erlang-study for worktile

https://worktile.com/project/6ab72269893943d98f11e30080f75dc9/page/065b281d10804baea8c65c654101e633

Pid = spawn(ModuleName,FunName,[Arg1,Arg2]).

Pid ! Msg

receive {From,Message} -> ... end

abc = 123. hello.erl

c(hello). erlc hello.erl

erl -noshell -s hello start -s init stop

afile_serevr.erl、afile_client.erl.

X = 20. X + 20. % and this is comment

2 + 3 * 4.

X = 123456789. XXXXX. X = 1234.

X = (2+4). Y = 10.

5/3. 4/2.

原子 atom abc 'abc'

元组 tuple

Person = {person,{name,joe},{height,1.82},{footsize,42}}.

F = {firstname,joe}. L = {lastname,armstrong}. P = {person,F,L}

Point = {point,10,45}. {point,X,Y} = Point. X. Y. {point,C,C} = Point.

Point1 = {point,25,25}. {point,C,C} = Point1.

列表 Drawing = [{square,{10,10},10},12]. ThingsToBuy = [{apples,10},{pears,6},{milk,3}]. ThingsToBuy1 = [{oranges,4},{newspaper,1}|ThingsToBuy]. [Buy1|ThingsToBuy2] = ThingsToBuy1. [Buy2,Buy3|ThingsToBuy3] = ThingsToBuy2.

Name = "Hello". [1,2,3].

[83,117,114,112,114,105,115,101]. [1,83,117,114,112,114,105,115,101].

I = $s.

X = "a\x{221e}b".

X = [97,98,99].

{X,abc} = {123,abc}.

{X,Y,Z} = {22,def,"cat"}.

geometry.erl

c(geometry).

geometry:area({rectangle,10,5}).

geometry:area({square,3}).

pwd(). ls(). cd(Dir).

Buy = [{oranges,4},{newspaper,1},{apples,10},{pears,6},{milk:3}].

c(shop). c(shop1). shop1:total([]). shop1:total([{milk,3}]). shop1:total(Buy).

fun 函数 Double = fun(X) -> 2*X end. Double(2).

Hypot = func(X,Y) -> math:sqrt(XX + YY) end. Hypot(3,4). Hypot(3).

TempConvert = fun({c,C}) -> {f, 32 + C*9/5}; ({f,F}) -> {c, (F-32)*5/9} end. TempConvert({c,100}). TempConvert({f,212}).

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

Fruit = [apple,pear,orange]. MakeTest = fun(L) -> (func(X) -> lists:member(X,L) end) end. IsFruit = MakeTest(Fruit). IsFruit(pear). IsFruit(dog).

定义自己的控制抽象 lib_misc.erl lib_misc:for(1,10,fun(I)->I*I end).

列表处理 mylists.erl mylist:sum([1,3,10]).

mylist:map(fun(X) ->2*X end,[1,2,3,4,5]).

shop2.erl

列表推倒

L = [1,2,3,4,5]. lists:map(fun(X) -> 2*X end,L).

[2 * X || X <- L].

[F(X) || X <- L]

快速排序 Quicksort lib_misc:qsort 毕达哥拉斯三元数组 lib_misc:pythag

内置函数 list_to_tuple([12,cat,"hello"]). time().

关卡

max(X,Y) when X > Y ->X; max(X,Y) -> Y.

f(X,Y) when is_integer(X),X > Y, Y < 6 -> ...

case 和 if 表达式

case Expression of Pattern1 [when Guard1] -> Expr_seq1; Pattern2 [when Guard2] -> Expr_seq2; end 可以通过模式匹配

if Guard1 -> Expr_seq1; Guard2 -> Expr_seq2; ... end

构建自然顺序的列表

some_func([H|T],...,Result,...) -> H1 = ... H ..., some_func(T,[H1|Result]); some_func([],...,Result,...) -> {...Result...}

List ++ [H].

-record(Name,{ Key1 = Default1, Key2 = Default2, ... Key3,% 相当于 Key3 = undefined ... })

records.hrl

rr("records.hrl").

#todo{}.

X1 = #todo{status=urgent,text="fix errata in bool"}. X2 = X1#todo{status=done}.

提取字段 #todo{who=W,text=Txt} = X2. W. Txt.

X2#todo.text.

映射组 map

#{Key1 Op Val1，Key2 Op Val2 ... KeyN Op ValN}. Op 是 => 或者 :=

F1 = #{a => 1,b=>2}. Facts = #{{wife,fred}=>"Sue",{age,fred} =>45,...}.

F2 = #{b=>2,a=>1}.

F1 = F2.

F3 = F1#{c => xx}. F4 = F1#{c := 3}.

模式匹配和内置函数 maps:

exit(Why).

throw(Why).

error(Why).

try FuncOrExpressionSeq of % of 可以省略 Pattern1 [when Guard1] -> Expressions1; Pattern2 [when Guard2] -> Expressions2; ... catch ExceptionType1:ExPattern1 [when ExGuard1] -> ExExpressions1; ExceptionType2:ExPattern2 [when ExGuard2] -> ExExpressions2; ... after　% after 可以省略 AfterExpressions end

<<5,10,20>>. <>. <<65,66,67>>.

list_to_binary(L).

Bin1 = <<1,2,3>>. Bin2 = <<4,5>>. Bin3 = <<6>>.

list_to_binary([Bin1,1,[2,3,Bin2],4|Bin3]).

term_to_binary(Term). binary_to_term(Bin).

位语法

M = <<X:3,Y:7,Z:6>>.

位语法表达式构建二进制型或者位串

apply(Mod,Func,[arg1,Arg2,...,ArgN]). 等价于 Mod:Func(arg1,Arg2,...,ArgN).

算数表达式

元数 函数所拥有的参数数量

sum(L) -> sum(L,0).

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

属性 -AtomTag() -recode 和-include 不属于属性

-module(moduleName). -import(Mod,[Name1/Arity1,Name2/Arity2,...]). -export([Name1/Arity1,Name2/Arity2,...]). abc.erl -compile(Options). % -compile(export_all). -vsn(Version). -author('xxxx@xxxx.com'). -behavior(module). -define(HELLO, 5).

-SomeTag(Value).

attrs:module_info().

块表达式 begin Expr1, ... end

动态代码载入 someModule:someFunction(...)

b.erl a.erl

函数引用

square(X) ->

宏定义 -define(Constant,Replacement). -define(Func(Var1,Var2,...Var),Replacement).

?MacroName 预定义宏 ?FILE ?MODULE ?LINE

宏控制流 -ifdef(Macro).

-undef(Macro).

-else

-endif

m1.erl

模式的匹配操作符

func1([{tag1,A,B}|T]) -> f(....,{tag1,A,B},....)

func1([{(tag1,A) = Z1,B}|T] = Z2) -> f(....,Z2,....) g(....,Z1,....)

进程字典

put(x,20)

引用 make_ref().

比较数据类型 X > Y X < Y X =< Y X >= Y

X == Y

X /= Y

X =:= Y 完全相等 X =/= Y 完全不等

_变量

walks.erl

-spec

-type

预定义类型

-type term().

-type boolean().

-type byte().

-type char().

....

dialyzer test1.erl

设置载入代码的路径

code:get_path().

code:add_patha(Dir). code:add_pathz(Dir).

.erlang 文件

erl -pa Dir1 -pa Dir2 .... -pz DirK1 -pz DirK2

Pid = spawn(Mod,Func,Args).
Pid = spawn(Func).
Pid ! Message

receive ... end

receive
    Pattern1 [when Guard1] ->
        Expression1;
    Pattern2 [when Guard2] ->
        Expression2;
    ...
after T ->
    Expression
end

area_server0.erl

Pid = spawn(area_server0,loop,[]).
Pid ! {rectangle,6,10}.
Pid ! {square,12}.

客户端-服务器

客户端总是通过像服务器发送一个请求来发起计算，服务端计算后生成回复，然后发送一个响应给客户端。

Pid = spawn(area_server1,loop,[]).
area_server1.rpc(Pid,{rectangle,6,10}).
area_server1.rpc(Pid,socks).

stimer.erl 定时器

注册进程

register(area,Pid).

area ! {rectangle,4,5}.

clock.erl 模拟时钟

查看 area_server_final.erl 尾递归的 loop 函数必须在最后

spawn(Func) spawn(MFA)

任其崩溃 让其他进程修复错误

进程 普通进程和系统进程 process_flag(trap_exit,true)

连接 A B 相互连接，其中任何一个终止会发错误信号 监视 监视是单向的 消息和错误信号 错误信号的接受 显示错误信号 exit(Why) 不可捕捉的错误信号 exit(Pid,kill)

P1 call link(P3)

-spec spawn_link(Fnc) -> Pid -spec spawn_link(Mod,Fuc,Args) -> Pid

-spec spawn_monitor(Fnc) -> Pid -spec spawn_monitor(Mod,Fuc,Args) -> Pid

{'DOWN',Ref,process,Pid,Why}

-spec link(Pid) -> true -spec unlink(Pid) -> true

-spec erlang:monitor(process,Item) -> Ref Item 可以是进程 Pid 或者注册名称

-spec exit(Why) -> none() 向连接的所有进程发送 Why 的退出信号 监视他的进程发送 DOWN消息 -spec exit(Pid,Why) ->true

容错式编程 lib_misc.erl

F = fun() ->
        receive
            X -> list_to_atom(X)
        end
    end.
Pid = spawn(F).

lib_misc:on_exit(Pid,fun(Why) ->
                        io:format("~p died with:~p~n",[Pid,Why])
                     end).

socket_dist/kvs.erl

kvs:start().
kvs:store({location,joe},"Stockholm").
kvs:store(weather,raining).
kvs:lookup({location,joe}).
kvs:lookup(weather).

erl -sname hf
kvs:start().
kvs:lookup(weather).

erl -sname hj
rpc:call('hf@haifeng',kvs,store,[weather,fine]).
rpc:call('hf@haifeng',kvs,lookup,[weather]).

erl -name hf -setcookie abc
erl -name hj -setcookie abc

rpc:call(Node,Mod,Function,Args).

分布式编程的库和内置函数

-spec spawn(Node,Func)->Pid

-spec spawn(Node,Mod,Func,Args)->Pid

-spec spawn_link(Node,Func)->Pid

-spec spawn_link(Node,Mod,Func,Args)->Pid

远程分裂示例

dist_demo.erl

cookie 保护系统

$HOME/.erlang.cookie

erl -setcookie xxxx

erlang:setcookie(node(),xxxx).

与外部程序通信

file filename filelib io

socket_examples.erl

B = socket_examples:nano_get_url().
io:format("~p~n",[B]).
string:tokens(binary_to_list(B),"\r\n").

socket_examples:start_nano_server().
socket_examples:nano_client_eval("list_to_tuple([2+3*4,10+20])").

gen_tcp gen_udp

顺序和并行服务器（分裂一个进程）

主动（非阻塞式{active,true}）和被动套接字（阻塞式{active,false}） 混合消息接受（部分阻塞式{active,once}）

https://github.com/joearms/ezwebframe

cowboy：https://github.com/ninenines/cowboy

key-value 存储

ets:new(Name,[Opt])

性能分析工具： cprof:start(). 各个函数调用次数 fprof 时间 eprf

运行时诊断 栈跟踪

http://erlangdisplay.iteye.com/blog/1214167

开放电信平台 行为模式 是一个回调函数作为参数的框架

server1.erl

server1:start(name_server,name_server).
name_server:add(joe,"at home").
name_server:find(joe).

server2:start(name_server,name_server).
name_server:add(joe,"at home").
name_server:find(joe).

gen_server

init handle_call handle_cast handle_info terminate code_change

my_bank.erl

my_bank:start().
my_bank:deposit("joe",10).
my_bank.new_account("joe").
my_bank:deposit("joe",40).
my_bank.withdraw("joe",15).
my_bank.withdraw("joe",45).

gen_server.call(Name,Msg).
gen_server:cast(Name,Msg).

错误记录器 erl -boot start_sasl -config elog2 报警管理 gen_event 监控树 gen_supervistor application:start

应用程序监视器 appmon:start().

rebar 管理代码 rebar.config Makefile cowboy