Clojurians Log v2

Hey guys. How does this function look (generating some fixture data):

(defn- insert-classes! [datasource]
  (let [teachers (db/find-by-keys datasource :user {:role (db/enum (:teacher user/roles))} {:columns [:id] :limit 2})]
    (doseq [t teachers]
      (db/insert-multi!
        datasource
        :class
        [:name :school :description :archived :teacher_id]
        (take 5 (repeatedly #(seq
                               [(first (names))
                                (first (co-names))
                                (join " " (take 3 (sentences)))
                                (rand-nth [true false])
                                (:user/id t)])))))
    (println "Inserted  classes")))

So the (names), (co-names) etc are all zero-arg side-effecting functions that do ... what?

And why are you calling seq on the vector?

@somedude314 Can you provide a bit more background on what exactly you're trying to do here?

Consuming this https://github.com/paraseba/faker/blob/master/src/faker/company.cljc#L32

… and this: https://github.com/paraseba/faker/blob/master/src/faker/name.cljc#L41

Because this works for me:

(take 5 (repeatedly #(seq [1 2])))

(take 5 (repeatedly [1 2]))

OK yeah this isn't how lazy-seqs work at all

on each call you are generating a lazy stream of names, and only consuming one, and on the next call you make a new stream

I am basically trying to populate the vector inline for insert-multi!

(repeatedly #(vector 1 2))

Looks like you should map over the various lazy fakers and make a vector: (map vector (names) (co-names) (map #(str/join " " %) (partition 3 (sentences))) ...)

Then (partition 5 ...) over that to get groups of five rows each.

What I can do about that when it’s an external library and I only need one name?

(repeatedly #(rand-nth [true false])) would give you the generator for the archived values in that (map vector ...)

I'd probably create the teacher ID series with (mapcat #(repeat 5 %) (map :user/id teachers)) and that would be the last sequence in that (map vector ...) -- the fifth and final of the sequence arguments.

That would also cause the number of teachers to control how many groups of 5 rows you got, so it would automatically grow as you changed the :limit to different values.

and finally (doseq [row-group (partition 5 (map vector (names) ...))] (jdbc/insert-multi! datasource :class [:name :school :description :archived :teacher_id] row-group)

See what I posted in the main channel.

So the key here is to take a series of (infinite) lazy sequences and use map vector to take corresponding elements from all of them and put them together in rows -- so this in turn would be an (infinite) lazy sequence of rows.

The (partition 5 ...) and the #(repeat 5 %) (inside the mapcat over the teachers) are related so pulling the 5 out of both as a local binding to class-size or something similar would make sure they stay in sync.

So you can see what I'm taking about on a small scale:

user=> (defn names [] (cycle ["Sean" "Adam"]))
#'user/names
user=> (defn co-names [] (cycle ["ACME" "Saint Mary's" "Collyer's"]))
#'user/co-names
user=> (take 2 (partition 5 (map vector (names) (co-names))))
((["Sean" "ACME"] ["Adam" "Saint Mary's"] ["Sean" "Collyer's"] ["Adam" "ACME"] ["Sean" "Saint Mary's"]) (["Adam" "Collyer's"] ["Sean" "ACME"] ["Adam" "Saint Mary's"] ["Sean" "Collyer's"] ["Adam" "ACME"]))
user=>

Thanks for the detailed input! Will try to put this together and see what I can come up with.

Here's the above with fake sentences added:

user=> (defn sentences [] (cycle (str/split "The quick brown fox jumped over the lazy dog" #" ")))
#'user/sentences
user=> (take 2 (partition 5 (map vector (names) (co-names) (map #(str/join " " %) (partition 3 (sentences))))))
((["Sean" "ACME" "The quick brown"] ["Adam" "Saint Mary's" "fox jumped over"] ["Sean" "Collyer's" "the lazy dog"] ["Adam" "ACME" "The quick brown"] ["Sean" "Saint Mary's" "fox jumped over"]) (["Adam" "Collyer's" "the lazy dog"] ["Sean" "ACME" "The quick brown"] ["Adam" "Saint Mary's" "fox jumped over"] ["Sean" "Collyer's" "the lazy dog"] ["Adam" "ACME" "The quick brown"]))
user=>