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2020-04-01

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#off-topic
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2020-04-01
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Jorin06:04:53

just fyi, there is a new #observability channel, for monitoring, logging, traces, alerting and higher level observability discussions :)

👍 12
dpsutton13:04:25

core.match lists a paper which mentions an optimizing compiler for a backtracking automata based matching solution. I could never find a copy of the referenced paper except the ACM archives are free to use now so its finally online for free if anyone is interested. https://dl.acm.org/doi/abs/10.1145/507635.507641

😯 4
dpsutton13:04:16

The tradeoff is one of code size versus run-time speed. Since core.match can throw some methodsize too large errors I wonder if this might be useful

souenzzo19:04:17

How do HTML relates with XML? HTML is a "superset" of XML? There is a subset of HTML that is XML, and all HTML features are accessible from this subset? Context: I'm planning to do a SSR library in clojure and thinking if use clojure.data.xml will be a powerful choice

Alex Miller (Clojure team)19:04:24

they are both markup languages but in general you should not expect to be able to parse html with an xml lib

kenj19:04:09

I thought the relationship was that XML and HTML had a common ancestor of SGML, but diverge from there

manutter5119:04:49

I seem to remember there being a variant called XHTML that was supposed to be XML-compliant HTML, but I don’t think it ever went anywhere.

souenzzo19:04:56

I think that the options are: 

(mylib/render ctx data) 
;; 1 => "<html>string</html>" ;; bad :(
;; 2 => [:html "hiccup-like"] ;; meh
;; 3 => #clojure.data.xml.Element{:tag :html :content "will be useful?"} ;; ??
;; 4 => #object["something like j2html representation"]
;; 5 - comments

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souenzzo19:04:50

Looking for https://developer.mozilla.org/en-US/docs/Glossary/XHTML Should be possible (and useful) to write a XHTML =xml/parse=> clojure.data.xml =custom-emit=> HTML

souenzzo19:04:21

I will use XHTML for now and maybe a custom-emit

manutter5119:04:50

Any reason why you don’t like hiccup syntax? To me it seems a lot more succinct.

souenzzo19:04:41

hiccup is nice to write/type, but i don't think that it's a good programmatic representation

manutter5119:04:15

You mean like it lacks something? Or it’s just too easy? 🙂

hiredman19:04:59

if you are manipulating it (creating it, but taking it and changing it) you constantly have to be checking if the second thing in a vector is a map or not

manutter5119:04:36

True. Would XHTML be better for that?

hiredman19:04:56

even though it is represented as data, it is a data format that is geared towards humans reading and writing it

hiredman19:04:23

it depends, xhtml is a serialization format, and you won't be directly manipulating that

hiredman19:04:36

you will be manipulating some data representation

hiredman19:04:54

the map representation clojure.data.xml uses is pretty good

hiredman19:04:19

(instaparse has a switch to do hiccup or map style parse trees)

manutter5119:04:25

I’m asking mostly out of idle curiosity, I don’t have a stake one way or another, but I’ve always found hiccup the easiest HTML-adjacent syntax to work with, so I’m surprised and interested in hearing about situations where it is arguably less than ideal.

hiredman19:04:28

it works very well if you are sort of top down building a page from fragments, it works worse if you then take that page and want to change some nested thing it

👆 4
Prakash19:04:39

there is also hickory that converts between hiccup style and data.xml style . I have used it for small things in past for editing html

manutter5119:04:11

Ok, so working with {:tag :div :attrs {:foo 1}} kind of stuff as opposed to [:div {:foo 1}]

Alex Miller (Clojure team)19:04:25

the biggest downside to programmatic use of hiccup is probably that it's at least partially positional

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manutter5119:04:26

if I’m remembering data.xml style right

lilactown19:04:44

hiccup is a PITA to work with programmatically

Alex Miller (Clojure team)19:04:13

positional stuff tends to be more compact and easier for people (b/c it's implicit) but harder for programs (b/c it's implicit) - usually maps are better there

Alex Miller (Clojure team)19:04:39

(spec 2 has a map syntax too)

👏 4
souenzzo20:04:48

With a poor benchmark, hiccup "emit" is 2x faster then data.xml

phronmophobic20:04:29

i thought much of the programmatic pain was alleviated by first normalizing any hiccup data before manipulating it?

manutter5120:04:40

I wrote a simple function that takes a vector of args and breaks it into opts and children based on whether or not the first value was a map. That made it pretty easy for me to work with hiccup for the use cases I was concerned with.

souenzzo21:04:46

(let [normalize-hiccup (fn normalize-hiccup [[tag & [attrs :as vs] :as element]]
                         (let [has-attrs? (map? attrs)
                               v {:tag      tag
                                  :attrs    (when has-attrs?
                                              attrs)
                                  :children (map normalize-hiccup (if has-attrs?
                                                                    (rest vs)
                                                                    vs))}]
                           (reify
                             ISeq
                             (first [this]
                               tag)
                             ILookup
                             (valAt [this key]
                               (key v))
                             (valAt [this key not-found]
                               (key v not-found))
                             Indexed
                             (nth [this i]
                               (nth element i))
                             (nth [this i not-found]
                               (nth element i not-found)))))
      hiccup (normalize-hiccup [:div {:foo 42}
                                [:div {}]])]
  {:as-hiccup (nth hiccup 1)
   :as-map    (:attrs hiccup)})
Just for fun

Kelsey Sorrels21:04:37

Can you license this? I want to use it in a project I'm working on.

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manutter5120:04:52

though that was more for generating hiccup than manipulating it, now I think of it.

manutter5120:04:45

but it seems like it wouldn’t be too hard to build on that to convert hiccup to data.xml-ish maps.