Building a shared library and executable from your julia code

1. Make sure all the packages and modules are precompiled. In my case the Julia 0.6 binary is downloaded and installed in ~/julia-0.6.

2. Clone this repo and use the juliac.jl script. The way to call it is as follows and make sure to run it from the static-julia directory:

   Usage: juliac.jl <Julia Program file> <Julia installation Path> [Julia Package Directory]

   In my case, I invoke it for hello.jl as follows. For now, make sure that the driver program is also in the static-julia directory: ~/julia-0.6/bin/julia juliac.jl hello.jl ~/julia-0.6 ~/.julia

3. A shared library containing the system image libhello.so, and a driver binary hello are created.

   $ ./hello
   hello, world
   f() = -0.37549581296986956

The plot command in hello.jl is only meant to exercise a bunch of Gadfly compilation. It is not expected to produce a plot in the terminal.

Under the hood

The juliac.jl script uses the --output-o switch to compile the user script into object code, and then builds it into the system image specified by the -J switch. This prepares an object file, which is then linked into a shared library containing the system image and user code. A driver script such as the one in program.c can then be used to build a binary that runs the julia code. For now, the image file has to be changed in program.c to match the name of the shared library containing the compiled julia program.

Instead of a driver script, the generated system image can be embedded into a larger program following the embedding examples and relevant sections in the Julia manual.

With julia 0.7, a single large binary can be created, which does not require the driver program to load the shared library. An example of that is in program2.c, where the image file is the binary itself.