE "GOBBLERS" .  EACH SQUARE IN GERMLAND
+INITIALLY IS VERDANT WITH FOOD.  BUT WHEN A GOBBLER ARRIVES, ALL OF
+THE FOOD ON THE SQUARE IS EATEN.  THE RESULT IS A BARREN
+SQUARE AND THE EATER IS FORCED TO MOVE ON.  THE GOAL OF PROGRAMS FOR
+GOBBLERS IS TO KEEP THEM MOVING AS LONG AS THERE IS ANY FOOD LEFT IN
+GERMLAND.  THE BASIC PROBLEM GOBBLERS FACE IS GETTING TRAPPED IN A
+REGION OF NO FOOD.
+
+HERE IS A LISTING OF A SIMPLE GOBBLER PROGRAM:
+
+	    TO GOBBLE
+	    10 EAT FOOD HERE
+	    20 IF FOODP NORTH THEN MOVE NORTH STOP
+	    30 IF FOODP SOUTH THEN MOVE SOUTH STOP
+	    40 IF FOODP EAST THEN MOVE EAST STOP
+	    50 IF FOODP WEST THEN MOVE WEST STOP
+	    END
+
+
+(DEFUN GOBBLE NIL 
+       (PROG NIL 
+	10.  (EAT (FOOD (HERE)))
+	20.  (COND ((FOODP (NORTH)) (MOVE (NORTH)) (STOP)))
+	30.  (COND ((FOODP (SOUTH)) (MOVE (SOUTH)) (STOP)))
+	40.  (COND ((FOODP (EAST)) (MOVE (EAST)) (STOP)))
+	50.  (COND ((FOODP (WEST)) (MOVE (WEST)) (STOP)))
+	     (END))) 
+(PRINC REPEAT-INTRO)
+
+(UNITE 'GOBBLE ':CONTENTS)
+
+(GRID 5.) 
+
+(SETQ :HUNGRY T) 
+
+(GERM 1.  '(0. 0.)) 
+
+(FILLFOOD 1.) 
+
+(READCH) 
+
+(PRINTGRID)
+(REPEAT (GOBBLE)) 
+
+NIL 
+FANCY/ GOBBLER 
+HERE IS A SIMILAR, BUT SOMEWHAT FANCIER
+GOBBLER. IT USES THE DIRECTIONAL PRIMITIVES, AND GOES AROUND
+THE GRID, RATHER THAN UP AND DOWN. IT LOOKS LIKE THIS:
+
+
+TO XGOBBLE
+10 LOCAL 'X
+20 MAKE 'X  0
+25 EAT FOOD HERE
+30 IF FOODP FRONT THEN MOVE FRONT STOP
+40 MAKE 'X  :X + 1 IF :X = 4 THEN STOP
+50 RIGHT 90 GO 30
+END
+
+
+
+
+
+(DEFUN XGOBBLE NIL 
+       (PROG (:X) 
+	10.  (LOCAL 'X)
+	20.  (MAKE 'X 0.)
+	25.  (EAT (FOOD (HERE)))
+	30.  (COND ((FOODP (FRONT)) (MOVE (FRONT)) (STOP)))
+	40.  (MAKE 'X (INFIX-PLUS :X 1.))
+	     (COND ((INFIX-EQUAL :X 4.) (STOP)))
+	50.  (RIGHT 90.)
+	     (GO 30.)
+	     (END))) 
+(UNITE 'XGOBBLE ':CONTENTS)
+
+(PRINC REPEAT-INTRO) 
+(GRID 5.) 
+
+(SETQ :HUNGRY T) 
+
+(GERM 1.  '(0. 0.)) 
+
+(FILLFOOD 1.) 
+
+(READCH) 
+
+(PRINTGRID)
+(REPEAT (XGOBBLE)) 
+
+NIL 
+ 
+
+GOAROUND 
+THE GERMLAND GRID MAY CONTAIN OBSTACLES, WHICH
+PRINT AS X'S. A GERM CANNOT MOVE ONTO A SQUARE
+WHICH IS AN OBSTACLE, BUT IT CAN DETECT WHETHER
+THE SQUARE ON ANY PARTICULAR SIDE OF IT CONTAINS
+AN OBSTACLE. THE FOLLOWING PROGRAM DEMONSTRATES THE
+USE OF OBSTACLES: THIS GERM EXPECTS TO START OUT
+NEXT TO A COLLECTION OF OBSTACLES, WHICH IT PROCEEDS
+TO GOAROUND.
+
+TO GOAROUND
+10 TEST TOUCH LEFTSIDE
+20 IFTRUE IF TOUCH FRONT THEN RIGHT 90 GO 20
+30 IFTRUE FORWARD 1 STOP
+40 RIGHT 270 FORWARD 1
+END
+
+
+(DEFUN GOAROUND NIL 
+       (PROG NIL 
+	10.  (TEST (TOUCH (LEFTSIDE)))
+	20.  (IFTRUE (COND ((TOUCH (FRONT)) (RIGHT 90.) (GO 20.))))
+	30.  (IFTRUE (FORWARD 1.) (STOP))
+	40.  (RIGHT 270.)
+	     (FORWARD 1.)
+	     (END))) 
+(UNITE 'GOAROUND ':CONTENTS)
+(PRINC REPEAT-INTRO) 
+(GRID 5.) 
+
+(SETQ :HUNGRY NIL) 
+
+(GERM 1.  '(4. 1.)) 
+
+(MAPC 'OBSTRUCT
+      '((1. 1.) (1. 2.) (2. 2.) (2. 3.) (3. 1.) (3. 2.))) 
+
+(READCH) 
+
+(PRINTGRID)
+(REPEAT (GOAROUND)) 
+
+NIL 
+
+NIL 
+
+