binary-experiments VS easyjevko.js

Yes, S-expressions come in many flavors, some more minimal than others, some binary. They are all truly wonderful.

The most wonderful to me are the simplest ones, and Jevko grows out of the same spirit as them.

However, it does not attempt to be a new flavor of S-expressions and diverges in ways which to me are worth looking at. I hope it can appeal and be useful not only to minimalist syntax enthusiasts.

BTW Some time ago I've been also experimenting with binary versions of Jevko, certainly with inspiration from both netstrings and Rivest's csexps:

https://github.com/jevko/binary-experiments#asttolengthprefi...

Since then I had some more ideas which I hope to get around to implementing at some point.

Short answer: in https://github.com/jevko/easyjevko.js a thing like [ my text ] is converted to a JS string " my text " -- all whitespace is preserved.

Responding to some points I left off here https://news.ycombinator.com/item?id=33336789

I guess the main one is this:

> If your audience is people like me, I think it would probably be worthwhile for you to spend some time up front describing the intended semantics of a data model, as I've attempted above, rather than leaving people to infer it from the grammar. (Maybe OCaml is not a good way to explain it, though.) You might also want to specify that leading and trailing whitespace in prefixes is not significant, though it is in the suffix ("body"); this would enable people to format their name-value pairs readably without corrupting the data. As far as I can tell, this addendum wouldn't interfere with any of your existing uses for Jevko, though in some cases it would simplify their implementations.

You're right, things should be explained more clearly (TODO). Especially the exact role of Jevko and treatment of whitespace. I'll try to improve that.

Here is a sketch of an explanation.

Plain Jevko is meant to be a low-level syntactic layer.

It takes care of turning a unicode sequence into a tree.

On this level, all whitespace is preserved in the tree.

To represent key-value pairs and other data, you most likely want another layer above Jevko -- this would be a Jevko-based format, such as queryjevko (somewhat explained below) or, a very similar one, easyjevko, implemented and very lightly documented here: https://github.com/jevko/easyjevko.js

Or you could have a markup format, such as https://github.com/jevko/markup-experiments#asttoxml5

This format layer defines certain restrictions which may make a subset of Jevkos invalid in it.

It also specifies how to interpret the valid Jevkos. This includes the treatment of whitespace, e.g. that a leading or trailing whitespace in prefixes is insignificant, but conditionally significant in suffixes, etc.

Different formats will define different restrictions and interpretations.

For example:

# queryjevko

queryjevko is a format which uses (a variant of) Jevko as a syntax. Only a subset of Jevko is valid queryjevko.

> I think this is a more useful level of abstraction, and it's more or less the level used by, for example, queryjevko.js's jevkoToJs, although that erroneously uses () instead of [].

The `()` are used on purpose -- queryjevko is meant to be used in URL query strings and be readable. If square brackets were used, things like JS' encodeURIComponent would escape them, making the string unreadable. Using `()` solves that. "~" is used instead of "`" for the same reason. So technically we are dealing not with a spec-compliant Jevko, but a trivial variant of it. Maybe I should write a meta-spec which allows one to pick the three special characters before instantiating itself into a spec. Anyway the parser implementation is configurable in that regard, so I simply configure it to use "~()" instead of "`[]".

> (Also, contrary to your assertion above that this is an example of "leaving [Jevko's data model] as-is", it forgets the order of the name-value pairs as well as I guess all but one of any duplicate set of fields with the same name and also the possibility that there could be both fields and a body.)

I meant [whitespace] rather than [Jevko's data model].

Again, queryjevko is a format which uses Jevko as an underlying syntax. It specifies how syntax trees are converted to JS values, by restricting the range of valid Jevkos. It also specifies conversion in the opposite direction, likewise placing restrictions on JS values that can be safely converted to queryjevko.

The order of name-value pairs happens to get preserved (because of the way JS works), but that's not necessarily relevant. If I were to write a cross-language spec for queryjevko, I'd probably specify that this shouldn't be relied upon.

Duplicate fields and Jevkos with both fields and a non-whitespace body will produce an error when converting Jevko->JS.

I hope this clarifies things somewhat.

Lastly, I'll respond to this for completeness:

> (By the way, if you want to attribute your JSON example for copyright reasons, you need to attribute it to its author or authors, not to the Wikipedia, which is just the site they posted it on.)

According to this:

https://en.wikipedia.org/wiki/Wikipedia:Reusing_Wikipedia_co...

there are 3 options, one of them being what I did, which is to include a link.

I think that's all.

Have a good one!