Updating looping example (#75)

* show looping by a counter index
* show accumulating data into an array
* show looping foreach object in an array

examples/108-looping/workflow.yaml

@@ -1,18 +1,43 @@
 
 operations:
-- message: This operation will repeat 5 times...
-  
-  values: # starts at zero
-    counter: 0 
 
-  operations: # runs the nested operations
-  - message: (['Task one, counter is ', counter])
-  - message: (['Task two, counter is ', counter])
+- message: This is an example of counting from 0 to 9
+- message: and building an `append` object to add to a `data` array
+
+- message: (['Looping... Index is ', index])
+
+  values: # count from 0 to 9 by 1
+    index: 0
+    data: []
+
+  operations:
+  - message: Nested work would go here
+    output: 
+      append: # append[] is added to data[] below
+      - id: (index)
+        formula: ( bits(index) | [].to_string(@) | join(' + ', @) )
+
+  output: 
+    data: ( [data, append] [] ) # combines array-of-arrays, then uses [] operator to flatten
+    index: (sum( [index, `1`] )) # increment index
+
+  repeat: # repeat until index is 10
+    condition: (index < `10`)
+
+
+- message: This is an example of looping through items in an array 
   
-  output: # increments counter before testing repeat.condition 
-    counter: (sum( [counter, `1`] ))
+- message: (['Looping... Current is ', to_string(current)])
+  values: 
+    foreach: (data) # keep track of remaining data to iterate
+    current: (data[0]) # and make the current item easy to access
+  condition: ( length(foreach) > `0` ) # don't run if there's no data
   
-  repeat: # while repeat.condition is true, operations and output will run again
-    condition: counter < `5`
-    delay: PT.2S
-    timeout: PT3S
+  operations:
+  - message: Nested work would go here
+
+  output:
+    current: (foreach[1]) # advance to the next data item
+    foreach: (foreach[1:]) # reduce the remaining data to iterate
+  repeat:
+    condition: ( length(foreach) > `0` ) # stop when there is no remaining data