1 files changed, 16 insertions, 0 deletions

diff --git a/interactive-edit-lens/src/Main.hs b/interactive-edit-lens/src/Main.hs
index c816515..21db685 100644
--- a/interactive-edit-lens/src/Main.hs
+++ b/interactive-edit-lens/src/Main.hs
@@ -92,6 +92,12 @@ instance Universe LineBreakState where
 instance Finite LineBreakState
 instance NFData LineBreakState
 
+data SwitchState = SwitchA | SwitchB
+  deriving (Eq, Ord, Enum, Bounded, Show, Read, Generic)
+instance Universe SwitchState
+instance Finite SwitchState
+instance NFData SwitchState
+
 dfstMap :: String -> Maybe SomeDFST
 dfstMap "double" = Just . SomeDFST $ DFST
   { stInitial = ()
@@ -228,6 +234,16 @@ dfstMap "linebreak" = Just . SomeDFST $ DFST
     ]
   , stAccept = Set.fromList universeF
   }
+dfstMap "switch" = Just . SomeDFST $ DFST
+  { stInitial = SwitchA
+  , stTransition = Map.fromList
+    [ ((SwitchA, 's'), (SwitchB, Seq.empty))
+    , ((SwitchB, 's'), (SwitchA, Seq.empty))
+    , ((SwitchA, 'p'), (SwitchA, Seq.singleton 'a'))
+    , ((SwitchB, 'p'), (SwitchB, Seq.singleton 'b'))
+    ]
+  , stAccept = Set.fromList [SwitchA, SwitchB]
+  }
 dfstMap _ = Nothing
 
 main :: IO ()