Refactor SMA implementation to lib/sma.myc

Move the SMA implementation from examples/err.myc and examples/sma.myc
to a new dedicated file in lib/. This change also cleans up unused code
and improves the SMA logic.

examples/err.myc

@@ -1,34 +0,0 @@
-(do
-  (def SMA 
-    (fn [length] 
-      (do
-        (def history (series :float))
-        (def sum 0.0)
-
-		(fn [val] 
-           (do 
-             (def hist_len (len history))
-             (if (>= hist_len length)
-               (assign sum (- sum (history (- hist_len 1))))
-               ...)
-
-  		  (push history val)
-            (assign sum (+ sum val))
-            (/ sum (len history))
-           )))))
-
-  (def sma10 (SMA 10))
-
-(sma10 1)
-(sma10 2)
-(sma10 3)
-(sma10 4)
-(sma10 5)
-(sma10 6)
-(sma10 7)
-(sma10 8)
-(sma10 9)
-(sma10 10)
-(sma10 11)
-
-)

examples/sma.myc

@@ -1,24 +1,12 @@
+;; Output: 5.5
+
 (do
-  (def SMA 
-    (fn [length] 
-      (do
-        (def history (series :float))
-        (push history 0)
-
-		(fn [val] 
-           (do 
-              (def sum (+ val (history 0)))
-			  (push history sum)
-              (/ sum length)
-           ))
-      )))
-
   (def sma20 (SMA 20))
 
-  (def n 100)
-  (while (> n 0) 
-    (do 
+  (def n 1000)
+  (while (> n 0)
+    (do
       (print "val=" n " sma20=" (sma20 n))
       (assign n (- n 1))
     ))
-)
+)

lib/sma.myc

@@ -0,0 +1,20 @@
+(do
+  (def SMA
+    (fn [length]
+      (do
+        (def history (series :float))
+        (def sum 0.0)
+
+		(fn [val]
+           (do
+             (def hist_len (len history))
+             (if (>= hist_len length)
+               (assign sum (- sum (history (- length 1)))))
+
+  		      (push history val)
+              (assign sum (+ sum val))
+
+              (if (>= hist_len length)
+                (/ sum length))
+           )))))
+)