我有两个文件，processes和calc（根据形状计算面积）。我是Erlang的新手，现在，我只想运行processes文件，该文件创建进程并从calc文件/模块调用area（）。
代码如下：
calc.erl:

- module(calc).
- export([start/0, area/0]).
- import(io, [fwrite/1]).

start() ->
    % Pid = spawn(fun() -> loop(Args here) end), 
    PID = spawn(calc, area, []),
    io:fwrite("PID: ~w", [PID]).
    % PID ! {self(), {rectangle, 10, 20}},

area() ->
    receive
        {From , {rectangle, X, Y}} ->
            From ! {rectangle, X*Y};
        {From, {square, X}} ->
            io:fwrite("in the Square area!"),
            From ! {square, X*X}
    end,
    area().

processes.erl:

-module(processes).
-export([execute/0]).
-import(io,[fwrite/1]).
-import(calc, [area/0]).

execute() ->
    PID = spawn(processes, area, []),
    Square_Area = PID ! {self(), {square, 10}},
    receive
        {rectangle, Area} ->
            io:fwrite("Rectangle area: ~w", [Area]);
        {square, Area} ->
            io:fwrite("Square area: ~w", [Area]);
        Other ->
            io:fwrite("In Other!")
    end,
    io:fwrite("Yolo: ~w", [Square_Area]).

当我在编译并运行processes.erl文件后运行命令processes:execute().时，我收到以下错误：

=ERROR REPORT==== 4-Sep-2022::20:24:26.720042 ===
Error in process <0.87.0> with exit value:
{undef,[{processes,area,[],[]}]}

这是因为第二个文件没有被加载还是我写错了命令？任何帮助都将不胜感激！