README.txt

Adapted from https://github.com/JuliaLang/PackageCompiler.jl/issues/144.

Compile the C code with 

gcc runjl.c -o runjl -Wall -std=gnu99 -I'/Applications/Julia-1.0.app/Contents/Resources/julia/include/julia' -DJULIA_ENABLE_THREADING=1 -fPIC -L'/Applications/Julia-1.0.app/Contents/Resources/julia/lib' -Wl,-rpath,'/Applications/Julia-1.0.app/Contents/Resources/julia/lib' -Wl,-rpath,'/Applications/Julia-1.0.app/Contents/Resources/julia/lib/julia' -ljulia

Use PackageCompiler.jl to produce a shared library from the Julia file.

fun.jl

Base.@ccallable function my_add(x::Cint, y::Cint)::Cint
    return x + y
end

runjl.c

#include <dlfcn.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include <julia.h>


int main()
{
    void *handle;
    int64_t (*my_add)(int64_t, int64_t);
    struct timespec ts0, ts1;
    int i = 0;

    jl_init_with_image(NULL, "builddir/fun.dylib");

    if ((handle = dlopen("builddir/fun.dylib", RTLD_LOCAL)) == NULL) {
        goto error;
    }
    if ((my_add = dlsym(handle, "my_add")) == NULL) {
        goto error;
    }

    clock_t begin, end;


    begin = clock();
    for (; i < 10000000; i++) {
        (*my_add)(5, 6);
    }
    end = clock();

    printf("%f\n", (double)(end - begin) / CLOCKS_PER_SEC);


    printf("5 + 6 = %lld\n", (*my_add)(5, 6));

    return 0;

error:
    fprintf(stderr, "Error: %s\n", dlerror());
    return -1;
}