Scheme - Convert boolean to string?

Question

I am having a tough time trying to find an example of converting a boolean to a string in Scheme.

My problem is that I use string-append to add a few strings together as part of a debugger. My fix was to check if equal to #t, then append "#t", and like-wise with #f.

My question- is there a method in Scheme to convert bools to strings? Something like bool->string?

My Code:

(if (equal? val #t)
                       (string-append (number->string count) ":" "#t")    
                       (string-append (number->string count) ":" "#f")    )

soegaard · Accepted Answer · 2012-11-09 19:04:17Z

4

Use format:

> (format "~a" #t)
"#t"
> (format "~a" #f)
"#f"

answered Nov 9, 2012 at 19:04

soegaard

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2 Comments

Asumu Takikawa Over a year ago

In the latest version of Racket (5.3.1), you can also use the ~a function: (~a #t). You'll need to (require racket/format).

C. K. Young Over a year ago

Very nice, I forgot that format already does the implicit string port thing.

C. K. Young · Accepted Answer · 2012-11-09 18:29:03Z

4

This might help you:

(define (->string x)
  (call-with-output-string
   (lambda (out)
     (display x out))))

This writes out any object to a string port and returns its string value.

> (->string #t)
"#t"
> (->string #f)
"#f"

answered Nov 9, 2012 at 18:29

C. K. Young

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Comments

alinsoar · Accepted Answer · 2012-11-09 18:35:28Z

3

(define (boolean-to-string val) (if val "#t" "#f"))

(string-append (number->string count) ":" (boolean-to-string val))

answered Nov 9, 2012 at 18:35

alinsoar

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