Calling Haskell From Go Example

I did it for the lulz.

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Building

Updating the source paths

Make sure to update the libraries path in main.go on the line

// #cgo LDFLAGS: Safe.o -L <...> -lHSbase-4.14.3.0 -lHSinteger-gmp-1.0.3.0 -lHSghc-prim-0.6.1 -lHSrts -lCffi -liconv -lm -ldl

-l parameters should remain - they specify the required Haskell libraries for linking. You may need to update the libraries versions.

Easy (Makefile)

Run:

make

and it should do the job.

Manual build

ghc -c -O Safe.hs
go build

If something goes wrong

Most likely some libraries are missing or not specified in main.go.

To verify which libraries and paths are in use on your system, follow the steps below.

Paste this source to a file named test.c

#include <HsFFI.h>
#ifdef __GLASGOW_HASKELL__
#include "Safe_stub.h"
#endif
#include <stdio.h>

int main(int argc, char *argv[])
{
    int i;
    hs_init(&argc, &argv);

    i = fibonacci_hs(42);
    printf("Fibonacci: %d\n", i);

    hs_exit();
    return 0;
}

Run:

ghc -c -O Safe.hs
ghc --make -no-hs-main -v -optc-O test.c Safe -o test

This will generate the compile and link commands for your version of C compiler. Check the output and use it as the guidance, and let the sun enlighten your treacherous path.

References

Based on the following materials:

• Calling Haskell From C
• Go: passing argv to C function