remove symbols as length notation

xenomorph/xenomorph/test/dict-test.rkt

@@ -75,9 +75,10 @@ https://github.com/mbutterick/restructure/blob/master/test/Struct.coffee
  "dict: support pre-encode hook"
  (parameterize ([current-output-port (open-output-bytes)])
    (define struct (x:dict #:pre-encode (λ (val)
-                         (hash-set! val 'nameLength (string-length (hash-ref val 'name))) val)
+                                         (hash-set! val 'nameLength (string-length (hash-ref val 'name)))
+                                         val)
                           'nameLength uint8
-                            'name (x:string 'nameLength)
+                          'name (x:string (λ (this) (hash-ref this 'nameLength)))
                           'age uint8))
    (encode struct (mhasheq 'name "roxyb" 'age 21))
    (check-equal? (get-output-bytes (current-output-port)) #"\x05roxyb\x15")))

xenomorph/xenomorph/test/versioned-dict-test.rkt

@@ -80,8 +80,8 @@ https://github.com/mbutterick/restructure/blob/master/test/VersionedStruct.coffe
                                              'gender 0)))))
 
 (test-case
- "versioned dict: decode should support parent version key"
- (let ([vstruct (x:versioned-dict x:version-key
+ "versioned dict: decode should support parent version key via procedure"
+ (let ([vstruct (x:versioned-dict (λ (p) (hash-ref p x:version-key))
                                   (dictify
                                    0 (dictify 'name (x:string #:length uint8 #:encoding 'ascii)
                                               'age uint8)

xenomorph/xenomorph/util.rkt

@@ -6,7 +6,6 @@
   (or (not x)
       (exact-nonnegative-integer? x)
       (procedure? x)
-      (symbol? x)
       (x:int? x)))
 
 (define (resolve-length x input-port [parent #f])

xenomorph/xenomorph/versioned-dict.rkt

@@ -1,6 +1,7 @@
 #lang debug racket/base
 (require "base.rkt"
          "dict.rkt"
+         "util.rkt"
          racket/dict
          racket/match
          racket/class
@@ -14,8 +15,7 @@ https://github.com/mbutterick/restructure/blob/master/src/VersionedStruct.coffee
 |#
 
 (define (version-type? x)
-  (for/or ([proc (list integer? procedure? xenomorphic? symbol?)])
-    (proc x)))
+  (and x (length-resolvable? x)))
 
 (define x:versioned-dict%
   (class x:dict%
@@ -25,7 +25,7 @@ https://github.com/mbutterick/restructure/blob/master/src/VersionedStruct.coffee
                 [(@version-key version-key)])
 
     (unless (version-type? @type)
-      (raise-argument-error 'x:versioned-dict "integer, procedure, symbol, or xenomorphic" @type))
+      (raise-argument-error 'x:versioned-dict "integer, procedure, or xenomorphic" @type))
     
     (unless (and (dict? @versions) (andmap (λ (v) (or (dict? v) (x:dict? v))) (dict-values @versions)))
       (raise-argument-error 'x:versioned-dict "dict of dicts or structish" @versions))
@@ -43,7 +43,6 @@ https://github.com/mbutterick/restructure/blob/master/src/VersionedStruct.coffee
       (define res (setup-private-fields port parent length))
       (define which-version (match @type
                               [(? integer? int) int]
-                              [(? symbol? key) #:when parent (dict-ref parent key)]
                               [(? procedure? proc) #:when parent (proc parent)]
                               [(or (? symbol?) (? procedure?))
                                (raise-argument-error 'decode "valid parent" parent)]