Foreign/C/Types.hs

    {-# LANGUAGE CPP #-}
    {-# LANGUAGE DerivingStrategies #-}
    {-# LANGUAGE GeneralizedNewtypeDeriving #-}
    {-# LANGUAGE MagicHash #-}
    {-# LANGUAGE NoImplicitPrelude #-}
    {-# LANGUAGE StandaloneDeriving #-}
    {-# LANGUAGE Trustworthy #-}
    {-# OPTIONS_GHC -Wno-unused-binds #-}
    -- XXX -Wno-unused-binds stops us warning about unused constructors,
    -- but really we should just remove them if we don't want them

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Foreign.C.Types
    -- Copyright   :  (c) The FFI task force 2001
    -- License     :  BSD-style (see the file libraries/base/LICENSE)
    --
    -- Maintainer  :  ffi@haskell.org
    -- Stability   :  provisional
    -- Portability :  portable
    --
    -- Mapping of C types to corresponding Haskell types.
    --
    -----------------------------------------------------------------------------

    module Foreign.C.Types
            ( -- * Representations of C types
              -- $ctypes

              -- ** #platform# Platform differences
              -- | This module contains platform specific information about types.
              -- __/As such, the types presented on this page reflect the/__
              -- __/platform on which the documentation was generated and may/__
              -- __/not coincide with the types on your platform./__

              -- ** Integral types
              -- | These types are represented as @newtype@s of
              -- types in "Data.Int" and "Data.Word", and are instances of
              -- 'Prelude.Eq', 'Prelude.Ord', 'Prelude.Num', 'Prelude.Read',
              -- 'Prelude.Show', 'Prelude.Enum', 'Data.Typeable.Typeable',
              -- 'Storable', 'Prelude.Bounded', 'Prelude.Real', 'Prelude.Integral'
              -- and 'Bits'.
              CChar(..),    CSChar(..),   CUChar(..)
            , CShort(..),   CUShort(..),  CInt(..),      CUInt(..)
            , CLong(..),    CULong(..)
            , CPtrdiff(..), CSize(..),    CWchar(..),    CSigAtomic(..)
            , CLLong(..),   CULLong(..), CBool(..)
            , CIntPtr(..),  CUIntPtr(..), CIntMax(..),   CUIntMax(..)

              -- ** Numeric types
              -- | These types are represented as @newtype@s of basic
              -- foreign types, and are instances of
              -- 'Prelude.Eq', 'Prelude.Ord', 'Prelude.Num', 'Prelude.Read',
              -- 'Prelude.Show', 'Prelude.Enum', 'Data.Typeable.Typeable' and
              -- 'Storable'.
            , CClock(..),   CTime(..),    CUSeconds(..), CSUSeconds(..)

            -- extracted from CTime, because we don't want this comment in
            -- the Haskell language reports:

            -- | To convert 'CTime' to 'Data.Time.UTCTime', use the following:
            --
            -- > \t -> posixSecondsToUTCTime (realToFrac t :: POSIXTime)
            --

              -- ** Floating types
              -- | These types are represented as @newtype@s of
              -- 'Prelude.Float' and 'Prelude.Double', and are instances of
              -- 'Prelude.Eq', 'Prelude.Ord', 'Prelude.Num', 'Prelude.Read',
              -- 'Prelude.Show', 'Prelude.Enum', 'Data.Typeable.Typeable', 'Storable',
              -- 'Prelude.Real', 'Prelude.Fractional', 'Prelude.Floating',
              -- 'Prelude.RealFrac' and 'Prelude.RealFloat'. That does mean
              -- that `CFloat`'s (respectively `CDouble`'s) instances of
              -- 'Prelude.Eq', 'Prelude.Ord', 'Prelude.Num' and
              -- 'Prelude.Fractional' are as badly behaved as `Prelude.Float`'s
              -- (respectively `Prelude.Double`'s).
            , CFloat(..),   CDouble(..)
            -- XXX GHC doesn't support CLDouble yet
            -- , CLDouble(..)

              -- See Note [Exporting constructors of marshallable foreign types]
              -- in Foreign.Ptr for why the constructors for these newtypes are
              -- exported.

              -- ** Other types

              -- Instances of: Eq and Storable
            , CFile,        CFpos,     CJmpBuf
            ) where

    import Foreign.Storable
    import Data.Bits        ( Bits(..), FiniteBits(..) )
    import Data.Int         ( Int8,  Int16,  Int32,  Int64  )
    import Data.Word        ( Word8, Word16, Word32, Word64 )

    import GHC.Base
    import GHC.Float
    import GHC.Enum
    import GHC.Real
    import GHC.Show
    import GHC.Read
    import GHC.Num

    #include "HsBaseConfig.h"
    #include "CTypes.h"

    -- | Haskell type representing the C @char@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CChar,HTYPE_CHAR)
    -- | Haskell type representing the C @signed char@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CSChar,HTYPE_SIGNED_CHAR)
    -- | Haskell type representing the C @unsigned char@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CUChar,HTYPE_UNSIGNED_CHAR)

    -- | Haskell type representing the C @short@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CShort,HTYPE_SHORT)
    -- | Haskell type representing the C @unsigned short@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CUShort,HTYPE_UNSIGNED_SHORT)

    -- | Haskell type representing the C @int@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CInt,HTYPE_INT)
    -- | Haskell type representing the C @unsigned int@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CUInt,HTYPE_UNSIGNED_INT)

    -- | Haskell type representing the C @long@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CLong,HTYPE_LONG)
    -- | Haskell type representing the C @unsigned long@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CULong,HTYPE_UNSIGNED_LONG)

    -- | Haskell type representing the C @long long@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CLLong,HTYPE_LONG_LONG)
    -- | Haskell type representing the C @unsigned long long@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CULLong,HTYPE_UNSIGNED_LONG_LONG)

    -- | Haskell type representing the C @bool@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    --
    -- @since 4.10.0.0
    INTEGRAL_TYPE_WITH_CTYPE(CBool,bool,HTYPE_BOOL)

    {-# RULES
    "fromIntegral/a->CChar"   fromIntegral = \x -> CChar   (fromIntegral x)
    "fromIntegral/a->CSChar"  fromIntegral = \x -> CSChar  (fromIntegral x)
    "fromIntegral/a->CUChar"  fromIntegral = \x -> CUChar  (fromIntegral x)
    "fromIntegral/a->CShort"  fromIntegral = \x -> CShort  (fromIntegral x)
    "fromIntegral/a->CUShort" fromIntegral = \x -> CUShort (fromIntegral x)
    "fromIntegral/a->CInt"    fromIntegral = \x -> CInt    (fromIntegral x)
    "fromIntegral/a->CUInt"   fromIntegral = \x -> CUInt   (fromIntegral x)
    "fromIntegral/a->CLong"   fromIntegral = \x -> CLong   (fromIntegral x)
    "fromIntegral/a->CULong"  fromIntegral = \x -> CULong  (fromIntegral x)
    "fromIntegral/a->CLLong"  fromIntegral = \x -> CLLong  (fromIntegral x)
    "fromIntegral/a->CULLong" fromIntegral = \x -> CULLong (fromIntegral x)

    "fromIntegral/CChar->a"   fromIntegral = \(CChar   x) -> fromIntegral x
    "fromIntegral/CSChar->a"  fromIntegral = \(CSChar  x) -> fromIntegral x
    "fromIntegral/CUChar->a"  fromIntegral = \(CUChar  x) -> fromIntegral x
    "fromIntegral/CShort->a"  fromIntegral = \(CShort  x) -> fromIntegral x
    "fromIntegral/CUShort->a" fromIntegral = \(CUShort x) -> fromIntegral x
    "fromIntegral/CInt->a"    fromIntegral = \(CInt    x) -> fromIntegral x
    "fromIntegral/CUInt->a"   fromIntegral = \(CUInt   x) -> fromIntegral x
    "fromIntegral/CLong->a"   fromIntegral = \(CLong   x) -> fromIntegral x
    "fromIntegral/CULong->a"  fromIntegral = \(CULong  x) -> fromIntegral x
    "fromIntegral/CLLong->a"  fromIntegral = \(CLLong  x) -> fromIntegral x
    "fromIntegral/CULLong->a" fromIntegral = \(CULLong x) -> fromIntegral x
    "fromIntegral/CBool->a"   fromIntegral = \(CBool   x) -> fromIntegral x
     #-}

    -- | Haskell type representing the C @float@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    FLOATING_TYPE(CFloat,HTYPE_FLOAT)
    -- | Haskell type representing the C @double@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    FLOATING_TYPE(CDouble,HTYPE_DOUBLE)
    -- XXX GHC doesn't support CLDouble yet

    {-# RULES
    "realToFrac/a->CFloat"    realToFrac = \x -> CFloat   (realToFrac x)
    "realToFrac/a->CDouble"   realToFrac = \x -> CDouble  (realToFrac x)

    "realToFrac/CFloat->a"    realToFrac = \(CFloat   x) -> realToFrac x
    "realToFrac/CDouble->a"   realToFrac = \(CDouble  x) -> realToFrac x
     #-}

    -- GHC doesn't support CLDouble yet
    -- "realToFrac/a->CLDouble"  realToFrac = \x -> CLDouble (realToFrac x)
    -- "realToFrac/CLDouble->a"  realToFrac = \(CLDouble x) -> realToFrac x

    -- | Haskell type representing the C @ptrdiff_t@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CPtrdiff,HTYPE_PTRDIFF_T)
    -- | Haskell type representing the C @size_t@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CSize,HTYPE_SIZE_T)
    -- | Haskell type representing the C @wchar_t@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CWchar,HTYPE_WCHAR_T)
    -- | Haskell type representing the C @sig_atomic_t@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    INTEGRAL_TYPE(CSigAtomic,HTYPE_SIG_ATOMIC_T)

    {-# RULES
    "fromIntegral/a->CPtrdiff"   fromIntegral = \x -> CPtrdiff   (fromIntegral x)
    "fromIntegral/a->CSize"      fromIntegral = \x -> CSize      (fromIntegral x)
    "fromIntegral/a->CWchar"     fromIntegral = \x -> CWchar     (fromIntegral x)
    "fromIntegral/a->CSigAtomic" fromIntegral = \x -> CSigAtomic (fromIntegral x)

    "fromIntegral/CPtrdiff->a"   fromIntegral = \(CPtrdiff   x) -> fromIntegral x
    "fromIntegral/CSize->a"      fromIntegral = \(CSize      x) -> fromIntegral x
    "fromIntegral/CWchar->a"     fromIntegral = \(CWchar     x) -> fromIntegral x
    "fromIntegral/CSigAtomic->a" fromIntegral = \(CSigAtomic x) -> fromIntegral x
     #-}

    -- | Haskell type representing the C @clock_t@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    ARITHMETIC_TYPE(CClock,HTYPE_CLOCK_T)
    -- | Haskell type representing the C @time_t@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    ARITHMETIC_TYPE(CTime,HTYPE_TIME_T)
    -- | Haskell type representing the C @useconds_t@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    --
    -- @since 4.4.0.0

    ARITHMETIC_TYPE(CUSeconds,HTYPE_USECONDS_T)
    -- | Haskell type representing the C @suseconds_t@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    --
    -- @since 4.4.0.0
    ARITHMETIC_TYPE(CSUSeconds,HTYPE_SUSECONDS_T)

    -- FIXME: Implement and provide instances for Eq and Storable
    -- | Haskell type representing the C @FILE@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    data CFile = CFile
    -- | Haskell type representing the C @fpos_t@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    data CFpos = CFpos
    -- | Haskell type representing the C @jmp_buf@ type.
    -- /(The concrete types of "Foreign.C.Types#platform" are platform-specific.)/
    data CJmpBuf = CJmpBuf

    INTEGRAL_TYPE(CIntPtr,HTYPE_INTPTR_T)
    INTEGRAL_TYPE(CUIntPtr,HTYPE_UINTPTR_T)
    INTEGRAL_TYPE(CIntMax,HTYPE_INTMAX_T)
    INTEGRAL_TYPE(CUIntMax,HTYPE_UINTMAX_T)

    {-# RULES
    "fromIntegral/a->CIntPtr"  fromIntegral = \x -> CIntPtr  (fromIntegral x)
    "fromIntegral/a->CUIntPtr" fromIntegral = \x -> CUIntPtr (fromIntegral x)
    "fromIntegral/a->CIntMax"  fromIntegral = \x -> CIntMax  (fromIntegral x)
    "fromIntegral/a->CUIntMax" fromIntegral = \x -> CUIntMax (fromIntegral x)
     #-}

    -- C99 types which are still missing include:
    -- wint_t, wctrans_t, wctype_t

    {- $ctypes

    These types are needed to accurately represent C function prototypes,
    in order to access C library interfaces in Haskell.  The Haskell system
    is not required to represent those types exactly as C does, but the
    following guarantees are provided concerning a Haskell type @CT@
    representing a C type @t@:

    * If a C function prototype has @t@ as an argument or result type, the
      use of @CT@ in the corresponding position in a foreign declaration
      permits the Haskell program to access the full range of values encoded
      by the C type; and conversely, any Haskell value for @CT@ has a valid
      representation in C.

    * @'sizeOf' ('Prelude.undefined' :: CT)@ will yield the same value as
      @sizeof (t)@ in C.

    * @'alignment' ('Prelude.undefined' :: CT)@ matches the alignment
      constraint enforced by the C implementation for @t@.

    * The members 'peek' and 'poke' of the 'Storable' class map all values
      of @CT@ to the corresponding value of @t@ and vice versa.

    * When an instance of 'Prelude.Bounded' is defined for @CT@, the values
      of 'Prelude.minBound' and 'Prelude.maxBound' coincide with @t_MIN@
      and @t_MAX@ in C.

    * When an instance of 'Prelude.Eq' or 'Prelude.Ord' is defined for @CT@,
      the predicates defined by the type class implement the same relation
      as the corresponding predicate in C on @t@.

    * When an instance of 'Prelude.Num', 'Prelude.Read', 'Prelude.Integral',
      'Prelude.Fractional', 'Prelude.Floating', 'Prelude.RealFrac', or
      'Prelude.RealFloat' is defined for @CT@, the arithmetic operations
      defined by the type class implement the same function as the
      corresponding arithmetic operations (if available) in C on @t@.

    * When an instance of 'Bits' is defined for @CT@, the bitwise operation
      defined by the type class implement the same function as the
      corresponding bitwise operation in C on @t@.

    -}