rename fields

xenomorph/xenomorph/array.rkt

@@ -16,28 +16,28 @@ https://github.com/mbutterick/restructure/blob/master/src/Array.coffee
 (define xarray%
   (class xenobase%
     (super-new)
-    (init-field type len length-type)
+    (init-field [(@type type)] [(@len len)] [(@length-type length-type)])
     
-    (unless (xenomorphic-type? type)
-      (raise-argument-error '+xarray "xenomorphic type" type))
-    (unless (length-resolvable? len)
-      (raise-argument-error '+xarray "length-resolvable?" len))
-    (unless (memq length-type '(bytes count))
-      (raise-argument-error '+xarray "'bytes or 'count" length-type))
+    (unless (xenomorphic-type? @type)
+      (raise-argument-error '+xarray "xenomorphic type" @type))
+    (unless (length-resolvable? @len)
+      (raise-argument-error '+xarray "length-resolvable?" @len))
+    (unless (memq @length-type '(bytes count))
+      (raise-argument-error '+xarray "'bytes or 'count" @length-type))
 
     (define/augride (xxdecode port parent)
-      (define new-parent (if (xint? len)
+      (define new-parent (if (xint? @len)
                              (mhasheq 'parent parent
                                       '_startOffset (pos port)
                                       '_currentOffset 0
-                                      '_length len)
+                                      '_length @len)
                              parent))
-      (define resolved-len (resolve-length len #:parent parent))
+      (define len (resolve-length @len #:parent parent))
       (cond
-        [(or (not resolved-len) (eq? length-type 'bytes))
+        [(or (not len) (eq? @length-type 'bytes))
          (define end-pos (cond
                            ;; resolved-len is byte length
-                           [resolved-len (+ (pos port) resolved-len)]
+                           [len (+ (pos port) len)]
                            ;; no resolved-len, but parent has length
                            [(and parent (not (zero? (dict-ref parent '_length))))
                             (+ (dict-ref parent '_startOffset) (dict-ref parent '_length))]
@@ -45,10 +45,10 @@ https://github.com/mbutterick/restructure/blob/master/src/Array.coffee
                            [else +inf.0]))
          (for/list ([i (in-naturals)]
                     #:break (or (eof-object? (peek-byte)) (= (pos port) end-pos)))
-           (send type xxdecode port new-parent))]
+           (send @type xxdecode port new-parent))]
         ;; we have resolved-len, which is treated as count of items
-        [else (for/list ([i (in-range resolved-len)])
-                (send type xxdecode port new-parent))]))
+        [else (for/list ([i (in-range len)])
+                (send @type xxdecode port new-parent))]))
 
     (define/augride (xxencode array port [parent #f])
       (unless (sequence? array)
@@ -60,17 +60,17 @@ https://github.com/mbutterick/restructure/blob/master/src/Array.coffee
                #;[item-count (length items)]
                #;[max-items (if (number? (xarray-len xa)) (xarray-len xa) item-count)])
           (for ([item array])
-            (send type xxencode item port parent))))
+            (send @type xxencode item port parent))))
       (cond
-        [(xint? len)
-         (let ([parent (mhash 'pointers null
-                              'startOffset (pos port)
-                              'parent parent)])
-           (dict-set! parent 'pointerOffset (+ (pos port) (xxsize array parent)))
-           (send len xxencode (length array) port) ; encode length at front
-           (encode-items parent)
-           (for ([ptr (in-list (dict-ref parent 'pointers))]) ; encode pointer data at end
-             (send (dict-ref ptr 'type) xxencode (dict-ref ptr 'val) port)))]
+        [(xint? @len)
+         (define new-parent (mhash 'pointers null
+                                   'startOffset (pos port)
+                                   'parent parent))
+         (dict-set! new-parent 'pointerOffset (+ (pos port) (xxsize array new-parent)))
+         (send @len xxencode (length array) port) ; encode length at front
+         (encode-items new-parent)
+         (for ([ptr (in-list (dict-ref new-parent 'pointers))]) ; encode pointer data at end
+           (send (dict-ref ptr 'type) xxencode (dict-ref ptr 'val) port))]
         [else (encode-items parent)]))
 
     (define/augride (xxsize [val #f] [parent #f])
@@ -78,15 +78,15 @@ https://github.com/mbutterick/restructure/blob/master/src/Array.coffee
                   (raise-argument-error 'xarray-size "sequence" val)))
       (cond
         [val (define-values (new-parent len-size)
-               (if (xint? len)
-                   (values (mhasheq 'parent parent) (send len xxsize))
+               (if (xint? @len)
+                   (values (mhasheq 'parent parent) (send @len xxsize))
                    (values parent 0)))
              (define items-size (for/sum ([item val])
-                                  (send type xxsize item new-parent)))
+                                  (send @type xxsize item new-parent)))
              (+ items-size len-size)]
-        [else (define item-count (resolve-length len #f #:parent parent))
-              (define item-size (send type xxsize #f parent))
-              (* item-size item-count)]))))
+        [else (define count (resolve-length @len #f #:parent parent))
+              (define size (send @type xxsize #f parent))
+              (* size count)]))))
 
 (define (+xarray [type-arg #f] [len-arg #f] [length-type-arg 'count]
                  #:type [type-kwarg #f]

xenomorph/xenomorph/bitfield.rkt

@@ -10,24 +10,26 @@ https://github.com/mbutterick/restructure/blob/master/src/Bitfield.coffee
 (define xbitfield%
   (class xenobase%
     (super-new)
-    (init-field type flags)
+    (init-field [(@type type)][(@flags flags)])
+    (unless (andmap (λ (f) (or (symbol? f) (not f))) @flags)
+      (raise-argument-error '+xbitfield "list of symbols" @flags))
 
     (define/augment (xxdecode port parent)
+      (define val (send @type xxdecode port))
       (define flag-hash (mhasheq))
-      (define val (send type xxdecode port))
-      (for ([(flag idx) (in-indexed flags)]
+      (for ([(flag idx) (in-indexed @flags)]
             #:when flag)
         (hash-set! flag-hash flag (bitwise-bit-set? val idx)))
       flag-hash)
 
     (define/augment (xxencode flag-hash port [parent #f])
-      (define bit-int (for/sum ([(flag idx) (in-indexed flags)]
+      (define bit-int (for/sum ([(flag idx) (in-indexed @flags)]
                                 #:when (and flag (dict-ref flag-hash flag #f)))
                         (arithmetic-shift 1 idx)))
-      (send type xxencode bit-int port))
+      (send @type xxencode bit-int port))
     
     (define/augment (xxsize [val #f] [parent #f])
-      (send type xxsize))))
+      (send @type xxsize))))
   
 (define (+xbitfield [type-arg #f] [flag-arg #f]
                     #:type [type-kwarg #f]
@@ -35,8 +37,6 @@ https://github.com/mbutterick/restructure/blob/master/src/Bitfield.coffee
                     #:subclass [class xbitfield%])
   (define type (or type-arg type-kwarg))
   (define flags (or flag-arg flag-kwarg null))
-  (unless (andmap (λ (f) (or (symbol? f) (not f))) flags)
-    (raise-argument-error '+xbitfield "list of symbols" flags))
   (new class [type type] [flags flags]))
 
 (module+ test

xenomorph/xenomorph/buffer.rkt

@@ -10,17 +10,19 @@ https://github.com/mbutterick/restructure/blob/master/src/Buffer.coffee
 (define xbuffer%
   (class xenobase%
     (super-new)
-    (init-field len)
+    (init-field [(@len len)])
+    (unless (length-resolvable? @len)
+      (raise-argument-error '+xbuffer "resolvable length" @len))
 
     (define/augment (xxdecode port parent)
-      (define decoded-len (resolve-length len #:parent parent))
-      (read-bytes decoded-len))
+      (define len (resolve-length @len #:parent parent))
+      (read-bytes len))
 
     (define/augment (xxencode buf port [parent #f])
       (unless (bytes? buf)
         (raise-argument-error 'xbuffer-encode "bytes" buf))
-      (when (xint? len)
-        (send len xxencode (bytes-length buf) port))
+      (when (xint? @len)
+        (send @len xxencode (bytes-length buf) port))
       (write-bytes buf port))
     
     (define/augment (xxsize [val #f] [parent #f])
@@ -28,12 +30,10 @@ https://github.com/mbutterick/restructure/blob/master/src/Buffer.coffee
                   (raise-argument-error 'xbuffer-size "bytes" val)))
       (if (bytes? val)
           (bytes-length val)
-          (resolve-length len val #:parent parent)))))
+          (resolve-length @len val #:parent parent)))))
 
 (define (+xbuffer [len-arg #f]
                   #:length [len-kwarg #f]
                   #:subclass [class xbuffer%])
   (define len (or len-arg len-kwarg #xffff))
-  (unless (length-resolvable? len)
-    (raise-argument-error '+xbuffer "resolvable length" len))
   (new class [len len]))

xenomorph/xenomorph/enum.rkt

@@ -10,29 +10,30 @@ https://github.com/mbutterick/restructure/blob/master/src/Enum.coffee
 (define xenum%
   (class xenobase%
     (super-new)
-    (init-field type values)
+    (init-field [(@type type)] [(@values values)])
+     
+    (unless (xenomorphic-type? @type)
+      (raise-argument-error '+xenum "xenomorphic type" @type))
+    (unless (list? @values)
+      (raise-argument-error '+xenum "list of values" @values))
 
     (define/augment (xxdecode port parent)
-      (define index (send type xxdecode port parent))
-      (or (list-ref values index) index))
+      (define index (send @type xxdecode port parent))
+      (or (list-ref @values index) index))
 
     (define/augment (xxencode val port [parent #f])
-      (define index (index-of values val))
+      (define index (index-of @values val))
       (unless index
         (raise-argument-error 'xenum-encode "valid option" val))
-      (send type xxencode index port parent))
+      (send @type xxencode index port parent))
     
     (define/augment (xxsize [val #f] [parent #f])
-      (send type xxsize val parent))))
+      (send @type xxsize val parent))))
 
 (define (+xenum [type-arg #f] [values-arg #f]
                 #:type [type-kwarg #f]
                 #:values [values-kwarg #f]
                 #:subclass [class xenum%])
   (define type (or type-arg type-kwarg))
-  (unless (xenomorphic-type? type)
-    (raise-argument-error '+xenum "xenomorphic type" type))
   (define values (or values-arg values-kwarg))
-  (unless (list? values)
-    (raise-argument-error '+xenum "list of values" values))
   (new class [type type] [values values]))

xenomorph/xenomorph/lazy-array.rkt

@@ -11,26 +11,26 @@ https://github.com/mbutterick/restructure/blob/master/src/LazyArray.coffee
 (define xlazy-array%
   (class xarray%
     (super-new)
-    (inherit-field type len)
+    (inherit-field [@type type] [@len len])
 
     (define/override (xxdecode port parent)
       (define starting-pos (pos port)) ; ! placement matters. `resolve-length` will change `pos`
-      (define decoded-len (resolve-length len #:parent parent))
-      (let ([parent (if (xint? len)
-                        (mhasheq 'parent parent
-                                 '_startOffset starting-pos
-                                 '_currentOffset 0
-                                 '_length len)
-                        parent)])
-        (define starting-pos (pos port))
-        (begin0
-          (for/stream ([index (in-range decoded-len)])
-            (define orig-pos (pos port))
-            (pos port (+ starting-pos (* (send type xxsize #f parent) index)))
-            (begin0
-              (send type xxdecode port parent)
-              (pos port orig-pos)))
-          (pos port (+ (pos port) (* decoded-len (send type xxsize #f parent)))))))
+      (define len (resolve-length @len #:parent parent))
+      (define new-parent (if (xint? @len)
+                             (mhasheq 'parent parent
+                                      '_startOffset starting-pos
+                                      '_currentOffset 0
+                                      '_length @len)
+                             parent))
+      (define stream-starting-pos (pos port))
+      (begin0
+        (for/stream ([index (in-range len)])
+          (define orig-pos (pos port))
+          (pos port (+ stream-starting-pos (* (send @type xxsize #f new-parent) index)))
+          (begin0
+            (send @type xxdecode port new-parent)
+            (pos port orig-pos)))
+        (pos port (+ (pos port) (* len (send @type xxsize #f new-parent))))))
 
     (define/override (xxencode val port [parent #f])
       (super xxencode (if (stream? val) (stream->list val) val) port parent))

xenomorph/xenomorph/number.rkt

@@ -26,13 +26,16 @@ https://github.com/mbutterick/restructure/blob/master/src/Number.coffee
 (define xnumber%
   (class xenobase%
     (super-new)
-    (init-field size endian)
-    (unless (exact-positive-integer? size)
-      (raise-argument-error 'xenomorph "exact positive integer" size))
-    (unless (memq endian '(le be))
-      (raise-argument-error 'xenomorph "'le or 'be" endian))
-    (field [bits (* size 8)])
-    (define/augment (xxsize . _) size)))
+    (init-field [(@size size)] [(@endian endian)])
+    
+    (unless (exact-positive-integer? @size)
+      (raise-argument-error 'xenomorph "exact positive integer" @size))
+    (unless (memq @endian '(le be))
+      (raise-argument-error 'xenomorph "'le or 'be" @endian))
+    
+    (field [@bits (* @size 8)])
+    
+    (define/augment (xxsize . _) @size)))
 
 (define (xint? x) (is-a? x xint%))
 
@@ -40,31 +43,31 @@ https://github.com/mbutterick/restructure/blob/master/src/Number.coffee
   (class xnumber%
     (super-new)
     (init-field signed)
-    (inherit-field endian size bits)
+    (inherit-field (@endian endian) (@size size) @bits)
     
     ;; if a signed integer has n bits, it can contain a number
     ;; between - (expt 2 (sub1 n)) and (sub1 (expt 2 (sub1 n)).
-    (define signed-max (sub1 (arithmetic-shift 1 (sub1 bits))))
+    (define signed-max (sub1 (arithmetic-shift 1 (sub1 @bits))))
     (define signed-min (sub1 (- signed-max)))
     (define delta (if signed 0 signed-min))
     (field [bound-min (- signed-min delta)]
            [bound-max (- signed-max delta)])
                 
     (define/augment (xxdecode port . _)
-      (define bs ((if (eq? endian system-endian) values reverse-bytes) (read-bytes size port)))
+      (define bs ((if (eq? @endian system-endian) values reverse-bytes) (read-bytes @size port)))
       (define uint (for/sum ([b (in-bytes bs)]
                              [i (in-naturals)])
                      (arithmetic-shift b (* 8 i))))
-      (if signed (unsigned->signed uint bits) uint))
+      (if signed (unsigned->signed uint @bits) uint))
                 
     (define/augment (xxencode val . _)
       (unless (<= bound-min val bound-max)
         (raise-argument-error 'encode
-                              (format "value that fits within ~a ~a-byte int (~a to ~a)" (if signed "signed" "unsigned") size bound-min bound-max) val))
+                              (format "value that fits within ~a ~a-byte int (~a to ~a)" (if signed "signed" "unsigned") @size bound-min bound-max) val))
       (for/fold ([bs null]
                  [val (exact-if-possible val)]
-                 #:result (apply bytes ((if (eq? endian 'be) values reverse) bs)))
-                ([i (in-range size)])
+                 #:result (apply bytes ((if (eq? @endian 'be) values reverse) bs)))
+                ([i (in-range @size)])
         (values (cons (bitwise-and val #xff) bs) (arithmetic-shift val -8))))))
 
 (define (+xint [size 2]
@@ -144,13 +147,13 @@ https://github.com/mbutterick/restructure/blob/master/src/Number.coffee
 (define xfloat%
   (class xnumber%
     (super-new)
-    (inherit-field size endian)
+    (inherit-field (@size size) (@endian endian))
                 
     (define/augment (xxdecode port . _)
-      (floating-point-bytes->real (read-bytes size port) (eq? endian 'be)))
+      (floating-point-bytes->real (read-bytes @size port) (eq? @endian 'be)))
                 
     (define/augment (xxencode val . _)
-      (real->floating-point-bytes val size (eq? endian 'be)))))
+      (real->floating-point-bytes val @size (eq? @endian 'be)))))
 
 (define (+xfloat [size 4] #:endian [endian system-endian])
   (new xfloat% [size size] [endian endian]))
@@ -166,11 +169,11 @@ https://github.com/mbutterick/restructure/blob/master/src/Number.coffee
 (define xfixed%
   (class xint%
     (super-new)
-    (init-field fracbits)
-    (unless (exact-positive-integer? fracbits)
-      (raise-argument-error '+xfixed "exact positive integer for fracbits" fracbits))
+    (init-field [(@fracbits fracbits)])
+    (unless (exact-positive-integer? @fracbits)
+      (raise-argument-error '+xfixed "exact positive integer for fracbits" @fracbits))
 
-    (define fixed-shift (arithmetic-shift 1 fracbits))
+    (define fixed-shift (arithmetic-shift 1 @fracbits))
                 
     (define/override (post-decode int)
       (exact-if-possible (/ int fixed-shift 1.0)))

xenomorph/xenomorph/optional.rkt

@@ -10,29 +10,25 @@ https://github.com/mbutterick/restructure/blob/master/src/Optional.coffee
 (define xoptional%
   (class xenobase%
     (super-new)
-    (init-field type condition)
+    (init-field [(@type type)] [(@condition condition)])
 
-    (unless (xenomorphic-type? type)
-      (raise-argument-error '+xoptional"xenomorphic type" type))
+    (unless (xenomorphic-type? @type)
+      (raise-argument-error '+xoptional"xenomorphic type" @type))
     
     (define (resolve-condition parent)
-      (define maybe-proc condition)
-      (if (procedure? maybe-proc)
-          (maybe-proc parent)
-          maybe-proc))
+      (define maybe-proc @condition)
+      (if (procedure? maybe-proc) (maybe-proc parent) maybe-proc))
 
     (define/augment (xxdecode port parent)
       (when (resolve-condition parent)
-        (send type xxdecode port parent)))
+        (send @type xxdecode port parent)))
 
     (define/augment (xxencode val port [parent #f])
       (when (resolve-condition parent)
-        (send type xxencode val port parent)))
+        (send @type xxencode val port parent)))
     
     (define/augment (xxsize [val #f] [parent #f])
-      (if (resolve-condition parent)
-          (send type xxsize val parent)
-          0))))
+      (if (resolve-condition parent) (send @type xxsize val parent) 0))))
 
 
 (define no-val (gensym))

xenomorph/xenomorph/pointer.rkt

@@ -17,7 +17,7 @@ https://github.com/mbutterick/restructure/blob/master/src/Pointer.coffee
     [(dict-ref parent 'parent #f) => find-top-parent]
     [else parent]))
 
-(define (resolve-void-pointer type val)
+(define (resolve-pointer type val)
   (cond
     [type (values type val)]
     [(xvoid-pointer? val) (values (xvoid-pointer-type val) (xvoid-pointer-value val))]
@@ -26,69 +26,69 @@ https://github.com/mbutterick/restructure/blob/master/src/Pointer.coffee
 (define xpointer%
   (class xenobase%
     (super-new)
-    (init-field offset-type type options)
+    (init-field [(@offset-type offset-type)][(@type type)] [(@options options)])
 
-    (define pointer-relative-to (dict-ref options 'relative-to))
-    (define allow-null (dict-ref options 'allowNull)) 
-    (define null-value (dict-ref options 'nullValue))
-    (define pointer-lazy? (dict-ref options 'lazy))
+    (define pointer-relative-to (dict-ref @options 'relative-to))
+    (define allow-null (dict-ref @options 'allowNull)) 
+    (define null-value (dict-ref @options 'nullValue))
+    (define pointer-lazy? (dict-ref @options 'lazy))
 
     (define/augment (xxdecode port parent)
-      (define offset (send offset-type xxdecode port parent))
+      (define offset (send @offset-type xxdecode port parent))
       (cond
         [(and allow-null (= offset null-value)) #f] ; handle null pointers
         [else
          (define relative (+ (case pointer-relative-to
                                [(local) (dict-ref parent '_startOffset)]
-                               [(immediate) (- (pos port) (send offset-type xxsize))]
+                               [(immediate) (- (pos port) (send @offset-type xxsize))]
                                [(parent) (dict-ref (dict-ref parent 'parent) '_startOffset)]
                                [(global) (or (dict-ref (find-top-parent parent) '_startOffset) 0)]
                                [else (error 'unknown-pointer-style)])))
          (define ptr (+ offset relative))
          (cond
-           [type (define (decode-value)
-                   (define orig-pos (pos port))
-                   (pos port ptr)
-                   (begin0
-                     (send type xxdecode port parent)
-                     (pos port orig-pos)))
-                 (if pointer-lazy? (delay (decode-value)) (decode-value))]
+           [@type (define (decode-value)
+                    (define orig-pos (pos port))
+                    (pos port ptr)
+                    (begin0
+                      (send @type xxdecode port parent)
+                      (pos port orig-pos)))
+                  (if pointer-lazy? (delay (decode-value)) (decode-value))]
            [else ptr])]))
 
-    (define/augment (xxencode val port [parent #f])
+    (define/augment (xxencode val-in port [parent #f])
       (unless parent ; todo: furnish default pointer context? adapt from Struct?
         (raise-argument-error 'xpointer-encode "valid pointer context" parent))
-      (if (not val)
-          (send offset-type xxencode null-value port)
-          (let* ([new-parent (case pointer-relative-to
-                               [(local immediate) parent]
-                               [(parent) (dict-ref parent 'parent)]
-                               [(global) (find-top-parent parent)]
-                               [else (error 'unknown-pointer-style)])]
-                 [relative (+ (case pointer-relative-to
-                                [(local parent) (dict-ref new-parent 'startOffset)]
-                                [(immediate) (+ (pos port) (send offset-type xxsize val parent))]
-                                [(global) 0]))])
-            (send offset-type xxencode (- (dict-ref new-parent 'pointerOffset) relative) port)
-            (let-values ([(type val) (resolve-void-pointer type val)])
-              (dict-set! new-parent 'pointers (append (dict-ref new-parent 'pointers)
-                                                      (list (mhasheq 'type type
-                                                                     'val val
-                                                                     'parent parent))))
-              (dict-set! new-parent 'pointerOffset
-                         (+ (dict-ref new-parent 'pointerOffset) (send type xxsize val parent)))))))
+      (cond
+        [val-in
+         (define new-parent (case pointer-relative-to
+                              [(local immediate) parent]
+                              [(parent) (dict-ref parent 'parent)]
+                              [(global) (find-top-parent parent)]
+                              [else (error 'unknown-pointer-style)]))
+         (define relative (+ (case pointer-relative-to
+                               [(local parent) (dict-ref new-parent 'startOffset)]
+                               [(immediate) (+ (pos port) (send @offset-type xxsize val-in parent))]
+                               [(global) 0])))
+         (send @offset-type xxencode (- (dict-ref new-parent 'pointerOffset) relative) port)
+         (define-values (type val) (resolve-pointer @type val-in))
+         (dict-update! new-parent 'pointers
+                       (λ (ptrs) (append ptrs (list (mhasheq 'type type 'val val 'parent parent)))))
+         (dict-set! new-parent 'pointerOffset
+                    (+ (dict-ref new-parent 'pointerOffset) (send type xxsize val parent)))]
+        [else (send @offset-type xxencode null-value port)]))
 
-    (define/augment (xxsize [val #f] [parent #f])
-      (let*-values ([(parent) (case pointer-relative-to
-                                [(local immediate) parent]
-                                [(parent) (dict-ref parent 'parent)]
-                                [(global) (find-top-parent parent)]
-                                [else (error 'unknown-pointer-style)])]
-                    [(type val) (resolve-void-pointer type val)])
-        (when (and val parent)
-          (dict-set! parent 'pointerSize (and (dict-ref parent 'pointerSize #f)
-                                              (+ (dict-ref parent 'pointerSize) (send type xxsize val parent)))))
-        (send offset-type xxsize)))))
+    (define/augment (xxsize [val-in #f] [parent #f])
+      (define new-parent (case pointer-relative-to
+                           [(local immediate) parent]
+                           [(parent) (dict-ref parent 'parent)]
+                           [(global) (find-top-parent parent)]
+                           [else (error 'unknown-pointer-style)]))
+      (define-values (type val) (resolve-pointer @type val-in))
+      (when (and val new-parent)
+        (dict-set! new-parent 'pointerSize
+                   (and (dict-ref new-parent 'pointerSize #f)
+                        (+ (dict-ref new-parent 'pointerSize) (send type xxsize val new-parent)))))
+      (send @offset-type xxsize))))
 
 (define (+xpointer [offset-arg #f] [type-arg #f]
                    #:offset-type [offset-kwarg #f]

xenomorph/xenomorph/reserved.rkt

@@ -10,10 +10,10 @@ https://github.com/mbutterick/restructure/blob/master/src/Reserved.coffee
 (define xreserved%
   (class xenobase%
     (super-new)
-    (init-field type count)
+    (init-field [(@type type)] [(@count count)])
 
-    (unless (xenomorphic-type? type)
-      (raise-argument-error '+xoptional"xenomorphic type" type))
+    (unless (xenomorphic-type? @type)
+      (raise-argument-error '+xoptional"xenomorphic type" @type))
 
     (define/augment (xxdecode port parent)
       (pos port (+ (pos port) (xxsize #f parent)))
@@ -23,7 +23,7 @@ https://github.com/mbutterick/restructure/blob/master/src/Reserved.coffee
       (make-bytes (xxsize val parent) 0))
     
     (define/augment (xxsize [val #f] [parent #f])
-      (* (send type xxsize) (resolve-length count #f #:parent parent)))))
+      (* (send @type xxsize) (resolve-length @count #f #:parent parent)))))
 
 (define (+xreserved [type-arg #f] [count-arg #f]
                     #:type [type-kwarg #f]