List and format

src/Data/Buuka.hs

@@ -8,6 +8,7 @@ module Data.Buuka
   , Buuka
 
   , insert
+  , elements
   )
   where
 
@@ -41,6 +42,9 @@ newtype Buuka = Buuka [BuukaEntry]
 insert :: BuukaEntry -> Buuka -> Buuka
 insert e (Buuka b) = Buuka (e : b)
 
+elements :: Buuka -> [BuukaEntry]
+elements (Buuka b) = b
+
 instance SafeJSON Buuka where
   type Version Buuka = 0
 

src/Operations.hs

@@ -1,6 +1,10 @@
 module Operations
-  ( module Operations.Insert )
+  ( module Operations.Insert
+  , module Operations.List
+  )
   where
 
 import Operations.Insert
        (insert)
+import Operations.List
+       (list)

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)