OMeta/JS Parser/Generator DSL

This is a proof of concept s-expression parser in OMeta/JS I just made in about 10 minutes, produces Javascript nested lists as the resulting AST, although I could easily produce output text in a different language like C or C++. OMeta/JS is a Parsing Expression Grammar DSL which uses Javascript as the host language.

ometa SexprParser {
    start      = sexpr*,
    sexpr      = spaces (atom | list),
    atom       = symbol | number,
    list       = "(" sexpr:h sexpr*:t spaces ")"            -> [h].concat(t)
               | "(" sexpr:e spaces ")"                     -> [e]
               | "(" blank ")"                              -> [],
    symbol     = firstAndRest(`letter, `letterOrDigit):s    -> s.join(''),
    digit      = ^digit:d                                   -> d.digitValue(),
    number     = number:n digit:d                           -> (n * 10 + d)
               | digit
}

$> SexprParser.matchAll("""
(print (add 1 2))
(map xarnicate
    (you me TheSussman)
    (100 200 300))
""", `start)

$> [[print, [add, 1, 2]], [map, xarnicate, [you, me, TheSussman], [100, 200, 300]]]

>>5

thanks for the info. i read (well, skimmed) the linked dissertation but it didn't mention things like "spaces", "firstAndRest", etc that you used in your example. did you define those earlier or are those part of the "standard library" and explained somewhere?