module Util
  ( toMaybe
  , dup
  , secondClassLensNames
  , (??)
  , Never
  , never
  , note
  ) where

import Data.Bool (bool)
import Lens.Micro.TH (LensRules, lensRules, lensField, DefName (TopName))
import Language.Haskell.TH (mkName, nameBase)
import Lens.Micro

toMaybe :: Bool -> a -> Maybe a
toMaybe p = if p then Just else const Nothing

dup :: a -> (a, a)
dup a = (a, a)

infixl 4 ??
(??) :: Functor f => f (a -> b) -> a -> f b
f ?? a = ($ a) <$> f

secondClassLensNames :: LensRules
secondClassLensNames = lensRules & lensField .~ (\_ _ n -> [TopName $ mkName $ nameBase n ++ "L"])

data Never

never :: Never -> a
never n = case n of

note :: a -> Maybe b -> Either a b
note _ (Just b) = Right b
note n Nothing = Left n