Topological sorting of a list of dependencies as pairs of {label, [label]}

tsort.erl

%% Topological sorting of a list of dependencies as pairs of
%% {label, [label]} where the list contains dependees.
%%
%% > tsort:tsort([{a,["b",c]}, {c, [1]}]).
%% ["b",1,c,a]

-module(tsort).

-export([tsort/1]).

-type dep_list() :: [{any(), [any()]}].
-spec tsort(dep_list()) -> [any()].
tsort(L) ->
    Graph = make_graph(L),
    try 
        digraph_utils:topsort(Graph)
    after
        digraph:delete(Graph)
    end.

make_graph(L) ->
    G = digraph:new([acyclic]),
    [add(X, G) || X <- L],
    G.

add({K, V}, G) ->
    digraph:add_vertex(G, K),
    [digraph:add_vertex(G, X) || X<-V],
    [digraph:add_edge(G, X, K) || X<-V].