List and format

src/Operations/List.hs

@@ -0,0 +1,29 @@
+{-# LANGUAGE LambdaCase #-}
+module Operations.List where
+
+import Control.Monad.Buuka
+import Control.Monad.Reader
+       (liftIO, asks)
+
+import Data.Foldable
+       (traverse_)
+
+import Data.Semigroup (Max(..))
+
+import Data.Buuka
+       (URL(..), BuukaEntry(..))
+import qualified Data.Buuka as B
+
+list :: BuukaM ()
+list =
+  buukaQ (asks (format . B.elements)) >>= traverse_ (liftIO . putStrLn)
+  where
+    format :: [BuukaEntry] -> [String]
+    format xs =
+      let formatted = zipWith formatEntry [1..] xs
+          indexWidth = getMax . foldMap (Max . length . fst) $ formatted
+      in fmap (\(idx,x) -> idx <> replicate (indexWidth - length idx) ' ' <> ". " <> x) formatted
+    formatEntry :: Int -> BuukaEntry -> (String, String)
+    formatEntry n = \case
+      BuukaEntry{title=Just t} -> (show n, t)
+      BuukaEntry{url=URL u} -> (show n, u)