mirror of
https://github.com/jtdaugherty/brick.git
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6f1b62ae53
This change is motivated by the API wart that results from the overloading of both "<>" and string literals that resulted in code like this: a :: AttrName a = "blah" <> "things" While this worked to create an AttrName with two segments, it is far too easy to read this as two strings concatenated. The overloading hides what is really going on with the segments of the attribute name. The way to write the above example after this change is: a :: AttrName a = attrName "blah" <> attrName "things"
82 lines
2.5 KiB
Haskell
82 lines
2.5 KiB
Haskell
{-# LANGUAGE CPP #-}
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module Main where
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import Control.Monad (void)
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import Control.Monad.State (modify)
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#if !(MIN_VERSION_base(4,11,0))
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import Data.Monoid ((<>))
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#endif
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import qualified Graphics.Vty as V
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import qualified Brick.Types as T
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import qualified Brick.Main as M
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import qualified Brick.Widgets.Center as C
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import Brick.Types
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( Widget
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, BrickEvent(..)
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)
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import Brick.Widgets.Core
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( Padding(..)
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, vBox
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, padTopBottom
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, withDefAttr
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, cached
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, padBottom
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, str
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)
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import Brick (on)
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import Brick.Widgets.Center
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( hCenter
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)
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import Brick.AttrMap
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( AttrName
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, attrName
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, attrMap
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)
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data Name = ExpensiveWidget
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deriving (Ord, Show, Eq)
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drawUi :: Int -> [Widget Name]
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drawUi i = [ui]
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where
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ui = C.vCenter $
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vBox $ hCenter <$>
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[ str "This demo shows how cached widgets behave. The top widget below"
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, str "is cacheable, so once it's rendered, brick re-uses the rendering"
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, str "each time it is drawn. The bottom widget is not cacheable so it is"
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, str "drawn on every request. Brick supports cache invalidation to force"
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, str "a redraw of cached widgets; we can trigger that here with 'i'. Notice"
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, str "how state changes with '+' aren't reflected in the cached widget"
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, str "until the cache is invalidated with 'i'."
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, padTopBottom 1 $
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cached ExpensiveWidget $
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withDefAttr emphAttr $ str $ "This widget is cached (state = " <> show i <> ")"
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, padBottom (Pad 1) $
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withDefAttr emphAttr $ str $ "This widget is not cached (state = " <> show i <> ")"
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, hCenter $ str "Press 'i' to invalidate the cache,"
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, str "'+' to change the state value, and"
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, str "'Esc' to quit."
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]
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appEvent :: BrickEvent Name e -> T.EventM Name Int ()
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appEvent (VtyEvent (V.EvKey (V.KChar '+') [])) = modify (+ 1)
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appEvent (VtyEvent (V.EvKey (V.KChar 'i') [])) = M.invalidateCacheEntry ExpensiveWidget
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appEvent (VtyEvent (V.EvKey V.KEsc [])) = M.halt
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appEvent _ = return ()
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emphAttr :: AttrName
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emphAttr = attrName "emphasis"
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app :: M.App Int e Name
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app =
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M.App { M.appDraw = drawUi
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, M.appStartEvent = return ()
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, M.appHandleEvent = appEvent
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, M.appAttrMap = const $ attrMap V.defAttr [(emphAttr, V.white `on` V.blue)]
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, M.appChooseCursor = M.neverShowCursor
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}
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main :: IO ()
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main = void $ M.defaultMain app 0
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