base-4.6.0.0: Basic libraries

Portabilityportable
Stabilityprovisional
Maintainer[email protected]
Safe HaskellTrustworthy

Foreign.C.Types

Contents

Description

Mapping of C types to corresponding Haskell types.

Synopsis

Representations of C types

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 (undefined :: CT) will yield the same value as sizeof (t) in C.
  • alignment (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 Bounded is defined for CT, the values of minBound and maxBound coincide with t_MIN and t_MAX in C.
  • When an instance of Eq or 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 Num, Read, Integral, Fractional, Floating, RealFrac, or 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.

Integral types

These types are are represented as newtypes of types in Data.Int and Data.Word, and are instances of Eq, Ord, Num, Read, Show, Enum, Typeable, Storable, Bounded, Real, Integral and Bits.

newtype CChar Source

Haskell type representing the C char type.

Constructors

CChar Int8 

newtype CSChar Source

Haskell type representing the C signed char type.

Constructors

CSChar Int8 

newtype CUChar Source

Haskell type representing the C unsigned char type.

Constructors

CUChar Word8 

newtype CShort Source

Haskell type representing the C short type.

Constructors

CShort Int16 

newtype CUShort Source

Haskell type representing the C unsigned short type.

Constructors

CUShort Word16 

newtype CInt Source

Haskell type representing the C int type.

Constructors

CInt Int32 

newtype CUInt Source

Haskell type representing the C unsigned int type.

Constructors

CUInt Word32 

newtype CLong Source

Haskell type representing the C long type.

Constructors

CLong Int64 

newtype CULong Source

Haskell type representing the C unsigned long type.

Constructors

CULong Word64 

newtype CSize Source

Haskell type representing the C size_t type.

Constructors

CSize Word64 

newtype CWchar Source

Haskell type representing the C wchar_t type.

Constructors

CWchar Int32 

newtype CLLong Source

Haskell type representing the C long long type.

Constructors

CLLong Int64 

newtype CULLong Source

Haskell type representing the C unsigned long long type.

Constructors

CULLong Word64 

Numeric types

These types are are represented as newtypes of basic foreign types, and are instances of Eq, Ord, Num, Read, Show, Enum, Typeable and Storable.

newtype CClock Source

Haskell type representing the C clock_t type.

Constructors

CClock Int64 

newtype CTime Source

Haskell type representing the C time_t type.

Constructors

CTime Int64 

newtype CUSeconds Source

Haskell type representing the C useconds_t type.

Constructors

CUSeconds Word32 

newtype CSUSeconds Source

Haskell type representing the C suseconds_t type.

Constructors

CSUSeconds Int64 

To convert CTime to UTCTime, use the following formula:

  posixSecondsToUTCTime (realToFrac :: POSIXTime)

Floating types

These types are are represented as newtypes of Float and Double, and are instances of Eq, Ord, Num, Read, Show, Enum, Typeable, Storable, Real, Fractional, Floating, RealFrac and RealFloat.

Other types

data CFile Source

Haskell type representing the C FILE type.

data CFpos Source

Haskell type representing the C fpos_t type.

data CJmpBuf Source

Haskell type representing the C jmp_buf type.