Some more work. Also, this is a Scots vending machine, dammit!

src/vending/core.clj

@@ -1,20 +1,19 @@
 (ns vending.core)
 
-(defn foo
-  "I don't do a whole lot."
-  [x]
-  (println x "Hello, World!"))
-
 
 
 (defn make-default-machine [] { :stock {:apples 5 :oranges 5 :lemons 5}
-	:coins {:dollars 1 :quarters 4 :dimes 4 :nickels 4}
+	:coins {:merk 1 :plack 4 :bawbee 4 :bodle 4}
 	:tendered nil
 	:last-message ""
 	:change nil
 	:output nil} )
 
-(def coin-values {:dollar 1 :quarter 0.25 :dime 0.10 :nickel 0.05})
+(def coin-values {:merk 1 :plack 0.25 :bawbee 0.10 :bodle 0.05})
+
+(keys coin-values)
+
+(.indexOf (keys coin-values) :bodle)
 
 (def item-prices {:apples 0.65 :oranges 1 :lemons 1.5})
 
@@ -22,31 +21,36 @@
 	(coin-values coin))
 
 (defn coins-value [coins]
+  "Sum the value of these coins."
 	(apply + (map coin-value coins)))
 
 (defn coin-return [machine]
+  "Return all tendered coins in this machine."
 	(assoc (dissoc machine :tendered) :change (:tendered machine)))
- 
+
 (defn add-coin [machine coin]
+  "Add this coin to this machine."
 	(assoc (dissoc machine :tendered) :tendered (cons coin (:tendered machine))))
 
 (defn add-coins [machine coins]
+  "Add these coins to this machine"
 	(cond (empty? coins) machine
 		true (add-coins (add-coin machine (first coins)) (rest coins))))
 
 (defn magic-inc [maybenum]
+  "A wrapper round inc which treats nil as zero."
 	(cond (nil? maybenum) 1
 		true (inc maybenum)))
 
 (defn sum-coin [coin sums]
-	(cond
-		(= coin :dollar) (update-in sums [:dollar] magic-inc) 
-		(= coin :quarter) (update-in sums [:quarter] magic-inc) 
-		(= coin :dime) (update-in sums [:dime] magic-inc) 
-		(= coin :nickel) (update-in sums [:nickel] magic-inc)))
+  "Adds this coin (assumed to be on of :merk, :plack, :bawbee, :bodle)
+  to this map of sums."
+	(update-in sums [coin] magic-inc))
 
-(defn sum-coins 
-	"Returns a map {:dollars :quarters :dimes :nickels}"
+(defn sum-coins
+	"takes a list in the form (:merk :merk :bawbee :plack :bodle) and returns
+  a map {:merk 2 :plack 1 :bawbee 1 :bodle 1}. Optional second argument: an
+  existing map in that general form."
 	([coins]
 		(sum-coins coins {}))
 	([coins sums]
@@ -62,52 +66,60 @@
 (defn subtract-nickle [list]
 	(subtract-denomination list 1))
 
-(defn subtract-dime [list]
+(defn subtract-bawbee [list]
 	(subtract-denomination list 2))
 
-(defn subtract-quarter [list]
+(defn subtract-plack [list]
 	(subtract-denomination list 3))
 
-(defn subtract-dollar [list]
+(defn subtract-merk [list]
 	(subtract-denomination list 4))
 
-(defn in-make-change [amount dollars quarters dimes nickels]
-	"Return a tuple (dollars quarters nickels dimes) which indicates the number remaining 
+(defn in-make-change [amount merk plack bawbee bodle]
+	"Return a tuple (merk plack bodle bawbee) which indicates the number remaining
 	after making change, or nil if not possible"
 	(cond
-		(= amount 0) (list dollars quarters dimes nickels)
-		(and (>= amount (:dollar coin-values)) (> dollars 0))
-			(in-make-change (- amount (:dollar coin-values)) (- dollars 1) quarters dimes nickels)
-		(and (>= amount (:quarter coin-values)) (> quarters 0))
-			(in-make-change (- amount (:quarter coin-values)) dollars (- quarters 1) dimes nickels)
-		(and (>= amount (:dime coin-values)) (> dimes 0))
-			(in-make-change (- amount (:dime coin-values)) dollars quarters (- dimes 1) nickels)
-		(and (>= amount (:nickel coin-values)) (> nickels 0))
-			(in-make-change (- amount (:nickel coin-values)) dollars quarters dimes (- nickels 1))))
+		(= amount 0) (list merk plack bawbee bodle)
+		(and (>= amount (:merk coin-values)) (> merk 0))
+			(in-make-change (- amount (:merk coin-values)) (- merk 1) plack bawbee bodle)
+		(and (>= amount (:plack coin-values)) (> plack 0))
+			(in-make-change (- amount (:plack coin-values)) merk (- plack 1) bawbee bodle)
+		(and (>= amount (:bawbee coin-values)) (> bawbee 0))
+			(in-make-change (- amount (:bawbee coin-values)) merk plack (- bawbee 1) bodle)
+		(and (>= amount (:bodle coin-values)) (> bodle 0))
+			(in-make-change (- amount (:bodle coin-values)) merk plack bawbee (- bodle 1))))
 
-(defn make-change [amount dollars quarters dimes nickels]
-	(map #(- %1 %2) (list dollars quarters dimes nickels) 
-		(in-make-change amount dollars quarters dimes nickels)
+(defn make-change [amount merk plack bawbee bodle]
+	(map #(- %1 %2) (list merk plack bawbee bodle)
+		(in-make-change amount merk plack bawbee bodle)
 		))
 
-(defn make-change-machine [machine change]
-	machine)
+(defn subtract-change [machine change]
+  "subtract this change from this machine")
+
+(defn make-change-machine [machine item-price change]
+    (let [
+      tend (sum-coins (:tendered machine))
+		change (make-change item-price (:merk tend) (:plack tend) (:bawbee tend) (:bodle tend))]
+      (cond (nil? change) machine)
+        true (assoc (dissoc (subtract-change machine change) :change ) :change change )))
 
 (defn remove-from-stock [machine item]
 	machine)
 
 (defn deliver-item [machine item change]
-	(make-change-machine 
-		(remove-from-stock 
-			(assoc (dissoc machine :output) :output (cons item (:output machine))) 
-			item) 
-		change)) 
+	(make-change-machine
+		(remove-from-stock
+			(assoc (dissoc machine :output) :output (cons item (:output machine)))
+			item)
+    (item item-prices)
+		change))
 
 
 (defn get-item [machine item]
 	(let [item-price (item item-prices)
 		tend (sum-coins (:tendered machine))
-		change (make-change item-price (:dollar tend) (:quarter tend) (:dime tend) (:nickel tend))]
+		change (make-change item-price (:merk tend) (:plack tend) (:bawbee tend) (:bodle tend))]
 	(cond (<= 0 (item (:stock machine))) (coin-return machine)
 		(<= (coins-value (:tendered machine)) item-price) (coin-return machine)
 		(empty? change) (coin-return)