5b0c027 · generic-lens

examples/Examples.hs+8

compare with master

unifiedsplit

@@ -20,6 +20,7 @@ import Data.Generics.Internal.Lens

20import Data.Generics.Product

21import Data.Generics.Sum

22import GHC.Generics

23+import Data.Generics.Labels

23

24

24data Animal = Animal

25data Animal = Animal

25 { name :: String

26 { name :: String

@@ -102,3 +103,10 @@ stuff ::

102 , HasField "bar" a' b' s t

103 , HasField "bar" a' b' s t

103 ) => s' -> t'

104 ) => s' -> t'

104stuff r = r & field @"test" . field @"bar" . position @15 .~ "hello"

105stuff r = r & field @"test" . field @"bar" . position @15 .~ "hello"

106+

107+stuff' ::

108+ ( HasPosition 15 s t a String

109+ , HasField "test" s' t' a' b'

110+ , HasField "bar" a' b' s t

111+ ) => s' -> t'

112+stuff' r = r & #test . #bar . position @15 .~ "hello"

generic-lens.cabal+1

@@ -25,6 +25,7 @@ library

25 , Data.Generics.Product.Positions

26 , Data.Generics.Product.Subtype

27 , Data.Generics.Product.Typed

28+ , Data.Generics.Labels

28

29

29 , Data.Generics.Sum

30 , Data.Generics.Sum

30 , Data.Generics.Sum.Any

31 , Data.Generics.Sum.Any

src/Data/Generics/Labels.hsnew file+36

@@ -0,0 +1,36 @@

1+{-# LANGUAGE CPP #-}

2+{-# LANGUAGE FlexibleInstances #-}

3+{-# LANGUAGE MultiParamTypeClasses #-}

4+{-# LANGUAGE ScopedTypeVariables #-}

5+{-# LANGUAGE TypeApplications #-}

6+{-# LANGUAGE TypeFamilies #-}

7+{-# LANGUAGE UndecidableInstances #-}

8+{-# OPTIONS_GHC -Wno-orphans #-}

9+

10+

11+--------------------------------------------------------------------------------

12+-- |

13+-- Module : Data.Generics.Labels

15+-- Maintainer : Csongor Kiss <kiss.csongor.kiss@gmail.com>

16+-- License : BSD3

17+-- Stability : experimental

18+-- Portability : non-portable

19+--

20+-- Provide an (orphan) IsLabel instance for field lenses

21+--

22+--------------------------------------------------------------------------------

23+

24+module Data.Generics.Labels () where

25+

26+import Data.Generics.Product

27+import GHC.OverloadedLabels

28+

29+

30+instance (HasField field s t a b, Functor f, sft ~ (s -> f t)) =>

31+ IsLabel field ((a -> f b) -> sft) where

32+#if __GLASGOW_HASKELL__ >= 802

33+ fromLabel = field @field

34+#else

35+ fromLabel _ = field @field

36+#endif