Pass primitive array to unsafe FFI as pointer.

Enable UnliftedFFITypes extension in your haskell code, use proper pointer type and HsInt to marshall ByteArray# and Int arguments on C side.

The second Int arguement is the element size not the bytes size.

USE THIS FUNCTION WITH UNSAFE FFI CALL ONLY.

Allocate some bytes and pass to FFI as pointer, freeze result into a PrimArray.

USE THIS FUNCTION WITH UNSAFE FFI CALL ONLY.

Pass PrimVector to unsafe FFI as pointer

The PrimVector version of withPrimArrayUnsafe.

The second Int arguement is the first element offset, the third Int argument is the element length.

USE THIS FUNCTION WITH UNSAFE FFI CALL ONLY.

Allocate a prim array and pass to FFI as pointer, freeze result into a PrimVector.

USE THIS FUNCTION WITH UNSAFE FFI CALL ONLY.

Allocate some bytes and pass to FFI as pointer, freeze result into a Bytes.

USE THIS FUNCTION WITH UNSAFE FFI CALL ONLY.

Create an one element primitive array and use it as a pointer to the primitive element.

Return the element and the computation result.

USE THIS FUNCTION WITH UNSAFE FFI CALL ONLY.

like withPrimUnsafe, but don't write initial value.

USE THIS FUNCTION WITH UNSAFE FFI CALL ONLY.

Pass primitive array list to unsafe FFI as StgArrBytes**.

Enable UnliftedFFITypes extension in your haskell code, use StgArrBytes**(>=8.10) or StgMutArrPtrs*(<8.10) pointer type and HsInt to marshall BAArray# and Int arguments on C side, check the example with BAArray#.

The second Int arguement is the list size.

USE THIS FUNCTION WITH UNSAFE FFI CALL ONLY.

Pass primitive array to safe FFI as pointer.

Use proper pointer type and HsInt to marshall Ptr a and Int arguments on C side. The memory pointed by 'Ptr a' will not moved during call. After call returned, pointer is no longer valid.

The second Int arguement is the element size not the bytes size.

Don't pass a forever loop to this function, see #14346.

Allocate a prim array and pass to FFI as pointer, freeze result into a PrimVector.

Pass PrimVector to safe FFI as pointer

The PrimVector version of withPrimArraySafe. The Ptr is already pointed to the first element, thus no offset is provided. After call returned, pointer is no longer valid.

Don't pass a forever loop to this function, see #14346.

Allocate a prim array and pass to FFI as pointer, freeze result into a PrimVector.

Allocate some bytes and pass to FFI as pointer, freeze result into a PrimVector.

Create an one element primitive array and use it as a pointer to the primitive element.

Don't pass a forever loop to this function, see #14346.

like withPrimSafe, but don't write initial value.

Pass primitive array list to safe FFI as pointer.

Use proper pointer type and HsInt to marshall Ptr (Ptr a) and Int arguments on C side. The memory pointed by 'Ptr a' will not moved during call. After call returned, pointer is no longer valid.

The second Int arguement is the list size.

Don't pass a forever loop to this function, see #14346.

Convert a PrimArray to a pinned one(memory won't moved by GC) if necessary.

Convert a PrimVector to a pinned one(memory won't moved by GC) if necessary.

Type alias for ByteArray#.

Describe a ByteArray# which we are going to pass across FFI. Use this type with UnliftedFFITypes extension, At C side you should use a proper const pointer type.

Don't cast BA# to Addr# since the heap object offset is hard-coded in code generator: Note [Unlifted boxed arguments to foreign calls]

In haskell side we use type system to distinguish immutable / mutable arrays, but in C side we can't. So it's users' responsibility to make sure the array content is not mutated (a const pointer type may help).

USE THIS TYPE WITH UNSAFE FFI CALL ONLY. A ByteArray# COULD BE MOVED BY GC DURING SAFE FFI CALL.

Type alias for MutableByteArray# RealWorld.

Describe a MutableByteArray# which we are going to pass across FFI. Use this type with UnliftedFFITypes extension, At C side you should use a proper pointer type.

Don't cast MBA# to Addr# since the heap object offset is hard-coded in code generator: Note [Unlifted boxed arguments to foreign calls]

USE THIS TYPE WITH UNSAFE FFI CALL ONLY. A MutableByteArray# COULD BE MOVED BY GC DURING SAFE FFI CALL.

Type alias for ArrayArray#.

Describe a array of ByteArray# which we are going to pass across FFI. Use this type with UnliftedFFITypes extension, At C side you should use StgArrBytes**(>=8.10) or StgMutArrPtrs*(<8.10) type from "Rts.h", example code modified from GHC manual:

// C source, must include the RTS to make the struct StgArrBytes
// available along with its fields: ptrs and payload.
#include "Rts.h"
// GHC 8.10 changes the way how ArrayArray# is passed to C, so...
#if __GLASGOW_HASKELL__ < 810
HsInt sum_first (StgMutArrPtrs *arr, HsInt len) {
  StgArrBytes **bufs = (StgArrBytes**)arr->payload;
#else
HsInt sum_first (StgArrBytes **bufs, HsInt len) {
#endif
  int res = 0;
  for(StgWord ix = 0;ix < len;ix++) {
     // payload pointer type is StgWord*, cast it before use!
     res = res + ((HsInt*)(bufs[ix]->payload))[0];
  }
  return res;
}

-- Haskell source, all elements in the argument array must be
-- either ByteArray# or MutableByteArray#. This is not enforced
-- by the type system in this example since ArrayArray is untyped.
foreign import ccall unsafe "sum_first" sumFirst :: BAArray# Int -> Int -> IO CInt

Clear MBA# with given length to zero.

Zero a structure.

There's no Storable or Prim constraint on a type, the length should be given in bytes.

The castPtr function casts a pointer from one type to another.

Copy some bytes from a null terminated pointer(without copying the null terminator).

You should consider using CBytes type for storing NULL terminated bytes first, This method is provided if you really need to read Bytes, there's no encoding guarantee, result could be any bytes sequence.

Copy some bytes from a pointer.

There's no encoding guarantee, result could be any bytes sequence.

Copy some bytes from a pointer.

There's no encoding guarantee, result could be any bytes sequence.

std::string Pointer tag.

Run FFI in bracket and marshall std::string* result into Haskell heap bytes, memory pointed by std::string* will be delete ed.

RealWorld is deeply magical. It is primitive, but it is not unlifted (hence ptrArg). We never manipulate values of type RealWorld; it's only used in the type system, to parameterise State#.