SWISH -- SWI-Prolog for SHaring

% Define which licenses are viral (they "infect" the whole project)
viral(gpl).

% Define compatibility (who can include whom)
compatible(mit, mit).
compatible(apache, mit).
compatible(apache, apache).
compatible(gpl, _).  % GPL can include anything

% Your app's dependency tree (declare as dynamic so we can modify)
:- dynamic uses/3.

uses(myapp, react, mit).
uses(myapp, tensorflow, apache).
uses(tensorflow, helper_lib, gpl).  % Ouch!

% Find viral infections recursively
% A project is "infected" if it uses GPL directly or indirectly
infected(Project) :- 
    uses(Project, _, License), viral(License).  % Direct GPL dependency
infected(Project) :- 
    uses(Project, Dep, _), infected(Dep).       % Transitive GPL dependency

% The key question: Can we keep it proprietary?
% Only if we're NOT infected by a viral license
can_be_proprietary(Project) :- \+ infected(Project).

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Start querying the license checker!
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% can_be_proprietary(myapp).
% infected(myapp).
% uses(myapp, What, _), infected(What).
% uses(tensorflow, What, License), viral(License).
% retract(uses(tensorflow, helper_lib, gpl)),
%    assertz(uses(tensorflow, helper_lib, mit)),
%    can_be_proprietary(myapp).
% infected(What).
% uses(_, _, License).
% uses(What, _, gpl).