I'm working with data readers and wondering why this works:

#inst"2016-11-09"
=> #inst"2016-11-09T00:00:00.000-00:00"

(defn read-baz [x]
  (mapv second x))

(binding [*data-readers* {'foo/baz #'user/read-baz}]
  #foo/baz{:a "a" :b "b"})

RuntimeException No reader function for tag foo/baz  clojure.lang.LispReader$CtorReader.readTagged (LispReader.java:1347)
RuntimeException Unmatched delimiter: )  clojure.lang.Util.runtimeException (Util.java:221)

The #inst data reader is “in scope” before you read any Clojure in.

(binding [*data-readers* {'foo/baz #‘user/read-baz}]
  (read-string "#foo/baz{:a \"a\" :b \”b\”}”))

Thanks @seancorfield is there any way to make sure #foo/baz is in scope in the same way?

Normally, data readers are processed by Clojure from a specific file, before it starts to read other code (that might contain tagged literals).

It will look for data_readers.clj at the root of the classpath at startup.

ah, gotcha. ok, thought that might be it but was making the assumption that binding would accomplish the same thing.

thanks!

See https://clojuredocs.org/clojure.core/*data-readers* for more detail.

Hi Clojurians, any suggestions about actively developed web-scraping library?

Not sure what you mean by “web-scraping”, but have a look at https://github.com/swannodette/enlive-tutorial/. The first part is about scraping web pages. Don't be mislead by the 2015 dates on the tutorial and Enlive itself. It's widely used and I think there are no new commits, because Christophe Grand deems it complete or good enough.

Thank you!

What's the common practice for using my own library fork as a dependency in production until the original catches up? Do I publish to clojars and remove it later, or use lein-git-deps plugin, or something else?

Well you can't remove it later, that would break repeatability.

But yes. Fork, patch, publish under your own organization and revert to upstream when you can.

Is there a way to later mark the jar as irrelevant and intentionally get low priority or hide it from search results? I don't want the repository to stay dirty and confuse others.

No and don't worry about it? This is literally why artifacts have organization qualifiers.

The key here is publishing it under your org name so folks can tell it's not the original. Some clown published their updated version of a common Java library (from Maven) under the original group ID on Clojars and now lein ancient thinks I need to update to that version. Very annoying!

> Is there a way to later mark the jar as irrelevant and intentionally get low priority or hide it from search results? I don't want the repository to stay dirty and confuse others. @yonatanel Use org.clojars.<your-username> : https://github.com/clojars/clojars-web/wiki/Groups#personal-groups

why not-empty, why not not-empty? ?

@doglooksgood functions ending in a question mark are predicates and should return a boolean value

not-empty returns the input collection if it’s not empty

see also some, for instance

@joost-diepenmaat 👍 That's make sense, thank you!

hi

Should empty keyword exist/work or is it incidental? (keyword "") => :

i think that's a bug, it shouldn't exist

@yonatanel I believe keyword rules only apply to those created by the reader, the function keyword accepts any string

is there a special significance to the lein 'dev' profile? will it be included by just running lein repl for example?

found my own answer here: https://practicalli.github.io/clojure/leiningen/profile.html

@yonatanel: http://clojure.org/guides/faq#unreadable_keywords

someone who can help me on my question on the beginners channel ?

@alexmiller: That faq list is getting meaty! I hadn't looked at it in a long while.

Is there a way to destructure a bunch of same-namespaced map keys without repeating the namespace? Perhaps aliasing the namespace just for the scope of destructuring?

@yonatanel in 1.9 you can use {:some-ns/keys [foo bar baz]} to destructure a map with keys :some-ns/foo, :some-ns/bar, and :some-ns/baz

Nice, thanks!

see the bottom of this section: http://clojure.org/reference/special_forms#_map_binding_destructuring

@bja Is there anything similar for select-keys?

is anyone aware of the timeline for euroclojure 2016 videos release?

@aaelony Someone here said two weeks a week ago

thanks, @yonatanel

just in time for Thxgiving then

@yonatanel: no (but you could build it)

@aaelony: working on it, soon

@alexmiller Can I extend the reader with something like #:my-ns[:a :b]?

No

We have discussed namespaced vectors a bit and eventually that may happen

Is there a beter alternative for learning as the brave book. I did the first two chapters and I find the exercises way to difficult for a beginner. I get more and more confused and frustated

But then it begs namespaced set syntax and that is pretty ugly looking

@roelofw: maybe Living Clojure?

@alexmiller I will take a look

Is there a way I can use apply with a java class constructor?

ie. (apply MyClass. constructor-arg-vector)

This Google Group thread more or less answers my question: https://groups.google.com/forum/#!topic/clojure/VfAobY8uWvU

I have some dependencies in a checkouts/ folder. When I run lein deps, why doesn't Leiningen see them? I get errors like Could not find artifact foo:jar:0.1.6-SNAPSHOT in clojars ()

there are a couple of things that can cause that, so I'll go through a couple that I have hit @creese

is the version number right in lein deps per whatever its labeled in the corresponding project.clj?

is the thing in the checkouts folder a symlink?

It is a symlink

and (here's the big one) did you remember to run lein install on the project youre depending on?

that one always gets me

Why do you need run lein install? I thought the whole point of checkouts was so you wouldn't have to

yeah, you do. lein checkouts is what it is.

¯\(ツ)/¯

Okay, I did that. Now it says it can't find it on the classpath.

The lib is in my .m2.

I removed the dep from my project.clj. Works now.

the reason is that usually you just put the cond and the result on the same line

(cond
    (< n 0) "negative"
    (> n 0) "positive"
    :else “zero”))

I know @cschep but when its a large clause, i like to put them on separate lines

I'm just not sure if its possible to write such an indentation spec. I end up indenting it manually which is a bit annoying, I'd like to be able to automatically format an entire file

not sure its a good idea, but i like

(cond
  (condition)
  #_=> (value)
  …)

ah right, right.

@adambros it might be a bit mysterious to people who aren't familiar with the reader macro

I find it a bit visually noisy as well

uuugh burned by (apply assoc m []) again!

every time!