Ashley Yakeley
At 2001-09-20 06:55, Manuel M. T. Chakravarty wrote:
The FFI does not ensure any type consistency between the arguments to `Ptr'/`ForeignPtr' and the corresponding C types.
I've been using 'Ptr Word8' with newArray to pass lists of bytes to C functions. They appear as unsigned char arrays in the C function. Is this wrong, or not guaranteed?
It is guaranteed that when you marshal a `[Word8]' into a `Ptr Word8' with newArray that you get a contiguous memory area filled with the bytes from the list. So, what you are doing is perfectly fine. What I meant with the remark that you quote is that if you would use foreign import foo :: Ptr Int -> IO Float with float foo (float *x) { return *x; } the system will not complain, but your program may dump core. Manuel