😼 mogge

Hello All 🙂

hi all 😄

morning!

rcfotd:

-------------------------
clojure.core/get-method
([multifn dispatch-val])
  Given a multimethod and a dispatch value, returns the dispatch fn
  that would apply to that value, or nil if none apply and no default

I used that this morning, oddly enough

really? it seems pretty niche

It is 😛. Quite a coincidence.

@yogidevbear I solved the puzzle here: https://gist.github.com/madstap/a01600d9243a6229e6689d24d9deb275

Not sure how nice the solution is, feedback welcome

@madstap That's awesome 🙂 Thanks for taking the time to look into it 👍

I feel like a #friday-puzzler channel in this slack group could be really interesting (esp. with so many active members)

Oh man, I never did it.

(defn f [ns total]
  (get (group-by #(reduce + %)
                 (mapcat clojure.math.combinatorics/combinations 
                         (repeat ns) 
                         (range 1 (inc (count ns)))))
       total))

@madstap so when looking at the results of (f [1 2 3 4 5] 5) and getting #{{3 1, 2 1} {4 1, 1 1} {5 1}}, am I reading the results correctly that it's one instance of 3 (`#{{3 1,`...) plus one instance of 2 (...`2 1},`...) equals 5?

Yeah

@peterwestmacott If I want to include the combinations namespace within a lein repl, do you know what the command is?

(require 'clojure.math.combinatorics)

Ta

but you maybe want to alias it to something: (require '[clojure.math.combinatorics :as combos])

That's pretty cool.

https://github.com/clojure/math.combinatorics looks like you need to depend on it?

FileNotFoundException Could not locate clojure/math/combinatorics__init.class or clojure/math/combinatorics.clj on classpath. clojure.lang.RT.load (RT.java:456)

I think he means that it's not included in vanilla clojure

you might need this in your project.clj: [org.clojure/math.combinatorics "0.1.4"]

Yeah, I'm trying to get it as an entire script I can drop into a repl for simplicity sake for demoing to people that haven't got an environment set up

I think you might be able to set it up with klipse in the browser

Supports cljs. I wonder if you cou— that ^

(eval (slurp "raw.githubusercontent.com..."))?

@peterwestmacott That just returns a string of the file...

yeah, sorry

And if I do read-string, it just reads the first form

in my haste I forgot the call to read-string

the point is that there will be a way to load the ns from a URL - but it probably isn’t what you actually want to do

But if I wanted to do that hack, how do I read all the forms to pass to eval? read-string just reads the first form

If you use boot it's just boot -d org.clojure/math.combinatorics:0.1.4 --file main.clj 😉

plug for https://twitter.com/frankiesardo/status/854997831979065344

#!/usr/bin/env boot
(set-env! :dependencies '[[org.clojure/math.combinatorics "0.1.4"]])
(require 'clojure.math.combinatorics)

(defn variations
  [numbers sum]
  (filter #(= sum (apply + %)) (clojure.math.combinatorics/subsets numbers)))

(defn -main [& args]
  (prn (variations [1 2 2 3 5] 5)))

boot is great for scripts

I have a feeling I missed something given @peterwestmacott's solution being different to mine, that I've missed something. Not sure though 🙂

Thanks Dominic 👍 I'll give it a go later and share the solution on the puzzle gist if you're okay with me sharing 🙂

yeah go ahead.

@jonpither I really enjoyed the article, thanks for the link earlier...

@jonpither Hmmm... I can't find it...

hmm, prob missed the target

Oh well 😞

https://news.ycombinator.com/item?id=14158080

Thanks @dominicm