diff --git a/collects/compiler/embed.ss b/collects/compiler/embed.ss
index 0346389379..9655186cf8 100644
--- a/collects/compiler/embed.ss
+++ b/collects/compiler/embed.ss
@@ -16,7 +16,7 @@
                      (opt-> (path-string?
                              any/c
                              any/c
-                             (listof (list/c (union boolean? symbol?) any/c))
+                             (listof (list/c (or/c boolean? symbol?) any/c))
                              (listof path-string?)
                              any/c
                              (listof string?))
diff --git a/collects/drscheme/private/language-configuration.ss b/collects/drscheme/private/language-configuration.ss
index d09d27f5fa..4e4c7fc98d 100644
--- a/collects/drscheme/private/language-configuration.ss
+++ b/collects/drscheme/private/language-configuration.ss
@@ -1203,7 +1203,7 @@
                                          (port? (list/c (and/c number? integer? exact? (>=/c 0))
                                                         (and/c number? integer? exact? (>=/c 0))
                                                         (and/c number? integer? exact? (>=/c 0))))
-                                         (union syntax? eof-object?))
+                                         (or/c syntax? eof-object?))
                                   (dynamic-require reader-spec 'read-syntax)
                                   (string->symbol (format "~s" lang-position))
                                   'drscheme))
diff --git a/collects/drscheme/private/module-language.ss b/collects/drscheme/private/module-language.ss
index 68d3f84cbf..2057686149 100644
--- a/collects/drscheme/private/module-language.ss
+++ b/collects/drscheme/private/module-language.ss
@@ -473,7 +473,7 @@
           ;; in the beginning of the editor
           ;; or #f if the beginning doesn't match "(module "
           (define/contract get-module-filename
-            (-> (union false/c string?))
+            (-> (or/c false/c string?))
             (λ ()
               (let ([open-paren (skip-whitespace 0)])
                 (or (match-paren open-paren "(")
@@ -481,7 +481,7 @@
                     (match-paren open-paren "{")))))
           
           (define/contract match-paren
-            (number? string? . -> . (union false/c string?))
+            (number? string? . -> . (or/c false/c string?))
             (λ (open-paren paren)
               (and (matches open-paren paren)
                    (let ([module (skip-whitespace (+ open-paren 1))])
diff --git a/collects/drscheme/private/tool-contracts.ss b/collects/drscheme/private/tool-contracts.ss
index 6655adbe4c..5b41631a60 100644
--- a/collects/drscheme/private/tool-contracts.ss
+++ b/collects/drscheme/private/tool-contracts.ss
@@ -63,12 +63,12 @@
    "Returns a list of all of the snipclasses in the current eventspace")
   
   (drscheme:eval:expand-program
-   ((union port? drscheme:language:text/pos?)
+   ((or/c port? drscheme:language:text/pos?)
     drscheme:language-configuration:language-settings?
     boolean?
     (-> void?)
     (-> void?)
-    ((union eof-object? syntax? (cons/c string? any/c))
+    ((or/c eof-object? syntax? (cons/c string? any/c))
      (-> any)
      . -> .
      any)
@@ -131,8 +131,8 @@
     (-> void?)
     (-> void?)
     . -> .
-    ((union port? drscheme:language:text/pos?)
-     ((union eof-object? syntax? (cons/c string? any/c))
+    ((or/c port? drscheme:language:text/pos?)
+     ((or/c eof-object? syntax? (cons/c string? any/c))
       (-> any)
       . -> .
       any)
@@ -154,8 +154,8 @@
     (-> void?)
     (-> void?)
     . -> .
-    ((union port? drscheme:language:text/pos?)
-     ((union eof-object? syntax? (cons/c string? any/c))
+    ((or/c port? drscheme:language:text/pos?)
+     ((or/c eof-object? syntax? (cons/c string? any/c))
       (-> any)
       . -> .
       any)
@@ -258,8 +258,8 @@
   
   (drscheme:debug:show-error-and-highlight
    (string? 
-    (union any/c exn?) 
-    (-> (listof srcloc?) (union false/c (listof (list/c (is-a?/c text%) number? number?))) any)
+    (or/c any/c exn?) 
+    (-> (listof srcloc?) (or/c false/c (listof (list/c (is-a?/c text%) number? number?))) any)
     . -> . 
     any)
    (msg exn highlight-errors)
@@ -271,9 +271,9 @@
    "This function should be called on the same thread/eventspace where the error happened.")
   
   (drscheme:debug:make-debug-error-display-handler
-   ((string? (union any/c exn?) . -> . any)
+   ((string? (or/c any/c exn?) . -> . any)
     . -> .
-    (string? (union any/c exn?) . -> . any))
+    (string? (or/c any/c exn?) . -> . any))
    
    (oedh)
    
@@ -419,7 +419,7 @@
   (drscheme:unit:open-drscheme-window
    (case->
     (-> (is-a?/c drscheme:unit:frame%))
-    ((union string? false/c) . -> . (is-a?/c drscheme:unit:frame%)))
+    ((or/c string? false/c) . -> . (is-a?/c drscheme:unit:frame%)))
    (() (filename))
    
    "Opens a drscheme frame that displays \\var{filename},"
@@ -447,9 +447,9 @@
   
   (drscheme:modes:add-mode
    (string?
-    (union false/c (is-a?/c mode:surrogate-text<%>))
+    (or/c false/c (is-a?/c mode:surrogate-text<%>))
     ((is-a?/c drscheme:rep:text%) number? . -> . boolean?)
-    ((union false/c (listof string?)) . -> . boolean?)
+    ((or/c false/c (listof string?)) . -> . boolean?)
     . -> .
     drscheme:modes:mode?)
    (name surrogate repl-submit matches-language)
@@ -517,7 +517,7 @@
    ".")
   
   (drscheme:modes:mode-surrogate
-   (drscheme:modes:mode? . -> . (union false/c (is-a?/c mode:surrogate-text<%>)))
+   (drscheme:modes:mode? . -> . (or/c false/c (is-a?/c mode:surrogate-text<%>)))
    (mode)
    "Extracts the surrogate of the mode."
    ""
@@ -535,7 +535,7 @@
    ".")
   
   (drscheme:modes:mode-matches-language
-   (drscheme:modes:mode? . -> . ((union false/c (listof string?)) . -> . boolean?))
+   (drscheme:modes:mode? . -> . ((or/c false/c (listof string?)) . -> . boolean?))
    (mode)
    "Extracts the language matching predicate of the mode."
    ""
@@ -573,7 +573,7 @@
    "windows. Also binds f5 to Execute and f1 to Help Desk.")
   
   (drscheme:rep:current-rep
-   (-> (union false/c (is-a?/c drscheme:rep:text%)))
+   (-> (or/c false/c (is-a?/c drscheme:rep:text%)))
    ()
    
    "This is a parameter whose value should not be set by tools."
@@ -584,7 +584,7 @@
    "in the context of a repl (eg, the test suite window).")
   
   (drscheme:rep:current-value-port
-   (-> (union false/c port?))
+   (-> (or/c false/c port?))
    ()
    "This is a parameter whose value is a port that"
    "prints in the REPL in blue. It is used to print"
@@ -785,7 +785,7 @@
    ".")
   
   (drscheme:language-configuration:make-language-settings
-   ((union (is-a?/c drscheme:language:language<%>) language-object)
+   ((or/c (is-a?/c drscheme:language:language<%>) language-object)
     any/c
     . -> .
     drscheme:language-configuration:language-settings?)
@@ -814,7 +814,7 @@
   (drscheme:language-configuration:language-settings-language
    (drscheme:language-configuration:language-settings?
     . -> .
-    (union (is-a?/c drscheme:language:language<%>) language-object))
+    (or/c (is-a?/c drscheme:language:language<%>) language-object))
    (ls)
    
    "Extracts the language field of a language-settings.")
@@ -828,9 +828,9 @@
   (drscheme:language-configuration:language-dialog
    (opt->
     (boolean? drscheme:language-configuration:language-settings?)
-    ((union false/c (is-a?/c top-level-window<%>))
+    ((or/c false/c (is-a?/c top-level-window<%>))
      boolean?)
-    (union false/c drscheme:language-configuration:language-settings?))
+    (or/c false/c drscheme:language-configuration:language-settings?))
    ((show-welcome? language-settings-to-show)
     ((parent #t)
      (manuals? #f)))
@@ -867,7 +867,7 @@
     ((is-a?/c vertical-panel%)
      (is-a?/c area-container<%>)
      drscheme:language-configuration:language-settings?)
-    ((union false/c (is-a?/c top-level-window<%>))
+    ((or/c false/c (is-a?/c top-level-window<%>))
      boolean?)
     drscheme:language-configuration:language-settings?)
    ((panel button-panel language-setting)
@@ -970,7 +970,7 @@
    ".")
   
   (drscheme:language:put-executable
-   ((is-a?/c top-level-window<%>) path? boolean? boolean? string? . -> . (union false/c path?))
+   ((is-a?/c top-level-window<%>) path? boolean? boolean? string? . -> . (or/c false/c path?))
    (parent program-filename mred? launcher? title)
    "Calls the MrEd primitive"
    "@flink put-file"
@@ -989,12 +989,12 @@
    "primitive.")
   
   (drscheme:language:create-executable-gui
-   ((union false/c (is-a?/c top-level-window<%>))
-    (union false/c string?)
-    (union (λ (x) (eq? x #t)) (symbols 'launcher 'standalone))
-    (union (λ (x) (eq? x #t)) (symbols 'mzscheme 'mred))
+   ((or/c false/c (is-a?/c top-level-window<%>))
+    (or/c false/c string?)
+    (or/c (λ (x) (eq? x #t)) (symbols 'launcher 'standalone))
+    (or/c (λ (x) (eq? x #t)) (symbols 'mzscheme 'mred))
     . -> .
-    (union false/c
+    (or/c false/c
            (list/c (symbols 'no-show 'launcher 'stand-alone)
                    (symbols 'no-show 'mred 'mzscheme)
                    string?)))
@@ -1017,8 +1017,8 @@
    "otherwise it will indicate the user's choice.")
   
   (drscheme:language:create-module-based-stand-alone-executable 
-   ((union path? string?)
-    (union path? string?) any/c any/c any/c boolean? boolean?
+   ((or/c path? string?)
+    (or/c path? string?) any/c any/c any/c boolean? boolean?
             . -> .
             void?)
    (program-filename
@@ -1055,7 +1055,7 @@
    "\\rawscm{namespace-require}. ")
   
   (drscheme:language:create-module-based-launcher
-   ((union path? string?) (union path? string?) any/c any/c any/c boolean? boolean?
+   ((or/c path? string?) (or/c path? string?) any/c any/c any/c boolean? boolean?
             . -> .
             void?)
    (program-filename
@@ -1305,7 +1305,7 @@
                     . -> .
                     (case-> (any/c . -> . void?) (-> any/c))))
      (create-executable (any/c
-                         (union (is-a?/c dialog%) (is-a?/c frame%))
+                         (or/c (is-a?/c dialog%) (is-a?/c frame%))
                          path?
                          drscheme:teachpack:teachpack-cache?
                          . -> .
@@ -1326,10 +1326,10 @@
      (get-language-name (-> string?))
      (get-language-numbers (-> (cons/c number? (listof number?))))
      (get-language-position (-> (cons/c string? (listof string?))))
-     (get-language-url (-> (union false/c string?)))
+     (get-language-url (-> (or/c false/c string?)))
      (get-one-line-summary (-> string?))
      (get-comment-character (-> (values string? char?)))
-     (get-style-delta (-> (union false/c
+     (get-style-delta (-> (or/c false/c
                                  (is-a?/c style-delta%)
                                  (listof (list/c (is-a?/c style-delta%) number? number?)))))
      (marshall-settings (any/c . -> . printable/c))
diff --git a/collects/framework/framework.ss b/collects/framework/framework.ss
index 0d8b5c469f..a04db310eb 100644
--- a/collects/framework/framework.ss
+++ b/collects/framework/framework.ss
@@ -228,7 +228,7 @@
     "default preferences.")
 
    (preferences:add-panel
-    ((union string? (cons/c string? (listof string?)))
+    ((or/c string? (cons/c string? (listof string?)))
      ((is-a?/c area-container-window<%>) 
       . ->d .
       (λ (parent)
@@ -494,13 +494,13 @@
     (opt->
      ()
      (string?
-      (union false/c path?)
+      (or/c false/c path?)
       boolean?
       string?
-      (union false/c byte-regexp?)
+      (or/c false/c byte-regexp?)
       string?
-      (union (is-a?/c top-level-window<%>) false/c))
-     (union false/c path?))
+      (or/c (is-a?/c top-level-window<%>) false/c))
+     (or/c false/c path?))
     (()
      ((name "Untitled")
       (directory #f)
@@ -518,12 +518,12 @@
    (finder:common-get-file
     (opt->
      ()
-     ((union path? false/c)
+     ((or/c path? false/c)
       string?
-      (union byte-regexp? false/c)
+      (or/c byte-regexp? false/c)
       string?
-      (union false/c (is-a?/c top-level-window<%>)))
-     (union path? false/c))
+      (or/c false/c (is-a?/c top-level-window<%>)))
+     (or/c path? false/c))
     (()
      ((directory #f)
       (prompt "Select File")
@@ -540,13 +540,13 @@
     (opt->
      ()
      (string?
-      (union false/c path?)
+      (or/c false/c path?)
       boolean?
       string?
-      (union false/c byte-regexp?)
+      (or/c false/c byte-regexp?)
       string?
-      (union (is-a?/c top-level-window<%>) false/c))
-     (union false/c path?))
+      (or/c (is-a?/c top-level-window<%>) false/c))
+     (or/c false/c path?))
     (()
      ((name "Untitled")
       (directory #f)
@@ -564,12 +564,12 @@
    (finder:std-get-file
     (opt->
      ()
-     ((union path? false/c)
+     ((or/c path? false/c)
       string?
-      (union byte-regexp? false/c)
+      (or/c byte-regexp? false/c)
       string?
-      (union false/c (is-a?/c top-level-window<%>)))
-     (union path? false/c))
+      (or/c false/c (is-a?/c top-level-window<%>)))
+     (or/c path? false/c))
     (()
      ((directory #f)
       (prompt "Select File")
@@ -586,13 +586,13 @@
     (opt->
      ()
      (string?
-      (union false/c path?)
+      (or/c false/c path?)
       boolean?
       string?
-      (union false/c byte-regexp?)
+      (or/c false/c byte-regexp?)
       string?
-      (union (is-a?/c top-level-window<%>) false/c))
-     (union false/c path?))
+      (or/c (is-a?/c top-level-window<%>) false/c))
+     (or/c false/c path?))
     (()
      ((name "Untitled")
       (directory #f)
@@ -614,12 +614,12 @@
    (finder:get-file
     (opt->
      ()
-     ((union path? false/c)
+     ((or/c path? false/c)
       string?
-      (union byte-regexp? string? false/c)
+      (or/c byte-regexp? string? false/c)
       string?
-      (union false/c (is-a?/c top-level-window<%>)))
-     (union path? false/c))
+      (or/c false/c (is-a?/c top-level-window<%>)))
+     (or/c path? false/c))
     (()
      ((directory #f)
       (prompt "Select File")
@@ -639,12 +639,12 @@
    (finder:common-get-file-list
     (opt->
      ()
-     ((union false/c path?)
+     ((or/c false/c path?)
       string?
-      (union false/c byte-regexp?)
+      (or/c false/c byte-regexp?)
       string?
-      (union false/c (is-a?/c top-level-window<%>)))
-     (union (listof path?) false/c))
+      (or/c false/c (is-a?/c top-level-window<%>)))
+     (or/c (listof path?) false/c))
     (()
      ((directory #f)
       (prompt "Select File")
@@ -699,7 +699,7 @@
     (handler)
     "Extracts the name from a handler.")
    (handler:handler-extension
-    (handler:handler? . -> . (union (path? . -> . boolean?) (listof string?)))
+    (handler:handler? . -> . (or/c (path? . -> . boolean?) (listof string?)))
     (handler)
     "Extracts the extension from a handler.")
    (handler:handler-handler
@@ -708,8 +708,8 @@
     "Extracs the handler's handling function")
    (handler:insert-format-handler
     (string?
-     (union string? (listof string?) (path? . -> . boolean?))
-     (path? . -> . (union false/c (is-a?/c frame:editor<%>)))
+     (or/c string? (listof string?) (path? . -> . boolean?))
+     (path? . -> . (or/c false/c (is-a?/c frame:editor<%>)))
      . -> .
      void?)
     (name pred handler)
@@ -744,9 +744,9 @@
 
    (handler:edit-file
     (opt->
-     ((union path? false/c))
+     ((or/c path? false/c))
      ((-> (is-a?/c frame:editor<%>)))
-     (union false/c (is-a?/c frame:editor<%>)))
+     (or/c false/c (is-a?/c frame:editor<%>)))
     ((filename)
      ((make-default (λ () ((handler:current-create-new-window) filename)))))
     "This function creates a frame or re-uses an existing frame to edit a file. "
@@ -790,8 +790,8 @@
 
    (handler:current-create-new-window
     (case->
-     (((union false/c path?) . -> . (is-a?/c frame%)) . -> . void)
-     (-> ((union false/c string?) . -> . (is-a?/c frame%))))
+     (((or/c false/c path?) . -> . (is-a?/c frame%)) . -> . void)
+     (-> ((or/c false/c string?) . -> . (is-a?/c frame%))))
     ((new-window-handler) ())
     "This is a parameter that controls how the framework"
     "creates new application windows."
@@ -805,7 +805,7 @@
     "\\end{schemedisplay}")
 
    (handler:open-file
-    (-> (union false/c (is-a?/c frame:basic<%>)))
+    (-> (or/c false/c (is-a?/c frame:basic<%>)))
     ()
     "This function queries the user for a filename and opens the file for"
     "editing. It uses "
@@ -1298,7 +1298,7 @@
    (scheme:text-balanced?
     (opt->
      ((is-a?/c text%))
-     (number? (union false/c number?))
+     (number? (or/c false/c number?))
      boolean?)
    ((text)
     ((start 0) (end #f)))
@@ -1516,7 +1516,7 @@
      "Builds a printed representation for a style-delta.")
     
     (color-prefs:unmarshall-style
-     (-> printable/c (union false/c (is-a?/c style-delta%)))
+     (-> printable/c (or/c false/c (is-a?/c style-delta%)))
      (marshalled-style-delta)
      "Builds a style delta from its printed representation."
      "Returns \\scheme|#f| if the printed form cannot be parsed.")
diff --git a/collects/framework/gui-utils.ss b/collects/framework/gui-utils.ss
index e8e058c380..5b3af90ef1 100644
--- a/collects/framework/gui-utils.ss
+++ b/collects/framework/gui-utils.ss
@@ -150,9 +150,9 @@
      (string?
       string?)
      (boolean?
-      (union false/c
-	     (is-a?/c frame%)
-	     (is-a?/c dialog%)))
+      (or/c false/c
+            (is-a?/c frame%)
+            (is-a?/c dialog%)))
      (symbols 'continue 'save 'cancel))
     ((filename action)
      ((can-save-now? #f)
@@ -175,7 +175,7 @@
       string?)
      (string?
       any/c
-      (union false/c (is-a?/c frame%) (is-a?/c dialog%))
+      (or/c false/c (is-a?/c frame%) (is-a?/c dialog%))
       (symbols 'app 'caution 'stop))
      any/c)
     ((message true-choice false-choice)
diff --git a/collects/framework/test.ss b/collects/framework/test.ss
index ea47ed507e..b9b9bb86e0 100644
--- a/collects/framework/test.ss
+++ b/collects/framework/test.ss
@@ -80,7 +80,7 @@
    ;; ((frame-has? p) f) =
    ;;    f is a frame and it has a child (in it or a subpanel) that responds #t to p
    (test:button-push
-    ((union (λ (str)
+    ((or/c (λ (str)
               (and (string? str)
                    (test:top-level-focus-window-has?
                     (λ (c)
@@ -104,7 +104,7 @@
     "active frame. Otherwise, it pushes the button argument.")
 
    (test:set-radio-box!
-    ((union string? (is-a?/c radio-box%)) (union string? number?) . -> . void?)
+    ((or/c string? (is-a?/c radio-box%)) (or/c string? number?) . -> . void?)
     (radio-box state)
     "Sets the radio-box to \\var{state}. If \\var{state} is a"
     "string, this function finds the choice with that label and"
@@ -122,7 +122,7 @@
     "Finds a \\iscmclass{radio-box} that has a label \\var{entry}"
     "and sets the radio-box to \\var{entry}.")
    (test:set-check-box!
-    ((union string? (is-a?/c check-box%)) boolean? . -> . void?)
+    ((or/c string? (is-a?/c check-box%)) boolean? . -> . void?)
     (check-box state)
     "Clears the \\iscmclass{check-box} item if \\var{state} is \\rawscm{\\#f}, and sets it"
     "otherwise."
@@ -132,7 +132,7 @@
     "otherwise it uses \\var{check-box} itself.")
 
    (test:set-choice!
-    ((union string? (is-a?/c choice%)) string? . -> . void?)
+    ((or/c string? (is-a?/c choice%)) string? . -> . void?)
     (choice str)
     "Selects \\var{choice}'s item \\var{str}. If \\var{choice} is a string,"
     "this function searches for a \\iscmclass{choice} with a label matching"
@@ -140,7 +140,7 @@
 
    (test:keystroke
     (opt->
-     ((union char? symbol?))
+     ((or/c char? symbol?))
      ((listof (symbols 'alt 'control 'meta 'shift 'noalt 'nocontrol 'nometea 'noshift)))
      void?)
     ((key)
diff --git a/collects/games/paint-by-numbers/solve.ss b/collects/games/paint-by-numbers/solve.ss
index a4c874feeb..6942103bbe 100644
--- a/collects/games/paint-by-numbers/solve.ss
+++ b/collects/games/paint-by-numbers/solve.ss
@@ -96,7 +96,7 @@
             ; (type: tally-row (list-of (union 'off 'on 'unknown 'maybe-off 'maybe-on 'mixed)))
             ; (type: try-row (list-of (union 'maybe-off 'maybe-on 'unknown)))
             (define try-row? (listof (symbols 'maybe-off 'maybe-on 'unknown)))
-            (define try-batch? (listof (union number? (listof try-row?))))
+            (define try-batch? (listof (or/c number? (listof try-row?))))
             
             ;    
             ; (type: board (list-of board-row))
diff --git a/collects/help/private/manuals.ss b/collects/help/private/manuals.ss
index 853db55ae1..de6ce7a610 100644
--- a/collects/help/private/manuals.ss
+++ b/collects/help/private/manuals.ss
@@ -23,9 +23,9 @@
                     [finddoc-page (string? string? . -> . string?)]
                     [get-doc-name (path? . -> . string?)]
                     [find-doc-directories (-> (listof path?))]
-                    [find-doc-directory (path? . -> . (union false/c path?))]
+                    [find-doc-directory (path? . -> . (or/c false/c path?))]
                     [find-doc-names (-> (listof (cons/c path? string?)))]
-                    [get-index-file (path? . -> . (union false/c path?))])
+                    [get-index-file (path? . -> . (or/c false/c path?))])
   
   (provide find-manuals)
 
diff --git a/collects/help/private/search.ss b/collects/help/private/search.ss
index 61b5f841a9..e17cdf784f 100644
--- a/collects/help/private/search.ss
+++ b/collects/help/private/search.ss
@@ -20,16 +20,16 @@
      (-> any)
      (string? any/c . -> . void?)
      (string? any/c . -> . void?)
-     (string? string? string? path? (union string? number? false/c) any/c . -> . void?)
+     (string? string? string? path? (or/c string? number? false/c) any/c . -> . void?)
      . -> .
-     (union string? false/c))]
+     (or/c string? false/c))]
    
    (build-string-finds/finds (string? 
                               boolean?
                               boolean?
                               . -> . 
                               (values (listof string?) 
-                                      (listof (union regexp? string?)))))
+                                      (listof (or/c regexp? string?)))))
    
    (non-regexp (string? . -> . string?)))
 
diff --git a/collects/help/private/standard-urls.ss b/collects/help/private/standard-urls.ss
index eff250946b..d314d395fb 100644
--- a/collects/help/private/standard-urls.ss
+++ b/collects/help/private/standard-urls.ss
@@ -20,12 +20,12 @@
                                any/c 
                                (listof path?)
                                any/c
-                               (union false/c string?) . -> . string?))
+                               (or/c false/c string?) . -> . string?))
    (make-results-url (string?
                       search-type? search-how? any/c 
                       (listof path?) 
                       any/c
-                      (union false/c string?)
+                      (or/c false/c string?)
                       . -> .
                       string?))
    (flush-manuals-url string?)
diff --git a/collects/htdp/image.ss b/collects/htdp/image.ss
index 63623c5a89..011cbcacee 100644
--- a/collects/htdp/image.ss
+++ b/collects/htdp/image.ss
@@ -330,37 +330,32 @@ plt/collects/tests/mzscheme/image-test.ss
                     (if (<= pre-x1 pre-x2)
                         (values pre-x1 pre-y1 pre-x2 pre-y2)
                         (values pre-x2 pre-y2 pre-x1 pre-y1))])
-        (let* ([line-w (+ (abs (- x2 x1)) 1)]
-               [line-h (+ (abs (- y2 y1)) 1)])
+        (let* ([line-w (abs (- x2 x1))]
+               [line-h (abs (- y2 y1))]
+               [build-snip
+                (λ (do-draw py-offset)
+                  (let* ([draw-proc 
+                          (make-color-wrapper color-in 'transparent 'solid do-draw)]
+                         [mask-proc
+                          (make-color-wrapper 'black 'transparent 'solid do-draw)]
+                         [line
+                          (make-simple-cache-image-snip (+ line-w 1) (+ line-h 1) px py draw-proc mask-proc)])
+                    (real-overlay/xy 'add-line i (+ px x1) (+ py py-offset) line)))])
           (if (y1 . <= . y2)
-              (let* ([do-draw
-                      (lambda (dc dx dy)
-                        (send dc draw-line 
-                              dx
-                              dy
-                              (+ dx (- x2 x1))
-                              (+ dy (- y2 y1))))]
-                     [draw-proc 
-                      (make-color-wrapper color-in 'transparent 'solid do-draw)]
-                     [mask-proc
-                      (make-color-wrapper 'black 'transparent 'solid do-draw)]
-                     [line
-                      (make-simple-cache-image-snip line-w line-h px py draw-proc mask-proc)])
-                (real-overlay/xy 'add-line i (+ px x1) (+ py y1) line))
-              (let* ([do-draw
-                      (lambda (dc dx dy)
-                        (send dc draw-line 
-                              dx
-                              (+ dy (- line-h 1))
-                              (+ dx (- line-w 1))
-                              dy))]
-                     [draw-proc 
-                      (make-color-wrapper color-in 'transparent 'solid do-draw)]
-                     [mask-proc
-                      (make-color-wrapper 'black 'transparent 'solid do-draw)]
-                     [line
-                      (make-simple-cache-image-snip line-w line-h px py draw-proc mask-proc)])
-                (real-overlay/xy 'add-line i (+ px x1) (+ py y2) line)))))))
+              (build-snip (λ (dc dx dy)
+                            (send dc draw-line 
+                                  dx
+                                  dy
+                                  (+ dx (- x2 x1))
+                                  (+ dy (- y2 y1))))
+                          y1)
+              (build-snip (λ (dc dx dy)
+                            (send dc draw-line 
+                                  dx
+                                  (+ dy line-h)
+                                  (+ dx line-w)
+                                  dy))
+                          y2))))))
 
   (define (text str size color-in)
     (check 'text string? str "string" "first")
@@ -484,6 +479,7 @@ plt/collects/tests/mzscheme/image-test.ss
   (define (make-simple-cache-image-snip w h px py dc-proc mask-proc)
     (let ([w (inexact->exact (ceiling w))]
 	  [h (inexact->exact (ceiling h))])
+      (printf "new w ~s new -h ~s\n" w h)
       (let ([argb-proc 
 	     (lambda (argb-vector dx dy)
 	       (let ([c-bm (build-bitmap (lambda (dc) (dc-proc dc 0 0)) w h)]
diff --git a/collects/mrlib/bitmap-label.ss b/collects/mrlib/bitmap-label.ss
index f9d7e0c1aa..5e23180d31 100644
--- a/collects/mrlib/bitmap-label.ss
+++ b/collects/mrlib/bitmap-label.ss
@@ -7,12 +7,12 @@
   (provide/contract
    [make-bitmap-label (opt->
                        (string?
-                        (union path-string?
+                        (or/c path-string?
                                (is-a?/c bitmap%)))
                        ((is-a?/c font%))
                        (is-a?/c bitmap%))]
    [bitmap-label-maker (string?
-			(union path-string?
+			(or/c path-string?
 			       (is-a?/c bitmap%))
 			. -> .
 			(any/c . -> . (is-a?/c bitmap%)))])
diff --git a/collects/mrlib/graph.ss b/collects/mrlib/graph.ss
index ebb7dc1128..ee0cd5f84e 100644
--- a/collects/mrlib/graph.ss
+++ b/collects/mrlib/graph.ss
@@ -34,54 +34,54 @@
 		       void?)
 		      ((is-a?/c graph-snip<%>)
 		       (is-a?/c graph-snip<%>)
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c brush%))
-		       (union false/c (is-a?/c brush%))
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c brush%))
+		       (or/c false/c (is-a?/c brush%))
 		       . -> .
 		       void?)
                       ((is-a?/c graph-snip<%>)
 		       (is-a?/c graph-snip<%>)
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c brush%))
-		       (union false/c (is-a?/c brush%))
-                       (union false/c string?)
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c brush%))
+		       (or/c false/c (is-a?/c brush%))
+                       (or/c false/c string?)
 		       . -> .
 		       void?)
                       ((is-a?/c graph-snip<%>)
 		       (is-a?/c graph-snip<%>)
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c brush%))
-		       (union false/c (is-a?/c brush%))
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c brush%))
+		       (or/c false/c (is-a?/c brush%))
 		       number?
                        number?
                        . -> .
 		       void?)
                       ((is-a?/c graph-snip<%>)
 		       (is-a?/c graph-snip<%>)
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c brush%))
-		       (union false/c (is-a?/c brush%))
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c brush%))
+		       (or/c false/c (is-a?/c brush%))
 		       number?
                        number?
-                       (union false/c string?)
+                       (or/c false/c string?)
                        . -> .
 		       void?)))
                     (add-links/text-colors
                      ((is-a?/c graph-snip<%>)
 		       (is-a?/c graph-snip<%>)
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c pen%))
-		       (union false/c (is-a?/c brush%))
-		       (union false/c (is-a?/c brush%))
-                       (union false/c (is-a?/c color%))
-                       (union false/c (is-a?/c color%))
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c pen%))
+		       (or/c false/c (is-a?/c brush%))
+		       (or/c false/c (is-a?/c brush%))
+                       (or/c false/c (is-a?/c color%))
+                       (or/c false/c (is-a?/c color%))
 		       number?
                        number?
-                       (union false/c string?)
+                       (or/c false/c string?)
                        . -> .
 		       void?)))
 
@@ -351,7 +351,7 @@
           (let* ([parents-and-children (append (get-all-parents snip)
                                                (get-all-children snip))]
                  [rects (eliminate-redundancies (get-rectangles snip parents-and-children))]
-                 [union (union-rects rects)]
+                 [or/c (or/c-rects rects)]
                  [text-height (call-with-values 
                                (λ () (send dc get-text-extent "Label" #f #f 0))
                                (λ (w h a s) h))]
@@ -366,9 +366,9 @@
                                                    (rect-top rect))
                                                    text-height)))])
             (cond
-              [(< (rect-area union)
+              [(< (rect-area or/c)
                   (apply + (map (lambda (x) (rect-area x)) rects)))
-               (invalidate-rect union)]
+               (invalidate-rect or/c)]
               [else
                (for-each invalidate-rect rects)]))))
       
@@ -414,7 +414,7 @@
                                         sy
                                         (+ (+ sx sw) self-offset)
                                         (+ (+ sy sh) self-offset h)))
-                           (union-rects (list main-snip-rect
+                           (or/c-rects (list main-snip-rect
                                               (snip->rect c/p))))])
                  (cons rect (loop (cdr c/p-snips))))]))))
 
@@ -432,7 +432,7 @@
            (- (rect-bottom rect)
               (rect-top rect))))
       
-      (define/private (union-rects rects)
+      (define/private (or/c-rects rects)
         (cond
           [(null? rects) (make-rect 0 0 0 0)]
           [else
@@ -928,7 +928,7 @@
     (and (< (min p1x p2x) x (max p1x p2x))
          (< (min p1y p2y) y (max p1y p2y))))
   
-  ;; find-intersection : number^8 -> (values (union #f number) (union #f number))
+  ;; find-intersection : number^8 -> (values (or/c #f number) (or/c #f number))
   ;; calculates the intersection between two line segments, 
   ;; described as pairs of points. Returns #f if they do not intersect
   (define (find-intersection x1 y1 x2 y2 x3 y3 x4 y4)
@@ -975,7 +975,7 @@
             (values int-x int-y)
             (values #f #f)))))
   
-  ;; find-mb : number number number number -> (values (union #f number) (union #f number))
+  ;; find-mb : number number number number -> (values (or/c #f number) (or/c #f number))
   ;; finds the "m" and "b" constants that describe the
   ;; lines from (x1, y1) to (x2, y2)
   (define (find-mb x1 y1 x2 y2)
diff --git a/collects/mrlib/private/aligned-pasteboard/pasteboard-lib.ss b/collects/mrlib/private/aligned-pasteboard/pasteboard-lib.ss
index c4d20bffbf..0083779483 100644
--- a/collects/mrlib/private/aligned-pasteboard/pasteboard-lib.ss
+++ b/collects/mrlib/private/aligned-pasteboard/pasteboard-lib.ss
@@ -11,7 +11,7 @@
   (provide/contract
    (pasteboard-root ((is-a?/c aligned-pasteboard<%>) . -> . (is-a?/c aligned-pasteboard<%>)))
    (pasteboard-parent
-    ((is-a?/c pasteboard%) . -> . (union (is-a?/c editor-canvas%) (is-a?/c editor-snip%) false/c))))
+    ((is-a?/c pasteboard%) . -> . (or/c (is-a?/c editor-canvas%) (is-a?/c editor-snip%) false/c))))
   
   ;; gets the top most aligned pasteboard in the tree of pasteboards and containers
   (define (pasteboard-root pasteboard)
@@ -35,5 +35,4 @@
          (send admin get-snip)]
         [(is-a? admin editor-admin%)
          (send pasteboard get-canvas)]
-        [else false])))
-  )
+        [else false]))))
diff --git a/collects/mrlib/private/aligned-pasteboard/snip-lib.ss b/collects/mrlib/private/aligned-pasteboard/snip-lib.ss
index d32eef28fd..266a0a6304 100644
--- a/collects/mrlib/private/aligned-pasteboard/snip-lib.ss
+++ b/collects/mrlib/private/aligned-pasteboard/snip-lib.ss
@@ -11,7 +11,7 @@
   ;; a snip
   (define snip? (is-a?/c snip%))
   ;; a snip to act as the varying argument to a recursive functions
-  (define linked-snip? (union snip? false/c))
+  (define linked-snip? (or/c snip? false/c))
   ;; a function to act on snips being mapped
   (define snip-visitor? any/c #;((snip?) (listof any/c) . ->* . (void)))
   ;; the rest of the lists passed to a snip mapping function
@@ -24,7 +24,7 @@
    (snip-height (snip? . -> . number?))
    (snip-min-width (snip? . -> . number?))
    (snip-min-height (snip? . -> . number?))
-   (snip-parent (snip? . -> . (union editor? false/c)))
+   (snip-parent (snip? . -> . (or/c editor? false/c)))
    (fold-snip ((snip? any/c . -> . any/c) any/c linked-snip? . -> . any/c))
    (for-each-snip any/c #;((snip-visitor? linked-snip?) rest-lists? . ->* . (void)))
    (map-snip any/c #;((snip-visitor? linked-snip?) rest-lists? . ->* . ((listof any/c))))
diff --git a/collects/mzlib/port.ss b/collects/mzlib/port.ss
index bc072e2cb7..a15c128b2d 100644
--- a/collects/mzlib/port.ss
+++ b/collects/mzlib/port.ss
@@ -64,7 +64,7 @@
 		    (peek-string-evt (exact-non-negative-integer? exact-non-negative-integer? evt?/false
 								  input-port-with-progress-evts? 
 								  . -> . evt?))
-		    (regexp-match-evt ((union regexp? byte-regexp? string? bytes?)
+		    (regexp-match-evt ((or/c regexp? byte-regexp? string? bytes?)
 				       input-port-with-progress-evts? 
 				       . -> . evt?))
 
diff --git a/collects/net/imap.ss b/collects/net/imap.ss
index 61d94ed92d..b7560362c7 100644
--- a/collects/net/imap.ss
+++ b/collects/net/imap.ss
@@ -13,8 +13,8 @@
    [imap-get-hierarchy-delimiter (imap-connection? . -> . bytes?)]
    [imap-list-child-mailboxes
     (case->
-     (imap-connection? (union false/c bytes?) . -> . (listof (list/c (listof symbol?) bytes?)))
-     (imap-connection? (union false/c bytes?) (union false/c bytes?)
+     (imap-connection? (or/c false/c bytes?) . -> . (listof (list/c (listof symbol?) bytes?)))
+     (imap-connection? (or/c false/c bytes?) (or/c false/c bytes?)
                        . -> .
                        (listof (list/c (listof symbol?) bytes?))))])
    
diff --git a/collects/net/url-structs.ss b/collects/net/url-structs.ss
index d6feda78af..315682a219 100644
--- a/collects/net/url-structs.ss
+++ b/collects/net/url-structs.ss
@@ -5,13 +5,13 @@
   (define-struct path/param (path param))
 
   (provide/contract
-   (struct url ([scheme (union false/c string?)]
-                [user (union false/c string?)]
-                [host (union false/c string?)]
-                [port (union false/c number?)]
+   (struct url ([scheme (or/c false/c string?)]
+                [user (or/c false/c string?)]
+                [host (or/c false/c string?)]
+                [port (or/c false/c number?)]
                 [path-absolute? boolean?]
                 [path (listof path/param?)]
                 [query (listof (cons/c symbol? string?))]
-                [fragment (union false/c string?)]))
-   (struct path/param ([path (union string? (symbols 'up 'same))]
+                [fragment (or/c false/c string?)]))
+   (struct path/param ([path (or/c string? (symbols 'up 'same))]
                        [param (listof string?)]))))
diff --git a/collects/net/url.ss b/collects/net/url.ss
index 9c9400cf74..daa4d021e8 100644
--- a/collects/net/url.ss
+++ b/collects/net/url.ss
@@ -28,12 +28,12 @@
    (struct path/param (path param)))
 
   (provide/contract
-   (string->url ((union bytes? string?) . -> . url?))
+   (string->url ((or/c bytes? string?) . -> . url?))
    (url->string (url? . -> . string?))
 
    (get-pure-port (opt-> (url?) ((listof string?)) input-port?))
    (get-impure-port (opt-> (url?) ((listof string?)) input-port?))
-   (post-pure-port (opt-> (url? (union false/c bytes?)) ((listof string?)) input-port?))
+   (post-pure-port (opt-> (url? (or/c false/c bytes?)) ((listof string?)) input-port?))
    (post-impure-port (opt-> (url? bytes?) ((listof string?)) input-port?))
    (display-pure-port (input-port? . -> . void?))
    (purify-port (input-port? . -> . string?))
@@ -46,6 +46,6 @@
    (combine-url/relative (url? string? . -> . url?))
    (url-exception? (any/c . -> . boolean?))
    (current-proxy-servers
-    (case-> ((union false/c (listof (list/c string? string? number?))) . -> . void?)
-            (-> (union false/c (listof (list/c string? string? number?))))))))
+    (case-> ((or/c false/c (listof (list/c string? string? number?))) . -> . void?)
+            (-> (or/c false/c (listof (list/c string? string? number?))))))))
 
diff --git a/collects/setup/getinfo.ss b/collects/setup/getinfo.ss
index 2e8e2a52a0..9b46cba34b 100644
--- a/collects/setup/getinfo.ss
+++ b/collects/setup/getinfo.ss
@@ -13,8 +13,8 @@
   (define path-or-string? (lambda (x) (or (path? x) (string? x))))
   
   (provide/contract
-   (get-info ((listof path-or-string?) . -> . (union info? boolean?)))
-   (get-info/full (path? . -> . (union info? boolean?)))
+   (get-info ((listof path-or-string?) . -> . (or/c info? boolean?)))
+   (get-info/full (path? . -> . (or/c info? boolean?)))
    (find-relevant-directories (opt-> ((listof symbol?))
                                      ((lambda (x) (or (eq? x 'preferred)
                                                       (eq? x 'all-available))))
diff --git a/collects/slideshow/slide.ss b/collects/slideshow/slide.ss
index c56943e9df..7697030c4b 100644
--- a/collects/slideshow/slide.ss
+++ b/collects/slideshow/slide.ss
@@ -75,7 +75,7 @@
 		    [slide/name/inset slide/title/inset-contract]
 		    [slide/name/tall/inset slide/title/inset-contract]
 		    [slide/name/center/inset slide/title/inset-contract]
-		    [comment (() (listof (union string? pict?)) . ->* . any)])
+		    [comment (() (listof (or/c string? pict?)) . ->* . any)])
   (provide most-recent-slide retract-most-recent-slide re-slide start-at-recent-slide
 	   scroll-transition pause-transition
 	   make-outline
diff --git a/collects/tests/drscheme/drscheme-test-util.ss b/collects/tests/drscheme/drscheme-test-util.ss
index c297ffa945..d30bcc3781 100644
--- a/collects/tests/drscheme/drscheme-test-util.ss
+++ b/collects/tests/drscheme/drscheme-test-util.ss
@@ -360,7 +360,7 @@
               (unless (eq? new-frame drs-frame)
                 (error 'set-language-level! "didn't get drscheme frame back, got: ~s\n" new-frame)))))))) 
 
-  (provide/contract [check-language-level ((union string? regexp?) . -> . void?)])
+  (provide/contract [check-language-level ((or/c string? regexp?) . -> . void?)])
   ;; checks that the language in the drscheme window is set to the given one.
   ;; clears the definitions, clicks execute and checks the interactions window.
   (define (check-language-level lang-spec)