s_expression = atom | quote | quasiquote | unquote | comment | cons | list;

quote = "'", s_expression;

quasiquote = "`", s_expression;

unquote = ",", s_expression;

cons = "(", s_expression, ".", s_expression, ")";

list = "(", {s_expression}, ")";


atom = package_symbol | symbol | literal | standard_rm;

package_symbol = [symbol], ":", symbol;

symbol = letter, {letter | number};

comment = ";" ?characters? "\n";

literal = string_literal | integer_literal | float_literal | rational_literal;

string_literal = """ ?string? """;

integer_literal = ["+"|"-"] {number};

float_literal = integer "." {number}; (* 123.4567 *)

rational_literal = integer "|" {number}; (* 8|9 -2|3 *)


standard_rm = "#", (char_literal | sharp_plus_minus | sharp_dot);

char_literal = "\", string; (* #\Space #\Newline #\2 #\a и т.д. *)

sharp_plus_minus = ("+"|"-"), s_expression, s_expresion;

sharp_dot = ".", s_expression;


letter = "a" | "b" | " ..." | "z";

number = "1" | "2" | " ..." | "9";