Safe Haskell | None |
---|
Documentation
:: Name | Name of the data type |
-> Callconv | Calling convention: CCall or StdCall |
-> Name | Name of the function used to transform symbol names |
-> Q [Dec] |
Generate dynamic linking FFI methods for each field in the first parameter
data DL
id :: a -> a
Identity function.
data FunPtr a
A value of type
is a pointer to a function callable
from foreign code. The type FunPtr
aa
will normally be a foreign type,
a function type with zero or more arguments where
- the argument types are marshallable foreign types,
i.e.
Char
,Int
,Double
,Float
,Bool
,Int8
,Int16
,Int32
,Int64
,Word8
,Word16
,Word32
,Word64
,
,Ptr
a
,FunPtr
a
or a renaming of any of these usingStablePtr
anewtype
. - the return type is either a marshallable foreign type or has the form
whereIO
tt
is a marshallable foreign type or()
.
A value of type
may be a pointer to a foreign function,
either returned by another foreign function or imported with a
a static address import like
FunPtr
a
foreign import ccall "stdlib.h &free" p_free :: FunPtr (Ptr a -> IO ())
or a pointer to a Haskell function created using a wrapper stub
declared to produce a FunPtr
of the correct type. For example:
type Compare = Int -> Int -> Bool foreign import ccall "wrapper" mkCompare :: Compare -> IO (FunPtr Compare)
Calls to wrapper stubs like mkCompare
allocate storage, which
should be released with freeHaskellFunPtr
when no
longer required.
To convert FunPtr
values to corresponding Haskell functions, one
can define a dynamic stub for the specific foreign type, e.g.
type IntFunction = CInt -> IO () foreign import ccall "dynamic" mkFun :: FunPtr IntFunction -> IntFunction