Changed the uses of flowAlgorithm to make better use of userErrLabel to give better error messages

checks/Check.hs

@@ -181,7 +181,7 @@ checkInitVar m graph startNode
        ,nodesToProcess = lpre graph
        ,nodesToReAdd = lsuc graph
        ,defVal = Everything
-       ,userErrLabel = show
+       ,userErrLabel = ("for node at: " ++) . show . fmap getNodeMeta . lab graph
       }
       
     getMeta :: Node -> Meta

checks/UsageCheckAlgorithms.hs

@@ -141,7 +141,7 @@ findReachDef graph startNode
         ,nodesToProcess = lpre graph
         ,nodesToReAdd = lsuc graph
         ,defVal = Map.empty
-        ,userErrLabel = show
+        ,userErrLabel = ("for node at: " ++) . show . fmap getNodeMeta . lab graph
       }
 
     readInNode' :: Node -> Var -> a -> Bool

flow/FlowAlgorithms.hs

@@ -129,9 +129,10 @@ flowAlgorithm funcs nodes (startNode, startVal)
                -- Pick the next node from the list and remove it:
           = do let (node, workList') = Set.deleteFindMin workList
                -- Process that node:
-               total <- foldWithEither (iterateNode vals) (Left $ show workList
-                 ++ userErrLabel
-                 funcs node) (nodesToProcess funcs node)
+               total <- foldWithEither (iterateNode vals) (Left $
+                 "Nodes still to process: " ++ show workList
+                 ++ " " ++ userErrLabel funcs node)
+                 (nodesToProcess funcs node)
                nodeVal <- Map.lookup node vals
                if total /= nodeVal
                  -- If the value has changed, that will cascade to affect all