WIP

lib/LiBro/Util.hs

@@ -2,9 +2,10 @@
 --    in more than one place.
 module LiBro.Util
   (
-  -- * Tree building
+  -- * Tree utilities
     ParentList
   , readForest
+  , findSubtree
   -- * Counting monad transformer
   , CountingT
   , next
@@ -59,6 +60,11 @@ readForest pairs =
                               Nothing -> []; Just [] -> []
                               Just xs -> fill cs <$> sort xs
 
+-- |  Find the first matching subtree of a forest
+findSubtree :: (a -> Bool) -> Forest a -> Maybe (Tree a)
+findSubtree pred forest = do
+  undefined
+
 -- |  Simple monad transformer that allows to read an increasing 'Int'.
 type CountingT m = StateT Int m
 

test/LiBro/UtilSpec.hs

@@ -18,6 +18,7 @@ import System.IO.Temp
 spec :: Spec
 spec = describe "Helper stuff" $ do
   forestFromParentList
+  findInForest
   countingT
   xlsx
   guarding
@@ -35,6 +36,10 @@ forestFromParentList = describe "Read Forest from parent list" $ do
         , Node 42 [ Node 84 [ Node (168 :: Int) [] ]]
         ]
 
+findInForest :: Spec
+findInForest = describe "Find matching subtrees in a forest" $ do
+  undefined
+
 countingT :: Spec
 countingT = describe "The CountingT 'monad transformer'" $ do
   let nextTimes n = replicateM n next