html.scm

(define (eval-html templ env)

  (define (lookup-var key env)
    (let ((pair (assoc key env)))
         (if (pair? pair)
            (cdr pair)
            '())))
             
  (define (tag? templ)
    (and (pair? templ) (symbol? (car templ))))

  (define (attr-list? templ)
    (and (pair? templ) (pair? (car templ))))

  (define (eval-attr-list templ)
    (cond ((null? templ) 'done)
          ((pair? (car templ))
           (let ((key (car (car templ)))
                 (val (cdr (car templ))))
                (display " ")
                (display key)
                (display "=\"")
                (display val)
                (display "\"")))))
        
  (define (eval-tag templ)
    (let ((tag (car templ))
          (tag-string (symbol->string (car templ))))
      (display "<")
      (display tag-string)

      (let ((next (cdr templ)))
        (if (or (null? next) (not (attr-list? (car next))))
            (begin (display ">") (eval-list next))
            (begin (eval-attr-list (car next)) (display ">") (eval-list (cdr next)))))

      (display "</")
      (display tag-string)
      (display ">")))

    (define (eval-list templ)
        (cond ((null? templ) 'done)
              ((tag? templ) 
                (eval-tag templ))
              (else 
                 (begin (eval (car templ)) (eval-list (cdr templ))))))

    (define (eval templ)
      (cond 
        ((list? templ) (eval-list templ))
        ((string? templ) (display templ))
        (else (error templ))))
    (eval templ))

(define template2
    '(ul
        (for-each person (get list))
            (li (ref item name) (ref item age))))
(define template
    '(html 
        (head
            (title "Plant o matic Web Page"))
        (body ((bgcolor . "yellow"))
            (h1 "Plant O matic")
            (h3 ((align . "right")) "New automatic plant feeding and watering")
            (p (font ((color . "green") 
                      (face . "comic sans")
                      (size . 2))
                       "Be the first in your neighborhood to own the plant-o-matic"))
            (p ((align . "center"))
                (font ((color . "#00FFFF") (face . "arial") (size 5))) "Don't Wait"
                (hr ((color . "purple"))))
            "this new " (b "product") " will save you " (u "time") ", "
            (p (em "money") (br) "and will keep your plants" (i "alive")))))
 
(eval-html template '(title . "Plant o matic Web Page"))