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('[email protected]'). -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