On Monday 05 December 2011, 11:39:06, Alexander.Vladislav.Popov wrote:
Hi, Haskellers.
I'm trying to compile following program (where Regex.Genex is a package what I need to produce all possible expresions by the given pattern and `adder' is just FFI sample):
-- genexlib.hs {-# LANGUAGE BangPatterns, ForeignFunctionInterface #-}
module GenexLib where
import Regex.Genex import System.IO import System.Environment
adder :: Int -> Int -> IO Int -- gratuitous use of IO adder x y = return (x+y) foreign export stdcall adder :: Int -> Int -> IO Int -- genexlib.hs end
// start.c #include
void HsStart() { int argc = 1; char* argv[] = {"ghcDll", NULL}; // argv must end with NULL
// Initialize Haskell runtime char** args = argv; hs_init(&argc, &args); }
void HsEnd() { hs_exit(); } // start.c end
I'm using ghc
ghc --version
The Glorious Glasgow Haskell Compilation System, version 7.0.2
compiling:
ghc -c genexlib.hs ghc -c start.c ghc -shared -o genexlib.dll genexlib.o genexlib_stub.o start.o
Why the separate compilation? Can't you compile them in one go?
genexlib.o:fake:(.text+0xd1): undefined reference to `__stginit_regexzmgenexzm0zi3zi2_RegexziGenex_' Creating library file: genexlib.dll.a collect2: ld returned 1 exit status
and get undefined reference.
But If I try to compile the executable from similar code:
ghc --make genexlib.hs -O2
By the way, --make is the default mode from ghc-7.0 on, so you don't need it here.
Where is my mistake? What am I doing wrong? In first case, when compiling shared dll, I tried to link libraries what I've found in `cabal' directory (like `libHSregex-genex-0.3.2.a') to work around errors but all in vain.
The fundamental thing is that in --make mode, GHC figures out the required Haskell dependencies itself. So it sees the import and looks in which package it's provided and links (if necessary) with that package. But when you tell it to link a couple of .o files, it's not in --make mode, so apart from the specified files it links in only symbols from a few select packages (I think the wired-in packages), so then you have to tell it which other packages it needs to link in. $ ghc -shared -package regex-genex -o genexlib.dll genexlib.o genexlib_stub.o start.o should fix the undefined reference.