Haskell calling D code through the FFI

[Jon via Digitalmars-d-learn]

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 at 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.