CODEWITHSUNDEEP
formattingschemeracketdouble-quotesquotation-marks
GDP2
GDP2

Reputation: 2018

Print raw control characters while preserving string delimiters in output (Racket)

I have a list in Racket like so:

'(some-symbol
  "some\ntext\ngoes in\nhere")

I want to print it out such that control characters like \n are translated to their actual values, in this case a linefeed. However, I also want the quotation marks of the string (i.e., the delimiters) to be preserved in the output a la write or print. The display function already does the first part of what I want, but it strips out quotation marks that are not escaped like \". E.g.:

racket@> (displayln '(some-symbol "some\ntext\ngoes in\nhere")) ;; I want the linefeeds as produced here
(some-symbol some
text
goes in
here)
racket@> (println '(some-symbol "some\ntext\ngoes in\nhere")) ;; But I also want the quotation marks as preserved here
'(some-symbol "some\ntext\ngoes in\nhere")
racket@>

Is there some way to get this sort of output effect in Racket without escaping string delimiters like \"? Also, I do not want the ' character, which precedes the list, in the output.

Upvotes: 1

Views: 187

Answers (1)

John Clements
John Clements

Reputation: 17203

It's not clear exactly what you want, so let's put a straw man out there for you to bash around:

#lang racket

(require rackunit)

;; find every string in an s-expression, add quotes to it:
(define (add-quotes s)
  (cond [(list? s)
         (map add-quotes s)]
        [(string? s)
         (string-append "\"" s "\"")]
        [else s]))

(check-equal? (add-quotes '((a b "cde") (("g") f)))
              '((a b "\"cde\"") (("\"g\"") f)))

;; display s with quotes around strings:
(define (funny-display s)
  (display (add-quotes s)))

Not what you wanted?

Upvotes: 1

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