ErLang编译出现问题，bad function arity

Question

-module(test).
-export(sum/1).


sum(L)->sum(L,0).
sum([],N)->N;

sum([H|T],N)->sum(T,H+N).

错误信息:

test.erl:2: bad function arity
test.erl:4: Warning: function sum/1 is unused
test.erl:5: Warning: function sum/2 is unused

Answer 1

谢谢！！