box

compile.rkt

@@ -159,7 +159,7 @@
                           `(,(make-AssignImmediateStatement 
                               target
                               (make-EnvLexicalReference (LocalAddress-depth lexical-pos)
-                                                        #f)))))]
+                                                        (LocalAddress-unbox? lexical-pos))))))]
       [(PrefixAddress? lexical-pos)
        (end-with-linkage linkage
                          cenv

lexical-env.rkt

@@ -7,6 +7,7 @@
 (provide find-variable 
          extend-lexical-environment
          extend-lexical-environment/names
+         extend-lexical-environment/boxed-names
          extend-lexical-environment/placeholders
          collect-lexical-references
          lexical-references->compile-time-environment)
@@ -39,7 +40,14 @@
                    [(symbol? elt)
                     (cond
                       [(eq? elt name)
-                       (make-LocalAddress depth)]
+                       (make-LocalAddress depth #f)]
+                      [else
+                       (loop (rest cenv) (add1 depth))])]
+
+                   [(box? elt)
+                    (cond
+                      [(eq? (unbox elt) name)
+                       (make-LocalAddress depth #t)]
                       [else
                        (loop (rest cenv) (add1 depth))])]
                    
@@ -73,6 +81,11 @@
   (append names cenv))
 
 
+(: extend-lexical-environment/boxed-names (CompileTimeEnvironment (Listof Symbol) -> CompileTimeEnvironment))
+(define (extend-lexical-environment/boxed-names cenv names)
+  (append (map (inst box Symbol) names) cenv))
+
+
 (: extend-lexical-environment/placeholders
    (CompileTimeEnvironment Natural -> CompileTimeEnvironment))
 ;; Add placeholders to the lexical environment (This represents what happens during procedure application.)
@@ -102,7 +115,7 @@
                      [(LocalAddress? addr)
                       (set-insert! lexical-references
                                    (make-EnvLexicalReference (LocalAddress-depth addr)
-                                                             #f))
+                                                             (LocalAddress-unbox? addr)))
                       (loop (rest addresses))]
                      [(PrefixAddress? addr)
                       (set-insert! prefix-references

lexical-structs.rkt

@@ -11,18 +11,12 @@
 (define-struct: Prefix ([names : (Listof Symbol)])
   #:transparent)
 
-#;(define-struct: FunctionExtension ([names : (Listof Symbol)])
-  #:transparent)
 
-#;(define-struct: LocalExtension ([names : (Listof Symbol)])
-  #:transparent)
-
-#;(define-struct: TemporaryExtension ([n : Natural])
-  #:transparent)
 
 
 (define-type CompileTimeEnvironmentEntry (U Prefix ;; a prefix
                                             Symbol
+                                            (Boxof Symbol) ;; A boxed local
                                             False
                                             #;FunctionExtension
                                             #;LocalExtension
@@ -35,7 +29,8 @@
 
 ;; A lexical address is a reference to an value in the environment stack.
 (define-type LexicalAddress (U LocalAddress PrefixAddress))
-(define-struct: LocalAddress ([depth : Natural])
+(define-struct: LocalAddress ([depth : Natural]
+                              [unbox? : Boolean])
   #:transparent)
 (define-struct: PrefixAddress ([depth : Natural]
                                [pos : Natural]