Re: [Json] Nudging the English-language vs. formalisms discussion forward

Bjoern Hoehrmann <> Wed, 19 February 2014 22:57 UTC

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From: Bjoern Hoehrmann <>
To: Phillip Hallam-Baker <>
Date: Wed, 19 Feb 2014 23:57:19 +0100
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Cc: Barry Leiba <>, JSON WG <>
Subject: Re: [Json] Nudging the English-language vs. formalisms discussion forward
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* Phillip Hallam-Baker wrote:
>It is obviously possible to create an ABNF description of JSON (call this X)
>It is thus possible to create an ABNF description of a Web Service message
>as an ABNF description. (Call this Y)
>What I think is going to be very hard is proving that a given Y is a subset
>of X. And if we do that we risk having specifications that are not actually
>JSON but only JSON-like.
>Unless that is we start off with a tool that generates Y in a fashion that
>makes it easy to check that it is a subset of X.

The main problem with using ABNF for Y is that it is tedious to write it
out properly, they want to write "example" and not a complex grammar for
all possible "\uXXXX" escape sequences. This is a common problem with
URI scheme specifications, for instance. Beyond that it is not really a
problem for a tool to compare two grammars as would be needed here (the
problem is undecidable in the most general case, but even then a regular
approximation could be used; I will probably release a tool later this
year that does something like this).
Björn Höhrmann · ·
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