diff --git a/syndicate/mc/preserve.rkt b/syndicate/mc/preserve.rkt
index 77012ac..1ccd553 100644
--- a/syndicate/mc/preserve.rkt
+++ b/syndicate/mc/preserve.rkt
@@ -17,6 +17,7 @@
 (require racket/set)
 (require bitsyntax)
 (require syndicate/support/struct)
+(require (only-in syntax/readerr raise-read-error))
 
 (require imperative-syndicate/assertions)
 (require imperative-syndicate/pattern)
@@ -246,8 +247,22 @@
 
 ;;---------------------------------------------------------------------------
 
+(define (skip-whitespace* i)
+  (regexp-match? #px#"^(\\s|,)*" i)
+  (match (peek-char i)
+    [#\; (regexp-match? #px#"[^\r\n]*[\r\n]" i) (skip-whitespace* i)]
+    [_ #t]))
+
+(define (parse-error* i fmt . args)
+  (define-values [line column pos] (port-next-location i))
+  (raise-read-error (format "read-preserve: ~a" (apply format fmt args))
+                    (object-name i)
+                    line
+                    column
+                    pos
+                    #f))
+
 (define (read-preserve [i (current-input-port)])
-  (local-require (only-in syntax/readerr raise-read-error))
   (local-require net/base64)
   (local-require file/sha1)
 
@@ -255,20 +270,8 @@
     (syntax-rules ()
       [(_ re pat) (app (lambda (v) (regexp-try-match re v)) pat)]))
 
-  (define (skip-whitespace)
-    (regexp-match? #px#"^(\\s|,)*" i)
-    (match (peek-char i)
-      [#\; (regexp-match? #px#"[^\r\n]*[\r\n]" i) (skip-whitespace)]
-      [_ #t]))
-
   (define (parse-error fmt . args)
-    (define-values [line column pos] (port-next-location i))
-    (raise-read-error (format "read-preserve: ~a" (apply format fmt args))
-                      (object-name i)
-                      line
-                      column
-                      pos
-                      #f))
+    (apply parse-error* i fmt args))
 
   (define (eof-guard ch)
     (match ch
@@ -278,6 +281,8 @@
   (define (peek/no-eof) (eof-guard (peek-char i)))
   (define (read/no-eof) (eof-guard (read-char i)))
 
+  (define (skip-whitespace) (skip-whitespace* i))
+
   (define (read-sequence terminator)
     (sequence-fold '() accumulate-value reverse terminator))
 
@@ -301,12 +306,14 @@
 
   (define PIPE #\|)
 
-  (define (read-raw-symbol)
-    (let loop ((acc '()))
-      (match (peek-char i)
-        [(or #\{ #\} #\[ #\] #\" #\; #\, #\# #\: (? char-whitespace?) (? eof-object?) (== PIPE))
-         (string->symbol (list->string (reverse acc)))]
-        [_ (loop (cons (read-char i) acc))])))
+  (define (read-raw-symbol acc)
+    (match (peek-char i)
+      [(or (? eof-object?)
+           (? char? (or #\( #\) #\{ #\} #\[ #\]
+                        #\" #\; #\, #\# #\: (== PIPE)
+                        (? char-whitespace?))))
+       (string->symbol (list->string (reverse acc)))]
+      [_ (read-raw-symbol (cons (read-char i) acc))]))
 
   (define (read-encoded-binary kind valid-char? finish)
     (let loop ((acc '()))
@@ -397,12 +404,12 @@
 
   (define (read-digit* acc-rev k)
     (match (peek-char i)
-      [(? char-numeric?) (read-digit* (cons (read-char i) acc-rev) k)]
+      [(? char? (? char-numeric?)) (read-digit* (cons (read-char i) acc-rev) k)]
       [_ (k acc-rev)]))
 
   (define (read-digit+ acc-rev k)
     (match (peek-char i)
-      [(? char-numeric?) (read-digit* (cons (read-char i) acc-rev) k)]
+      [(? char? (? char-numeric?)) (read-digit* (cons (read-char i) acc-rev) k)]
       [_ (parse-error "Incomplete number")]))
 
   (define (read-fracexp acc-rev)
@@ -424,7 +431,11 @@
     (define s (list->string (reverse acc-rev)))
     (define n (string->number s))
     (when (not n) (parse-error "Invalid number: ~v" s))
-    n)
+    (if (flonum? n)
+        (match (peek-char i)
+          [(or #\f #\F) (read-char i) (real->single-flonum n)]
+          [_ n])
+        n))
 
   (define (read-number)
     (match (peek/no-eof)
@@ -441,8 +452,11 @@
   (define (collect-fields head)
     (skip-whitespace)
     (match (peek-char i)
-      [#\( (collect-fields (build-record head (read-sequence #\))))]
-      [_ head]))
+      [#\(
+       (read-char i)
+       (collect-fields (build-record head (read-sequence #\))))]
+      [_
+       head]))
 
   (define (read-value)
     (skip-whitespace)
@@ -472,12 +486,17 @@
               [_
                (parse-error "Invalid preserve value")])]
        [#\: (parse-error "Unexpected key/value separator between items")]
-       [_ (read-raw-symbol)])))
+       [_ (read-raw-symbol '())])))
 
   (read-value))
 
 (define (string->preserve s)
-  (read-preserve (open-input-string s)))
+  (define p (open-input-string s))
+  (define v (read-preserve p))
+  (skip-whitespace* p)
+  (when (not (eof-object? (peek-char p)))
+    (parse-error* p "Unexpected text following preserve"))
+  v)
 
 ;;---------------------------------------------------------------------------
 
@@ -545,81 +564,90 @@
 
   (define (d bs) (decode bs void))
 
-  (define-syntax (check-both-directions stx)
+  (define-syntax (cross-check stx)
     (syntax-case stx ()
-      ((_ v (b ...))
-       #'(let ((val v)) (check-both-directions v v (b ...))))
-      ((_ forward back (b ...))
+      ((_ text v (b ...))
+       #'(let ((val v)) (cross-check text v v (b ...))))
+      ((_ text forward back (b ...))
        #`(let ((loc #,(source-location->string #'forward)))
+           (check-equal? (string->preserve text) back)
            (check-equal? (d (encode forward)) back loc)
            (check-equal? (d (encode back)) back loc)
            (check-equal? (d (expected b ...)) back loc)
            (check-equal? (encode forward) (expected b ...) loc)
            ))))
 
-  (define-syntax (check-both-directions/nondeterministic stx)
+  (define-syntax (cross-check/nondeterministic stx)
     (syntax-case stx ()
-      ((_ v (b ...))
-       #'(let ((val v)) (check-both-directions/nondeterministic v v (b ...))))
-      ((_ forward back (b ...))
+      ((_ text v (b ...))
+       #'(let ((val v)) (cross-check/nondeterministic text v v (b ...))))
+      ((_ text forward back (b ...))
        #`(let ((loc #,(source-location->string #'forward)))
+           (check-equal? (string->preserve text) back)
            (check-equal? (d (encode forward)) back loc)
            (check-equal? (d (encode back)) back loc)
            (check-equal? (d (expected b ...)) back loc)
            ))))
 
-  (check-both-directions (capture (discard)) (#x91 #x80))
-  (check-both-directions (observe (speak (discard) (capture (discard))))
-                         (#xA1 #xB3 #x75 "speak" #x80 #x91 #x80))
-  (check-both-directions '(1 2 3 4) (#xC4 #x11 #x12 #x13 #x14))
-  (check-both-directions (stream-of 'sequence (sequence->generator '(1 2 3 4)))
-                         '(1 2 3 4)
-                         (#x2C #x11 #x12 #x13 #x14 #x3C))
-  (check-both-directions '(-2 -1 0 1) (#xC4 #x1E #x1F #x10 #x11))
-  (check-both-directions "hello" (#x55 "hello"))
-  (check-both-directions (stream-of 'string (sequence->generator '(#"he" #"llo")))
-                         "hello"
-                         (#x25 #x62 "he" #x63 "llo" #x35))
-  (check-both-directions (stream-of 'string (sequence->generator '(#"he" #"ll" #"" #"" #"o")))
-                         "hello"
-                         (#x25 #x62 "he" #x62 "ll" #x60 #x60 #x61 "o" #x35))
-  (check-both-directions (stream-of 'byte-string (sequence->generator '(#"he" #"ll" #"" #"" #"o")))
-                         #"hello"
-                         (#x26 #x62 "he" #x62 "ll" #x60 #x60 #x61 "o" #x36))
-  (check-both-directions (stream-of 'symbol (sequence->generator '(#"he" #"ll" #"" #"" #"o")))
-                         'hello
-                         (#x27 #x62 "he" #x62 "ll" #x60 #x60 #x61 "o" #x37))
-  (check-both-directions `("hello" there #"world" () ,(set) #t #f)
-                         (#xC7 #x55 "hello" #x75 "there" #x65 "world" #xC0 #xD0 #x01 #x00))
+  (cross-check "capture(discard())" (capture (discard)) (#x91 #x80))
+  (cross-check "observe(speak(discard(), capture(discard())))"
+               (observe (speak (discard) (capture (discard))))
+               (#xA1 #xB3 #x75 "speak" #x80 #x91 #x80))
+  (cross-check "[1, 2, 3, 4]" '(1 2 3 4) (#xC4 #x11 #x12 #x13 #x14))
+  (cross-check "[1 2 3 4]"
+               (stream-of 'sequence (sequence->generator '(1 2 3 4)))
+               '(1 2 3 4)
+               (#x2C #x11 #x12 #x13 #x14 #x3C))
+  (cross-check " [ -2 -1 0 1 ] " '(-2 -1 0 1) (#xC4 #x1E #x1F #x10 #x11))
+  (cross-check "\"hello\"" "hello" (#x55 "hello"))
+  (cross-check "\"hello\""
+               (stream-of 'string (sequence->generator '(#"he" #"llo")))
+               "hello"
+               (#x25 #x62 "he" #x63 "llo" #x35))
+  (cross-check "\"hello\""
+               (stream-of 'string (sequence->generator '(#"he" #"ll" #"" #"" #"o")))
+               "hello"
+               (#x25 #x62 "he" #x62 "ll" #x60 #x60 #x61 "o" #x35))
+  (cross-check "#\"hello\""
+               (stream-of 'byte-string (sequence->generator '(#"he" #"ll" #"" #"" #"o")))
+               #"hello"
+               (#x26 #x62 "he" #x62 "ll" #x60 #x60 #x61 "o" #x36))
+  (cross-check "hello"
+               (stream-of 'symbol (sequence->generator '(#"he" #"ll" #"" #"" #"o")))
+               'hello
+               (#x27 #x62 "he" #x62 "ll" #x60 #x60 #x61 "o" #x37))
+  (cross-check "[\"hello\" there #\"world\" [] #set{} #true #false]"
+               `("hello" there #"world" () ,(set) #t #f)
+               (#xC7 #x55 "hello" #x75 "there" #x65 "world" #xC0 #xD0 #x01 #x00))
 
-  (check-both-directions -257 (#x42 #xFE #xFF))
-  (check-both-directions -256 (#x42 #xFF #x00))
-  (check-both-directions -255 (#x42 #xFF #x01))
-  (check-both-directions -254 (#x42 #xFF #x02))
-  (check-both-directions -129 (#x42 #xFF #x7F))
-  (check-both-directions -128 (#x41 #x80))
-  (check-both-directions -127 (#x41 #x81))
-  (check-both-directions -4 (#x41 #xFC))
-  (check-both-directions -3 (#x1D))
-  (check-both-directions -2 (#x1E))
-  (check-both-directions -1 (#x1F))
-  (check-both-directions 0 (#x10))
-  (check-both-directions 1 (#x11))
-  (check-both-directions 12 (#x1C))
-  (check-both-directions 13 (#x41 #x0D))
-  (check-both-directions 127 (#x41 #x7F))
-  (check-both-directions 128 (#x42 #x00 #x80))
-  (check-both-directions 255 (#x42 #x00 #xFF))
-  (check-both-directions 256 (#x42 #x01 #x00))
-  (check-both-directions 32767 (#x42 #x7F #xFF))
-  (check-both-directions 32768 (#x43 #x00 #x80 #x00))
-  (check-both-directions 65535 (#x43 #x00 #xFF #xFF))
-  (check-both-directions 65536 (#x43 #x01 #x00 #x00))
-  (check-both-directions 131072 (#x43 #x02 #x00 #x00))
+  (cross-check "-257" -257 (#x42 #xFE #xFF))
+  (cross-check "-256" -256 (#x42 #xFF #x00))
+  (cross-check "-255" -255 (#x42 #xFF #x01))
+  (cross-check "-254" -254 (#x42 #xFF #x02))
+  (cross-check "-129" -129 (#x42 #xFF #x7F))
+  (cross-check "-128" -128 (#x41 #x80))
+  (cross-check "-127" -127 (#x41 #x81))
+  (cross-check "-4" -4 (#x41 #xFC))
+  (cross-check "-3" -3 (#x1D))
+  (cross-check "-2" -2 (#x1E))
+  (cross-check "-1" -1 (#x1F))
+  (cross-check "0" 0 (#x10))
+  (cross-check "1" 1 (#x11))
+  (cross-check "12" 12 (#x1C))
+  (cross-check "13" 13 (#x41 #x0D))
+  (cross-check "127" 127 (#x41 #x7F))
+  (cross-check "128" 128 (#x42 #x00 #x80))
+  (cross-check "255" 255 (#x42 #x00 #xFF))
+  (cross-check "256" 256 (#x42 #x01 #x00))
+  (cross-check "32767" 32767 (#x42 #x7F #xFF))
+  (cross-check "32768" 32768 (#x43 #x00 #x80 #x00))
+  (cross-check "65535" 65535 (#x43 #x00 #xFF #xFF))
+  (cross-check "65536" 65536 (#x43 #x01 #x00 #x00))
+  (cross-check "131072" 131072 (#x43 #x02 #x00 #x00))
 
-  (check-both-directions 1.0f0 (#b00000010 #b00111111 #b10000000 0 0))
-  (check-both-directions 1.0 (#b00000011 #b00111111 #b11110000 0 0 0 0 0 0))
-  (check-both-directions -1.202e300 (#x03 #xFE #x3C #xB7 #xB7 #x59 #xBF #x04 #x26))
+  (cross-check "1.0f" 1.0f0 (#b00000010 #b00111111 #b10000000 0 0))
+  (cross-check "1.0" 1.0 (#b00000011 #b00111111 #b11110000 0 0 0 0 0 0))
+  (cross-check "-1.202e300" -1.202e300 (#x03 #xFE #x3C #xB7 #xB7 #x59 #xBF #x04 #x26))
 
   (check-equal? (d (expected #x25 #x51 "a" #x35)) (void)) ;; Bad chunk type: must be bytes
   (check-equal? (d (expected #x25 #x71 "a" #x35)) (void)) ;; Bad chunk type: must be bytes
@@ -631,13 +659,13 @@
   (check-equal? (d (expected #x26 #x61 "a" #x36)) #"a")
   (check-equal? (d (expected #x27 #x61 "a" #x37)) 'a)
 
-
   (struct date (year month day) #:prefab)
   (struct thing (id) #:prefab)
   (struct person thing (name date-of-birth) #:prefab)
   (struct titled person (title) #:prefab)
 
-  (check-both-directions
+  (cross-check
+   "[titled person 2 thing 1](101, \"Blackwell\", date(1821 2 3), \"Dr\")"
    (titled 101 "Blackwell" (date 1821 2 3) "Dr")
    (#xB5                                                ;; Record, generic, 4+1
       #xC5                                                ;; Sequence, 5
@@ -656,21 +684,30 @@
       #x52 #x44 #x72                                      ;; String, "Dr"
       ))
 
-  (check-both-directions (record 'discard '()) (discard) (#x80))
-  (check-both-directions (record 'discard '(surprise)) '#s(discard surprise) (#x81 #x78 "surprise"))
-  (check-both-directions (record 'capture '(x)) (capture 'x) (#x91 #x71 "x"))
-  (check-both-directions (record 'observe '(x)) (observe 'x) (#xA1 #x71 "x"))
-  (check-both-directions (record 'observe '(x y)) '#s(observe x y) (#xA2 #x71 "x" #x71 "y"))
-  (check-both-directions (record 'other '(x y))
-                         '#s(other x y)
-                         (#xB3 #x75 "other" #x71 "x" #x71 "y"))
-  (check-both-directions (record "aString" '(3 4)) (#xB3 #x57 "aString" #x13 #x14))
-  (check-both-directions (record (discard) '(3 4)) (#xB3 #x80 #x13 #x14))
+  (cross-check "discard()" (record 'discard '()) (discard) (#x80))
+  (cross-check "discard(surprise)"
+               (record 'discard '(surprise))
+               '#s(discard surprise)
+               (#x81 #x78 "surprise"))
+  (cross-check "capture(x)" (record 'capture '(x)) (capture 'x) (#x91 #x71 "x"))
+  (cross-check "observe(x)" (record 'observe '(x)) (observe 'x) (#xA1 #x71 "x"))
+  (cross-check "observe(x y)" (record 'observe '(x y)) '#s(observe x y) (#xA2 #x71 "x" #x71 "y"))
+  (cross-check "other(x y)"
+               (record 'other '(x y))
+               '#s(other x y)
+               (#xB3 #x75 "other" #x71 "x" #x71 "y"))
+  (cross-check "\"aString\"(3 4)"
+               (record "aString" '(3 4))
+               (#xB3 #x57 "aString" #x13 #x14))
+  (cross-check "discard()(3, 4)"
+               (record (discard) '(3 4))
+               (#xB3 #x80 #x13 #x14))
 
   (check-equal? (d (expected #x2C #x00 #x00)) (void)) ;; missing end byte
   (check-equal? (d (expected #xC3 #x00 #x00)) (void)) ;; missing element
 
-  (check-both-directions/nondeterministic
+  (cross-check/nondeterministic
+   "{a: 1, \"b\": #true, [1 2 3]: #\"c\", {first-name:\"Elizabeth\"}:{surname:\"Blackwell\"}}"
    (hash 'a 1
          "b" #t
          '(1 2 3) #"c"
@@ -727,7 +764,8 @@ EOF
 EOF
                                              ))
 
-    (check-both-directions/nondeterministic
+    (cross-check/nondeterministic
+     "{\"Image\": {\"Width\":  800,\"Height\": 600,\"Title\":  \"View from 15th Floor\",\"Thumbnail\": {\"Url\":    \"http://www.example.com/image/481989943\",\"Height\": 125,\"Width\":  100},\"Animated\" : false,\"IDs\": [116, 943, 234, 38793]}}"
      rfc8259-example1
      (#xe2
         #x55 "Image"
@@ -748,7 +786,8 @@ EOF
                               #x43 #x00 #x97 #x89
      ))
 
-    (check-both-directions/nondeterministic
+    (cross-check/nondeterministic
+     "[{\"precision\": \"zip\",\"Latitude\":  37.7668,\"Longitude\": -122.3959,\"Address\":   \"\",\"City\":      \"SAN FRANCISCO\",\"State\":     \"CA\",\"Zip\":       \"94107\",\"Country\":   \"US\"},{\"precision\": \"zip\",\"Latitude\":  37.371991,\"Longitude\": -122.026020,\"Address\":   \"\",\"City\":      \"SUNNYVALE\",\"State\":     \"CA\",\"Zip\":       \"94085\",\"Country\":   \"US\"}]"
      rfc8259-example2
      (#xc2
         #xef #x10