Wow, thank you Simon. That was above and beyond.
I should have thought of ~a to start with. With your pointers I came up
with a less flexible solution that is sufficient to the current issue:
#lang racket/base
(require racket/format
racket/string)
(define my-keys '("bacon" "eggs" "pancakes"))
(define my-vals '("turkey" "whites" "blueberry"))
(define (make-str keys vals)
(define width (apply max (map string-length keys)))
(string-join
(for/list ([k keys]
[v vals])
(format "\t~a" (~a (~a k #:width width) v #:separator "\t")))
"\n"))
(displayln (make-str my-keys my-vals))
On Thu, Sep 9, 2021 at 4:11 PM [email protected] <[email protected]>
wrote:
> I am not really aware of a function that does this you could try digging
> into the implementation of raise-arguments-error,
> usually I roll my own implementation depending on what I really want to
> output.
> racket/format and its ~a, ~v, etc. have a lot of useful optional keyword
> arguments like #:align #:pad-string #:width etc.
>
> This isn't totally what you want, but maybe it has something that is
> useful to you.
> This or similar code is what I have used sometimes:
>
> #lang racket
>
> (define current-prefix-length (make-parameter 0))
> (define (prefixln #:prefix [prefix ""]
> #:align [align 'left]
> . message)
> (displayln (apply ~a (list* (~a prefix #:width (current-prefix-length)
> #:align align)
> message))))
>
> (define-syntax-rule (with-indent body ...)
> (parameterize ([current-prefix-length (+ (current-prefix-length) 2)])
> body ...))
>
> (define (example-func1)
> (prefixln "start of example func1")
> (with-indent
> (example-func2))
> (prefixln "end of example func1"))
>
> (define (example-func2)
> (prefixln "start of example func2")
> (prefixln "end of example func2"))
>
>
> (module+ main
>
> (displayln "Hello checkout these values:")
> (define example-values
> (hash 'foo 123
> 'this-is-a-long-key "some value"
> 'blabla #f
> "cake" "is a lie"))
>
> ;; ugly oneliner to calculate prefix width
> (current-prefix-length (+ 2 (foldl max 0 (map (compose1 string-length
> ~a) (hash-keys example-values)))))
>
> (for ([(k v) (in-hash example-values)]) ;; probably sorting or assoc
> list would make sense too...
> (prefixln #:prefix (~a k ": ") #:align 'right
> v))
>
> (current-prefix-length 0)
> (displayln "")
> (displayln "indentation through multiple nested calls:")
> (with-indent
> (example-func1)))
>
> If you use a current-prefix-string parameter instead you can create other
> interesting things like lines indented with indentation level indicators,
> etc.:
> indent0
> | indent1
> | | indent2
> | indent1
> indent0
>
> But I am getting too off-topic...
>
> Simon
>
> [email protected] schrieb am Mittwoch, 8. September 2021 um 15:41:56
> UTC+2:
>
>> raise-arguments-errors produces neatly stacked key/value pairs with
>> whitespace arranged such that values line up even when keys are of
>> different lengths. Is there an easy way to get that for something that is
>> not an error? I've been through both The Printer and the
>> raise-arguments-error sections in the Reference and can't find anything.
>>
>> For example:
>>
>> (doit "x" 1 "foo" 2 "super" 3)
>>
>> Returns the string "x 1\nfoo 2\super 3"
>>
>>
>>
>>
>> --
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