如何从 Dialyzer 修复 "will never return since the success typing is [...] and the contract is.."？

Question

我正在使用 Dialyzer 修复 Erlang 代码中的错误。

io:format(IoDevice, "[]");

此行产生以下错误：

The call io:format(IoDevice::pid(),[91 | 93,...]) 
  will never return since the success typing is
  (atom() | binary() | string(),[any()]) -> 'ok' 
  and the contract is (Format,Data) -> 'ok' 
  when Format :: format(), Data :: [term()]

我无法理解问题所在，谁能解释一下？

谢谢

Answer 1

我推荐阅读io manual page。它的用法很简单：

1> io:format("hello ~p~n", [world]). % ~n means newline
hello world
ok
2> io:format("hello ~p~n", [<<"world">>]).             
hello <<"world">>
ok
3> io:format("hello ~s~n", [<<"world">>]).
hello world
ok

在上面的透析器中告诉你 io:format/2（format/2 表示接受 2 个参数的函数 format）接受 atom() 或 string() 或 binary() 作为第一个参数，一个包含零个或多个元素的列表作为第二个参数。根据您的代码，透析器检测到 IoDevice 是 Erlang pid() 而不是 string() 或 binary().

如何从 Dialyzer 修复 "will never return since the success typing is [...] and the contract is.."？

How do I fix a "will never return since the success typing is [...] and the contract is.." from Dialyzer?

erlang

dialyzer