Use promises for current-type-names.

collects/typed-racket/private/with-types.rkt

@@ -1,6 +1,6 @@
 #lang racket/base
 
-(require racket/require
+(require racket/require racket/promise
          (for-template
           (except-in racket/base for for* with-handlers lambda λ define)
           "../base-env/prims.rkt"
@@ -79,8 +79,8 @@
                  ;; this parameter is just for printing types
                  ;; this is a parameter to avoid dependency issues
                  [current-type-names
-                  (lambda ()
-                    (append
+                  (delay
+                    (append 
                      (type-name-env-map (lambda (id ty)
                                           (cons (syntax-e id) ty)))
                      (type-alias-env-map (lambda (id ty)

collects/typed-racket/tc-setup.rkt

@@ -2,7 +2,7 @@
 
 (require (rename-in "utils/utils.rkt" [infer r:infer])
          (except-in syntax/parse id)
-         racket/pretty
+         racket/pretty racket/promise
          (private type-contract)
          (types utils convenience)
          (typecheck typechecker provide-handling tc-toplevel)
@@ -50,7 +50,7 @@
                      ;; this parameter is just for printing types
                      ;; this is a parameter to avoid dependency issues
                      [current-type-names
-                      (lambda ()
+                      (delay
                         (append
                          (type-name-env-map (lambda (id ty)
                                               (cons (syntax-e id) ty)))

collects/typed-racket/types/printer.rkt

@@ -1,6 +1,6 @@
 #lang racket/base
 
-(require racket/require racket/match unstable/sequence racket/string
+(require racket/require racket/match unstable/sequence racket/string racket/promise
          (prefix-in s: srfi/1)
          (path-up "rep/type-rep.rkt" "rep/filter-rep.rkt" "rep/object-rep.rkt"
                   "rep/rep-utils.rkt" "types/abbrev.rkt" "types/subtype.rkt"
@@ -21,7 +21,7 @@
 ;; has-name : Type -> Maybe[Symbol]
 (define (has-name? t)
   (and print-aliases
-       (for/first ([(n t*) (in-pairs (in-list ((current-type-names))))]
+       (for/first ([(n t*) (in-pairs (in-list (force (current-type-names))))]
                    #:when (and (Type? t*) (type-equal? t t*)))
          n)))
 
@@ -86,7 +86,7 @@
                 [(cons name (and t* (Union: elts)))
                  (subtype t* t)]
                 [_ #f]))
-            ((current-type-names))))
+            (force (current-type-names))))
   ;; names and the sets themselves (not the union types)
   ;; we use srfi/1 lsets as sets, to use custom type equality.
   (define candidates

collects/typed-racket/utils/tc-utils.rkt

@@ -6,7 +6,7 @@ don't depend on any other portion of the system
 |#
 
 (provide (all-defined-out) (all-from-out "disappeared-use.rkt"))
-(require "syntax-traversal.rkt" racket/dict "disappeared-use.rkt"
+(require "syntax-traversal.rkt" racket/dict "disappeared-use.rkt" racket/promise
 	 syntax/parse (for-syntax racket/base syntax/parse) racket/match)
 
 ;; a parameter representing the original location of the syntax being
@@ -151,7 +151,7 @@ don't depend on any other portion of the system
 
 ;; parameter for currently-defined type aliases
 ;; this is used only for printing type names
-(define current-type-names (make-parameter (lambda () '())))
+(define current-type-names (make-parameter (delay '())))
 
 ;; for reporting internal errors in the type checker
 (define-struct (exn:fail:tc exn:fail) ())