Re: Haskell calling D code through the FFI
Jon via Digitalmars-d-learn digitalmars-d-learn@puremagic.com writes: So that does indeed solve some of the problems. However, using this method, when linking I get two errors, undefined reference rt_init() and rt_term() I had just put these methods in the header file. If I put wrappers around these functions and export I get the rt_init, rt_term is private. rt_init is part of druntime. You need to link druntime into your program in order to make it work.
Re: Haskell calling D code through the FFI
Hi, thank you!! I have modified the program based on a previous suggestion. rt_init is called before using any D functionality and rt_term is called after using D functionality. I did this by: 1) Placing int rt_init(); and int rt_term(); into the header file that Haskell reads 2) Creating Haskell stubs foreign import ccall unsafe FunctionsInD.h rt_init d_init :: IO CInt foreign import ccall unsafe FunctionsInD.h rt_term d_term :: IO CInt And then in the Main haskell program, in main, the function starts with d_init and ends with d_term I'm pretty sure this is working nicely, because I can allocate structs with the new keyword in D, and this led to segfaults before using rt_init and rt_term. I think the problem I was having was trying to do this in a stupid way i.e. put wrappers around init and term on the D side. However, I still do not know how to compile without the using a fake main. Compiling with -c -lib does still give me a _Dmain undefined reference. I did dmd -c -lib FunctionsInD.d ghc --make Main.hs FunctionsInD.a -lphobos2 And get /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/libphobos2.so: undefined reference to `_Dmain' On Wednesday, 6 August 2014 at 11:03:33 UTC, David Soria Parra via Digitalmars-d-learn wrote: Jon via Digitalmars-d-learn digitalmars-d-learn@puremagic.com writes: So that does indeed solve some of the problems. However, using this method, when linking I get two errors, undefined reference rt_init() and rt_term() I had just put these methods in the header file. If I put wrappers around these functions and export I get the rt_init, rt_term is private. rt_init is part of druntime. You need to link druntime into your program in order to make it work.
Re: Haskell calling D code through the FFI
On Monday, 4 August 2014 at 20:48:09 UTC, Jon wrote:
For reasons I don't completely understand, you also need a fake
main function, dummy.d:
void main(){}
Note that this is not necessary if you compile with -lib e.g.:
dmd -lib -oflibtest.a test.d
and then
ghc Main.hs --make -omain libtest.a
I don't have gdc or ldc installed but as far as I know ldc has a
-lib flag as well.
Re: Haskell calling D code through the FFI
Oh great thank you. I think that might solve the majority of the
confusion I was having. One thing I can't figure out though, is
getting garbage collection to work as expected. If I have a
function that allocates a pointer to a struct using new, I get an
error on linking _dAlloc... not found. But maybe compiling as a
lib will solve this too.
On Tuesday, 5 August 2014 at 21:28:08 UTC, David Soria Parra
wrote:
On Monday, 4 August 2014 at 20:48:09 UTC, Jon wrote:
For reasons I don't completely understand, you also need a
fake main function, dummy.d:
void main(){}
Note that this is not necessary if you compile with -lib e.g.:
dmd -lib -oflibtest.a test.d
and then
ghc Main.hs --make -omain libtest.a
I don't have gdc or ldc installed but as far as I know ldc has
a -lib flag as well.
Re: Haskell calling D code through the FFI
So that does indeed solve some of the problems. However, using
this method, when linking I get two errors, undefined reference
rt_init() and rt_term() I had just put these methods in the
header file. If I put wrappers around these functions and export
I get the rt_init, rt_term is private.
On Tuesday, 5 August 2014 at 21:28:08 UTC, David Soria Parra
wrote:
On Monday, 4 August 2014 at 20:48:09 UTC, Jon wrote:
For reasons I don't completely understand, you also need a
fake main function, dummy.d:
void main(){}
Note that this is not necessary if you compile with -lib e.g.:
dmd -lib -oflibtest.a test.d
and then
ghc Main.hs --make -omain libtest.a
I don't have gdc or ldc installed but as far as I know ldc has
a -lib flag as well.
Re: Haskell calling D code through the FFI
On Tuesday, 5 August 2014 at 23:23:43 UTC, Jon wrote: So that does indeed solve some of the problems. However, using this method, when linking I get two errors, undefined reference rt_init() and rt_term() I had just put these methods in the header file. If I put wrappers around these functions and export I get the rt_init, rt_term is private. It works for me, here are the main parts of my Makefile: DC = ~/bin/dmd main: Main.hs FunctionsInD.a ghc -o main Main.hs FunctionsInD.a ~/lib/libphobos2.a -lpthread FunctionsInD.a: FunctionsInD.d $(DC) -c -lib FunctionsInD.d I passed in the phobos object directly because I don't know how to specify the ~/lib directory on the ghc command line.
Haskell calling D code through the FFI
TLDR -- Calling D code from Haskell through the FFI works with
DMD but not with GDC or LDC2.
The time consuming version:
Since D allows C to directly call it, if the D code is wrapped in
extern (C){ ... }, I thought it should be possible to call such D
code from Haskell using the FFI.
The FFI in Haskell allows directly calling C code given a header
file, the name of a function, and its C-type. So I made a D file
with the functions I want to call, FunctionsInD.d
extern (C){
int d_f(int x){
return x+2;
}
int d_g(int x, int y){
return x+y;
}
}
Then made a header file, FunctionsInD.h
int d_f(int x);
int d_g(int x, int y);
Then the Haskell wrapper ToD.hs:
module ToD where
import Foreign.C
foreign import ccall FunctionsInD.h d_f
c_f :: CInt - CInt
foreign import ccall FunctionsInD.h d_g
c_g :: CInt - CInt - CInt
h_f :: Int - Int -- the pure haskell version
h_f x = fromIntegral (c_f (fromIntegral x))
h_g :: Int - Int - Int
h_g x y = fromIntegral (c_g (fromIntegral x) (fromIntegral y))
For reasons I don't completely understand, you also need a fake
main function, dummy.d:
void main(){}
And a driver for test, Main.hs:
module Main where
import ToD
main :: IO ()
main = do
let (a,b) = (h_f 3, h_g 3 4)
sequence_ [putStrLn (show a), putStrLn (show b)]
To put this all together, here is the makefile.
DC = dmd
# DC = ldc2
# DC = ldmd2
# DC = gdc
main: FunctionsInD.o FunctionsInD.h dummy.o
ghc Main.hs --make -o main_ffi_test FunctionsInD.o
dummy.o -lphobos2
clean:
rm FunctionsInD.o dummy.o main_ffi_test
FunctionsInD.o FunctionsInD.d:
$(DC) -c FunctionsInD.d
dummy.o: dummy.d
$(DC) -c dummy.d
The question: if I comment out DC=dmd, and uncomment any of the
other options, the build fails. The problem is that ghc
complains of multiple definitions of main (not with DMD only GDC
and LDC2). If I remove dummy.o from the ghc line, I get,
undefined reference to _DMain.
But wait! It gets weirder. I can compile FunctionsInD.d with
GDC or LDC2, as long as I compile dummy.d with DMD, everything
works fine.
Once I get through this hump, I will try to get on with more
interesting interfaces, like strings and structs.
Re: Haskell calling D code through the FFI
Don't forget to call rt_init: http://dlang.org/phobos/core_runtime.html#.rt_init
Re: Haskell calling D code through the FFI
On Monday, 4 August 2014 at 21:10:46 UTC, safety0ff wrote: Don't forget to call rt_init: http://dlang.org/phobos/core_runtime.html#.rt_init Where/when should I call this?
Re: Haskell calling D code through the FFI
On Monday, 4 August 2014 at 21:14:17 UTC, Jon wrote: On Monday, 4 August 2014 at 21:10:46 UTC, safety0ff wrote: Don't forget to call rt_init: http://dlang.org/phobos/core_runtime.html#.rt_init Where/when should I call this? Before calling any D functions, but usually it's simplest to call it early in main. It initializes the GC and notifies the D runtime of its existence. For simple D functions you might get away without calling it.
Re: Haskell calling D code through the FFI
I get Error: core.runtime.rt_init is private. And Error: core.runtime.init is not accessible. On Monday, 4 August 2014 at 21:22:37 UTC, safety0ff wrote: On Monday, 4 August 2014 at 21:14:17 UTC, Jon wrote: On Monday, 4 August 2014 at 21:10:46 UTC, safety0ff wrote: Don't forget to call rt_init: http://dlang.org/phobos/core_runtime.html#.rt_init Where/when should I call this? Before calling any D functions, but usually it's simplest to call it early in main. It initializes the GC and notifies the D runtime of its existence. For simple D functions you might get away without calling it.
Re: Haskell calling D code through the FFI
On Monday, 4 August 2014 at 21:35:21 UTC, Jon wrote: I get Error: core.runtime.rt_init is private. And Error: core.runtime.init is not accessible. I would add them to the header and Haskell wrapper (FunctionsInD.h and ToD.hs.) The signatures are: int rt_init(); int rt_term(); When it is linked it will find the symbols in druntime.
Re: Haskell calling D code through the FFI
Yes, thank you. That is exactly what I did. On Monday, 4 August 2014 at 21:48:40 UTC, safety0ff wrote: On Monday, 4 August 2014 at 21:35:21 UTC, Jon wrote: I get Error: core.runtime.rt_init is private. And Error: core.runtime.init is not accessible. I would add them to the header and Haskell wrapper (FunctionsInD.h and ToD.hs.) The signatures are: int rt_init(); int rt_term(); When it is linked it will find the symbols in druntime.
Re: Haskell calling D code through the FFI
As a note, I can interact with strings as expected, but working with structs looks like it will take a little bit of work. On Monday, 4 August 2014 at 22:17:36 UTC, Jon wrote: Yes, thank you. That is exactly what I did. On Monday, 4 August 2014 at 21:48:40 UTC, safety0ff wrote: On Monday, 4 August 2014 at 21:35:21 UTC, Jon wrote: I get Error: core.runtime.rt_init is private. And Error: core.runtime.init is not accessible. I would add them to the header and Haskell wrapper (FunctionsInD.h and ToD.hs.) The signatures are: int rt_init(); int rt_term(); When it is linked it will find the symbols in druntime.
