utils: Explicitly document the untyped submodule.

scribblings/utils.scrbl

@@ -392,10 +392,10 @@ a couple conversions.
 (lists-transpose '((a b) (1 2 3) (#t)))
 ]
 
-As of 2022-03-31, Typed Racket cannot convert the type of
-@racket[lists-transpose] to a contract.  To use @racket[lists-transpose] from
-untyped code, require it from the @racket[untyped] submodule: @racket[(require
-(submod dds/utils untyped))].
+As of 2022-04-07, Typed Racket cannot convert the type of
+@racket[lists-transpose] to a contract.  The @seclink["untyped"]{untyped
+submodule} provides a version of this function which can be used in
+untyped code.
 
 }
 
@@ -516,3 +516,32 @@ Converts 0 to @racket[#f] and 1 to @racket[#t].
 (01->boolean 0)
 (01->boolean 1)
 ]}
+
+@section[#:tag "untyped"]{Untyped code}
+
+@defmodule[(submod dds/utils untyped)]
+
+@(require (for-label (only-in racket/contract/base listof any/c)))
+
+This submodule contains some functions whose types cannot be converted to
+contracts by Typed Racket.
+
+@(define utils-evaluator/untyped
+  (parameterize ([sandbox-output 'string]
+  		 [sandbox-error-output 'string]
+		 [sandbox-memory-limit 50])
+   (make-evaluator 'racket #:requires '((submod "utils.rkt" untyped)))))
+
+@defproc[(lists-transpose [lists (listof (listof any/c))])
+			  (listof (listof any/c))]{
+
+Transposes a list of lists.  The length of the resulting list is the length of
+the shortest list in @racket[lists].
+
+This function is essentially @racket[in-parallel], wrapped in
+a couple conversions.
+
+@examples[#:eval utils-evaluator/untyped
+(lists-transpose '((a b) (1 2)))
+(lists-transpose '((a b) (1 2 3) (#t)))
+]}