@danielsz: you are hitting https://github.com/clojars/clojars-web/issues/514 - I'll deploy the fix for that tonight

the workaround is to rm -rf ~/.m2/repository/org/danielsz/system/0.3.0-SNAPSHOT

@tcrawley: Thank you!

For developing a publically available REST API, what tools are most often used? I assume liberator is still favored.

@danielsz: that issue is now fixed in production, sorry it tripped you up

@tcrawley no problem at all, thank you so much for the quick response. Big relief :-)

Can you extend a multimethod by creating an alias for an existing dispatch key?

@jindrichm: That's what :hierarchy option in multimethods is for. Also allows to add/remove "aliases" during runtime.

@rauh: That only works when the dispatch value can be derived, right? Moreover, you cannot extend third-party multimethod.

@jindrichm: 2x correct . You probably could mess with get-method and then dynamically add it.

any multimethod definition that can only return a fixed set of values is broken by design, IMHO -- not that this would help you, though

@schaueho: What do you mean by returning a fixed set of values?

e.g. if the dispatch method would only ever return :a, 😛 or :c, regardless of the dispatch value

maybe I misunderstand the problem you're trying to solve

That's not the problem I want to solve. There's a third-party multimethod dispatching on strings, for which I want to reuse implementation for a specific dispatch value.

@rauh: Thanks, using get-method works (albeit it's a bit ugly).

Is there any way to remove a previously extended type from a clojure protocol ?

I thought I could do it by changing the implementation of the function to identity, but of course that would still catch the interface

Perhaps clearer: In an external namespace a protocol function is defined for clojure.lang.Associative, which will handle maps, vectors and map entries. However, I only want it to handle Maps (IPersistentMap ?)

So I need to retract the extend-type for Associative

And extend-type for IPersistentMap

this is really weird. I'm getting the same compiler error no matter what is in a file

CompilerException java.lang.IllegalArgumentException: Parameter declaration missing, compiling:([REDACTED].clj:12:1)

every time

never mind

I had a duplicate file with the same namespace in my test sources

weird

How can I archive this (nth (:children (nth (:children (nth menu-h 0)) 1)) 1) with a clojure function, to process arbitrary depths?

archive?

You meant "achieve"?

maybe you want get-in

> (get-in {:x [{:y 3}]} [:x 0 :y])
3

Anyone here tried using GravityLabs Goose (https://github.com/GravityLabs/goose) with Clojure? There used to be some ports and/or wrappers, but they've all gone unmaintained. If not, got a Clojure alternative to Goose for content extraction?

@danielgrosse: what @rm said get-in, or even with threading macro: (-> menu-h (nth 0) :children (nth 1) :children (nth 1)). Or do you mean you want to somehow automate the construction of that "path"?

Question: I've been happily using transit-cljs for json+transit parsing, so I'm looking at transit-clj for JSON parsing on the backend. I've worked through the transit-clj readme and can now convert a JSON string to Clojure data, viz.: (transit/read (transit/reader (ByteArrayInputStream. (.getBytes "{\"name\":\"Donald\",\"age\":19}")) :json)) I can certainly do this. But because it just seems more baroque than the ClojureScript version, I wanted to confirm that this is indeed how I ought to be parsing JSON with Transit in Clojure. Specifically, if I have a file containing thousands of lines, each containing valid JSON ("line-delimited JSON"), that I ought to be converting each line's string to a byte array, then a ByteArrayInputStream, then a transit reader, before invoking transit/read

@fasiha @rm Thanks for the advises. I want to build the command by a given vector [0 1 3] where each number is the position in the structure.

@danielgrosse: try this: (get-in MY-MAP (flatten (map #(vector % :children) [0 1 3]))), replace MY-MAP with your actual map, and [0 1 3] with your path. To see how this works:

cljs.user=> (flatten (map #(vector % :children) [0 1 3]))
(0 :children 1 :children 3 :children)

(You could build that path vector many ways, e.g., instead of flatten and map, you could probably use into)

@fasiha: thank you very much. This is genious

@fasiha: @danielgrosse (mapcat #(vector % :children) [0 1 3])

Another one would be (interleave [..] (repeat :children))

When I want to follow a path through a nested map, how can I gather information on each object into a new map?

@danielgrosse: You're probably going to end up using clojure.walk, or something like spectre (https://github.com/nathanmarz/specter).

I’m trying to implement a protocol that is in a different ns using extend, but it isn’t working for me. I might be missing something obvious. E.g:

(ns prots.blues
  (:require [prots.protocols :as p]))

(deftype BluesPlayer [fname lname]
  p/Speaks
  (speak [this] "HOO"))

(extend BluesPlayer
  p/Rocks
  {:rocks (fn [this] "HOOOO")})

(def wolf (BluesPlayer. "Wolfy" "Howls"))

rauh++

@roberto Look at the curly braces around :rocks, plus you made :rocks a keyword instead of the function name symbol

I thought it was supposed to be a map https://clojuredocs.org/clojure.core/extend

I find it easier to use extend-type when extending in another namespace (extend-type BluesPlayer p/Rocks (rocks [_] "HOOOO"))

extend-type didn’t work either

I used extend because extend-type wraps around extend anyway

was just trying to get something working and figure out what was the issue, so I went one layer lower

http://clojure.github.io/clojure/clojure.core-api.html#clojure.core/extend-type

I think the issue has to do with the protocol being in a different namespace

if I put the protocol in the same namespace, then extend and extend-type work

Nah, just been extending protocols in another namespace for half a day and it works quite alright

what version of clojure are you using?

1.7, trying out in 1.8 now

OK, works in both versions

Took a while because I autoimported the wrong Java class

So what I did was require the namespace the protocol is in under an alias, and referred the protocol function name

oh, do you have to do anything special to the files with the protocols? Like maybe do a :gen-class ?

oh

(:require [clojure.java.jmx :as jmx :refer [objects->data]])

I wonder if that is the expected behavior

will try that, thank you for you help

Then my extend-type was something like this: (extend-type ArrayType jmx/Destract (objects->data [cd] (bean cd)))

Refer seems not to be necessary, this works as well (extend-type ArrayType jmx/Destract (jmx/objects->data [cd] (bean cd)))

hmmm, this is frustrating, it isn’t working for me

Somehow I didnt expect your BluesPlayer to have two protocols

Usually it's one protocol, like IMakeMusic, with speak and rock as functions inside that protocol

yeah, i was trying to see if this works http://davedellacosta.com/cljs-protocols

that shows that you can extend a type with multiple protocols

that works fine for me, it just doesn’t work when I extract protocols into their own files. I’ll take a break from this for now. It was just an academic exercise I was trying.

OK, GL

hello all

how can I remove a span tag with a specific class from html using enlive?

or maybe other solutions

I think Clojure can sometimes be faster than Scala at run time because Clojure needs to allocate less anonymous functions. Am I correct? Example: https://gist.github.com/borkdude/2772ccead843832c0956 Every time you update the map inside the atom you need to allocate an anonymous function. In clojure you can just pass assoc + args, no overhead.

How can I run tests on https://github.com/dakrone/lein-bikeshed if lein test doesn’t work?

lein test fails which is weird

Anyway I’ll look into that

Okay, it’s clear that they’re written to fail, why is this?

can destructuring be used in a binding form?

my usecase is that I have some dynamic variables that I want to set to be equal to the value of some keys in an .edn file and I don't want to repeat myself too much

@urbanslug: I think it's just to serve as an example of "bad formatted files, with trailing newlines". Running lein bikeshed on the project shows (among other stuff):

[...]
Checking for files ending in blank lines.
Badly formatted files:
/home/nicolas/projects/lein-bikeshed/test/bikeshed/core_test.clj
/home/nicolas/projects/lein-bikeshed/test/bikeshed/core_test.cljs
[...]

so it's not actual tests, just example "totally broken" files

(to run lein bikeshed I first added :plugins [[lein-bikeshed "0.3.0"]])

looks like destructuring can't be used in a binding

has to be wrapped in an outer let

that's a shame

about to write my first midje tests, for a channel. This is where all hell breaks loose in Scala (testing async code). I'm hoping for the best here... any advice?

@fommil that's right about binding. You can see the relevant code here: https://github.com/clojure/clojure/blob/clojure-1.7.0/src/clj/clojure/core.clj#L1849

My advice re: midje + core.async is just to <!! the channel and check the value on it. What you don't want to do is assert inside the async thread

@isaac_cambron: cool thanks, I started doing that it's good to get the approach confirmed. Can clojure run tests in parallel? I can see this slowing things down if I'm blocking everywhere.

is there an alternative to core/time that returns the time?

(my test is asserting on minimal timings of things)

There System/nanoTime

I've never run tests in parallel, though I'm sure there's a way

yeah but that's just now. core/time takes a function to wrap

I can write my own

my first clojure macro

heh, I was about to ask some questions about midje, then I realised they have 80 pages on their wiki

is there a better notation than this for a midje assertion? (just {:result :ping :time (partial <= 50.0)}). The partial is a bit ugly

the partial also reads the wrong way round

(this asserts that the LHS takes at last 50 milliseconds, but reads as "at most")

#(<= 50 %) is nicer

is there a way to define a destructuring in a single place? for example, when working with sente i find that i’m doing this all over the place

(let [{[ev-id ev-data] :event :as message} (<! chsk-recv)]
  …)

doing something like this feels weird

(defn -ev-id
  [{[ev-id] :event}]
  ev-id)

(defn -ev-data
  [{[_ ev-data] :event}]
  ev-data)

@akjetma: maybe you could define a kind of middleware that transforms your arguments into a more convenient format

@akjetma: I'd also like to know the answer. I'd considered maybe writing a macro with explicit named parameters

there's a name for those kinds of macros...

a sort of intentional variable capture

now, a macro that could automatically generate such a macro