Overloaded records in Haskell.

OverloadedRecords.hs

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE OverloadedLabels #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeFamilies #-}

import qualified Control.Lens as Lens
import qualified Data.Default.Class as Default
import qualified Data.OverloadedRecords as OverloadedRecords
import qualified Data.OverloadedRecords.TH as OverloadedRecords


data A = A { aX :: Bool, aY :: Bool } deriving (Show)

$(OverloadedRecords.overloadedRecord Default.def ''A)


data B = B { bX :: Char, bZ :: Char } deriving (Show)

$(OverloadedRecords.overloadedRecord Default.def ''B)


main :: IO ()
main = do
    let a = A False True
    print (OverloadedRecords.get #x a) -- False
    print (a Lens.^. #y) -- True
    print (OverloadedRecords.set' #x True a) -- A {aX = True, aY = True}
    print (a Lens.& #y Lens..~ False) -- A {aX = False, aY = False}

    let b = B '@' '#'
    print (OverloadedRecords.get #x b) -- '@'
    print (b Lens.^. #z) -- '#'
    print (OverloadedRecords.set' #x '$' b) -- B {bX = '$', bZ = '#'}
    print (b Lens.& #z Lens..~ '!') -- B {bX = '@', bZ = '!'}