Implement calling Julia from q

[abalkin]

References

• JuliaPy/pyjulia
• File locations
• Using julia-config in Makefiles

TODO

1. Implement J) language for kdb+. ENH Embed Julia in kdb+. #7.
2. Install q components in Pkg.build("JuQ"). ENH #6 Install server components during the package build. #8.
3. Detect presence kdb+ symbols in executable and don't load c.so. Server-side code #10.
4. Rethrow exceptions and convert some returned scalar values. ENH #1 Call Julia from kdb+ server improvements. #29.

Locating libjulia:

julia> Libdl.dlpath("libjulia")
"/Applications/Julia-0.6.app/Contents/Resources/julia/lib/libjulia.0.6.0.dylib"

Also

julia> JULIA_HOME
"/Applications/Julia-0.6.app/Contents/Resources/julia/bin"

julia> LOAD_PATH
2-element Array{Any,1}:
 "/Applications/Julia-0.6.app/Contents/Resources/julia/local/share/julia/site/v0.6"
 "/Applications/Julia-0.6.app/Contents/Resources/julia/share/julia/site/v0.6"

[abalkin]

Julia should be able to create an object callable from q by creating a C ABI function and passing a pointer to it to dl(). See "Creating C-Compatible Julia Function Pointers".

[abalkin]

#41 demonstrates feasibility of creating q functions by calling dl and cfunction on Julia functions. Making this convenient (define convert(K, x::Function)?) is left for another issue.