Add instances for text

src/lib/Witch/Instances.hs

@@ -22,6 +22,8 @@ import qualified Data.Map as Map
 import qualified Data.Ratio as Ratio
 import qualified Data.Sequence as Seq
 import qualified Data.Set as Set
+import qualified Data.Text as Text
+import qualified Data.Text.Lazy as LazyText
 import qualified Data.Word as Word
 import qualified Numeric.Natural as Natural
 import qualified Witch.Cast as Cast
@@ -763,6 +765,28 @@ instance Cast.Cast ShortByteString.ShortByteString [Word.Word8] where
 instance Cast.Cast ShortByteString.ShortByteString ByteString.ByteString where
   cast = ShortByteString.fromShort
 
+-- Text
+
+instance Cast.Cast String Text.Text where
+  cast = Text.pack
+
+instance Cast.Cast Text.Text String where
+  cast = Text.unpack
+
+instance Cast.Cast Text.Text LazyText.Text where
+  cast = LazyText.fromStrict
+
+-- LazyText
+
+instance Cast.Cast String LazyText.Text where
+  cast = LazyText.pack
+
+instance Cast.Cast LazyText.Text String where
+  cast = LazyText.unpack
+
+instance Cast.Cast LazyText.Text Text.Text where
+  cast = LazyText.toStrict
+
 fromNonNegativeIntegral :: (Integral s, Num t) => s -> Maybe t
 fromNonNegativeIntegral x = if x < 0 then Nothing else Just $ fromIntegral x
 

src/test/Main.hs

@@ -19,6 +19,8 @@ import qualified Data.Map as Map
 import qualified Data.Ratio as Ratio
 import qualified Data.Sequence as Seq
 import qualified Data.Set as Set
+import qualified Data.Text as Text
+import qualified Data.Text.Lazy as LazyText
 import qualified Data.Word as Word
 import qualified Numeric.Natural as Natural
 import qualified Test.Hspec as Hspec
@@ -1567,6 +1569,46 @@ main = Hspec.hspec . Hspec.describe "Witch" $ do
       test $ f (ShortByteString.pack [0x00]) `Hspec.shouldBe` ByteString.pack [0x00]
       test $ f (ShortByteString.pack [0x0f, 0xf0]) `Hspec.shouldBe` ByteString.pack [0x0f, 0xf0]
 
+    -- Text
+
+    Hspec.describe "Cast String Text" $ do
+      let f = Witch.cast @String @Text.Text
+      test $ f "" `Hspec.shouldBe` Text.pack ""
+      test $ f "a" `Hspec.shouldBe` Text.pack "a"
+      test $ f "ab" `Hspec.shouldBe` Text.pack "ab"
+
+    Hspec.describe "Cast Text String" $ do
+      let f = Witch.cast @Text.Text @String
+      test $ f (Text.pack "") `Hspec.shouldBe` ""
+      test $ f (Text.pack "a") `Hspec.shouldBe` "a"
+      test $ f (Text.pack "ab") `Hspec.shouldBe` "ab"
+
+    Hspec.describe "Cast Text LazyText" $ do
+      let f = Witch.cast @Text.Text @LazyText.Text
+      test $ f (Text.pack "") `Hspec.shouldBe` LazyText.pack ""
+      test $ f (Text.pack "a") `Hspec.shouldBe` LazyText.pack "a"
+      test $ f (Text.pack "ab") `Hspec.shouldBe` LazyText.pack "ab"
+
+    -- LazyText
+
+    Hspec.describe "Cast String LazyText" $ do
+      let f = Witch.cast @String @LazyText.Text
+      test $ f "" `Hspec.shouldBe` LazyText.pack ""
+      test $ f "a" `Hspec.shouldBe` LazyText.pack "a"
+      test $ f "ab" `Hspec.shouldBe` LazyText.pack "ab"
+
+    Hspec.describe "Cast LazyText String" $ do
+      let f = Witch.cast @LazyText.Text @String
+      test $ f (LazyText.pack "") `Hspec.shouldBe` ""
+      test $ f (LazyText.pack "a") `Hspec.shouldBe` "a"
+      test $ f (LazyText.pack "ab") `Hspec.shouldBe` "ab"
+
+    Hspec.describe "Cast LazyText Text" $ do
+      let f = Witch.cast @LazyText.Text @Text.Text
+      test $ f (LazyText.pack "") `Hspec.shouldBe` Text.pack ""
+      test $ f (LazyText.pack "a") `Hspec.shouldBe` Text.pack "a"
+      test $ f (LazyText.pack "ab") `Hspec.shouldBe` Text.pack "ab"
+
 test :: Hspec.Example a => a -> Hspec.SpecWith (Hspec.Arg a)
 test = Hspec.it ""
 

witch.cabal

@@ -21,6 +21,7 @@ common basics
     , base >= 4.13.0 && < 4.16
     , bytestring >= 0.10.12 && < 0.11
     , containers >= 0.6.2 && < 0.7
+    , text >= 1.2.4 && < 1.3
   default-language: Haskell2010
   ghc-options:
     -Weverything