文 Statement

<statement>

::= <block-statement>
| <expression-statement>
| <variable-definition-statement>
| <assignment-statement>
| <if-statement>
| <while-statement>
| <for-statement>
| | |

<block-statement>

::= { <statement>* }

<expression-statement>

::= <expression> ;

<variable-definition-statement>

::= let <identifier> (: <type-representation>)? = <expression> ;

<assignment-statement>

::= <assignable-expression> = <expression> ;

<assignable-expression>

::= <identifier>
| <assignable-expression> . <identifier>
| <assignable-expression> [ <expression> ]

<if-statement>

::= if <expression> <block-statement>
(else if <expression> <block-statement>)*
(else <block-statement>)?

<while-statement>

::= while <expression> <block-statement>

<for-statement>

::= for <identifier> in <expression> <block-statement>

<optional-statement>

::= some <identifier> = <expression> <block-statement> none <block-statement>

検討中。以下のように書けるようにするかもしれない

let opt_v: V? = foo();
some v = opt_v {
  // v を使った処理
  bar(v);
} none {
  // 値がない場合の処理
}

::= “try” “=” “catch”

::= “match” “{” ( “=>” )* (“_” “=>” )? “}”