More improvements to forth style

02-go-forth/tf-02.py

@@ -73,19 +73,21 @@ def frequencies():
     heap['word_list'] = stack.pop()
     heap['word_freqs'] = {}
     # A little flavour of the real Forth style here...
-    stack.append(0) # Counter of words at stack[0]
+    stack.append(0) # Counter of words, at stack[0]
     while stack[-1] != len(heap['word_list']):
         stack.append(heap['word_list'][stack[-1]]) # Push the word, stack[1]
         # ... but the following line is not in style, because the naive implementation 
         # would be too slow, or we'd need to implement faster, hash-based search
         if stack[-1] in heap['word_freqs']:
-            stack.append(heap['word_freqs'][stack[1]]) # push the frequency, stack[2]
-            stack[2] = stack[2] + 1 # Swap the tuple the stack with a new one
+            # Increment the frequency, postfix style: f 1 +
+            stack.append(heap['word_freqs'][stack[1]]) # push the frequency
+            stack.append(1) # push 1
+            stack.append(stack.pop() + stack.pop()) # add
         else:
             stack.append(1) # Push 1 in stack[2]
         heap['word_freqs'][stack.pop()] = stack.pop()  # Load the updated freq back onto the heap
 
-        # Increment the counter
+        # Increment the counter, postfix style
         stack.append(1)
         stack.append(stack.pop() + stack.pop()) # Add the operands on the stack
     # Done with iteration. Pop the counter