Foreign.C.Types

Copyright	(c) The FFI task force 2001
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	[email protected]
Stability	provisional
Portability	portable
Safe Haskell	Trustworthy
Language	Haskell2010

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.

newtype CSChar Source

Haskell type representing the C signed char type.

newtype CUChar Source

Haskell type representing the C unsigned char type.

newtype CShort Source

Haskell type representing the C short type.

newtype CUShort Source

Haskell type representing the C unsigned short type.

newtype CInt Source

Haskell type representing the C int type.

newtype CUInt Source

Haskell type representing the C unsigned int type.

newtype CLong Source

Haskell type representing the C long type.

newtype CULong Source

Haskell type representing the C unsigned long type.

newtype CPtrdiff Source

Haskell type representing the C ptrdiff_t type.

newtype CSize Source

Haskell type representing the C size_t type.

newtype CWchar Source

Haskell type representing the C wchar_t type.

newtype CSigAtomic Source

Haskell type representing the C sig_atomic_t type.

newtype CLLong Source

Haskell type representing the C long long type.

newtype CULLong Source

Haskell type representing the C unsigned long long type.

newtype CIntPtr Source

newtype CUIntPtr Source

newtype CIntMax Source

newtype CUIntMax Source

Numeric types

These types 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.

newtype CTime Source

Haskell type representing the C time_t type.

newtype CUSeconds Source

Haskell type representing the C useconds_t type.

Since: 4.4.0.0

newtype CSUSeconds Source

Haskell type representing the C suseconds_t type.

Since: 4.4.0.0

To convert CTime to UTCTime, use the following:

\t -> posixSecondsToUTCTime (realToFrac t :: 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.

newtype CFloat Source

Haskell type representing the C float type.

newtype CDouble Source

Haskell type representing the C double type.

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.