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Predicate json_object/1
Availability::- use_module(library(http/json_convert)).
Sourcejson_object(+Declaration)
Declare a JSON object. The declaration takes the same format as using in record/1 from library(record). E.g. 
?- json_object
      point(x:int, y:int, z:int=0).

The type arguments are either types as know to library(error) or functor names of other JSON objects. The constant any indicates an untyped argument. If this is a JSON term, it becomes subject to json_to_prolog/2. I.e., using the type list(any) causes the conversion to be executed on each element of the list.

If a field has a default, the default is used if the field is not specified in the JSON object. Extending the record type definition, types can be of the form (Type1|Type2). The type null means that the field may not be present.

Conversion of JSON to Prolog applies if all non-defaulted arguments can be found in the JSON object. If multiple rules match, the term with the highest arity gets preference.

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Carlo Capelli said (2013-07-15T13:33:22):0 upvotes 0 0 downvotes
Picture of user Carlo Capelli.

This is more a test of the tagging system. Jan answered a question from Wouter explaining a declaration detail, that is really useful to know.


:- use_module(library(http/json_convert)).

:- json_object coord(x:float, y:float).
:- json_object circle(center:coord/2).

test:-
  prolog_to_json(circle(coord(3.4, 5.6)), JSON_Object),
  format(user_output, '~w', JSON_Object).

Note the arity added to qualify center. With that

?- test.
json([center=json([x=3.4,y=5.6])])
true.

I've simplified Wouter's question, removing type specifications...