Expose maybeTryCast function

src/lib/Witch.hs

@@ -140,6 +140,7 @@ module Witch
   , Witch.Utility.as
   , Witch.Utility.over
   , Witch.Utility.via
+  , Witch.Utility.maybeTryCast
   , Witch.Utility.tryVia
 
   -- ** Unsafe

src/lib/Witch/Instances.hs

@@ -59,27 +59,27 @@ instance Cast.Cast Int.Int8 Integer where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int8 Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int8 Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int8 Word.Word32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int8 Word.Word64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int8 Word where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral' when the input is non-negative.
 instance TryCast.TryCast Int.Int8 Natural.Natural where
-  tryCast = maybeTryCast fromNonNegativeIntegral
+  tryCast = Utility.maybeTryCast fromNonNegativeIntegral
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Int.Int8 Float where
@@ -93,7 +93,7 @@ instance Cast.Cast Int.Int8 Double where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int16 Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Int.Int16 Int.Int32 where
@@ -113,27 +113,27 @@ instance Cast.Cast Int.Int16 Integer where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int16 Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int16 Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int16 Word.Word32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int16 Word.Word64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int16 Word where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral' when the input is non-negative.
 instance TryCast.TryCast Int.Int16 Natural.Natural where
-  tryCast = maybeTryCast fromNonNegativeIntegral
+  tryCast = Utility.maybeTryCast fromNonNegativeIntegral
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Int.Int16 Float where
@@ -147,11 +147,11 @@ instance Cast.Cast Int.Int16 Double where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int32 Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int32 Int.Int16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Int.Int32 Int.Int64 where
@@ -159,7 +159,7 @@ instance Cast.Cast Int.Int32 Int.Int64 where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int32 Int where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Int.Int32 Integer where
@@ -167,32 +167,32 @@ instance Cast.Cast Int.Int32 Integer where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int32 Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int32 Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int32 Word.Word32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int32 Word.Word64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int32 Word where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral' when the input is non-negative.
 instance TryCast.TryCast Int.Int32 Natural.Natural where
-  tryCast = maybeTryCast fromNonNegativeIntegral
+  tryCast = Utility.maybeTryCast fromNonNegativeIntegral
 
 -- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
 -- inclusive.
 instance TryCast.TryCast Int.Int32 Float where
-  tryCast = maybeTryCast $ \s -> if -maxFloat <= s && s <= maxFloat
+  tryCast = Utility.maybeTryCast $ \s -> if -maxFloat <= s && s <= maxFloat
     then Just $ fromIntegral s
     else Nothing
 
@@ -204,19 +204,19 @@ instance Cast.Cast Int.Int32 Double where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int64 Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int64 Int.Int16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int64 Int.Int32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int64 Int where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Int.Int64 Integer where
@@ -224,39 +224,39 @@ instance Cast.Cast Int.Int64 Integer where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int64 Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int64 Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int64 Word.Word32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int64 Word.Word64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int.Int64 Word where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral' when the input is non-negative.
 instance TryCast.TryCast Int.Int64 Natural.Natural where
-  tryCast = maybeTryCast fromNonNegativeIntegral
+  tryCast = Utility.maybeTryCast fromNonNegativeIntegral
 
 -- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
 -- inclusive.
 instance TryCast.TryCast Int.Int64 Float where
-  tryCast = maybeTryCast $ \s -> if -maxFloat <= s && s <= maxFloat
+  tryCast = Utility.maybeTryCast $ \s -> if -maxFloat <= s && s <= maxFloat
     then Just $ fromIntegral s
     else Nothing
 
 -- | Uses 'fromIntegral' when the input is between -9,007,199,254,740,991 and
 -- 9,007,199,254,740,991 inclusive.
 instance TryCast.TryCast Int.Int64 Double where
-  tryCast = maybeTryCast $ \s -> if -maxDouble <= s && s <= maxDouble
+  tryCast = Utility.maybeTryCast $ \s -> if -maxDouble <= s && s <= maxDouble
     then Just $ fromIntegral s
     else Nothing
 
@@ -264,15 +264,15 @@ instance TryCast.TryCast Int.Int64 Double where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int Int.Int16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int Int.Int32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Int Int.Int64 where
@@ -284,39 +284,39 @@ instance Cast.Cast Int Integer where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int Word.Word32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int Word.Word64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Int Word where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral' when the input is non-negative.
 instance TryCast.TryCast Int Natural.Natural where
-  tryCast = maybeTryCast fromNonNegativeIntegral
+  tryCast = Utility.maybeTryCast fromNonNegativeIntegral
 
 -- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
 -- inclusive.
 instance TryCast.TryCast Int Float where
-  tryCast = maybeTryCast $ \s -> if -maxFloat <= s && s <= maxFloat
+  tryCast = Utility.maybeTryCast $ \s -> if -maxFloat <= s && s <= maxFloat
     then Just $ fromIntegral s
     else Nothing
 
 -- | Uses 'fromIntegral' when the input is between -9,007,199,254,740,991 and
 -- 9,007,199,254,740,991 inclusive.
 instance TryCast.TryCast Int Double where
-  tryCast = maybeTryCast $ \s ->
+  tryCast = Utility.maybeTryCast $ \s ->
     if (toInteger (maxBound :: Int) <= maxDouble)
         || (-maxDouble <= s && s <= maxDouble)
       then Just $ fromIntegral s
@@ -326,43 +326,43 @@ instance TryCast.TryCast Int Double where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Int.Int16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Int.Int32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Int.Int64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Int where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Word.Word32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Word.Word64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Integer Word where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromInteger' when the input is non-negative.
 instance TryCast.TryCast Integer Natural.Natural where
@@ -371,19 +371,19 @@ instance TryCast.TryCast Integer Natural.Natural where
   -- @fromIntegral@ with @fromInteger@, we can work around the bug.
   -- https://mail.haskell.org/pipermail/haskell-cafe/2021-March/133540.html
   tryCast =
-    maybeTryCast $ \s -> if s < 0 then Nothing else Just $ fromInteger s
+    Utility.maybeTryCast $ \s -> if s < 0 then Nothing else Just $ fromInteger s
 
 -- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
 -- inclusive.
 instance TryCast.TryCast Integer Float where
-  tryCast = maybeTryCast $ \s -> if -maxFloat <= s && s <= maxFloat
+  tryCast = Utility.maybeTryCast $ \s -> if -maxFloat <= s && s <= maxFloat
     then Just $ fromIntegral s
     else Nothing
 
 -- | Uses 'fromIntegral' when the input is between -9,007,199,254,740,991 and
 -- 9,007,199,254,740,991 inclusive.
 instance TryCast.TryCast Integer Double where
-  tryCast = maybeTryCast $ \s -> if -maxDouble <= s && s <= maxDouble
+  tryCast = Utility.maybeTryCast $ \s -> if -maxDouble <= s && s <= maxDouble
     then Just $ fromIntegral s
     else Nothing
 
@@ -411,7 +411,7 @@ instance Cast.Cast Word.Word8 Natural.Natural where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word8 Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word.Word8 Int.Int16 where
@@ -445,7 +445,7 @@ instance Cast.Cast Word.Word8 Double where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word16 Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word.Word16 Word.Word32 where
@@ -465,11 +465,11 @@ instance Cast.Cast Word.Word16 Natural.Natural where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word16 Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word16 Int.Int16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word.Word16 Int.Int32 where
@@ -499,11 +499,11 @@ instance Cast.Cast Word.Word16 Double where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word32 Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word32 Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word.Word32 Word.Word64 where
@@ -511,7 +511,7 @@ instance Cast.Cast Word.Word32 Word.Word64 where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word32 Word where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word.Word32 Natural.Natural where
@@ -519,15 +519,15 @@ instance Cast.Cast Word.Word32 Natural.Natural where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word32 Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word32 Int.Int16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word32 Int.Int32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word.Word32 Int.Int64 where
@@ -535,7 +535,7 @@ instance Cast.Cast Word.Word32 Int.Int64 where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word32 Int where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word.Word32 Integer where
@@ -544,7 +544,7 @@ instance Cast.Cast Word.Word32 Integer where
 -- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
 -- inclusive.
 instance TryCast.TryCast Word.Word32 Float where
-  tryCast = maybeTryCast
+  tryCast = Utility.maybeTryCast
     $ \s -> if s <= maxFloat then Just $ fromIntegral s else Nothing
 
 -- | Uses 'fromIntegral'.
@@ -555,19 +555,19 @@ instance Cast.Cast Word.Word32 Double where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word64 Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word64 Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word64 Word.Word32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word64 Word where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word.Word64 Natural.Natural where
@@ -575,23 +575,23 @@ instance Cast.Cast Word.Word64 Natural.Natural where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word64 Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word64 Int.Int16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word64 Int.Int32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word64 Int.Int64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word.Word64 Int where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word.Word64 Integer where
@@ -600,28 +600,28 @@ instance Cast.Cast Word.Word64 Integer where
 -- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
 -- inclusive.
 instance TryCast.TryCast Word.Word64 Float where
-  tryCast = maybeTryCast
+  tryCast = Utility.maybeTryCast
     $ \s -> if s <= maxFloat then Just $ fromIntegral s else Nothing
 
 -- | Uses 'fromIntegral' when the input is between -9,007,199,254,740,991 and
 -- 9,007,199,254,740,991 inclusive.
 instance TryCast.TryCast Word.Word64 Double where
-  tryCast = maybeTryCast
+  tryCast = Utility.maybeTryCast
     $ \s -> if s <= maxDouble then Just $ fromIntegral s else Nothing
 
 -- Word
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word Word.Word32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word Word.Word64 where
@@ -633,23 +633,23 @@ instance Cast.Cast Word Natural.Natural where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word Int.Int16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word Int.Int32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word Int.Int64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Word Int where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Word Integer where
@@ -658,13 +658,13 @@ instance Cast.Cast Word Integer where
 -- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
 -- inclusive.
 instance TryCast.TryCast Word Float where
-  tryCast = maybeTryCast
+  tryCast = Utility.maybeTryCast
     $ \s -> if s <= maxFloat then Just $ fromIntegral s else Nothing
 
 -- | Uses 'fromIntegral' when the input is between -9,007,199,254,740,991 and
 -- 9,007,199,254,740,991 inclusive.
 instance TryCast.TryCast Word Double where
-  tryCast = maybeTryCast $ \s ->
+  tryCast = Utility.maybeTryCast $ \s ->
     if (toInteger (maxBound :: Word) <= maxDouble) || (s <= maxDouble)
       then Just $ fromIntegral s
       else Nothing
@@ -673,43 +673,43 @@ instance TryCast.TryCast Word Double where
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Word.Word8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Word.Word16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Word.Word32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Word.Word64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Word where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Int.Int8 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Int.Int16 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Int.Int32 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Int.Int64 where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryCast.TryCast Natural.Natural Int where
-  tryCast = maybeTryCast Bits.toIntegralSized
+  tryCast = Utility.maybeTryCast Bits.toIntegralSized
 
 -- | Uses 'fromIntegral'.
 instance Cast.Cast Natural.Natural Integer where
@@ -718,13 +718,13 @@ instance Cast.Cast Natural.Natural Integer where
 -- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
 -- inclusive.
 instance TryCast.TryCast Natural.Natural Float where
-  tryCast = maybeTryCast
+  tryCast = Utility.maybeTryCast
     $ \s -> if s <= maxFloat then Just $ fromIntegral s else Nothing
 
 -- | Uses 'fromIntegral' when the input is between -9,007,199,254,740,991 and
 -- 9,007,199,254,740,991 inclusive.
 instance TryCast.TryCast Natural.Natural Double where
-  tryCast = maybeTryCast
+  tryCast = Utility.maybeTryCast
     $ \s -> if s <= maxDouble then Just $ fromIntegral s else Nothing
 
 -- Float
@@ -785,7 +785,7 @@ instance TryCast.TryCast Float Natural.Natural where
 
 -- | Uses 'toRational' when the input is not NaN or infinity.
 instance TryCast.TryCast Float Rational where
-  tryCast = maybeTryCast
+  tryCast = Utility.maybeTryCast
     $ \s -> if isNaN s || isInfinite s then Nothing else Just $ toRational s
 
 -- | Uses 'realToFrac'.
@@ -850,7 +850,7 @@ instance TryCast.TryCast Double Natural.Natural where
 
 -- | Uses 'toRational' when the input is not NaN or infinity.
 instance TryCast.TryCast Double Rational where
-  tryCast = maybeTryCast
+  tryCast = Utility.maybeTryCast
     $ \s -> if isNaN s || isInfinite s then Nothing else Just $ toRational s
 
 -- | Uses 'realToFrac'. This necessarily loses some precision.
@@ -865,7 +865,7 @@ instance Integral a => Cast.Cast a (Ratio.Ratio a) where
 
 -- | Uses 'Ratio.numerator' when the denominator is 1.
 instance (Eq a, Num a) => TryCast.TryCast (Ratio.Ratio a) a where
-  tryCast = maybeTryCast $ \s ->
+  tryCast = Utility.maybeTryCast $ \s ->
     if Ratio.denominator s == 1 then Just $ Ratio.numerator s else Nothing
 
 -- | Uses 'fromRational'. This necessarily loses some precision.
@@ -896,14 +896,14 @@ instance Num a => Cast.Cast a (Complex.Complex a) where
 
 -- | Uses 'Complex.realPart' when the imaginary part is 0.
 instance (Eq a, Num a) => TryCast.TryCast (Complex.Complex a) a where
-  tryCast = maybeTryCast $ \s ->
+  tryCast = Utility.maybeTryCast $ \s ->
     if Complex.imagPart s == 0 then Just $ Complex.realPart s else Nothing
 
 -- NonEmpty
 
 -- | Uses 'NonEmpty.nonEmpty'.
 instance TryCast.TryCast [a] (NonEmpty.NonEmpty a) where
-  tryCast = maybeTryCast NonEmpty.nonEmpty
+  tryCast = Utility.maybeTryCast NonEmpty.nonEmpty
 
 -- | Uses 'NonEmpty.toList'.
 instance Cast.Cast (NonEmpty.NonEmpty a) [a] where
@@ -1085,12 +1085,6 @@ instance
 fromNonNegativeIntegral :: (Integral s, Num t) => s -> Maybe t
 fromNonNegativeIntegral x = if x < 0 then Nothing else Just $ fromIntegral x
 
-maybeTryCast
-  :: (s -> Maybe t) -> s -> Either (TryCastException.TryCastException s t) t
-maybeTryCast f s = case f s of
-  Nothing -> Left $ TryCastException.TryCastException s Nothing
-  Just t -> Right t
-
 -- | The maximum integral value that can be unambiguously represented as a
 -- 'Float'. Equal to 16,777,215.
 maxFloat :: Num a => a

src/lib/Witch/Utility.hs

@@ -125,6 +125,24 @@ tryInto
   -> Either (TryCastException.TryCastException source target) target
 tryInto = TryCast.tryCast
 
+-- | This function can be used to implement 'TryCast.tryCast' with a function
+-- that returns 'Maybe'. For example:
+--
+-- > -- Avoid this:
+-- > tryCast x = case f x of
+-- >   Nothing -> Left $ TryCastException x Nothing
+-- >   Just y -> Right y
+-- >
+-- > -- Prefer this:
+-- > tryCast = maybeTryCast f
+maybeTryCast
+  :: (source -> Maybe target)
+  -> source
+  -> Either (TryCastException.TryCastException source target) target
+maybeTryCast f s = case f s of
+  Nothing -> Left $ TryCastException.TryCastException s Nothing
+  Just t -> Right t
+
 -- | This is similar to 'via' except that it works with 'TryCast.TryCast'
 -- instances instead. This function is especially convenient because juggling
 -- the types in the 'TryCastException.TryCastException' can be tedious.