Minor changes

project.clj

@@ -1,5 +1,5 @@
 (defproject mw-engine "0.1.0-SNAPSHOT"
-  :description "FIXME: write description"
+  :description "Cellular automaton world builder."
   :url "http://example.com/FIXME"
   :license {:name "Eclipse Public License"
             :url "http://www.eclipse.org/legal/epl-v10.html"}

src/mw_engine/core.clj

@@ -1,5 +1,6 @@
 (ns mw-engine.core
-  (:use mw-engine.world
+  (:require mw-engine.world
+        mw-engine.natural-rules
         mw-engine.utils))
 
 ;; every rule is a function of two arguments, a cell and a world. If the rule
@@ -8,60 +9,6 @@
 ;;
 ;; Rules are applied in turn until one matches.
 
-
-(def treeline 10)
-
-(def natural-rules
-  (list 
-    ;; Randomly, birds plant tree seeds into pasture.
-    (fn [cell world] (cond (and (= (:state cell) :pasture)(< (rand 10) 1))(merge cell {:state :scrub})))
-    ;; Scrub below the treeline grows gradually into forest
-    (fn [cell world] 
-      (cond (and 
-              (= (:state cell) :scrub)
-              (< (:altitude cell) treeline)) 
-        (merge cell {:state :scrub2})))
-    (fn [cell world] (cond (= (:state cell) :scrub2) (merge cell {:state :forest})))
-    ;; Forest on fertile land at low altitude grows to climax
-    (fn [cell world] 
-      (cond 
-        (and 
-          (= (:state cell) :forest) 
-          (> (:fertility cell) 10)) 
-        (merge cell {:state :climax})))
-    ;; Climax forest occasionally catches fire (e.g. lightning strikes)
-    (fn [cell world] (cond (and (= (:state cell) :climax)(< (rand 10) 1)) (merge cell {:state :fire})))
-    ;; Climax forest neighbouring fires is likely to catch fire
-    (fn [cell world]
-      (cond 
-        (and (= (:state cell) :climax)
-             (< (rand 3) 1)
-             (not (empty? (get-neighbours-with-state world (:x cell) (:y cell) 1 :fire))))
-        (merge cell {:state :fire})))
-    ;; After fire we get waste
-    (fn [cell world] (cond (= (:state cell) :fire) (merge cell {:state :waste})))
-    ;; And after waste we get pioneer species; if there's a woodland seed 
-    ;; source, it's going to be scrub, otherwise grassland.
-    (fn [cell world]
-      (cond
-        (and (= (:state cell) :waste)
-             (not 
-               (empty? 
-                 (flatten 
-                   (list 
-                     (get-neighbours-with-state world (:x cell) (:y cell) 1 :scrub2)
-                     (get-neighbours-with-state world (:x cell) (:y cell) 1 :forest)
-                     (get-neighbours-with-state world (:x cell) (:y cell) 1 :climax))))))
-        (merge cell {:state :scrub})))
-    (fn [cell world]
-      (cond (= (:state cell) :waste)
-        (merge cell {:state :pasture})))
-    ;; Forest increases soil fertility
-    (fn [cell world]
-      (cond (member? (:state cell) '(:forest :climax))
-        (merge cell {:fertility (+ (:fertility cell) 1)})))
-  ))
-
 (defn transform-cell 
   "Derive a cell from this cell of this world by applying these rules."
   [cell world rules]
@@ -96,3 +43,10 @@
   [world rules generations]
   (let [state (list world rules)]
     (take generations (iterate transform-world-state state))))
+
+(defn animate-world
+  [world rules generations]
+  (let [state (list world rules)]
+    (dorun 
+      (take generations (iterate transform-world-state state)))
+    nil))

src/mw_engine/utils.clj

@@ -2,4 +2,10 @@
 
 (defn member? 
   "True if elt is a member of col."
-  [elt col] (some #(= elt %) col)) 
+  [elt col] (some #(= elt %) col)) 
+
+(defn population [cell species]
+  "Return the population of this species in this cell.
+   Species is assumed to be a keyword whose value in a cell should be an
+   integer."
+  (or (get cell species) 0))

src/mw_engine/world.clj

@@ -1,4 +1,5 @@
 (ns mw-engine.world
+  (:use mw-engine.utils)
   (:require [clojure.math.combinatorics :as combo]))
 
 (defn make-cell 
@@ -39,12 +40,19 @@
     (nth (nth world y) x)))
 
 (defn get-neighbours 
+  ([world x y depth]
   "Get the neighbours to distance depth of the cell at x, y in this world."
-  [world x y depth]
   (map #(get-cell world (first %) (first (rest %))) 
        (combo/cartesian-product 
          (range (- x depth) (+ x depth)) 
          (range (- y depth) (+ y depth)))))
+  ([world cell depth]
+    "Get the neighbours to distance depth of this cell in this world."
+    (get-neighbours world (:x cell) (:y cell) depth))
+  ([world cell]
+    "Get the immediate neighbours of this cell in this world"
+    (get-neighbours world cell 1)))
+  
 
 (defn get-neighbours-with-state 
   "Get the neighbours to distance depth of the cell at x, y in this world which
@@ -63,7 +71,10 @@
   "Format one row in the state of a world for printing"
   [row]
   (apply str  
-         (map #(format "%10s" (truncate-state % 10)) row)))
+         (map #(format "%10s(%d/%d)" 
+                       (truncate-state % 10)
+                       (population % :deer)
+                       (population % :wolves)) row)))
 
 (defn print-world
   "Print the current state of this world, and return nil"