Types.hs

{-# LANGUAGE CPP, PackageImports #-}
#if __GLASGOW_HASKELL__ >= 701
{-# LANGUAGE Safe #-}
#endif

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

          -- ** Integral types
          -- | These types are 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', 'Storable',
          -- 'Prelude.Bounded', 'Prelude.Real', 'Prelude.Integral' and
          -- 'Bits'.
          CChar,  CSChar,  CUChar
        , CShort, CUShort, CInt,   CUInt
        , CLong,  CULong
        , CPtrdiff, CSize, CWchar, CSigAtomic
        , CLLong, CULLong
        , CIntPtr, CUIntPtr
        , CIntMax, CUIntMax

          -- ** Numeric types
          -- | These types are 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' and 'Storable'.
        , CClock,   CTime

          -- ** Floating types
          -- | These types are 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', 'Storable',
          -- 'Prelude.Real', 'Prelude.Fractional', 'Prelude.Floating',
          -- 'Prelude.RealFrac' and 'Prelude.RealFloat'.
        , CFloat,  CDouble
-- GHC doesn't support CLDouble yet
#ifdef HASKELL_REPORT
        , CLDouble
#endif
          -- ** Other types

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

  ) where
import "base" Foreign.C.Types

{- $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@.

-}