Return a list of subdirs of a given dir

src/Vervis.hs

@@ -14,6 +14,19 @@
  -}
 
 module Vervis
-    (
+    ( subdirs
     )
 where
+
+import Data.Maybe (mapMaybe)
+import System.Directory.Tree
+
+subdirs :: FilePath -> IO [FilePath]
+subdirs dir = do
+    _base :/ tree <- buildL dir
+    return $ case tree of
+        Dir _ cs ->
+            let dirName (Dir n _) = Just n
+                dirName _         = Nothing
+            in  mapMaybe dirName cs
+        _ -> []

vervis.cabal

@@ -29,7 +29,8 @@ library
   exposed-modules:     Vervis
   -- other-modules:       
   -- other-extensions:    
-  build-depends:       base >=4.8 && <5
+  build-depends:       base           >=4.8  && <5
+                     , directory-tree >=0.12
   hs-source-dirs:      src
   default-language:    Haskell2010
   ghc-options:         -Wall