新作言語のEBNFを書いていくスレ

**デフォルトの名無しさん** · 2021/12/23(木) 04:14:23.80

文法はWikiを見てね↓
https://ja.wikipedia.org/wiki/EBNF

↓は四則演算の実装

program = expr ;
expr = term , [ add sub op , term ] ;
term = factor , [ mul div op , factor ] ;
factor = number | "(" expr ")" ;
number = [ "-" ] , digit , [ { digit } ] ;
digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
add sub op = "+" | "-" ;
mul div op = "*" | "/" ;

**デフォルトの名無しさん** · 2021/12/23(木) 04:59:10.83

WikipediaをWikiという人間は信用されまふぇんよ？（＾＾

**デフォルトの名無しさん** · 2021/12/23(木) 05:02:18.02

ごめんお(´・ω・｀)

**デフォルトの名無しさん** · 2021/12/23(木) 19:08:34.36

“Wiki”,[“pedia”]

**デフォルトの名無しさん** · 2021/12/24(金) 07:01:52.28

if statement = "if" , expr . "

**デフォルトの名無しさん** · 2021/12/27(月) 18:14:40.87

<Exp> ::= <Const> | <Var> | <Form>

<Form> ::= <If> | <Lambda> | <Apply> | <Let> | <Letrec>

<If> ::= "[" IF "," <Exp> "," <Exp> "," <Exp> "]"

<Lambda> ::= "[" LAMBDA "," "[" <Var1> "," ... "," <VarN> "]" "," <Exp> "]" /* N >= 1 */

<Apply> ::= "[" <Exp1> "," ... "," <ExpN> "]" /* N >= 2 */

<Let> ::= "[" LET "," <Exp> "," <Bind1> "," ... "," <BindN> "]" /* N >= 0 */
<Bind> ::= "[" <Var> "," <Exp> "]"

<Letrec> ::= "[" LETREC "," <Exp> "," "[" <RecBind1> "," ... "," <RecBindN> "]" "]" /* N >= 0 */
<RecBind> ::= "[" <Var> "|" <Lambda> "]"

6 · 2021/12/27(月) 18:45:41.62

>>5 の例として、階乗(FACT)と最大公約数(GCD)

[LETREC, [@fact, 4],
　　[@fact, LAMBDA, [@x],
　　　　[IF, [LE, @x, 1],
　　　　　　1,
　　　　　　[MUL, @x, [@fact, [SUB, @x, 1]]]]]] ;

[LETREC, [@gcd, 16, 28],
　　[@gcd, LAMBDA, [@a, @b],
　　　　[IF, [EQ, @b, 0],
　　　　　　@a,
　　　　　　[@gcd, @b, [MOD, @a, @b]]]]]