Add a mode argument to pretty-format.

... which controls whether it uses `print`, `write` or `display`.

Obsoletes most of `unstable/pretty`.

pkgs/racket-doc/scribblings/reference/pretty-print.scrbl

@@ -54,14 +54,21 @@ Same as @racket[pretty-print], but @racket[v] is printed like
 @racket[display] instead of like @racket[print].}
 
 
-@defproc[(pretty-format [v any/c] [columns exact-nonnegative-integer? (pretty-print-columns)])
+@defproc[(pretty-format [v any/c] [columns exact-nonnegative-integer? (pretty-print-columns)]
+                        [#:mode mode (or/c 'print 'write 'display) 'print])
          string?]{
 
 Like @racket[pretty-print], except that it returns a string containing
 the pretty-printed value, rather than sending the output to a port.
 
 The optional argument @racket[columns] argument is used to
-parameterize @racket[pretty-print-columns].}
+parameterize @racket[pretty-print-columns].
+
+The keyword argument @racket[mode] controls whether printing is done like
+either @racket[pretty-print] (the default), @racket[pretty-write] or
+@racket[pretty-display].
+
+@history[#:changed "6.2.900.15" @elem{Added a @racket[mode] argument.}]}
 
 
 @defproc[(pretty-print-handler [v any/c]) void?]{

pkgs/racket-test-core/tests/racket/pretty.rktl

@@ -425,7 +425,35 @@
                           '(1 2 3 4 5)))])
       (try-print pretty-print val 10 "(list\n (DUO\n  '(a\n    b\n    c\n    d\n    e)\n  '(1\n    2\n    3\n    4\n    5)))\n")
       (try-print pretty-write val 10 "((DUO\n  (a\n   b\n   c\n   d\n   e)\n  (1\n   2\n   3\n   4\n   5)))\n")
-      (try-print pretty-display val 10 "((DUO\n  (a\n   b\n   c\n   d\n   e)\n  (1\n   2\n   3\n   4\n   5)))\n"))))
+      (try-print pretty-display val 10 "((DUO\n  (a\n   b\n   c\n   d\n   e)\n  (1\n   2\n   3\n   4\n   5)))\n")))
+
+  (test "(DUO 1 2)"
+        pretty-format (duo 1 2) 40 #:mode 'print)
+  (test "(DUO 1 2)"
+        pretty-format (duo 1 2) 40 #:mode 'write)
+  (test "(DUO 1 2)"
+        pretty-format (duo 1 2) 40 #:mode 'display)
+
+  (test "(DUO \"a\" 'b)"
+        pretty-format (duo "a" 'b) #:mode 'print 40)
+  (test "(DUO \"a\" b)"
+        pretty-format (duo "a" 'b) #:mode 'write 40)
+  (test "(DUO a b)"
+        pretty-format (duo "a" 'b) #:mode 'display 40)
+
+  (test "(DUO\n \"abcdefghijklmno\"\n 'b)"
+        pretty-format (duo "abcdefghijklmno" 'b) 20 #:mode 'print)
+  (test "(DUO\n \"abcdefghijklmno\"\n b)"
+        pretty-format (duo "abcdefghijklmno" 'b) 20 #:mode 'write)
+  (test "(DUO\n abcdefghijklmno\n b)"
+        pretty-format (duo "abcdefghijklmno" 'b) 20 #:mode 'display)
+
+  (test "(list\n (DUO\n  \"abcdefghijklmno\"\n  'b))"
+        pretty-format (list (duo "abcdefghijklmno" 'b)) 20 #:mode 'print)
+  (test "((DUO\n  \"abcdefghijklmno\"\n  b))"
+        pretty-format (list (duo "abcdefghijklmno" 'b)) 20 #:mode 'write)
+  (test "((DUO\n  abcdefghijklmno\n  b))"
+        pretty-format (list (duo "abcdefghijklmno" 'b)) 20 #:mode 'display))
 
 ;; ----------------------------------------
 

racket/collects/racket/pretty.rkt

@@ -1622,17 +1622,19 @@
 			 ;; Print as a fraction.
 			 (number->string x)))))))]))
   
-  (define pretty-format
+  (define (pretty-format t [w (pretty-print-columns)] #:mode [mode 'print])
-    (case-lambda
-      [(t) (pretty-format t (pretty-print-columns))]
-      [(t w)
     (parameterize ([pretty-print-columns w])
       (let ([op (open-output-string)])
-           (pretty-print t op)
+        ((case mode
+           [(print)   pretty-print]
+           [(write)   pretty-write]
+           [(display) pretty-display]
+           [else (raise-argument-error 'pretty-format "(or/c 'print 'write display)" mode)])
+         t op)
         (let ([s (get-output-string op)])
           (if (eq? w 'infinity)
               s
-                 (substring s 0 (- (string-length s) 1))))))]))
+              (substring s 0 (- (string-length s) 1)))))))
 
   
   )