Huh, that's an useless script, isn't it?.bnf

<program> ::= <lines>
<lines> ::= (<line> <line_delimitor>)+
<line> ::= <input> | <output> | <ret> | <compound_ret>
<input> ::= ">" <var>
<output> ::= "<" <expr>
<expr> ::= <literal> | <var> | "(" <expr> ")" | <expr> <binary_op> <expr> | <unary_op> <expr> | <function_invoke>
<function_invoke> ::= <function_identifier> "(" <arguments>? ")"
<arguments> ::= <expr> ("," <expr>)*
<function_identifier> ::= <alpha> (<alpha> | [0-9] | "_")*
<binary_op> ::= "+" | "-" | "*" | "/" | "%" | <comparetion_op>
<comparetion_op> ::= "<" | "<=" | ">" | ">=" | "==" | "!=" | "===" | "!=="
<for_range> ::= "for(" <var> " in " <range> ")" <block>
<block> ::= "{" <lines> "}"
<range> ::= <int> ".." <int> | "(" <expr> ")" ".." "(" <expr> ")"
<unary_op> ::= "+" | "-" | "~"
<literal> ::= <int> | <bool> | <str>
<int> ::= [0-9]+
<bool> ::= "true" | "false"
/* これ合ってる？ */
<str> ::= "\x22" <any>* "\x22"
/* これも合ってる？ */
<any> ::= "\x00" | "\x01" | "\x02" | "\x03" | "\x04" | "\x05" | "\x06" | "\x07" | "\x08" | "\x09" | "\x0A" | "\x0B" | "\x0C" | "\x0D" | "\x0E" | "\x0F" | "\x10" | "\x11" | "\x12" | "\x13" | "\x14" | "\x15" | "\x16" | "\x17" | "\x18" | "\x19" | "\x1A" | "\x1B" | "\x1C" | "\x1D" | "\x1E" | "\x1F" | "\x20" | "\x21" | "\x22" | "\x23" | "\x24" | "\x25" | "\x26" | "\x27" | "\x28" | "\x29" | "\x2A" | "\x2B" | "\x2C" | "\x2D" | "\x2E" | "\x2F" | "\x30" | "\x31" | "\x32" | "\x33" | "\x34" | "\x35" | "\x36" | "\x37" | "\x38" | "\x39" | "\x3A" | "\x3B" | "\x3C" | "\x3D" | "\x3E" | "\x3F" | "\x40" | "\x41" | "\x42" | "\x43" | "\x44" | "\x45" | "\x46" | "\x47" | "\x48" | "\x49" | "\x4A" | "\x4B" | "\x4C" | "\x4D" | "\x4E" | "\x4F" | "\x50" | "\x51" | "\x52" | "\x53" | "\x54" | "\x55" | "\x56" | "\x57" | "\x58" | "\x59" | "\x5A" | "\x5B" | "\x5C" | "\x5D" | "\x5E" | "\x5F" | "\x60" | "\x61" | "\x62" | "\x63" | "\x64" | "\x65" | "\x66" | "\x67" | "\x68" | "\x69" | "\x6A" | "\x6B" | "\x6C" | "\x6D" | "\x6E" | "\x6F" | "\x70" | "\x71" | "\x72" | "\x73" | "\x74" | "\x75" | "\x76" | "\x77" | "\x78" | "\x79" | "\x7A" | "\x7B" | "\x7C" | "\x7D" | "\x7E" | "\x7F" | "\x80" | "\x81" | "\x82" | "\x83" | "\x84" | "\x85" | "\x86" | "\x87" | "\x88" | "\x89" | "\x8A" | "\x8B" | "\x8C" | "\x8D" | "\x8E" | "\x8F" | "\x90" | "\x91" | "\x92" | "\x93" | "\x94" | "\x95" | "\x96" | "\x97" | "\x98" | "\x99" | "\x9A" | "\x9B" | "\x9C" | "\x9D" | "\x9E" | "\x9F" | "\xA0" | "\xA1" | "\xA2" | "\xA3" | "\xA4" | "\xA5" | "\xA6" | "\xA7" | "\xA8" | "\xA9" | "\xAA" | "\xAB" | "\xAC" | "\xAD" | "\xAE" | "\xAF" | "\xB0" | "\xB1" | "\xB2" | "\xB3" | "\xB4" | "\xB5" | "\xB6" | "\xB7" | "\xB8" | "\xB9" | "\xBA" | "\xBB" | "\xBC" | "\xBD" | "\xBE" | "\xBF" | "\xC0" | "\xC1" | "\xC2" | "\xC3" | "\xC4" | "\xC5" | "\xC6" | "\xC7" | "\xC8" | "\xC9" | "\xCA" | "\xCB" | "\xCC" | "\xCD" | "\xCE" | "\xCF" | "\xD0" | "\xD1" | "\xD2" | "\xD3" | "\xD4" | "\xD5" | "\xD6" | "\xD7" | "\xD8" | "\xD9" | "\xDA" | "\xDB" | "\xDC" | "\xDD" | "\xDE" | "\xDF" | "\xE0" | "\xE1" | "\xE2" | "\xE3" | "\xE4" | "\xE5" | "\xE6" | "\xE7" | "\xE8" | "\xE9" | "\xEA" | "\xEB" | "\xEC" | "\xED" | "\xEE" | "\xEF" | "\xF0" | "\xF1" | "\xF2" | "\xF3" | "\xF4" | "\xF5" | "\xF6" | "\xF7" | "\xF8" | "\xF9" | "\xFA" | "\xFB" | "\xFC" | "\xFD" | "\xFE" | "\xFF"
<var> ::= (<alpha> | "_") (<alpha> | [0-9] | "_")*
<alpha> ::= [A-Z] | [a-z]
<line_delimitor> ::= ";" "\n"
<ret> ::= <var> "=" <expr>
<compound_ret> ::= <var> <compound_ret_op> <expr>
<compound_ret_op> ::= ("+" | "-" | "*" | "/" | "%" | "&&" | "||") "="