Simple Lisp grammar

gistfile1.lisp

(grammar ((Expression < (/ String List Atom)))
         ((String     <- (:"\"") "[^\"]*" (: "\"")))
         ((List       < (: "\\(") (* Expression) (: "\\)"))
                        `($(car List)
                          $(cdr List)))
         ((Atom       <- (/ Number Symbol)))
         ((Number     <- "[+\\-]?[0-9]+(\\.[0-9]*)?")
                         `($(car Number)
                           ($(str->num (caadr Number)))))
         ((Symbol     <- (! Number) "[^\\(\\)\"';\\s]+")
                         `($(car Symbol)
                           ($(str->symbol (caadr Symbol)))))
         ((Spacing    <- (* (/ Comment "[\\s]+"))))
         ((Comment    <- (: ";" "[^\n]*\n"))))

(Expression "(define (compose f g)
               (lambda (arg) (f (g arg))))")