Welcome to the CHICKEN Scheme pasting service

#!/usr/bin/csi -s
(import comparse)
(import srfi-14)

(define (as-symbol parser)
  (bind (as-string parser)
        (lambda (s)
          (result (string->symbol s)))))

(define (as-number parser)
  (bind (as-string parser)
        (lambda (s)
          (result (string->number s)))))

(define symbol
  (as-symbol (char-seq-match '(: symbol))))

(define ws
  (zero-or-more (in char-set:whitespace)))

(define begin-curly (is #\{))
(define end-curly (is #\}))

(define curly
  (recursive-parser
   (enclosed-by (preceded-by begin-curly ws)
                (any-of
                 (sequence*
                  ((first-value value)
                   (more-values (zero-or-more value)))
                  (result (cons first-value more-values)))
                 (result '()))
                end-curly)))

(define value
  (enclosed-by ws (any-of curly symbol) ws))


(define infix-expr (enclosed-by ws curly ws))

(print "Works: {a b c {d e}}")
(write (parse infix-expr "{a b c {d e}}"))
(newline)

(print "Doesn't work: {a b c {d e} a}")
(write (parse infix-expr "{a b c {d e} a}"))
(newline)