GAP.jl Julia package

This repository contains the GAP.jl Julia package, as well as the GAP packages JuliaInterface and JuliaExperimental developed for the GAP-Julia integration as part of the OSCAR project.

WARNING: GAP.jl is intended as a low-level interface between GAP and Julia. Therefore, for the most part it does not attempt (besides some general conveniences) to provide a very “Julia-ish” interface to GAP objects and functions, nor a “GAP-ish” interface to Julia objects and functions. Instead, this is left to higher-level code, for example in the Oscar.jl package.

To install this package in Julia:

using Pkg; Pkg.add("GAP")

After entering the following in Julia,

using GAP

one may access any global GAP variable by prefixing its name with GAP.Globals., and call GAP functions like Julia functions. For example:

julia> GAP.Globals.SymmetricGroup(3)
GAP: SymmetricGroup( [ 1 .. 3 ] )

The Julia types Int64 and Bool are automatically converted to GAP objects when passed as arguments to GAP functions. Several others basic types of objects can be converted using the GapObj constructor. For example, here we convert a Vector{Int} to a GAP list:

julia> x = GapObj([1,2,3])
GAP: [ 1, 2, 3 ]

For nested objects, one can use the optional recursive keyword argument:

julia> GapObj([1,2,[3,4,5]])
GAP: [ 1, 2, <Julia: [3, 4, 5]> ]

julia> GapObj([1,2,[3,4,5]]; recursive=true)
GAP: [ 1, 2, [ 3, 4, 5 ] ]

Converting GAP objects to native Julia objects is done using suitable Julia constructors. For example, to convert the GAP list of integers we defined earlier back to Julia, we might do this:

julia> Vector{Int}(x)
3-element Vector{Int64}:
 1
 2
 3

You can temporarily switch to a GAP prompt using GAP.prompt():

julia> GAP.prompt();
gap> G := SymmetricGroup(5);
Sym( [ 1 .. 5 ] )
gap> quit;

julia> GAP.Globals.G
GAP: Sym( [ 1 .. 5 ] )

For more information on these and other capabilities of this package, please consult the GAP.jl manual.

Issues should be reported via our issue tracker.

Responsible for GAP.jl within the OSCAR project are Thomas Breuer and Max Horn.

All code in this repository is preliminary work.

It comes with absolutely no warranty and will most likely have errors. If you use it for computations, please check the correctness of the result very carefully.

Also, everything in this repository might change in the future, so currently any update can break the code you wrote upon functionality from packages in this repository.

This software is licensed under the LGPL, version 3, or any later version.

The development of this Julia package is supported by the Deutsche Forschungsgemeinschaft DFG within the Collaborative Research Center TRR 195.