Query with regexes

src/Data/Query.hs

@@ -8,10 +8,12 @@ module Data.Query
     -- * Combinators
   , startsWith
   , endsWith
+  , regex
   , (.&&.)
 
     -- * Evaluating queries
   , evaluate
+  , predicate
   )
   where
 
@@ -25,7 +27,7 @@ import Text.Regex.TDFA
        ((=~))
 
 import Data.Functor.Foldable
-       (Fix(..))
+       (Fix(..), cata)
 
 data Field a where
   Url :: Field String
@@ -47,6 +49,9 @@ startsWith field x = Fix (StartsWith field x)
 endsWith :: Field String -> String -> Query
 endsWith field x = Fix (EndsWith field x)
 
+regex :: Field String -> String -> Query
+regex field x = Fix (Regex field x)
+
 (.&&.) :: Query -> Query -> Query
 a .&&. b = Fix (And a b)
 
@@ -59,3 +64,6 @@ evaluate = \case
   Regex Url x -> \BuukaEntry{url=URL u} -> u =~ x
   Regex Title x -> \BuukaEntry{title=t} -> maybe False (=~ x) t
   And a b -> \e -> a e && b e
+
+predicate :: Query -> BuukaEntry -> Bool
+predicate = cata evaluate

src/Operations.hs

@@ -1,6 +1,7 @@
 module Operations
   ( module Operations.Insert
   , module Operations.List
+  , module Operations.Query
   )
   where
 
@@ -8,3 +9,5 @@ import Operations.Insert
        (insert)
 import Operations.List
        (list)
+import Operations.Query
+       (query)

src/Operations/Query.hs

@@ -0,0 +1,23 @@
+module Operations.Query where
+
+import Data.Query
+
+import Control.Monad.Buuka
+import Control.Monad.Reader
+
+import Data.Foldable
+       (traverse_)
+
+import Data.Buuka
+       (Buuka)
+import qualified Data.Buuka as B
+
+import Operations.Format
+
+query :: Field String -> String -> BuukaM ()
+query field q =
+  buukaQ (asks go) >>= traverse_ (liftIO . putStrLn)
+  where
+    go :: Buuka -> [String]
+    go b = formatEntries b (filter (predicate (regex field q)) . B.elements $ b)
+