diff --git a/src/lib/Witch.hs b/src/lib/Witch.hs index 528cff2..94a1d3e 100644 --- a/src/lib/Witch.hs +++ b/src/lib/Witch.hs @@ -55,9 +55,6 @@ module Witch -- * Data types , Witch.TryCastException.TryCastException(..) - -- ** Casting - , Witch.Casting.Casting(Casting) - -- * Notes -- ** Motivation @@ -193,7 +190,6 @@ module Witch ) where import qualified Witch.Cast -import qualified Witch.Casting import Witch.Instances () import qualified Witch.Lift import qualified Witch.TryCast diff --git a/src/lib/Witch/Casting.hs b/src/lib/Witch/Casting.hs deleted file mode 100644 index a3e0138..0000000 --- a/src/lib/Witch/Casting.hs +++ /dev/null @@ -1,62 +0,0 @@ -{-# LANGUAGE FlexibleInstances #-} -{-# LANGUAGE MultiParamTypeClasses #-} -{-# LANGUAGE ScopedTypeVariables #-} -{-# LANGUAGE TypeApplications #-} - -module Witch.Casting where - -import qualified Data.Bifunctor as Bifunctor -import qualified Data.Function as Function -import qualified Witch.Cast as Cast - --- | This type mostly exists to make it easier to derive instances through --- some other type. It does this by leaning on the 'Cast.Cast' type class. For --- example, consider this data type: --- --- > data Toggle = Off | On --- > instance Cast Toggle String where --- > cast toggle = case toggle of --- > Off -> "off" --- > On -> "on" --- --- If you wanted to implement a 'Show' instance for @Toggle@ by going through --- a 'String', you would need to write something like this: --- --- > instance Show Toggle where --- > show = show . into @String --- --- That may not very complicated, but at the same time it is not very --- interesting. And it can be tricky if you want to keep other instances (like --- 'Read') in sync. That's where the 'Casting' type comes in! You can --- derive the above instance like so: --- --- > data Toggle = Off | On --- > deriving Show via Casting Toggle String -newtype Casting source target - = Casting source - --- | Uses @coerce@. -instance Cast.Cast s (Casting s t) - --- | Uses @coerce@. -instance Cast.Cast (Casting s t) s - -instance (Cast.Cast t s, Bounded t) => Bounded (Casting s t) where - maxBound = Cast.cast $ Cast.cast @t @s maxBound - minBound = Cast.cast $ Cast.cast @t @s minBound - -instance (Cast.Cast s t, Cast.Cast t s, Enum t) => Enum (Casting s t) where - fromEnum = fromEnum . Cast.cast @s @t . Cast.cast - toEnum = Cast.cast . Cast.cast @t @s . toEnum - -instance (Cast.Cast s t, Eq t) => Eq (Casting s t) where - (==) = Function.on (==) $ Cast.cast @s @t . Cast.cast - -instance (Cast.Cast s t, Ord t) => Ord (Casting s t) where - compare = Function.on compare $ Cast.cast @s @t . Cast.cast - -instance (Cast.Cast t s, Read t) => Read (Casting s t) where - readsPrec = fmap (fmap . Bifunctor.first $ Cast.cast . Cast.cast @t @s) . readsPrec - -instance (Cast.Cast s t, Show t) => Show (Casting s t) where - show = show . Cast.cast @s @t . Cast.cast diff --git a/src/test/Main.hs b/src/test/Main.hs index cdc0b4a..fafb84e 100644 --- a/src/test/Main.hs +++ b/src/test/Main.hs @@ -1659,46 +1659,6 @@ main = Hspec.hspec . Hspec.describe "Witch" $ do let f = Witch.cast @(Witch.TryCastException Bool Int) @LazyText.Text test $ f (Witch.TryCastException False Nothing) `Hspec.shouldBe` LazyText.pack "TryCastException @Bool @Int False Nothing" - -- Casting - - Hspec.describe "Casting" $ do - - Hspec.describe "Bounded" $ do - - Hspec.it "maxBound" $ do - maxBound `Hspec.shouldBe` Age maxBound - - Hspec.it "minBound" $ do - minBound `Hspec.shouldBe` Age minBound - - Hspec.describe "Enum" $ do - - Hspec.prop "fromEnum" $ \x -> - fromEnum (Age x) === fromEnum x - - Hspec.prop "toEnum" $ \x -> - toEnum x === Age (toEnum x) - - Hspec.describe "Eq" $ do - - Hspec.prop "==" $ \x -> - Age x === Age x - - Hspec.describe "Ord" $ do - - Hspec.prop "compare" $ \x y -> - compare (Age x) (Age y) === compare x y - - Hspec.describe "Read" $ do - - Hspec.prop "readMaybe" $ \x -> - Read.readMaybe x === fmap Age (Read.readMaybe x) - - Hspec.describe "Show" $ do - - Hspec.prop "show" $ \x -> - show (Age x) === show x - test :: Hspec.Example a => a -> Hspec.SpecWith (Hspec.Arg a) test = Hspec.it "" @@ -1716,7 +1676,7 @@ instance Exception.Exception Untested newtype Age = Age Int.Int8 - deriving (Bounded, Enum, Eq, Ord, Read, Show) via Witch.Casting Age Int.Int8 + deriving (Eq, Show) instance Witch.Cast Age Int.Int8 diff --git a/witch.cabal b/witch.cabal index d9114f4..fb7ff6b 100644 --- a/witch.cabal +++ b/witch.cabal @@ -47,7 +47,6 @@ library exposed-modules: Witch Witch.Cast - Witch.Casting Witch.Identity Witch.Instances Witch.Lift