[nithril]

XSLT/XPath have evolved since XSLT 1.0.

Features are now available like key (index) to greatly speedup the processing. Good XSLT implementation like Saxon definitively helps as well on the perf aspect.

When it comes to transform XML to something else, XSLT is quite handy by structuring the logic.

[sam_lowry_]

Keys were a thing in XSLT 1.x already.

XSLT 2+ was more about side effects.

I never really grokked later XSLT and XPath standards though.

XSLT 1.0 had a steep learning curve, but it was elegant in a way poetry is elegant because of extra restrictions imposed on it compared to prose. You really had to stretch your mind to do useful stuff with it. Anyone remembers Muenchian grouping? It was gorgeous.

Newer standards lost elegance and kept the ugly syntax.

No wonder they lost mindshare.

[jerf]

"Newer standards lost elegance and kept the ugly syntax."

My biggest problem with XSLT is that I've never encountered a problem that I wouldn't rather solve with an XPath library and literally any other general purpose programming language.

When XSLT was the only thing with XPath you could rely on, maybe it had an edge, but once everyone has an XPath library what's left is a very quirky and restrictive language that I really don't like. And I speak Haskell, so the critic reaching for the reply button can take a pass on the "Oh you must not like functional programming" routine... no, Haskell is included in that set of "literally any other general purpose programming language" above.

[yoz]

Serious question: would it be worth the effort to treat XSLT as a compilation target for a friendlier language, either extant or new?

There's clearly value in XSLT's near-universal support as a web-native system. It provides templating out of the box without invoking JavaScript, and there's demand for that[1]. But it still lacks decent in-browser debugging which JS has in spades.

[1] https://justinfagnani.com/2025/06/26/the-time-is-right-for-a...

[bokchoi]

I just posted this in another comment: https://github.com/Juniper/libslax/wiki/Intro

[sam_lowry_]

SLAX is great, unfortunately it was released a bit too late.

XML world is full of ugly standards and failed contenders. None remembers RelaxNG. But had reacher expressive power than XMLSchema and a human-readable syntax.

[bokchoi]

Schematron!

[jerf]

It would at least be an interesting project. If someone put the elbow grease into it it is distinctly possible that an XSLT stylesheet could be not just converted to JS (which is obviously true and just a matter of effort), but converted to something that is at least on the edge of human usable and editable, and some light refactoring away from being decent code.

[smrtinsert]

Pretty true. I created a simplified XPath layer to a stax parser back in the day and it was a break through in xml usability.

[bokchoi]

I haven't tried it yet, but I came across this alternate syntax for XSLT which is much more friendly:

https://github.com/Juniper/libslax/wiki/Intro

It looks like it was developed by Juniper and has shipped in their routers?

[amy214]

Just to add to this, we know have XXSLT which solves a lot of the original problems with XSLT.

Just to frame this people, imagine a JSON-based programming language for transforming JSON files into other JSON files and the program is also in JSON and turing complete. Now imagine it's not JSON but XML! Now any program can read it! Universal code, magic!

The idea behind XXSLT is now, we actually have a program whose job it is to specify a program. So we have a XML file which specifies a second XML file, which is the program, whose job it is to transform XML to XML. As we all know, layers of abstraction are always good, and common formats such as XML are especially good, so what we have now is the ability to generate a whole family and diverse ontology of programs, all of them XML, all of them by and for XML. Imagine the compiling with your favourite XML-based compilation chain!

[echelon]

XSLT just needs a different, non-XML serialization.

XML (the data structure) needs a non-XML serialization.

Similar to how Semantic Web's Owl has four different serializations, only one of them being the XML serialization. (eg. Owl can be represented in Functional, Turtle, Manchester, Json, and N-triples syntaxes.)

[alganet]

> XML (the data structure) needs a non-XML serialization.

That's YAML, and it is arguibly worse. Here's a sample YAML 1.2 document straight from their spec:

    %TAG !e! tag:example.com,2000:app/
    ---
    - !local foo
    - !!str bar
    - !e!tag%21 baz

Nightmare fuel. Just by looking at it, can you tell what it does?

--

Some notes:

- SemWeb also has JSON-LD serialization. It's a good compromise that fits modern tooling nicely.

- XML is still a damn good compromise between human readable and machine readable. Not perfect, but what is perfect anyway?

- HTML5 is now more complex than XHTML ever was (all sorts of historical caveats in this claim, I know, don't worry).

- Markup beauty is relative, we should accept that.

[bokchoi]

I just posted this in another comment: https://github.com/Juniper/libslax/wiki/Intro

[marcosdumay]

> XML (the data structure) needs a non-XML serialization.

KDL is a very interesting attempt, but my impression is that people are already trying to shove way too much unnecessary complexity into it.

IMO, the KDL's document transformation is not a really good example of a better XSLT, tough. I mean, it's better, but it probably can still be improved a lot.

[int_19h]

XQuery is pretty close to "XSLT with sane syntax", if that's what you mean.

But the fundamental problem here is the same: no matter what new things are added to the spec, the best you can hope for in browsers is XSLT 1.0, even though we've had XSLT 3.0 for 8 years now.

[j45]

This is very understandable, where I get left at is the remaining gap between XML and XSLTs and where JSON or another format can cover.

Trying to close the gap often ends up creating more complexity than intended, or maybe even more than XML in some hands.

It definitely would be an interesting piece.

[jimbokun]

You're looking for S-expressions.

[SkiFire13]

S-expressions only represent nested lists. You need some other convention _on top of them_ to represent other kind of data, and that's generally the hard part.

[thechao]

Can you name a non-Saxon XSLT processor? I'd really like one. Preferably, open-source.

[jraph]

- Browsers are XSLT (1.0) processors.

- Xee: https://github.com/Paligo/xee

- xrust: https://docs.rs/xrust/latest/xrust/xslt/

- XJSLT (compiles XSLT to JS): https://github.com/egh/xjslt

Xee is WIP AFAIK and I don't know the maturity of xrust and XJSLT.

[thechao]

Yeah... I posted too quickly: I want XSLT 3. The 1 & 2 specs are good first attempts, but are very difficult to use, effectively. As another poster also commented: it'd be nice if the implementation wasn't tied to XML, as well!

Also, I want a cookie & a pony.

[jraph]

I guess Xee is the most promising option then :-) But indeed not ready yet.

[badmintonbaseba]

I only know libxslt, but it's XSLT 1.0 and some of EXSLT. I don't recommend.

[dolmen]

libxslt, despites being available widely, must not be recommended. https://lwn.net/SubscriberLink/1025971/73f269ad3695186d/