[erlang-questions] No JSON/MAPS interoperability in 17.0?

Pierre Fenoll <>
Sat Mar 8 14:47:33 CET 2014


Let's not forget though that most languages implementation of JSON uses
hash tables.
Before 17.0, the JSON mapping used lists; taking lookup linear time.
Maps have a lookup time of O(log n).
That's still not O(1)…


Cheers,
-- 
Pierre Fenoll



On 8 March 2014 14:42, Carsten Bormann <> wrote:

> It is true that different applications may need different mappings of the
> JSON data model into the data model of the specific application, but the
> following is not a valid reason:
>
> On 08 Mar 2014, at 13:14, Jesper Louis Andersen <
> > wrote:
>
> > And to make things worse, there are small fluctuations in the "standard"
> which make it hard to create proper support. Adding a `json` module to the
> standard library is asking for jumping into this minefield.
>
> The “standard” has been stable since RFC 4627, which was published in July
> 2006.
> Since, ECMA TC39 (the committee for changing JavaScript) has decided to
> allow top-level numbers, primitives (false, true, null), and strings; the
> IETF has reluctantly followed this change and published RFC 7159 with that
> change.
>
> Apart from the question whether one should accept top-level
> numbers/primitives/strings (and it is easy for an application to follow the
> Postel principle here: be liberal in what you accept and conservative in
> what you send), there has been no “fluctuation” in JSON.
>
> With the acceptance of UTF-8 strings (“binaries”) into the Erlang world,
> there is a straightforward mapping of JSON data into the Erlang model.
> Mapping back may require a bit more application knowledge (e.g., how do
> you encode non-JSON concepts such as atoms?), but a basic mapping can
> easily be part of the standard library, certainly easier than for ASN.1 or
> XML.
>
> Grüße, Carsten
>
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