Hi Mike,
On Thu, Feb 20, 2014 at 8:34 AM, Mike Meyer
Running a simple logic in the kernel, it doesn't call GC.
Having looked over the source, I couldn't get much of a feel for it - it mostly seemed to be FFI & type declarations. Which does make sense since the goal is to provide strong type checking in the kernel. Maybe I'm looking in the wrong place in that rather large repository?
You are right. It's just "exercise". I would like to prove that can write code with functional language in interrupt context.
My question is how much does coding to meet the requirements for a device driver - not doing GC being one of them - warp the resulting Haskell code? Is it still pretty much idiomatic Haskell, or would it be easier for a Haskell programmer to figure out the C it replaced? Most of the time I've seen people try and get a modern language to meet such requirements (me included), you might as well have stuck with C as far as code improvement goes.
This exercise has logic code at following. https://github.com/metasepi/netbsd-arafura-s1/blob/arafura-s1/metasepi/sys/h... https://github.com/metasepi/netbsd-arafura-s1/blob/arafura-s1/metasepi/sys/h... https://github.com/metasepi/netbsd-arafura-s1/blob/arafura-s1/metasepi/sys/h... I re-write these from NetBSD's implementation, for a month. But now can get more speed with our new tool, convert C language API definition into Haskell API definition semi-automatically. https://github.com/ajhc/struct2hs Following is usage of the tool. $ struct2hs $HOME/src/netbsd-arafura-s1/obj/tooldir/bin/i486--netbsdelf-gcc "-Di386 -I$HOME/src/netbsd-arafura-s1/sys/arch/i386/compile/obj/GENERIC_HS ... sys/dev/pci/hdaudio/hdaudio.c | tail -15 newtype {-# CTYPE "struct pdevinit" #-} Pdevinit = Pdevinit () foreign import primitive "const.sizeof(struct pdevinit)" sizeOf_Pdevinit :: Int foreign import primitive "const.offsetof(struct pdevinit, pdev_attach)" offsetOf_Pdevinit_pdev_attach :: Int p_Pdevinit_pdev_attach :: Ptr Pdevinit -> IO (Ptr (Ptr (FunPtr (Int -> IO ())))) p_Pdevinit_pdev_attach p = return $ plusPtr p $ offsetOf_Pdevinit_pdev_attach foreign import ccall "dynamic" call_Pdevinit_pdev_attach :: FunPtr (Int -> IO ()) -> Int -> IO () foreign import primitive "const.offsetof(struct pdevinit, pdev_count)" offsetOf_Pdevinit_pdev_count :: Int p_Pdevinit_pdev_count :: Ptr Pdevinit -> IO (Ptr Int) p_Pdevinit_pdev_count p = return $ plusPtr p $ offsetOf_Pdevinit_pdev_count
One of the advantages C has in the kernel - the BSD kernels, anyway, reading Linux kernel makes me queasy - is that it isn't that different from C in userland. And the kernel groups have been working on reducing over the differences.
I hope so... But, I think Ajhc is not good for real kernel products, after this hard challenge. ATS language is much betther than Ajhc. Hongwei, as ATS author, says following. I perfectly agree his opinion. http://metasepi.org/posts/2013-12-24-jats-ug.html#%E4%B8%80%E9%80%9A%E3%81%A... Regards, -- Kiwamu Okabe