Added an old draft of the syntax/parse interface.

syntax-parse-draft.rkt

@@ -0,0 +1,42 @@
+#lang racket
+
+(require generic-syntax-expanders
+         (for-syntax syntax/parse
+                     generic-syntax-expanders/private/expanders
+                     generic-syntax-expanders)
+         (for-meta 2
+                   racket/base
+                   racket/syntax
+                   generic-syntax-expanders))
+
+(begin-for-syntax
+  (define-syntax ~expand
+    (pattern-expander
+     (λ (stx)
+       (syntax-case stx ()
+         [(_ type id extra-pat ...)
+          ;(expander-type? #'type)
+          (with-syntax ([t-expander? (format-id #'type "~a-expander?" #'type)]
+                        [t-expander-type (format-id #'type "~a-expander-type" #'type)]
+                        [id.fully-expanded (format-id #'id "~a.fully-expanded" #'id)])
+            #'(~and (~var id)
+                    ((~var exp (static t-expander?
+                                       (format "a ~a expander" (syntax-e #'id))))
+                     exp-arg (... ...))
+                    (~bind [id.fully-expanded
+                            (expand-syntax-tree-with-expanders-of-type t-expander-type
+                                                                       #'id)])
+                    (~parse (~and _ extra-pat ...) #'id.fully-expanded)))])))))
+
+
+(define-expander-type foo)
+(define-syntax foo
+  (syntax-parser
+    [(_ a:id (~expand foo b) c)
+     #'b.fully-expanded]))
+
+(define-foo-expander f-ex
+  (λ (stx)
+    #''works!))
+
+(foo a (f-ex blah blah) c) ;; => 'works!