gproc example queries

example_gproc_queries.erl

%% Gproc Example queries
1> Table = gproc:table().
{qlc_handle,{qlc_table,#Fun<gproc.13.93641566>,true,
                       undefined,undefined,#Fun<gproc.16.93641566>,undefined,
                       #Fun<gproc.17.93641566>,undefined,'=:=',undefined,
                       no_match_spec}}

%% query all registered gproc local names
2> Q_names = qlc:q([{X, P} || {{n,l,X},P,_} <- Table]).
{qlc_handle,{qlc_lc,#Fun<erl_eval.20.99386804>,
                    {qlc_opt,false,false,-1,any,[],any,524288,allowed}}}

%% query all registered gproc local properties
2> Q_props = qlc:q([{X, P} || {{p,l,X},P,_} <- Table]).
{qlc_handle,{qlc_lc,#Fun<erl_eval.20.99386804>,
                    {qlc_opt,false,false,-1,any,[],any,524288,allowed}}}
3> qlc:e(Q_names).
...
4> qlc:e(Q_props).
...