Update

comun.md

@@ -88,7 +88,86 @@ The following code translates [brainfuck](brainfuck.md) to comun (proving comun
 .
 ```
 
-TODO: more, code examples, compare the above with C, ...
+The following is our standardized **[divisor tree](divisor_tree.md)** program written in comun:
+
+```
+# pops a number (< 1000) and prints it
+numPrint999:
+  $0 99 > ? $0 100 / "0" + -> .
+  $0 9 > ?  $0 10 / 10 % "0" + -> .
+  10 % "0" + ->
+.
+
+# converts single digit to number (or -1 if invalid)
+digitToNum:
+  $0
+
+  $0 "0" >= >< "9" <= & ?
+    "0" -
+  ;
+    ^ -1
+  .
+.
+
+# takes x, pops it and recursively prints its divisor tree
+printDivisorTree:
+  -1 -1                 # divisors: a, b
+
+  $2 2 / @@             # for i = x / 2
+                        # stack now: x a b i
+    $0 1 <= ?
+      !@
+    .
+
+    $3 $1 % 0 = ?       # i divides x?
+      $0 $:3            # a = i
+      $3 $1 / $:2       # b = x / i
+
+      $2 $2 <= ?        # a <= b?
+        !@
+      .
+    .
+
+    --                  # decrement i
+  .
+  ^                     # pop i
+
+  "(" ->
+
+  $0 -1 != ?
+    printDivisorTree
+    " " ->
+    >< numPrint999      # print x
+    " " ->
+    printDivisorTree
+  ;
+    ^ ^                 # pop a, b
+    numPrint999
+  .
+
+  ")" ->
+.
+
+@@                      # read numbers from the user
+  0 10 "enter a number:" -->
+
+  0                     # x
+  @@                    # read x
+    <-
+    $0 10 = ? ^ !@ .    # newline?
+    digitToNum
+    $0 -1 = ? !. .      # wrong digit? then end
+    >< 10 * +
+  .
+
+  $0 1000 < ?           # x < 1000?
+    printDivisorTree
+    10 ->               # newline
+  ;
+    !@
+  .
+.
+```
 
 ## See Also