Sprachdefinition (EBNF)

$\displaystyle \flq expression\frq\$	$\textstyle ::=$	$\displaystyle \flq abstraction\frq\ \vert$
		$\displaystyle \flq reference\frq\ \vert$
		$\displaystyle \flq synthesis\frq\$
$\displaystyle \flq abstraction\frq\$	$\textstyle ::=$	$\displaystyle '(' \: define \: \flq variable\frq\$
		$\displaystyle \flq expression\frq\ \: ')' \: \vert$
		$\displaystyle '(lambda (' \: \{ \flq variable \frq\ \} \: ')'$
		$\displaystyle \flq expression\frq\ \{\flq expression\frq\} \: ')'$
$\displaystyle \flq reference\frq\$	$\textstyle ::=$	$\displaystyle \flq variable\frq\$
$\displaystyle \flq synthesis\frq\$	$\textstyle ::=$	$\displaystyle '(' \: \flq expression\frq\$
		$\displaystyle \{ \flq expression\frq\ \} \: ')'$
$\displaystyle \flq variable\frq\$	$\textstyle ::=$	$\displaystyle \flq symbol\frq\$