brick/programs/AttrDemo.hs
Jonathan Daugherty 3081e7367d Replace "Name" type with custom name type variable everywhere
This experimental change makes it possible to:
* Avoid runtime errors due to name typos
* Achieve compile-time guarantees about name matching and usage
* Force widget functions to be name-agnostic by being polymorphic
  in their name type
* Clean up focus handling by making it possible to pattern-match
  on cursor location names

The change also made many types more heavyweight and in some cases
this is unpleasant when we don't want to have to care about names.
But in those cases we can just use 'n' or '()' depending on how
concrete we need to be.  I'm not yet sure how this is going to play
out in practice.
2016-03-04 14:42:49 -08:00

66 lines
1.9 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
module Main where
import Data.Monoid
import Graphics.Vty
( Event, Attr, white, blue, cyan, green, red, yellow
, black
)
import Brick.Main
import Brick.Types
( Widget
)
import Brick.Widgets.Core
( (<=>)
, withAttr
, vBox
, str
)
import Brick.Util (on, fg)
import Brick.AttrMap (attrMap, AttrMap)
ui :: Widget ()
ui =
vBox [ str "This text uses the global default attribute."
, withAttr "foundFull" $
str "Specifying an attribute name means we look it up in the attribute tree."
, (withAttr "foundFgOnly" $
str ("When we find a value, we merge it with its parent in the attribute")
<=> str "name tree all the way to the root (the global default).")
, withAttr "missing" $
str "A missing attribute name just resumes the search at its parent."
, withAttr ("general" <> "specific") $
str "In this way we build complete attribute values by using an inheritance scheme."
, withAttr "foundFull" $
str "You can override everything ..."
, withAttr "foundFgOnly" $
str "... or only you want to change and inherit the rest."
, str "Attribute names are assembled with the Monoid append operation to indicate"
, str "hierarchy levels, e.g. \"window\" <> \"title\"."
]
globalDefault :: Attr
globalDefault = white `on` blue
theMap :: AttrMap
theMap = attrMap globalDefault
[ ("foundFull", white `on` green)
, ("foundFgOnly", fg red)
, ("general", yellow `on` black)
, ("general" <> "specific", fg cyan)
]
app :: App () Event ()
app =
App { appDraw = const [ui]
, appHandleEvent = resizeOrQuit
, appStartEvent = return
, appAttrMap = const theMap
, appChooseCursor = neverShowCursor
, appLiftVtyEvent = id
}
main :: IO ()
main = defaultMain app ()