From 830cdb695e58938bc51ac072fe537fc17468d293 Mon Sep 17 00:00:00 2001
From: Jonathan Daugherty <cygnus@foobox.com>
Date: Mon, 11 May 2015 07:55:48 -0700
Subject: [PATCH] Use lenses in test program

---
 brick.cabal      |  3 ++-
 programs/Main.hs | 31 ++++++++++++++++++-------------
 2 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/brick.cabal b/brick.cabal
index b9abe9e..a218990 100644
--- a/brick.cabal
+++ b/brick.cabal
@@ -29,7 +29,8 @@ executable brick
   build-depends:       base,
                        brick,
                        vty >= 5.2.9,
-                       data-default
+                       data-default,
+                       lens
 
 executable brick-rogue
   hs-source-dirs:      programs
diff --git a/programs/Main.hs b/programs/Main.hs
index 88d4417..0a7b60c 100644
--- a/programs/Main.hs
+++ b/programs/Main.hs
@@ -1,48 +1,53 @@
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TemplateHaskell #-}
 module Main where
 
+import Control.Lens
 import Data.Default
+import Data.Monoid
 import Graphics.Vty
 import System.Exit
 
 import Brick
 
 data St =
-    St { stEditor :: Editor
-       , trans :: Location
+    St { _stEditor :: Editor
+       , _trans :: Location
        }
 
+makeLenses ''St
+
 eName :: Name
 eName = Name "edit"
 
 drawUI :: St -> [Widget]
 drawUI st = [top]
     where
-        top = translated (trans st) $
+        top = translated (st^.trans) $
               bordered $
               hLimit 40 $
               vBox [ "Top"
                    , hBorder '-'
                    , hBox [ " Edit: "
-                          , hLimit 20 $ edit (stEditor st) `withAttr` (cyan `on` blue)
+                          , hLimit 20 $ edit (st^.stEditor) `withAttr` (cyan `on` blue)
                           ]
                    ]
 
 handleEvent :: Event -> St -> IO St
 handleEvent e st =
     case e of
-        EvKey KEsc [] -> exitSuccess
-        EvKey KEnter [] -> error $ editStr $ stEditor st
-        EvKey KLeft [MCtrl] -> return $ st { trans = trans st `locOffset` (Location (-1, 0)) }
-        EvKey KRight [MCtrl] -> return $ st { trans = trans st `locOffset` (Location (1, 0)) }
-        EvKey KUp [MCtrl] -> return $ st { trans = trans st `locOffset` (Location (0, -1)) }
-        EvKey KDown [MCtrl] -> return $ st { trans = trans st `locOffset` (Location (0, 1)) }
-        ev -> return $ st { stEditor = editEvent ev (stEditor st) }
+        EvKey KEsc []         -> exitSuccess
+        EvKey KEnter []       -> error $ editStr $ st^.stEditor
+        EvKey KLeft [MCtrl]   -> return $ st & trans %~ (<> (Location (-1, 0)))
+        EvKey KRight [MCtrl]  -> return $ st & trans %~ (<> (Location (1, 0)))
+        EvKey KUp [MCtrl]     -> return $ st & trans %~ (<> (Location (0, -1)))
+        EvKey KDown [MCtrl]   -> return $ st & trans %~ (<> (Location (0, 1)))
+        ev                    -> return $ st & stEditor %~ (editEvent ev)
 
 initialState :: St
 initialState =
-    St { stEditor = editor eName ""
-       , trans = Location (0, 0)
+    St { _stEditor = editor eName ""
+       , _trans = Location (0, 0)
        }
 
 theApp :: App St Event