diff --git a/collects/macro-debugger/syntax-browser/browser.ss b/collects/macro-debugger/syntax-browser/browser.ss
index a2e99dbc54..f1c827caf5 100644
--- a/collects/macro-debugger/syntax-browser/browser.ss
+++ b/collects/macro-debugger/syntax-browser/browser.ss
@@ -1,6 +1,6 @@
 
 (module browser mzscheme
-  (require (lib "unitsig.ss")
+  (require (lib "unit.ss")
            "interfaces.ss"
            "frame.ss"
            "implementation.ss")
@@ -8,12 +8,14 @@
   (provide-signature-elements snip^)
   
   (define browser@
-    (compound-unit/sig 
+    (compound-unit
       (import)
-      (link [PREFS : prefs^          (global-prefs@)]
-            [IMPL  : implementation^ (implementation@)]
-            [FRAME : browser^        (frame@ PREFS (IMPL widget))])
-      (export (open FRAME))))
-  
-  (define-values/invoke-unit/sig browser^ browser@)
+      (link [((PREFS : prefs^))    global-prefs@]
+            [((WIDGET : widget^)) implementation@]
+            [((FRAME : browser^))  frame@ PREFS WIDGET])
+      (export FRAME)))
+
+  (define-values/invoke-unit browser@
+    (import)
+    (export browser^))
   )
diff --git a/collects/macro-debugger/syntax-browser/frame.ss b/collects/macro-debugger/syntax-browser/frame.ss
index e6a6af266a..eb478d1ea7 100644
--- a/collects/macro-debugger/syntax-browser/frame.ss
+++ b/collects/macro-debugger/syntax-browser/frame.ss
@@ -1,7 +1,7 @@
 
 (module frame mzscheme
   (require (lib "class.ss")
-           (lib "unitsig.ss")
+           (lib "unit.ss")
            (lib "mred.ss" "mred")
            (lib "framework.ss" "framework")
            (lib "list.ss")
@@ -10,10 +10,11 @@
   (provide frame@)
   
   (define frame@
-    (unit/sig browser^
+    (unit
       (import prefs^
               widget^)
-      
+      (export browser^)
+
       ;; browse-syntax : syntax -> void
       (define (browse-syntax stx)
         (browse-syntaxes (list stx)))
diff --git a/collects/macro-debugger/syntax-browser/implementation.ss b/collects/macro-debugger/syntax-browser/implementation.ss
index 7562b936e2..48ae42e8c7 100644
--- a/collects/macro-debugger/syntax-browser/implementation.ss
+++ b/collects/macro-debugger/syntax-browser/implementation.ss
@@ -1,6 +1,6 @@
 
 (module implementation mzscheme
-  (require (lib "unitsig.ss")
+  (require (lib "unit.ss")
            "interfaces.ss"
            "widget.ss"
            "syntax-snip.ss"
@@ -19,69 +19,55 @@
   ;; We create a new unit/sig out of their invocation
 
   (define snip-keymap@
-    (compound-unit/sig
+    (compound-unit
       (import [MENU : context-menu^]
               [SNIP : snip^])
-      (link [KEYMAP : keymap^ (keymap@ MENU SNIP)]
-            [SNIP-KEYMAP : keymap^ (snip-keymap-extension@ KEYMAP)])
-      (export (open SNIP-KEYMAP))))
+      (link [((KEYMAP : keymap^))      keymap@ MENU SNIP]
+            [((SNIP-KEYMAP : keymap^)) snip-keymap-extension@ KEYMAP])
+      (export SNIP-KEYMAP)))
   
   (define snip-implementation@
-    (compound-unit/sig 
+    (compound-unit
       (import)
-      (link [PREFS       : prefs^ (prefs@)]
-            [MENU        : context-menu^ (context-menu@)]
-            [KEYMAP      : keymap^ (snip-keymap@ MENU SNIP)]
-            [SNIP-CLASS  : snipclass^ (snipclass@ SNIP)]
-            [SNIP        : snip^ (snip@ PREFS KEYMAP MENU SNIP-CLASS)])
-      (export (open PREFS) (open SNIP) (open SNIP-CLASS))))
-  (define-values/invoke-unit/sig ((open snip^) (open prefs^) (open snipclass^))
-    snip-implementation@)
-  
-  (define global-prefs@
-    (unit/sig prefs^
-      (import)
-      (rename (-width pref:width)
-              (-height pref:height)
-              (-props-percentage pref:props-percentage))
-      (define -width pref:width)
-      (define -height pref:height)
-      (define -props-percentage pref:props-percentage)))
-  
-  (define global-snip@
-    (unit/sig snip^
-      (import)
-      (rename (-syntax-snip syntax-snip)
-              (-syntax-snip% syntax-snip%))
-      (define -syntax-snip syntax-snip)
-      (define -syntax-snip% syntax-snip%)))
+      (link [((PREFS : prefs^)) prefs@]
+            [((MENU : context-menu^)) context-menu@]
+            [((KEYMAP : keymap^)) snip-keymap@ MENU SNIP]
+            [((SNIP-CLASS : snipclass^)) snipclass@ SNIP]
+            [((SNIP : snip^)) snip@ PREFS KEYMAP MENU SNIP-CLASS])
+      (export PREFS SNIP SNIP-CLASS)))
+  (define-values/invoke-unit snip-implementation@
+    (import)
+    (export snip^ prefs^ snipclass^))
+
+  (define global-prefs@ (unit-from-context prefs^))
+
+  (define global-snip@ (unit-from-context snip^))
 
   ;; Everyone else re-uses the global-snip@ unit
   
   (define widget-keymap@
-    (compound-unit/sig
+    (compound-unit
       (import [MENU : context-menu^]
               [SNIP : snip^])
-      (link [KEYMAP : keymap^ (keymap@ MENU SNIP)]
-            [WKEYMAP : keymap^ (widget-keymap-extension@ KEYMAP)])
-      (export (open WKEYMAP))))
-  
+      (link [((KEYMAP : keymap^)) keymap@ MENU SNIP]
+            [((WKEYMAP : keymap^)) widget-keymap-extension@ KEYMAP])
+      (export WKEYMAP)))
+
   (define widget-context-menu@
-    (compound-unit/sig
+    (compound-unit
       (import)
-      (link [MENU : context-menu^ (context-menu@)]
-            [WMENU : context-menu^ (widget-context-menu-extension@ MENU)])
-      (export (open WMENU))))
+      (link [((MENU : context-menu^)) context-menu@]
+            [((WMENU : context-menu^)) widget-context-menu-extension@ MENU])
+      (export WMENU)))
   
-  ;; implementation@ : implementation^
+  ;; implementation@ : snip^ widget^
   (define implementation@
-    (compound-unit/sig
+    (compound-unit
       (import)
-      (link [SNIP          : snip^         (global-snip@)]
-            [MENU          : context-menu^ (widget-context-menu@)]
-            [KEYMAP        : keymap^       (widget-keymap@ MENU SNIP)]
-            [WIDGET        : widget^       (widget@ KEYMAP)])
-      (export (unit SNIP snip)
-              (unit WIDGET widget))))
-  
+      (link [((SNIP : snip^)) global-snip@]
+            [((MENU : context-menu^)) widget-context-menu@]
+            [((KEYMAP : keymap^)) widget-keymap@ MENU SNIP]
+            [((WIDGET : widget^)) widget@ KEYMAP])
+      (export SNIP WIDGET)))
+
   )
diff --git a/collects/macro-debugger/syntax-browser/interfaces.ss b/collects/macro-debugger/syntax-browser/interfaces.ss
index 2b41baadf6..babd7b6f72 100644
--- a/collects/macro-debugger/syntax-browser/interfaces.ss
+++ b/collects/macro-debugger/syntax-browser/interfaces.ss
@@ -1,7 +1,7 @@
 
 (module interfaces mzscheme
   (require (lib "class.ss")
-           (lib "unitsig.ss"))
+           (lib "unit.ss"))
   (provide (all-defined))
 
   ;; Signatures
@@ -55,10 +55,6 @@
     (;; syntax-widget%
      syntax-widget%))
 
-  (define-signature implementation^
-    ([unit widget : widget^]
-     [unit snip : snip^]))
-  
   ;; Class Interfaces
 
   ;; syntax-controller<%>
diff --git a/collects/macro-debugger/syntax-browser/keymap.ss b/collects/macro-debugger/syntax-browser/keymap.ss
index 79e8480642..4ca331ffc1 100644
--- a/collects/macro-debugger/syntax-browser/keymap.ss
+++ b/collects/macro-debugger/syntax-browser/keymap.ss
@@ -1,7 +1,7 @@
 
 (module keymap mzscheme
   (require (lib "class.ss")
-           (lib "unitsig.ss")
+           (lib "unit.ss")
            (lib "mred.ss" "mred")
            "interfaces.ss"
            "partition.ss")
@@ -9,8 +9,9 @@
            context-menu@)
   
   (define context-menu@
-    (unit/sig context-menu^
+    (unit
       (import)
+      (export context-menu^)
 
       (define context-menu%
         (class popup-menu%
@@ -103,8 +104,9 @@
           ))))
   
   (define keymap@
-    (unit/sig keymap^
+    (unit
       (import context-menu^ snip^)
+      (export keymap^)
       
       (define syntax-keymap%
         (class keymap%
diff --git a/collects/macro-debugger/syntax-browser/prefs.ss b/collects/macro-debugger/syntax-browser/prefs.ss
index 944ec9ec6f..233b35677d 100644
--- a/collects/macro-debugger/syntax-browser/prefs.ss
+++ b/collects/macro-debugger/syntax-browser/prefs.ss
@@ -1,6 +1,6 @@
 
 (module prefs mzscheme
-  (require (lib "unitsig.ss")
+  (require (lib "unit.ss")
            (lib "framework.ss" "framework")
            "interfaces.ss")
   (provide prefs@)
@@ -14,8 +14,9 @@
            [(newval) (preferences:set 'prop newval)]))]))
 
   (define prefs@
-    (unit/sig prefs^
+    (unit
       (import)
+      (export prefs^)
       
       (preferences:set-default 'SyntaxBrowser:Width 700 number?)
       (preferences:set-default 'SyntaxBrowser:Height 600 number?)
diff --git a/collects/macro-debugger/syntax-browser/snipclass.ss b/collects/macro-debugger/syntax-browser/snipclass.ss
index ce5854c702..13be5daf50 100644
--- a/collects/macro-debugger/syntax-browser/snipclass.ss
+++ b/collects/macro-debugger/syntax-browser/snipclass.ss
@@ -1,7 +1,7 @@
 
 (module snipclass mzscheme
   (require (lib "class.ss")
-           (lib "unitsig.ss")
+           (lib "unit.ss")
            (lib "mred.ss" "mred")
            (lib "match.ss")
            (lib "string.ss")
@@ -10,8 +10,10 @@
   (provide snipclass@)
   
   (define snipclass@
-    (unit/sig snipclass^
+    (unit
       (import snip^)
+      (export snipclass^)
+
       ;; COPIED AND MODIFIED from mrlib/syntax-browser.ss
       (define syntax-snipclass%
         (class snip-class%
@@ -61,7 +63,7 @@
       [else stx]))
   
   (define (unmarshall-object obj)
-    (let ([unknown (λ () (string->symbol (format "unknown: ~s" obj)))])
+    (let ([unknown (lambda () (string->symbol (format "unknown: ~s" obj)))])
       (if (and (pair? obj)
                (symbol? (car obj)))
           (case (car obj)
diff --git a/collects/macro-debugger/syntax-browser/syntax-snip.ss b/collects/macro-debugger/syntax-browser/syntax-snip.ss
index 440e02be49..097a2e9e14 100644
--- a/collects/macro-debugger/syntax-browser/syntax-snip.ss
+++ b/collects/macro-debugger/syntax-browser/syntax-snip.ss
@@ -1,7 +1,7 @@
 
 (module syntax-snip mzscheme
   (require (lib "class.ss")
-           (lib "unitsig.ss")
+           (lib "unit.ss")
            (lib "mred.ss" "mred")
            (lib "framework.ss" "framework")
            "interfaces.ss"
@@ -12,12 +12,13 @@
            snip-keymap-extension@)
   
   (define snip@
-    (unit/sig snip^
+    (unit
       (import prefs^
               keymap^
               context-menu^
               snipclass^)
-      
+      (export snip^)
+
       ;; syntax-snip : syntax -> snip
       (define (syntax-snip stx)
         (new syntax-snip% (syntax stx)))
@@ -201,9 +202,10 @@
       ))
 
   (define snip-keymap-extension@
-    (unit/sig keymap^
-      (import (pre : keymap^))
-      
+    (unit
+      (import (prefix pre: keymap^))
+      (export keymap^)
+
       (define syntax-keymap%
         (class pre:syntax-keymap%
           (init-field snip)
@@ -214,23 +216,6 @@
                         (lambda (i e)
                           (send snip show-props)))))))
   
-  #;
-  (define snip-context-menu-extension@
-    (unit/sig context-menu^
-      (import (pre : context-menu^))
-      
-      (define context-menu%
-        (class pre:context-menu%
-          (init-field snip)
-
-          (define/override (after-selection-items)
-            (super after-selection-items)
-            (new menu-item% (label "Show syntax properties")
-                 (parent this)
-                 (callback (lambda _ (send snip show-props))))
-            (void))
-          
-          (super-new (controller (send snip get-controller)))))))
   
   
   (define style:normal (make-object style-delta% 'change-normal))
diff --git a/collects/macro-debugger/syntax-browser/widget.ss b/collects/macro-debugger/syntax-browser/widget.ss
index 91c541fac6..40dc3e8c0b 100644
--- a/collects/macro-debugger/syntax-browser/widget.ss
+++ b/collects/macro-debugger/syntax-browser/widget.ss
@@ -1,7 +1,7 @@
 
 (module widget mzscheme
   (require (lib "class.ss")
-           (lib "unitsig.ss")
+           (lib "unit.ss")
            (lib "mred.ss" "mred")
            (lib "framework.ss" "framework")
            (lib "list.ss")
@@ -17,9 +17,10 @@
            widget-context-menu-extension@)
 
   (define widget@
-    (unit/sig widget^
+    (unit
       (import keymap^)
-      
+      (export widget^)
+
       ;; syntax-widget%
       ;; A syntax-widget creates its own syntax-controller.
       (define syntax-widget%
@@ -140,9 +141,10 @@
       ))
 
   (define widget-keymap-extension@
-    (unit/sig keymap^
-      (import (pre : keymap^))
-      
+    (unit
+      (import (prefix pre: keymap^))
+      (export keymap^)
+
       (define syntax-keymap%
         (class pre:syntax-keymap%
           (init-field widget)
@@ -157,14 +159,15 @@
           ))))
   
   (define widget-context-menu-extension@
-    (unit/sig context-menu^
-      (import (pre : context-menu^))
-      
+    (unit
+      (import (prefix pre: context-menu^))
+      (export context-menu^)
+
       (define context-menu%
         (class pre:context-menu%
           (inherit-field keymap)
           (inherit-field props-menu)
-          
+
           (define/override (on-demand)
             (send props-menu set-label
                   (if (send (send keymap get-widget) props-shown?)
diff --git a/collects/macro-debugger/tool.ss b/collects/macro-debugger/tool.ss
index 652fdb2f53..689ab92e83 100644
--- a/collects/macro-debugger/tool.ss
+++ b/collects/macro-debugger/tool.ss
@@ -3,10 +3,6 @@
   (require (lib "class.ss")
            (lib "list.ss")
            (lib "unit.ss")
-           (only (lib "unitsig.ss") 
-                 unit/sig 
-                 compound-unit/sig
-                 define-values/invoke-unit/sig)
            (lib "mred.ss" "mred")
            (lib "framework.ss" "framework")
            (lib "tool.ss" "drscheme")
@@ -19,28 +15,20 @@
            (prefix sb: "syntax-browser/embed.ss"))
 
   (define view-base/tool@
-    (unit/sig view:view-base^
-        (import)
+    (unit
+      (import)
+      (export view:view-base^)
       (define base-frame%
         (frame:standard-menus-mixin frame:basic%))))
 
   (define stepper@
-    (compound-unit/sig
+    (compound-unit
       (import)
-      (link [BASE : view:view-base^ (view-base/tool@)]
-            [STEPPER : view:view^ (view:pre-stepper@ BASE)])
-      (export (open STEPPER))))
+      (link [((BASE : view:view-base^)) view-base/tool@]
+            [((STEPPER : view:view^)) view:pre-stepper@ BASE])
+      (export STEPPER)))
 
-  #;(define stepper@
-      (compound-unit/sig
-        (import)
-        (link (PREFS : view:prefs^ (view:prefs@))
-              (SB   : sb:implementation^ (sb:implementation@))
-              (BASE : view:view-base^ (view-base/tool@))
-              (VIEW : view:view^ (view:view@ PREFS BASE SB)))
-        (export (open VIEW))))
-  
-  (define-values/invoke-unit/sig view:view^ stepper@)
+  (define-values/invoke-unit stepper@ (import) (export view:view^))
 
   (provide tool@)
 
diff --git a/collects/macro-debugger/view/browse-deriv.ss b/collects/macro-debugger/view/browse-deriv.ss
index 85a1582851..776b59e9c9 100644
--- a/collects/macro-debugger/view/browse-deriv.ss
+++ b/collects/macro-debugger/view/browse-deriv.ss
@@ -2,7 +2,7 @@
 (module browse-deriv mzscheme
   (require (lib "class.ss")
            (lib "plt-match.ss")
-           (lib "unitsig.ss")
+           (lib "unit.ss")
            (lib "mred.ss" "mred")
            (lib "framework.ss" "framework")
            (lib "hierlist.ss" "hierlist"))
@@ -25,8 +25,9 @@
      ))
 
   (define deriv@
-    (unit/sig node^
+    (unit
       (import)
+      (export node^)
       
       ;; Node = (union Derivation Transformation)
 
@@ -76,8 +77,9 @@
       ))
   
   (define browser@
-    (unit/sig browser^
+    (unit
       (import node^)
+      (export browser^)
       
       (define callback-hierlist%
         (class hierarchical-list%
@@ -131,11 +133,11 @@
   
   
   (define app@
-    (compound-unit/sig
+    (compound-unit
       (import)
-      (link [NODE : node^ (deriv@)]
-            [BROWSER : browser^ (browser@ NODE)])
-      (export (open BROWSER))))
+      (link [((NODE node^)) deriv@]
+            [((BROWSER browser^)) browser@ NODE])
+      (export BROWSER)))
   
-  (define-values/invoke-unit/sig browser^ app@)
+  (define-values/invoke-unit app@ (export browser^))
   )
diff --git a/collects/macro-debugger/view/gui.ss b/collects/macro-debugger/view/gui.ss
index 76dc640b6c..884e2f67a4 100644
--- a/collects/macro-debugger/view/gui.ss
+++ b/collects/macro-debugger/view/gui.ss
@@ -1,7 +1,7 @@
 
 (module gui mzscheme
   (require (lib "class.ss")
-           (lib "unitsig.ss")
+           (lib "unit.ss")
            (lib "list.ss")
            (lib "mred.ss" "mred")
            (lib "framework.ss" "framework")
@@ -32,10 +32,11 @@
   ;; Macro Stepper
 
   (define view@
-    (unit/sig view^
+    (unit
       (import prefs^
               view-base^
-              (sb : sb:widget^))
+              (prefix sb: sb:widget^))
+      (export view^)
 
       (define macro-stepper-config%
         (class object%
@@ -592,8 +593,9 @@
   ;; Extensions
   
   (define keymap-extension@
-    (unit/sig sb:keymap^
-      (import (pre : sb:keymap^))
+    (unit
+      (import (prefix pre: sb:keymap^))
+      (export sb:keymap^)
       
       (define syntax-keymap%
         (class pre:syntax-keymap%
@@ -619,8 +621,9 @@
                             (refresh))))))))
   
   (define context-menu-extension@
-    (unit/sig sb:context-menu^
-      (import (pre : sb:context-menu^))
+    (unit
+      (import (prefix pre: sb:context-menu^))
+      (export sb:context-menu^)
       
       (define context-menu%
         (class pre:context-menu%
@@ -658,9 +661,10 @@
           (super-new)))))
   
   (define browser-extension@
-    (unit/sig sb:widget^
-      (import (pre : sb:widget^)
+    (unit
+      (import (prefix pre: sb:widget^)
               sb:keymap^)
+      (export sb:widget^)
       
       (define syntax-widget%
         (class pre:syntax-widget%
@@ -676,37 +680,35 @@
   ;; Linking
   
   (define context-menu@
-    (compound-unit/sig
+    (compound-unit
       (import)
-      (link [SB:MENU : sb:context-menu^ (sb:widget-context-menu@)]
-            [V:MENU : sb:context-menu^ (context-menu-extension@ SB:MENU)])
-      (export (open V:MENU))))
+      (link [((SB:MENU : sb:context-menu^)) sb:widget-context-menu@]
+            [((V:MENU : sb:context-menu^)) context-menu-extension@ SB:MENU])
+      (export V:MENU)))
   
   (define keymap@
-    (compound-unit/sig
+    (compound-unit
       (import [MENU : sb:context-menu^]
               [SNIP : sb:snip^])
-      (link [SB:KEYMAP : sb:keymap^ (sb:widget-keymap@ MENU SNIP)]
-            [V:KEYMAP : sb:keymap^ (keymap-extension@ SB:KEYMAP)])
-      (export (open V:KEYMAP))))
-  
+      (link [((SB:KEYMAP : sb:keymap^)) sb:widget-keymap@ MENU SNIP]
+            [((V:KEYMAP : sb:keymap^)) keymap-extension@ SB:KEYMAP])
+      (export V:KEYMAP)))
+
   (define widget@
-    (compound-unit/sig
-      (import [KEYMAP : sb:keymap^]
-              [MENU : sb:context-menu^])
-      (link [SB:WIDGET : sb:widget^ (sb:widget@ KEYMAP)]
-            [V:WIDGET : sb:widget^ (browser-extension@ SB:WIDGET KEYMAP)])
-      (export (open V:WIDGET))))
+    (compound-unit
+      (import [KEYMAP : sb:keymap^])
+      (link [((SB:WIDGET : sb:widget^)) sb:widget@ KEYMAP]
+            [((V:WIDGET : sb:widget^)) browser-extension@ SB:WIDGET KEYMAP])
+      (export V:WIDGET)))
   
   (define pre-stepper@
-    (compound-unit/sig
+    (compound-unit
       (import [BASE : view-base^])
-      (link [PREFS : prefs^ (prefs@)]
-            [MENU : sb:context-menu^ (context-menu@)]
-            [KEYMAP : sb:keymap^ (keymap@ MENU SNIP)]
-            [SNIP : sb:snip^ (sb:global-snip@)]
-            [WIDGET : sb:widget^ (widget@ KEYMAP MENU)]
-            [VIEW : view^ (view@ PREFS BASE WIDGET)])
-      (export (open VIEW))))
-  
+      (link [((PREFS : prefs^)) prefs@]
+            [((MENU : sb:context-menu^)) context-menu@]
+            [((KEYMAP : sb:keymap^)) keymap@ MENU SNIP]
+            [((SNIP : sb:snip^)) sb:global-snip@]
+            [((WIDGET : sb:widget^)) widget@ KEYMAP]
+            [((VIEW : view^)) view@ PREFS BASE WIDGET])
+      (export VIEW)))
   )
diff --git a/collects/macro-debugger/view/interfaces.ss b/collects/macro-debugger/view/interfaces.ss
index 515941126a..16698a2cba 100644
--- a/collects/macro-debugger/view/interfaces.ss
+++ b/collects/macro-debugger/view/interfaces.ss
@@ -1,6 +1,6 @@
 
 (module interfaces mzscheme
-  (require (lib "unitsig.ss"))
+  (require (lib "unit.ss"))
   (provide (all-defined))
   
   ;; Signatures
diff --git a/collects/macro-debugger/view/prefs.ss b/collects/macro-debugger/view/prefs.ss
index 4d0e2dd790..391b7419d8 100644
--- a/collects/macro-debugger/view/prefs.ss
+++ b/collects/macro-debugger/view/prefs.ss
@@ -1,6 +1,6 @@
 
 (module prefs mzscheme
-  (require (lib "unitsig.ss")
+  (require (lib "unit.ss")
            (lib "framework.ss" "framework")
            "interfaces.ss")
   (provide prefs@)
@@ -14,8 +14,9 @@
            [(newval) (preferences:set 'prop newval)]))]))
 
   (define prefs@
-    (unit/sig prefs^
+    (unit
       (import)
+      (export prefs^)
       
       (preferences:set-default 'MacroStepper:Frame:Width 700 number?)
       (preferences:set-default 'MacroStepper:Frame:Height 600 number?)
diff --git a/collects/macro-debugger/view/view.ss b/collects/macro-debugger/view/view.ss
index 8842013ae7..e45a4c8418 100644
--- a/collects/macro-debugger/view/view.ss
+++ b/collects/macro-debugger/view/view.ss
@@ -1,6 +1,6 @@
 
 (module view mzscheme
-  (require (lib "unitsig.ss")
+  (require (lib "unit.ss")
            (lib "mred.ss" "mred")
            (lib "framework.ss" "framework")
            "interfaces.ss"
@@ -8,15 +8,19 @@
   (provide (all-defined))
 
   (define view-base@
-    (unit/sig view-base^
+    (unit
       (import)
+      (export view-base^)
+
       (define base-frame%
         (frame:standard-menus-mixin (frame:basic-mixin frame%)))))
 
-  (define-values/invoke-unit/sig view^
-    (compound-unit/sig
+  (define-values/invoke-unit
+    (compound-unit
       (import)
-      (link [BASE : view-base^ (view-base@)]
-            [STEPPER : view^ (pre-stepper@ BASE)])
-      (export (open STEPPER))))
+      (link [((BASE : view-base^)) view-base@]
+            [((STEPPER : view^)) pre-stepper@ BASE])
+      (export STEPPER))
+    (import)
+    (export view^))
   )