Re: Simple list of key-value pairs?

[Zelphir Kaltstahl <zelphirkaltstahl@posteo.de>]

Hi!

I think I would give the pairs together in an association list and use alist
procedures to work with that. Then you could also only have one backtick, at the
start of the alist:

~~~~
`((attr . ,val)
  (attr . ,val)
  (attr . ,val)
  (attr . ,val))
~~~~

Looks simpler to me and fewer special characters.

Regards,
Zelphir

On 7/8/21 4:37 PM, Hartmut Goebel wrote:
> Hi,
>
> I'm seeking advice for passing simple key-value pairs to a function and
> generate a string out of these values. Neither the names not the number of
> keys is known in advance.
>
> Background: This shall become a generic function for generating URI
> query-strings.
>
> My current approach please see below. Anyhow, I'm wondering whether the quite
> and quasiquote can be replaced by something simpler.
>
> (use-modules (ice-9 match))
>
> (define limit 100)
> (define evaluation "linux")
>
> (define* (api-uri base path #:rest query)
>
>   (define (build-query-string kv)
>     (match kv
>        ((name #f) #f)
>        ((name (? string? value))
>         (string-append name "=" value))  ; FIXME: encode
>        ((name (? number? value))
>         (string-append name "=" (number->string value)))))
>
>
>   (format #t "~%Query: ~a~%~%" query)
>   (let ((query-string
>      (when query
>        (string-join
>         (filter (lambda (x) x) (map build-query-string query))
>         "&"))))
>     (format #t "~%Query-String: ~a~%~%" query-string)
>     ;; todo: build uri incl. query-string
>   ))
>
>
> (api-uri "https://ci.guix.gnu.org" "/api/jobs")
> (api-uri "https://ci.guix.gnu.org" "/api/jobs"
>      `("nr" ,limit)
>      `("evaluation" ,evaluation)
>      `("system" ,#f))
>
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