Syntax style ideas for a statically-typed lisp

syntax-style-ideas.scm

;; A translation of the example on http://nightmare.com/rushing/irken/irken/lang.html


;; Type definition follows Haskell's approach 

(data (tree a)
      empty
      (node a (tree a) (tree a)))


;; Function has type and arity defined after the name
;; patterns against that type are matched after that

(def (indent int bool) 
     (0 false) 
     (n (begin (print "   ") (indent (- n 1)))))


;; So e.g: whenever 'print' is called with an int and a tree of anything,
;; this is the definition to use:

(def (print int (tree a) bool)
     (d empty false)
     (d (node val left right) (begin
                               (indent d)
                               (print (+ d 1) left)
                               (print val)
                               (print "\n") 
                               (print (+ d 1) right))))

(let ((t (tree int)) 
      (node 5
            (node 7 empty (node 12 empty empty))
            (node 9 empty empty)))
  (print 0 t))