Comment by duncanawoods | Hacker News Reader

Comment by duncanawoods | Hacker News Reader

I believe the fundamental pain of xslt was... that it was an FP language. When teaching XSLT, the difference between those who said "its elegant" vs. those who said "its pain" - is whether the individual could grok FP.

Angle bracket overload, verbosity of end tags, library support, poor whitespace handling, namespace pain were all obstacles too but it was FP that made standard problems feel like math proofs and for developers to take days to solve problems they could code in minutes in their usual OO/imperative language.

When I see the pain FP causes in the real world I'm never quite sure whether its nature or nurture. I currently believe its a bit of both but the nature part will always hobble FP adoption - if you find algebraic proofs elegant, you will like FP. If you are "normal" and proving a theorem fills you with terror then you would prefer your programming language to resemble a a cookery recipe.

I also believe all templating, especially for code-generation, requires three brains - understanding the input data-structure, understanding the processing of the template and understanding the behaviour of the output. Each keystroke in your templating language has to be carried out with full understanding of all three parts. Its too much for those if they still struggle with more common two brain programming problems.

> I believe the fundamental pain of xslt was... that it was an FP language.

From the post I linked in my other comment

> Oh, and the fact that you can call a language functional when it lacks first class functions makes my eye twitch. I'm tempted to upload a video of my eye twitching just to prove it.

That seems like the difference between object-based (early VB) and object-oriented.

XSLT is referentially transparent (no setf for you) but withholds from you most of the goodies that people take for granted in functional or logic programming.

You could see it was written by well-intentioned FP enthusiasts. IMO the best alternative at the time when XSLT was developed would have been XMLPerl - embedding an imperative language in something that deals with the XML-specific parts appropriately. But Perl was never enterprisey enough, and XmlPerl died a painless death.

> I believe the fundamental pain of xslt was... that it was an FP language. When teaching XSLT, the difference between those who said "its elegant" vs. those who said "its pain" - is whether the individual could grok FP.

I've heard this before, but I don't find it to be true for me anyway. XSLT has never really clicked for me, while I really like Clojure and OCaml. Maybe the FP is part of the problem, but I also think XSLT is just a particularly obtuse functional language. XSLT makes it hard to figure out how to express even moderately complex algorithms (e.g. a map-reduce function is literally just that in Scheme, while I'm not sure I could write one correctly without several tries in XSLT) — and once you do express them, they're buried under an impenetrable mound of XML boilerplate that makes them hard to maintain or understand later.

That was my experience working on a huge XML/XSLT project recently. Agreed.

The FP bit was fine. It's wrapping the functional program in the most obtuse syntax known to man (apart from C++ template syntax which at least has the get-out clause that it was never meant to be a turing complete programming language that programmers took seriously and used to get real work done) that's the problem.

Full disclosure: My last exposure to XSLT was a long, long time ago and I've been carefully avoiding it ever since.

It's more of a declarative language. Like Prolog.

I dont think its really either a functional programming language (no first class functions), or a logic programming language like Prolog (not implemented via unification). It is a declarative language that is in an independent category.

I really enjoyed proving theorems for analysis - I have an undergrad degree in mathematics - but not so much algebraic proofs. Where does that put me? :)

In any case, we know that algebraists who program also use Maple, Magma, Mathematica, R, and Sage, or even straight Python, C, etc. FP languages are a minority even in the professional mathematics world.

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