Introduction to Erlang/OTP

Erlang 入門括弧が要らない！ Windowsでも楽ちん！並行プログラミングもOK！英語OKなら何気に資料も多いぞ！・・・そんな関数型言語 Erlang にIT土方系PHPerが果敢にも挑戦している最中です。 id:msakamoto-sf 坂本　昌彦 [email_address]

最初に場所を提供していただきました株式会社　 EC ナビ様ありがとう御座います！ヽ (´ ー `) ノ

Erlangって？ ,[object Object],[object Object],[object Object],[object Object],[object Object]

「あーらん」？ ,[object Object],[object Object],[object Object],[object Object]

知名度UPのきっかけ。 ,[object Object],[object Object],[object Object],[object Object]

なぜLisp/Schemeじゃないの？ ,[object Object],[object Object],[object Object],[object Object],[object Object]

なぜErlang？ ,[object Object],[object Object],[object Object],[object Object],[object Object]

PHPerのアナタにこそErlang(w ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Erlang/OTP ,[object Object],[object Object],[object Object],[object Object],[object Object]

Windows用のバイナリ ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Erlangの世界（０） - ようこそ、Erlangの世界へ - ,[object Object]

"Hello, Erlang!" ,[object Object],-module(hello). -export([start/0]). start() -> io:format("Hello, Erlang!~n").

"Hello, Erlang!" ,[object Object],C:n_vitrorlang>erl Eshell V5.6.3 (abort with ^G) 1> c(hello) . {ok,hello} 2> hello:start(). Hello, Erlang! ok

"-module(hello)." ,[object Object],[object Object],[object Object]

"-export([start/0])." ,[object Object],[object Object],[object Object],[object Object]

start() -> io:format("Hello, Erlang!~n"). ,[object Object],[object Object],[object Object],[object Object]

"c(hello)." ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

"hello:start()." ,[object Object]

Erlangの世界（１） ,[object Object]

変数名は大文字で始まる英数字とアンダースコア("_") ,[object Object],C:n_vitrorlang>erl Eshell V5.6.3 (abort with ^G) 1> Var1 = 100. 100 2> Var1_2 = 200. 200 3> var2 = 300. ** exception error: no match of right hand side value 300 4> Var2-1 = 400. * 1: illegal pattern OK! NG!

変数への代入は一度だけ！ ,[object Object],9> Var1 = 100. 100 10> Var1 = "ABCD". ** exception error: no match of right hand side value "ABCD" 11> b(). Var1 = 100 ok

「束縛」？ ,[object Object],[object Object],11> b(). Var1 = 100 ok 12> f(). ok 13> Var1 = "ABCD". "ABCD"

Erlangの世界（２） ,[object Object]

C言語での列挙型。定数みたいな。 ,[object Object],[object Object],[object Object],[object Object],17> hello. hello 18> 'Friday Night'. 'Friday Night' 19> 'user_01@example.com'. 'user_01@example.com'

Erlangの世界（３） ,[object Object]

複数の変数をひとまとめにする単位 ,[object Object],[object Object],[object Object],[object Object],1> X = {1, "hello", world }. {1,"hello",world} 2> Y = { {orange, 100}, {apple, 300} }. {{orange,100},{apple,300}}

タプルの値の取得（１） ,[object Object],3> {V1, V2} = X. ** exception error: no match of right hand side value {1,"hello",world} 4> {V1, V2, V3} = X. {1,"hello",world} 5> V1. 1 6> V2. "hello" 7> V3. world

タプルの値の取得（２） ,[object Object],9> V1 = { apple, 100 }. {apple,100} 10> V2 = { orange, 200 }. {orange,200} 11> { apple, Price } = V1. {apple,100} 12> { orange, Price_orange } = V1. ** exception error: no match of right hand side value {apple,100} 13> { orange, Price_orange } = V2. {orange,200} 14> { Price, Price_orange }. {100,200}

Erlangの世界（４） ,[object Object]

いわゆる配列 ,[object Object],1> X = [1, "Hello", world, 2 + 3, { apple, 10 }, [ 4, 5, 6 ] ]. [1,"Hello",world,5,{apple,10},[4,5,6]]

値の取得（HeadとTail） ,[object Object],[object Object],[object Object],2> lists:nth(1, X). 1 3> [H | T] = X. [1,"Hello",world,5,{apple,10},[4,5,6]] 4> H. 1 5> T. ["Hello",world,5,{apple,10},[4,5,6]]

Erlangの世界（５） ,[object Object]

連想配列みたいな。 ,[object Object],[object Object],-record(person, { %% デフォルト値有り name = "anonymous", %% デフォルト値無し age, weight }).

レコードの作成・参照 ,[object Object],1> rr("records.hrl"). [person] 2> V1 = #person{}. #person{name = "anonymous",age = undefined, weight = undefined} 3> V2 = #person{ name = "Jon", age = 20, weight = 60 }. #person{name = "Jon",age = 20,weight = 60} 4> V3 = #person{ name = "Smith", age = 30, weight = 58 }. #person{name = "Smith",age = 30,weight = 58} 5> #person{ name = N, age = A, weight = W } = V3. #person{name = "Smith",age = 30,weight = 58} 6> [ N, A, W ]. ["Smith",30,58]

Erlangの世界（６） ,[object Object]

引数の数の異なる関数は区別される。 ,[object Object],-module(funtest1). -export([funtest/0, funtest/1, funtest/2]). funtest() -> -1. funtest(N) -> N * 2. funtest(N, M) -> N + M. -> 1> c(funtest1). {ok,funtest1} 2> { funtest1:funtest(), funtest1:funtest(10), funtest1:funtest(20, 30) }. {-1,20,50}

"ガード"による区別 ,[object Object],-module(funtest2). -export([fact/1]). fact(N) when N > 0 -> N * fact(N - 1); fact(0) -> 1. -> 1> c(funtest2). {ok,funtest2} 2> funtest2:fact(5). 120

fun() ,[object Object],1> Double = fun(X) -> X * 2. * 1: syntax error before: '.' 1> Double = fun(X) -> X * 2 end. #Fun<erl_eval.6.13229925> 2> L = [ 1, 2, 3, 4]. [1,2,3,4] 3> lists:map(Double, L). [2,4,6,8]

今回はここまで。 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Introduction to Erlang/OTP

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