diff --git a/decode.rkt b/decode.rkt
index 3a349f4..0b7b190 100644
--- a/decode.rkt
+++ b/decode.rkt
@@ -237,6 +237,16 @@
 
 
 
+;; recursive whitespace test
+(define/contract (whitespace? x)
+  (any/c . -> . boolean?)
+  (cond
+    [(or (string? x) (symbol? x)) (->boolean (regexp-match #px"^\\s+$" (->string x)))]
+    [(equal? "" x) #t] ; empty string is deemed whitespace
+    [(or (list? x) (vector? x)) (andmap whitespace? (->list x))]
+    [else #f]))
+
+
 ;; is x a paragraph break?
 (define/contract (paragraph-break? x #:pattern [paragraph-pattern #px"^\n\n+$"])
   ((any/c) (#:pattern pregexp?) . ->* . boolean?)
diff --git a/main.rkt b/main.rkt
index 48d6574..e877dbf 100644
--- a/main.rkt
+++ b/main.rkt
@@ -42,28 +42,35 @@
                                                            (cons `(meta "here" ,inner-here) meta-elements)))))
    
    
+   
+   
    ;; set up the 'main export
+   (require pollen/decode)
+   (require (only-in racket/list filter-not))
    (define here-ext (car (regexp-match #px"\\w+$" inner-here-path)))
    (define wants-decoder? (member here-ext (list "pd" "ptree")))
-   (define main (apply (if wants-decoder?
-                           ;; 'root is the hook for the decoder function.
-                           ;; If it's not a defined identifier, it just hits #%top and becomes `(root ,@body ...)
-                           root
-                           ;; for preprocessor output, just make a string. Converts x-expressions to HTML.
-                           (λ xs (apply string-append (map (dynamic-require 'xml 'xexpr->string) xs))))
-                       (cdr main-without-metas))) ;; cdr strips placeholder-root tag
-   
-   
-   ;; derive 'here & 'here-path from the hash (because they might have been overridden in the source) 
-   (define here (hash-ref metas "here"))
-   (define here-path (hash-ref metas "here-path"))
-   
-   (provide metas main here here-path
-            ;; hide the exports that were only for internal use.
-            (except-out (all-from-out 'inner) inner-here inner-here-path main-raw #%top))
-   
-   ;; for output in DrRacket
-   (module+ main
-     (if wants-decoder? 
-         (print main) 
-         (display main)))))
+   ;(print (cdr main-without-metas))
+   (define main (apply (cond
+                         [(equal? here-ext "ptree") (λ xs (decode (cons 'ptree-root xs)
+                                                      #:xexpr-elements-proc (λ(xs) (filter-not whitespace? xs))))]
+                         ;; 'root is the hook for the decoder function.
+                         ;; If it's not a defined identifier, it just hits #%top and becomes `(root ,@body ...)
+                         [wants-decoder? root]
+                         ;; for preprocessor output, just make a string. Converts x-expressions to HTML.
+                         [else (λ xs (apply string-append (map (dynamic-require 'xml 'xexpr->string) xs)))])
+(cdr main-without-metas))) ;; cdr strips placeholder-root tag
+
+
+;; derive 'here & 'here-path from the hash (because they might have been overridden in the source) 
+(define here (hash-ref metas "here"))
+(define here-path (hash-ref metas "here-path"))
+
+(provide metas main here here-path
+         ;; hide the exports that were only for internal use.
+         (except-out (all-from-out 'inner) inner-here inner-here-path main-raw #%top))
+
+;; for output in DrRacket
+(module+ main
+  (if wants-decoder? 
+      (print main) 
+      (display main)))))
diff --git a/predicates.rkt b/predicates.rkt
index 6b0e81b..03f2e2c 100644
--- a/predicates.rkt
+++ b/predicates.rkt
@@ -27,14 +27,6 @@
   ((txexpr? x) . and . ((car x) . in? . project-block-tags)))
 
 
-;; recursive whitespace test
-(define+provide/contract (whitespace? x)
-  (any/c . -> . boolean?)
-  (cond
-    [(or (vector? x) (list? x) (set? x)) (andmap whitespace? (->list x))]
-    [(equal? "" x) #t] ; empty string is deemed whitespace
-    [(or (symbol? x) (string? x)) (->boolean (regexp-match #px"^\\s+$" (->string x)))]
-    [else #f]))