-- Hoogle documentation, generated by Haddock -- See Hoogle, http://www.haskell.org/hoogle/ -- | Convert values from one type into another. -- -- Witch converts values from one type into another. @package witch @version 0.0.0.4 -- | This module provides the Cast type class for converting values -- between various types. This aims to be a common interface for the -- various xToY or yFromX functions you might write -- instead. It is inspired by the std::convert::From trait that -- the Rust programming language provides. -- -- Many Haskell libraries already provide similar functionality. Here's -- how this module compares to them: -- -- module Witch -- | This type class represents a way to convert values from some type into -- another type. The constraint Cast a b means that you can -- convert from a value of type a into a value of type -- b. -- -- This is primarily intended for "zero cost" conversions like -- newtypes. For example if you wanted to have a type to -- represent someone's name, you could say: -- -- 
--   newtype Name = Name String
--   instance Cast String Name
--   instance Cast Name String
--
-- -- And then you could convert back and forth between Names and -- Strings: -- -- 
--   let someString = "Taylor"
--   let someName = Name someString
--   into @Name someString -- convert from string to name
--   into @String someName -- convert from name to string
--
-- -- This type class does not have any laws, but it does have some -- expectations: -- -- class Cast source target -- | This method implements the conversion of a value between types. In -- practice most instances don't need an explicit implementation. At call -- sites you'll usually want to use from or into instead of -- cast. -- -- The default implementation of cast simply calls coerce, -- which works for types that have the same runtime representation. cast :: Cast source target => source -> target -- | This method implements the conversion of a value between types. In -- practice most instances don't need an explicit implementation. At call -- sites you'll usually want to use from or into instead of -- cast. -- -- The default implementation of cast simply calls coerce, -- which works for types that have the same runtime representation. cast :: (Cast source target, Coercible source target) => source -> target -- | This function converts a value from one type into another. This is -- intended to be used with the TypeApplications language -- extension. The Ambiguous type in the signature makes a type -- application required. If you'd prefer not to provide a type -- application, use cast instead. -- -- As an example, here are a few ways to convert from an Int into -- an Integer: -- -- 
--   from @Int @Integer 123
--   from @_ @Integer (123 :: Int)
--   from @Int @_ 123 :: Integer
--   from @Int 123 :: Integer
--
-- -- Often the context around an expression will make the explicit type -- signatures unnecessary. If you find yourself using a partial type -- signature, consider using into instead. For example: -- -- 
--   let someInt = 123 :: Int
--   from @_ @Integer someInt -- avoid this
--   into @Integer someInt -- prefer this
--
from :: forall s target source. (Ambiguous s ~ source, Cast source target) => source -> target -- | This function converts a value from one type into another. This is the -- same as from except that the type variables are in the opposite -- order. into :: forall t source target. (Ambiguous t ~ target, Cast source target) => source -> target -- | This function converts a value from one type into another by going -- through some third type. This is the same as calling cast (or -- from or into) twice, but can sometimes be more -- convenient. -- -- Note that the type in the middle of the conversion is the first type -- variable of this function. In other words, via @b @a @c first -- converts from a to b, and then from b to -- c. Often both a and c will be inferred from -- context, which means you can just write via @b. via :: forall through source target. (Cast source through, Cast through target) => source -> target instance Witch.Cast a a instance Witch.Cast a (x -> a) instance Witch.Cast a [a] instance Witch.Cast a (GHC.Maybe.Maybe a) instance Witch.Cast a (Data.Either.Either a x) instance Witch.Cast a (Data.Either.Either x a) instance Witch.Cast Data.Void.Void x instance Witch.Cast (a, x) a instance Witch.Cast (x, a) a instance Witch.Cast (a, b) (b, a) instance Witch.Cast (GHC.Base.NonEmpty a) [a] instance Witch.Cast GHC.Word.Word8 GHC.Word.Word16 instance Witch.Cast GHC.Word.Word16 GHC.Word.Word32 instance Witch.Cast GHC.Word.Word32 GHC.Word.Word64 instance Witch.Cast GHC.Types.Word GHC.Natural.Natural instance Witch.Cast GHC.Natural.Natural GHC.Integer.Type.Integer instance Witch.Cast GHC.Int.Int8 GHC.Int.Int16 instance Witch.Cast GHC.Int.Int16 GHC.Int.Int32 instance Witch.Cast GHC.Int.Int32 GHC.Int.Int64 instance Witch.Cast GHC.Types.Int GHC.Integer.Type.Integer instance Witch.Cast GHC.Integer.Type.Integer GHC.Real.Rational instance Witch.Cast GHC.Types.Float GHC.Types.Double instance Witch.Cast GHC.Types.Bool GHC.Types.Int instance Witch.Cast GHC.Types.Char GHC.Types.Int instance Witch.Cast [GHC.Word.Word8] Data.ByteString.Internal.ByteString instance Witch.Cast Data.ByteString.Internal.ByteString [GHC.Word.Word8] instance Witch.Cast Data.ByteString.Internal.ByteString Data.ByteString.Lazy.Internal.ByteString instance Witch.Cast Data.ByteString.Lazy.Internal.ByteString Data.ByteString.Internal.ByteString instance Witch.Cast GHC.Base.String Data.Text.Internal.Text instance Witch.Cast Data.Text.Internal.Text GHC.Base.String instance Witch.Cast Data.Text.Internal.Text Data.Text.Internal.Lazy.Text instance Witch.Cast Data.Text.Internal.Lazy.Text Data.Text.Internal.Text instance Witch.Cast [a] (Data.Sequence.Internal.Seq a) instance Witch.Cast (Data.Sequence.Internal.Seq a) [a] instance GHC.Classes.Ord a => Witch.Cast [a] (Data.Set.Internal.Set a) instance Witch.Cast (Data.Set.Internal.Set a) [a] instance GHC.Classes.Ord k => Witch.Cast [(k, v)] (Data.Map.Internal.Map k v) instance Witch.Cast (Data.Map.Internal.Map k v) [(k, v)]