Erlang 备忘清单

erl

q().

-module(module_name).
-export([function_name/arity, ...]).

function_name(Args) ->
    % Function body.
    Result.

-export([function1/0, function2/1]).

% 单行注释
% 这是一个注释

VarName = Value. % 变量名必须以大写字母开头
Age = 25.
Name = "Alice".

atom.       % 例子：atom, 'Atom with spaces'

123.        % 整数
3.14.       % 浮点数

true.
false.

"Hello, World!".

{ok, "Success"}.

[1, 2, 3].
[H|T] = [1, 2, 3]. % H = 1, T = [2, 3]

#{key1 => value1, key2 => value2}.

if
    Condition1 -> Expression1;
    Condition2 -> Expression2;
    true -> DefaultExpression
end.

case Expression of
    Pattern1 -> Expression1;
    Pattern2 -> Expression2;
    _ -> DefaultExpression
end.

% 无参函数
my_function() ->
    ok.

% 有参函数
add(A, B) ->
    A + B.

% 生成 1 到 10 的列表
[ X || X <- lists:seq(1, 10)].

% 生成 1 到 10 中的偶数
[ X || X <- lists:seq(1, 10), X rem 2 == 0].

spawn(Module, Function, Args).

% 示例
Pid = spawn(fun() -> io:format("Hello from process~n") end).

Pid ! Message.

% 示例
Pid ! {hello, self()}.

receive
    Pattern1 -> Expression1;
    Pattern2 -> Expression2;
    after Timeout -> TimeoutExpression
end.

{ok, Value} = {ok, 42}.

lists:append(List1, List2).
lists:map(Function, List).
lists:filter(Function, List).
lists:foldl(Function, Acc, List).

element(N, Tuple).
setelement(N, Tuple, Value).
tuple_size(Tuple).

string:len(String).
string:concat(String1, String2).
string:tokens(String, Delimiters).

file:read_file(Filename).
file:write_file(Filename, Data).
file:delete(Filename).

lists:map(fun(X) -> X * 2 end, [1, 2, 3]).
lists:filter(fun(X) -> X rem 2 == 0 end, [1, 2, 3, 4]).

string:len("Hello").
string:upper("hello").

{ok, File} = file:open("test.txt", [write]).
file:write(File, "Hello, file!").
file:close(File).

-module(server).
-export([start/0, loop/0]).

start() ->
    spawn(fun loop/0).

loop() ->
    receive
        {echo, Msg} ->
            io:format("Echo: ~p~n", [Msg]),
            loop();
        stop ->
            io:format("Server stopping~n"),
            ok;
        _ ->
            io:format("Unknown message~n"),
            loop()
    end.

Pid = spawn(Module, Function, Args).

Pid ! Message.

receive
    Pattern1 -> Actions1;
    Pattern2 -> Actions2;
    ...
end.

link(Pid).
unlink(Pid).

MonitorRef = erlang:monitor(process, Pid).
erlang:demonitor(MonitorRef).

try Expression of
    Pattern -> Result
catch
    Class:Reason -> Handler
end.

• throw
• error
• exit

try Expression of
    Pattern -> Result
catch
    Type:Reason -> ErrorHandlingExpression
end.

erl -name nodename@hostname -setcookie Cookie

net_adm:ping(Node).

{remote_process, 'remote_node@host'} ! Message.

-module(my_gen_server).
-behaviour(gen_server).

-export([start_link/0, init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).

start_link() ->
    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

init([]) ->
    {ok, #state{}}.

handle_call(Request, From, State) ->
    {reply, Reply, State}.

handle_cast(Msg, State) ->
    {noreply, State}.

handle_info(Info, State) ->
    {noreply, State}.

terminate(Reason, State) ->
    ok.

code_change(OldVsn, State, Extra) ->
    {ok, State}.

gen_server:start_link({local, Name}, Module, Args, Options).
gen_server:call(ServerRef, Request).
gen_server:cast(ServerRef, Msg).

-module(module_name_tests).
-include_lib("eunit/include/eunit.hrl").

simple_test() ->
    ?assertEqual(Expected, Actual).

complex_test_() ->
    [
        {"Test case 1", ?_assertEqual(Expected1, Actual1)},
        {"Test case 2", ?_assertEqual(Expected2, Actual2)}
    ].

# 在命令行中运行
erl -eval "eunit:test(module_name)" -s init stop