I implemented a map-indexed-2d, give it a 2d vector, it will spit out a 2d lazy seq with the same shape. But I need to get-in on the result, get-in doesn't apply to lazy seqs. What can I do?

(for [y ys x xs] (f (get-entry x y))) ?

@leira Make it return a 2d vector instead of a 2d lazy seq in the first place? (vec (map-indexed ,,,))

yeah thx

I got the same suggestion in #clojurescript, but map-indexed-2d loses laziness~

@leira nth?

or https://github.com/clojure/clojure-contrib/blob/a6a92b9b3d2bfd9a56e1e5e9cfba706d1aeeaae5/modules/map-utils/src/main/clojure/clojure/contrib/map_utils.clj#L22 ?

?

Thank you @mfikes

assert returns nil; what is the best way to do an assert that returns obj ? I want to basically "assert this obj is not nil, and return original value" I'm not sure if this is better written as a function or a macro

@qqq why would you want to do it like that? It seems like an use case for if-let which checks whether some function returns something which is not nil.

@qqq

(defn assert-or-value
  [x]
  (assert x)
  x)

@qqq but it seems there is no sense in such behavior.

since this function does not change the output, there is no sense in re-defining the value. I mean, if you write something like this (let [x (assert-or-value x)]) it will look weird

(doto x assert)

I have code of the form

(let [ ... ]
  (code))

@qqq just wrap all the bindings with if-let, if one of them fails, code will not be called

@qqq you could use the else clause to log something, so you know where it went wrong

I have an irritating issue with Leiningen REPL. Every time I try to close an IDE (IDEA + Cursive) that has started lein repl via a bash script, it hangs on Waiting for process detach. If I kill the REPL process, everything continues as it should have. If instead I press "Cancel" in the IDEA dialog, it doesn't wait, but the REPL process is still there, parentless. Is there anything I can do to make IDEA kill REPL?

Is anyone working on a Clojure to LLL to Ethereum Virtual Machine bytecode compiler?

LLL isn't precisely a LISP, but it's LISP-like

Probably I can reformulate the question - is there any way to make lein repl exit on Ctrl+C?

I want to parse a array of bufferedImage. I need the first three values, modify them and then take the next 3. Currently I use a loop construct, but this tooks really long. Now my idea was to use r/reduce, to speed it up. How could I go through the array, always using three values at once?

hello guys

i'm asking about situation which i have (deftype X [id name]) , then i would like to assign id automatically without declare it at (X. id name), is there a good way to do it?

so only i have (deftype X [name]) and id is generated automatically and i able to do something like (.id x) for example

As far as I know, people usually create a constructor function: (defn make-x [name] (X. (generate-id) name))

@p-himik i know this so do you think there is something better ?

Better from what perspective?

for example hiding (generate-id) part

(X. name)

Well, the constructor function does exactly that, it's just named differently. If you want both the same name and an implicit field, I don't think that's possible.

I have two different standalone projects that I want to send data between. Both are backend, so no need for websockets. but I want to send data back and forth between the two using Transit. Should I roll my own low-level socket thingie, or should I use something else?

henrik maybe google protobuf

@henrik WebSockets can be still be used in your situation. Check this out: https://github.com/ptaoussanis/sente It supports Transit out of the box Other projects linked on that page are pretty good, too. Personally, I use Chord.

Hello guys. I'm asking if someone have faced use Kafka from clojure. I have been looking for a client and the most updated client, his last commit was 6 months ago. In theory we have planned use version 1.0 of Kafka. Thanks for advanced.

Interestingly, ClojureScript gives true.

case has a special case for seqs

Yeah but it works for positive numbers

but that should only be true for lists not vectors... hm

Yes, as per the documentation: "Note that since lists are used to group multiple constants that map to the same expression, a vector can be used to match a list if needed."

(compare 3 2) and 1 works; same for (compare 3 3) and 0

user=> (case ["a" (int -1)] ["a" -1] true false)
false
user=> (case ["a" (long -1)] ["a" -1] true false)
true

looks like a bug in clojure

user=> (case -1 -1 true false)
true
user=> (case [-1] [-1] true false)
true
user=> (case (int -1) -1 true false)
true
user=> (case [(int 1)] [1] true false)
true
user=> (case [(int -1)] [-1] true false)
false

integers are kind of rare so maybe that's why people don't run into this more often

oh it only happens with vectors containing negative integers

I have a good idea of why this happens

if you can log this in jira I might have a look this evening

I think that's directed at @ml ? 🙂

anybody willing :)

That drove me crazy 😄 yeah I'll try 1.9 later to confirm if it is still the case

@ml it is

opened one 🙂

@ml, link?

https://dev.clojure.org/jira/browse/CLJ-2275

@ml, you could reduce the repro to what @bronsa wrote (`compare` or the 2-element vector don't help trace down the bug)

clojurescript doesn't make a lot of sense as it doesn't distinguish Long vs Int

it's ok I'll edit your ticket

@bronsa Very curious how this could potentially be fixed since Integer. and Long. have different hash codes? Wouln't the compiler have to generate 2**n different cases for a match on a vector with n elements?

no

we could switch to hashEq rather than hashCode

which hashes equally for integers and longs

Oh I see. 🙂

@bronsa I think it is using hasheq?

it isn't

and it's not as straightforward as s/hashCode/hashEq/ unfortunately

I realize there are a lot of cases

prep-hashes implicitely assumes that on collision nodes h(h(v)) == h(v) where h = hashing and v = collision test

which holds true for hashCode of numbers but not for hashEq

hmm, subtle

yeah

I should have a patch ready in by the end of the day

well, that’s a bug then

yep

(case (int -1) -1 true false) is not doing what is implied right?

it is

oh, that’s in the expr not the case

the bug only happens when case uses hashing comparison + a collision happens

I read the (int -1) as a case of “int” and “-1", but that’s the expression, so nvm

hah

case's grouping gets me way too often

yeah, I’m sensitized to look for it now :)

I've added a patch for CLJ-2275, pretty straightforward apart from quite a tricky line which I commented on

This SO question came about because the person was re-implementing zipmap and rolling up their function args with & instead of just naming them keys and vals. so the first answer says to overcome this by using apply, I suggested naming the args. Please vote on your preferred solution: https://stackoverflow.com/questions/47517056/how-to-re-implement-zipmap-in-clojure/47518278

lein doo gives me Exception in thread "main" java.lang.RuntimeException: No such var: string/includes?, compiling:(cljs/util.cljc:157:13), followed by a long stacktrace with compiler internals. How do I know which cljs/util.cljs it refers to? It’s apparently from some dependency, not from my project.

I have a string of length 29. I want to create 10 strings of length 2, by dropping every 3rd char from the string.

Current idea is to convert to a list of chars, and use drop / partition, but I'm wondering if there ar better string functions.

partitioner has a [n step coll] arity so just (parititon 2 3 <your-words>)

(map #(apply str %) (partition-all 2 3 "abcdefghijklmnopqrstuvxyzabc"))

(partition 2 3 ...) is nice

Hi Clojurians. I’m trying to build a simple REST api + clojurescript with re-frame and reagent.. and sass. So I was thinking to use chestnut template for this. Would it be an overkill?

@bravilogy it’s useful to start from scratch but there’s a lot of instant gratification from using chestnut; either approach is fine

Does anyone have any experience using grpc/protobufs from Clojure? I want to use Google Cloud APIs and extract data out of them as persistent maps; I could use the Java API but that means writing a bunch of POJO<=>persistent data structure mapping code that I don’t really need. I guess what I’m saying is: is there a https://github.com/portkey-cloud/aws-clj-sdk for grpc?

If I was writing this from scratch I’d assume I’d write a grpc to gloss compiler

I do want to start from scratch, but I’m scared of stuartsierra.component library :)) I still don’t quite understand why do I have to use it in the applications. And I’m thinking that I’ll be spending a lot of time figuring out where / how / why to use it in my application

whereas chestnut just has it all set up