Re: help with guile-json inconsistencies

[swedebugia <swedebugia@riseup.net>]

On 2018-12-10 08:27, Aleix Conchillo Flaqué wrote:
> On Sun, Dec 9, 2018 at 10:33 PM Aleix Conchillo Flaqué
> <aconchillo@gmail.com> wrote:
>>
>> On Sun, Dec 9, 2018 at 2:56 AM Aleix Conchillo Flaqué
>> <aconchillo@gmail.com> wrote:
>>>
>>> Hi guilers,
>>>
>>> a new guile-json issue came to me recently:
>>>
>>> https://github.com/aconchillo/guile-json/issues/22
>>>
>>> I don't really have a solution yet on how to solve this, so I would
>>> love some advice. The issue is that one can do:
>>>
>>>    (scm->json '(1 2 3)) which returns [1,2,3]
>>>
>>> however, if you do:
>>>
>>>    (scm->json '((1 2 3)) it returns {"1":[2,3]} but one would probably
>>> expect [[1,2,3]]
>>>    (scm->json '((1 2 3) (4 5 6)) it returns {"1":[2,3], "4":[5,6]} but
>>> one would probably expect [[1,2,3], [4,5,6]]
>>>
>>> I guess the first question is, does everyone else feel the same way
>>> about the return value?
>>>
>>> The problem is that there's a function that checks if something is an
>>> alist by basically checking if it's a pair? recursively and if so, it
>>> builds a json object.
>>>
>>
>> Just to clarify, the problem is not when parsing JSON to scheme data
>> types, this is fine as internally guile-json uses hash tables and
>> lists properly.
>>
>> The problem is with going from scheme to json. For convenience,
>> guile-json doesn't expect a hash table from the user, instead it tries
>> to guess what's a list and what's an alist however, that seems not
>> really distinguishable. That is, there's no way to tell if '((1 2)) is
>> [[1, 2]] or {"1" : [2]} or  {"1" : "2"}.
>>
>> I guess going back to a macro approach for these type of cases would
>> help (even though I had the same problem with my initial macro).
>>
> 
> Answering myself again. Re-adding the macro fixes the issue, but with
> a breaking change.
> 
> (scm->json '(1 2 3))
>        -> [1,2,3]
> 
> (scm->json '((1 2 3) (4 5 6)))
>        -> [[1,2,3],[4,5,6]]
> 
> (scm->json (json (object ("key1" "value1") ("key2" (1 2 3)))))
>        -> {"key2":[1,2,3],"key1":"value1"}
> 
> (scm->json `((1 2 3) ,(json (object (4 5)))))
>        -> [[1,2,3],{"4":5}]
> 
> So, the (json) macro is only needed to specify JSON objects, otherwise
> you can use scheme types directly (and lists are always arrays).

Nice to hear you solved it :)

Both Guix and guile-wikidata use guile-json but only from json->scm and 
that works flawlessly. Thanks for creating and maintaining this lib.

-- 
Cheers
Swedebugia