doc: add intermediate representation language

doc/sample/Sum.im

@@ -1,29 +1,28 @@
 package net.doorstuck.test
 
-cout put:'Finds the sum of a set of numbers.'
+cout put:'Finds the sum of a set of numbers.'.
 
-sum = 0
+sum = 0.
 
 while true do
-    cout print:'Number (blank to finish): '
-    cout flush
+    cout print:'Number (blank to finish): '.
+    cout flush.
 
-    input = ''
-    v = 0
-    cin get:input
+    v = 0.
+    input = cin readLine.
 
     if input == '' then
         break
     end
 
-    try
-        v = Int parse:input
-    catch (#err:number_format, err)
-        cout put:'{input} is not a valid number.'
+    v = Int parse:input.
+
+    if v == null then
+        cout put:'{input} is not a valid number.'.
         continue
     end
 
-    sum += v
+    sum += v.
 end
 
 cout put:'Sum: {sum}'