erlang实现字符串某个字符替换

replvar(S, _Var, undefined) ->
    S;
replvar(S, Var, Val) ->

    re:replace(S, Var, Val, [global, {return, list}]).

start(Type) ->
    Topic = replvar(Type, "_", "-"),
    io:format("topic is a: ~p~n", [Topic]).