Clojurians Log v2

> Do I just get used to calling vec or into [] everytime I want to use a seq function? No. Only every time you need a vector. Or every time you need a non-lazy result and want to create it with transducers.

If you want / need a specific type of sequence, consider transducers. They give you that control, and spares you the cost of allocating intermediate sequences. Sean Corfield's transducer into on Civitas is excellent: https://clojurecivitas.github.io/clojure/transducers/what_if.html

As Eugene, I normally stick to seqs when I code, converting to vectors and sets only when needed.

And if you want to get deeper into it, perhaps you could describe the perceived problem(s). The way the question is phrased sort of implies the problems that seqs cause are intrinsically, objectively problematic, so it's possible that an analogy might be if the question were "I can't freely mutate my local bindings and that's a problem, do I have to use atoms every time?". There's probably a way to make immutable bindings less of a hurdle. Another option that's out there is specter (<https://github.com/redplanetlabs/specter>). It's quite a different approach to manipulating collections, but it mostly (always?) retains the input collection type, and some find that its style works for them.

> As Eugene, I normally stick to seqs when I code I actually almost always use (into [] ...) because I "need" non-lazy results. :) I find it simpler, easier to reason about, easier to debug if something goes wrong. And usually it's more performant as well.

@highpressurecarsalesm I would be open to making fuller use of seqs and I don't think there is anything wrong with them. First, I'll tell you what prompted this question. I was programming the reverse card in Uno and I accidentally wrote (update game :players reverse) instead of (update game :players #(vec (reverse %)) . Then I called

(defn current-player
  [game]
  (get-in game [:players (:i game)]))

A small note: instead of (vec (reverse some-vec)) you should use (vec (rseq some-vec)).

@p-himik @teodorlu I haven't thought much about transducers. I'll have to look into those

If transducers are intimidating at first (as they are for many), you can chain together the transformations with comp and/or -> /`->>`, applying vec or into [] at the end of the pipeline

What problem are you getting?

@didibus see my comment to Bob above. My vector got turned into a seq, then I was no longer able to access its elements using get coll i

Ah ya, sorry had missed that comment.

I'd say one thing that's not obvious. Is that you need to decide between coll functions or seq functions. And you need to be aware of that. It's a little tricky at first, but you get used to it.

Just remember that all seq functions return sequences. So if you want something else, you need to add a last step to get what you want. There's not much difference since everything is creating a new vector anyways, since it's all immutable. So it's not like you're missing out on in-place mutation.

@didibus yeah, I get the idea of choosing. The trouble is that many clojure.core seq functions don't have a corresponding coll function, so I'm stuck calling vec or set etc. when I want to preserve the collection type. That's okay--in Java I had to call .toList() after a .stream() call, not much different 🙂

Ya absolutely. I think more recent versions added a few more "v" ending variants for convenience around this. But I'd say, the idea is that you do a "pipeline of transforms" and then go back to wtv coll type you wanted if that's what you need. And the reason it's like this, is because since colls are immutable, you don't need a variant of every function specialized to inline mutation of that particular structure. So it goes:

(->> <from-coll>
     transform
     transform
     (into <type>))

(into []
  (comp transform
        transform)
  <from-coll>)

This is my favorite question I think (not that I’m anything but a novice myself).

cf. https://clojurians.slack.com/archives/C053AK3F9/p1746934158512559

And as to your prompt, > If I have a vector, there is a reason I’m using a vector, and I want to avoid accidentally turning it into a seq. what is the reason in this case?

@james.amberger it is an interesting discussion that cuts to the heart of what Clojure is about. As for the reason, see my response to @highpressurecarsalesm earlier in this thread: https://clojurians.slack.com/archives/C053AK3F9/p1758471168899829?thread_ts=1758454483.607889&amp;cid=C053AK3F9

ok, there is a reason you are using a vector. What is it?

@james.amberger He's doing O(1) random access use get by index