SASS-like Thing in Scheme

schass.scm

;; Let's you do this:
;;
;; (make-css
;;  '(("body.loading"
;;     (font-size "12px")
;;     (color "#fff")
;;     (" ul#sidenav"
;;      (" li"
;;       (blah "blah"))))))
;;
;; Returned is a string that looks like this:
;;
;; body.loading { font-size: 12px; color: #fff; }
;; body.loading ul#sidenav li { blah: blah; }

(define (make-css els)
  (let outer ((els els) (ctx "") (out ""))
    (if (null? els) out
	(let* ((el (car els))
	       (selector (car el)))
	  (let inner ((rules (cdr el)) (out out) (children-out ""))
	    (if (null? rules)
		(if (zero? (string-length out))
		    children-out
		    (string-append ctx selector " { " out "}\n" children-out))
		(let* ((rule (car rules)) (label (car rule)))
		  (if (string? label)
		      (inner (cdr rules)
			     out
			     (string-append children-out
					    (outer rules
						   (string-append ctx selector)
						   "")))
		      (let ((body (cdr rule)))
			(inner (cdr rules)
			       (string-append out
					      (symbol->string label)
					      ": "
					      (car body)
					      "; ")
			       children-out))))))))))