update check-duplicates with #:default kw arg

typed-racket-lib/typed-racket/base-env/base-env.rkt

@@ -3323,10 +3323,22 @@
    (->key (-lst a) (-> b b -Boolean) #:key (-> a b) #f #:cache-keys? -Boolean #f (-lst a)))))
 (check-duplicates
  (-poly
-  (a b)
+  (a b c)
   (cl->*
-   (->optkey (-lst a) ((-> a a Univ)) #:key (-> a a) #f (-opt a))
-   (->optkey (-lst a) ((-> b b Univ)) #:key (-> a b) #f (-opt a)))))
+   (->optkey (-lst a) ((-> a a Univ))
+             #:key (-> a a) #f
+             (-opt a))
+   (->optkey (-lst a) ((-> b b Univ))
+             #:key (-> a b) #f
+             (-opt a))
+   (->optkey (-lst a) ((-> a a Univ))
+             #:key (-> a a) #f
+             #:default (-> c) #f
+             (Un a c))
+   (->optkey (-lst a) ((-> b b Univ))
+             #:key (-> a b) #f
+             #:default (-> c) #f
+             (Un a c)))))
 (remove-duplicates
  (-poly
   (a b)

typed-racket-test/unit-tests/typecheck-tests.rkt

@@ -1439,6 +1439,22 @@
         [tc-e (remf symbol? '(a b c)) (-lst (one-of/c 'a 'b 'c))]
         [tc-e (remf* symbol? '(a b c)) (-lst (one-of/c 'a 'b 'c))]
         [tc-e (check-duplicates '("a" "a" "b")) (-opt -String)]
+        [tc-e (check-duplicates '("a" "a" "b") string=?) (-opt -String)]
+        ;[tc-e ((inst check-duplicates String Number)
+        ;       '("a" "aa" "aaa")
+        ;       #:key string-length)
+        ;      (-opt -String)]
+        [tc-e ((inst check-duplicates String Any 'nope)
+               '("a" "a" "b")
+               string=?
+               #:default (λ () 'nope))
+              (Un (-val 'nope) -String)]
+        [tc-e ((inst check-duplicates String Number 'nope)
+               '("Hello" "world")
+               =
+               #:key string-length
+               #:default (λ () 'nope))
+              (Un -String (-val 'nope))]
 
         ;;Path tests
         (tc-e (path-string? "foo") -Boolean)