I see Phil is quite the evangelist for that position -- running counter to many others in the Clojure community, including Rich 🙂

(and that is from three years ago -- with no action taken in Kibit I believe? 🙂 )

More because of laziness than anything else 😛

and 5.5 years ago

that Kibit warning is actually what introduced me to the notion that when might be preferable to an if with no else clause, because the codebases I was working on never used when

Question: How do I invoke a java method when I have it's hame as a clojure symbol ? 1. I have java class Foo 2. I do (:members (clojure.reflect/reflect Foo)) -- I get a list of members. 3. I do (:name (first (:members (clojure.reflect/reflect Foo))))) -- I now have the name of one of the functions, as a clojure symbol. 4. How do I invoke this? 5. Normally, I would do (.memberFunc Foo ... ) -- but right now, I have a var in clojure, whose value is memberFunc -- how do I invoke it ?

@qqq ^^

G'day! I've been trying to pull a text file from S3 using clojure.core/slurp, passing in a URL that contains a username & password element (e.g. ). It looks like slurp drops the username and password though, as I'm getting back 401s. Hitting the same URL from the command line (via wget) works fine, so it's not an issue with the URL. Any pointers?

@rauh: that worked; thanks!

@deactivateduser10790: java problem 😞

slurp seems to expand into code like

(.openStream (.toURL (java.net.URI. "")))

https://stackoverflow.com/questions/496651/connecting-to-remote-url-which-requires-authentication-using-java

@deactivateduser10790 for anything more serious including authentication you should use something like https://github.com/dakrone/clj-http

#planck will do this out of the box as well:

Planck 2.8.1
ClojureScript 1.9.946
    Docs: (doc function-name-here)
          (find-doc "part-of-name-here")
  Source: (source function-name-here)
    Exit: Control+D or :cljs/quit or exit or quit
 Results: Stored in vars *1, *2, *3, an exception in *e

cljs.user=> (require '[planck.core :refer [slurp]])
nil
cljs.user=> (slurp "")

Is there a way I can connect to a running JAR. Is socket server repl the way to do it? I want to run a JAR and then connect to it using a REPL and then be able to redefine some function or debug something in the function

Hi, some one know good stack for work with reactive (choreography) architecture in clojure?

@xtreak29, yes the socket server is built for that. Also check out https://github.com/Unrepl/unravel

@pesterhazy Thanks :thumbsup:

this is a sanity check, as something is not working as expected: (.field-name SomeClass) should also work if field-name is a field name of a Superclass of Someclass right ?

yes

if it's public, that is

and if SomeClass is actually some-class-instance

otherwise for static field use SomeClass/field instead

Is there any company owner here ? Company that is using clojure for production ?

how would you run clojure app with nginx ? (proxy_pass and supervisor)

@qqq @rauh Hmm, so Reflector is bad... Alright, there you go

(let [s "String"
      m 'getBytes]
  (eval `(. ~s ~m)))

@aisamu: I don't have the names upfront, I have to query the JVM to get the names 🙂 // I guess this can be done at macro expansion time, but I'd prefer to avoid amcros if possible.

@aisamu why would you do that

@qqq You definitely want to avoid macros there... I should have put more 😭 's at the end!

using reflection is a much better solution if you actually need this, which you shouldn't

😈

(r/reflect Stream$StreamCanBuildFrom)

{:bases #{scala.collection.generic.GenTraversableFactory$GenericCanBuildFrom}, :flags #{:public}, :members #{#clojure.reflect.Constructor{:name scala.collection.immutable.Stream$StreamCanBuildFrom, :declaring-class scala.collection.immutable.Stream$StreamCanBuildFrom, :parameter-types [], :exception-types [], :flags #{:public}}}}

@qqq don't think you're going to get a good answer to that. Scala mucks with Java types a lot. Probably better to write this interop code in Java, or to call Clojure from Scala.

The latter probably being the cleanest way. Clojure's java API is much cleaner than Scala's

What’s the best way to get Rails-style db migrations in clojure?

I’m starting a new Luminus project this morning, it comes with a lot of great stuff out of the box but I don’t want to write all my CREATE TABLE statements by hand

Luminus uses migratus, I believe

but I don’t think it reverse-engineers your db/model for you

Don’t be afraid of writing them by hand. Less can go wrong if you do semi manual dB management

right, migratus doesn’t quite have what I want. It will generate an empty .up.sql and .down.sql for me but doesn’t have a dsl for column definitions etc.

Auto migrators always do something wrong it seems

Best system I've had with devs and DBAs is one where you have a base DB via a .sql text file, then incremental changes via commented .sql files, all named via a incrementing number.

Kindof like git for a DB.

there's also ragtime & joplin @maxfurman, but they don't have column def dsls either - but then they aren't tied to sql stores either, so column def dsls don't make much sense in their context

I always cheat: use a GUI SQL tool to lay out my db schema, then select “Copy CREATE TABLE Script…” or whatever.

DB diffing tools are also really nice for that

MS SQL had a "export diff as script" that was super helpful

Also console logs that capture your changes real-time as you edit columns/tables in the GUI.

and if you're working with MS SQL in production, the red gate tools are worthwhile. for data diffing and schema diffing

The big thing is at some point you need to take the changes to prod, and as a former DBA I really really hate using tools for that. So much can go wrong.

I guess I’m surprised the clj community hasn’t come up with a lib that matches what you get from rails or django

I'd more say that some of us consider what those frameworks do to be "the wrong way" 🙂

Though there are projects like http://sqlkorma.com

though I prefer HugSQL myself.

I was looking at Korma, and it doesn’t have ddl

Dropping a bunch of indicies and FKs and then re-adding them may be fine for smaller databases, but I've seen SQL servers crash on stuff like that when you get 100M+ rows in a table. In those places you need surgical edits that are sympathetic to the underlying server design.

so even if I wanted to add it (not sure if I want an ORM), I couldn’t use it in the migrations anyway

I've used this homegrown minimalist migration framework: https://gist.github.com/pesterhazy/9f7c0a7a9edd002759779c1732e0ac43

PostgreSQL only ^^

Yeah, as far as the ORM stuff goes HugSQL is pretty awesome. SQL is a powerful tool, leverage it don't hide it behind a DSL. And no need for a ORM when you have hashmaps

(what was that thing from Rich's talk? ORM = OMG 😛 )

@pesterhazy Not quite what I’m looking for - I want to write my migrations in clj code and not write any sql

@tbaldridge but I’m lazyyyy

@maxfurman honestly I'd reconsider the approach - SQL is the root DSL for this

@maxfurman https://github.com/jkk/honeysql check out HoneySQL

All I want is a cheeseburger and you guys keep handing me broccoli

But SQL gives you power 🙂 the more you understand your datastore the more you can leverage.

Sorry, we want you to be healthy 😛

writing code in a db-independent fashion is ultimately a fool's errant

We're using honeySQL ❤️

"we want to be able to switch out the db" is understandable but usually overengineering

honeySQL is nice when you want to generate queries from data... though there were some limitations when i last tried it

i've never worked on a bigger-than-trivial project which didn't come to depend on particular features of the underlying db, making switching out the db an arduous task

Alright, I guess broccoli it is 🙃

In our project, we are using HugSQL. It’s a library to generate clojure functions from raw sql queries.

With yesql and its analogies, you may face a situation when you need some extra syntax that was not designed to be used with data structures.

Say, Postgres carries lots of stuff you cannot express with vectors/maps

- embed JRuby - use Rails migrations - profit!

what is the default method/library for solving systems of equations or sets of constraints?

I have several dimensions: some are defined scalars, some are defined ranges, and I need to solve for possible (say int ranges) combinations of undefined dimensions.

it is sort of knapsack problem, but I don't need to solve for the most optimal values; rather I'd like to get range of viable solutions

core.logic somehow feels overkill, can't explain why

datomic's or datascript's datalog?

@misha I'd go for core.logic

or maybe loco https://github.com/aengelberg/loco

loco looks easy

oh noes, it is 2 years stale, looks like it is abandonware!

[off topic] given that we are in lisp, why libs such as loco introduce their own symbols rather then reusing clojure's or, and, let, range, etc?

loco - clojure only :(

its wraps a java constraint solver

yeah, I see that, thanks, @dpsutton should have mentioned I need it to run on clients too

sorry. i didn't mean to point out the obvious 🙂

Anybody know of a clojure library for manipulating jar files?

Anybody know of a clojure library for making custom jar files?

is there anything builtin for updating values across entire map?

(update-vals {:a 1 :b 2} (partial + 3)) ;;=> {:a 4, :b 5}

@misha I bet Specter offers something...

...otherwise I'd probably do (reduce-kv (fn [m k v] (assoc m k (+ 3 v))) {} {:a 1 :b 2})

I did it with reduce-kv, but feels like I can compose something existing

I can think of a way with zipmap, juxt, and map but I think reduce-kv is much cleaner... 🙂

@misha map-vals is in most utility libraries. My go-to one for this is medley, which is very light.

anyone else encountered broken leiningen plugins with 2.8 release? Eastwood and bikeshed fail for me now

yep, this is a known issue https://github.com/technomancy/leiningen/issues/2328

@seancorfield agree. @dominicm thanks

@misha Specter solution: (transform MAP-VALS (partial + 3) m)

@schmee for some reason I am still caution of using specter

don’t be, it’s a great library! 😄

at least give a try and see if it works for you 🙂

I think it tends to be sort of all or nothing: either you use it all over the place, or don't use it at all

yeah, it’s no fun to add a dependency just to use it in one place

but you tend to see use-cases for specter that aren’t obvious at first when you start using it

i kinda wish there was a more concise way of merging two maps in clj

something like JS's spread operator

@yedi what kind of merge do you want?

I’m lacking imagination and have no idea how spread would help you merge maps

so instead of something like this

(merge props
       {:key1 somethign
        :key2 something-else})

{:key1 something
 :key2 something-else
 #...props}

assoc

which isn't that much more concise heh

(assoc props :key1 somethign :key2 somthing-else)

right

my main issue i think is just the extra indentation of having the (merge) or (assoc) call

which becomes an issue when writing hiccup code

(assoc
 props
 :thing1 something
 :thing2 something-else)

any decent editor should indent like that as long as the first arg is on the next line

yea i guess that'd be fine, just the extra line because you have the assoc call

it's a pretty silly thing for me to want tbh

but that kinda spread operator would make the code ever so slightly more concise

could it be a macro or reader literal instead of an operator?

#spread[props :thing1 somethign :thing2 something2]

can’t use {} because of reader rules, but it looks decent

this is a bizarre question

you could even name it #… if you really want to

@ghadi it seems like a syntax request to me really

yup: why send syntax in to do a function call's job?

heh yea #_ could be cool

#{:reasons}

@yedi or just (def … assoc) and call it a day?

(set (vector :i-can-understand))

oh, reader macros mean you can define that but not call it directly, too bad

anyone experienced using kafka? I’m setting it up and wondering what the experience is using java APIs vs wrappers like franzy https://github.com/ymilky/franzy

I have had decent luck with a very thin clj-kafka wrapper for the basics plus raw interop whenever I need a non-default option, YMMV

PSA: don't shadow core functions with variable names. especially meta

haha, those bugs are fun

still bitter about using a library whose api was implemented in terms of proxy and thus shadowed my this in method definitions

I think that is the only anaphoric macro in core :)