fix graph tests

src/Util/Graph.hs

@@ -32,13 +32,14 @@ module Util.Graph
   , build
   , strictlyDominate
   , strictlyPostDominate
-  , traverseM_
+  , topologicalTraverse
   ) where
 
 import Control.Lens ((%=))
 import Control.Monad
 import Control.Monad.Except
 import Control.Monad.State
+import Data.Monoid
 import Data.Functor
 import Data.Generics.Labels
 import Data.List qualified as List
@@ -144,8 +145,8 @@ update bd init =
 build :: (Eq ni, Ord ni) => GraphBuilder ni nd ed a -> Either Text (Graph ni nd ed)
 build bd = update bd empty
 
-traverseM_ :: (Eq ni, Ord ni, Monad m) => (ni -> nd -> m a) -> Graph ni nd ed -> m ()
-traverseM_ f g@Graph {nodes = nodes} = recurse initIndegree g
+topologicalTraverse :: (Eq ni, Ord ni, Monoid (f a)) => (ni -> nd -> f a) -> Graph ni nd ed -> f a
+topologicalTraverse f g@Graph {nodes = nodes} = recurse initIndegree g
   where
     initIndegree = Map.mapWithKey (\i d -> length $ inBound i g) nodes
     findZeroIndegree :: Map ni Int -> [ni]
@@ -154,14 +155,14 @@ traverseM_ f g@Graph {nodes = nodes} = recurse initIndegree g
       let m' = List.foldl' (\m (_, ni, _) -> Map.adjust (\x -> x - 1) ni m) m $ outBound i g
           m'' = Map.delete i m'
        in m''
-    recurse indegree g = do
+    recurse indegree g =
       let zeroIndegree = findZeroIndegree indegree
-      case zeroIndegree of
-        [] -> return ()
-        (n : ns) -> do
-          f n (Maybe.fromJust $ lookupNode n g)
-          let indegree' = updateIndegree n indegree g
-          recurse indegree' g
+      in case zeroIndegree of
+        [] -> mempty
+        (n : ns) ->
+          let ele = f n (Maybe.fromJust $ lookupNode n g)
+              indegree' = updateIndegree n indegree g
+          in ele <> recurse indegree' g
 
 newtype Memoize ni m a = Memoize
   { unmem :: State m a

test/GraphSpec.hs

@@ -44,25 +44,25 @@ specTrivialGraph = do
      in Map.size (Graph.nodes trivialGraph) == 2
   where
     constructTrivialGraph = do
-      Graph.addNode "1" "d1"
-      Graph.addNode "2" "d2"
-      Graph.addEdge "1" "2" "1-2"
+      Graph.addNode 1 "d1"
+      Graph.addNode 2 "d2"
+      Graph.addEdge 1 2 "1-2"
 
 specCyclicGraph :: SpecWith ()
 specCyclicGraph = do
   it "construct a cyclic graph" $
     let constructG = do
-          Graph.addNode "1" "d1"
-          Graph.addNode "2" "d2"
-          Graph.addNode "3" "d3"
-          Graph.addEdge "1" "2" "1-2"
-          Graph.addEdge "2" "3" "2-3"
-          Graph.addEdge "3" "1" "3-1"
+          Graph.addNode 1 "d1"
+          Graph.addNode 2 "d2"
+          Graph.addNode 3 "d3"
+          Graph.addEdge 1 2 "1-2"
+          Graph.addEdge 2 3 "2-3"
+          Graph.addEdge 3 1 "3-1"
         (Right cyclicGraph) = Graph.build constructG
      in Map.size (Graph.nodes cyclicGraph) == 3
           && Map.size (Graph.edges cyclicGraph) == 3
-          && ( let inEdges = Graph.inBound "3" cyclicGraph
-                   outEdges = Graph.outBound "3" cyclicGraph
+          && ( let inEdges = Graph.inBound 3 cyclicGraph
+                   outEdges = Graph.outBound 3 cyclicGraph
                 in length inEdges == 1
                      && getNodeData ((\(src, _, _) -> src) (head inEdges) ) cyclicGraph == Just "d2"
                      && length outEdges == 1
@@ -71,32 +71,21 @@ specCyclicGraph = do
   where
     getNodeData n g = Map.lookup n (Graph.nodes g)
 
-newtype TraverseMonad ni a = TraverseMonad
-  {runTraverse :: State [ni] a}
-  deriving
-    ( Functor,
-      Applicative,
-      Monad,
-      MonadState [ni]
-    )
-
-sortedList :: (Ord ni) => Graph ni nd ed -> [ni]
-sortedList g =
-  let (_, s) = (runState $ runTraverse (Graph.traverseM_ (\ni _ -> modify' (\l -> l ++ [ni])) g)) []
-   in s
+topologicalSort :: (Ord ni) => Graph ni nd ed -> [ni]
+topologicalSort = Graph.topologicalTraverse (\ni _ -> [ni]) 
 
 traverseGraph :: SpecWith ()
 traverseGraph = do
   it "traverse graph in topological order" $
     let constructG = do
-          Graph.addNode "1" "d1"
-          Graph.addNode "2" "d2"
-          Graph.addNode "3" "d3"
-          Graph.addNode "4" "d4"
-          Graph.addEdge "4" "2" "4-2"
-          Graph.addEdge "4" "3" "4-3"
-          Graph.addEdge "2" "1" "2-1"
-          Graph.addEdge "3" "1" "3-1"
+          Graph.addNode 1 "d1"
+          Graph.addNode 2 "d2"
+          Graph.addNode 3 "d3"
+          Graph.addNode 4 "d4"
+          Graph.addEdge 4 2 "4-2"
+          Graph.addEdge 4 3 "4-3"
+          Graph.addEdge 2 1 "2-1"
+          Graph.addEdge 3 1 "3-1"
         (Right graph) = Graph.build constructG
-        lst = sortedList graph
-     in head lst == "4" && last lst == "1"
+        lst = topologicalSort graph
+     in head lst == 4 && last lst == 1