Portability | portable |
---|---|
Stability | provisional |
Maintainer | ffi@haskell.org |
Safe Haskell | Trustworthy |
Mapping of C types to corresponding Haskell types.
- newtype CChar = CChar Int8
- newtype CSChar = CSChar Int8
- newtype CUChar = CUChar Word8
- newtype CShort = CShort Int16
- newtype CUShort = CUShort Word16
- newtype CInt = CInt Int32
- newtype CUInt = CUInt Word32
- newtype CLong = CLong Int32
- newtype CULong = CULong Word32
- newtype CPtrdiff = CPtrdiff Int32
- newtype CSize = CSize Word32
- newtype CWchar = CWchar Int32
- newtype CSigAtomic = CSigAtomic Int32
- newtype CLLong = CLLong Int64
- newtype CULLong = CULLong Word64
- newtype CIntPtr = CIntPtr Int32
- newtype CUIntPtr = CUIntPtr Word32
- newtype CIntMax = CIntMax Int64
- newtype CUIntMax = CUIntMax Word64
- newtype CClock = CClock Int32
- newtype CTime = CTime Int32
- newtype CUSeconds = CUSeconds Word32
- newtype CSUSeconds = CSUSeconds Int32
- newtype CFloat = CFloat Float
- newtype CDouble = CDouble Double
- data CFile
- data CFpos
- data CJmpBuf
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 ofCT
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 forCT
has a valid representation in C. -
will yield the same value assizeOf
(undefined
:: CT)sizeof (t)
in C. -
matches the alignment constraint enforced by the C implementation foralignment
(undefined
:: CT)t
. - The members
peek
andpoke
of theStorable
class map all values ofCT
to the corresponding value oft
and vice versa. - When an instance of
Bounded
is defined forCT
, the values ofminBound
andmaxBound
coincide witht_MIN
andt_MAX
in C. - When an instance of
Eq
orOrd
is defined forCT
, the predicates defined by the type class implement the same relation as the corresponding predicate in C ont
. - When an instance of
Num
,Read
,Integral
,Fractional
,Floating
,RealFrac
, orRealFloat
is defined forCT
, the arithmetic operations defined by the type class implement the same function as the corresponding arithmetic operations (if available) in C ont
. - When an instance of
Bits
is defined forCT
, the bitwise operation defined by the type class implement the same function as the corresponding bitwise operation in C ont
.
Integral types
These types are are represented as newtype
s 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
.
Haskell type representing the C char
type.
Haskell type representing the C signed char
type.
Haskell type representing the C unsigned char
type.
Haskell type representing the C short
type.
Haskell type representing the C unsigned short
type.
Haskell type representing the C int
type.
Haskell type representing the C unsigned int
type.
Haskell type representing the C long
type.
Haskell type representing the C unsigned long
type.
Haskell type representing the C ptrdiff_t
type.
Haskell type representing the C size_t
type.
Haskell type representing the C wchar_t
type.
newtype CSigAtomic Source
Haskell type representing the C sig_atomic_t
type.
Haskell type representing the C long long
type.
Haskell type representing the C unsigned long long
type.
Numeric types
These types are are represented as newtype
s of basic
foreign types, and are instances of
Eq
, Ord
, Num
, Read
,
Show
, Enum
, Typeable
and Storable
.
Haskell type representing the C clock_t
type.
Haskell type representing the C time_t
type.
Haskell type representing the C useconds_t
type.
newtype CSUSeconds Source
Haskell type representing the C suseconds_t
type.
To convert CTime
to UTCTime
, use the following formula:
posixSecondsToUTCTime (realToFrac :: POSIXTime)
Floating types
These types are are represented as newtype
s of
Float
and Double
, and are instances of
Eq
, Ord
, Num
, Read
,
Show
, Enum
, Typeable
, Storable
,
Real
, Fractional
, Floating
,
RealFrac
and RealFloat
.
Haskell type representing the C float
type.
Haskell type representing the C double
type.