@m131 I have a tiny test coverage tool that does this with namespace finding and then alter-var-root. You could have a look.

@alfred.xiao cool - one small thing I notice reading - you could just use clojure.core/run! instead of your doseq-with function - it's designed for exactly that type of usage (though it takes the args in flipped order)

also, since nothing can access the return value of a finally clause, you could use run! there too (instead of the mapv in evaluate-test-coverage)

Thanks @noisesmith Didn’t know run! was there

yeah, IMHO it's underutilized

Today I Learned to Load File before I Load Block

is cascalog dead?

thanks for the link @alfred.xiao - looks interesting

https://github.com/ahungry/determinism - that's what I am thinking/working on

with results that are trackable (and reflective of runtime code paths) I think you could easily trace a path and see if a potential return value of some fn is incompatible with the input value of another fn to safeguard against regressions

@m131 somewhat related, i have been working on something to modify / transform source code in various ways. one motivator was to produce detailed execution traces (e.g. by running code after inserting tap> or some other logging form at the beginning of function bodies), save them, and analyze them for various purposes. source modification was the approach considered because it seemed likely to work for jvm / clr clojure as well cljs.

Nice, that would be great to have

This maybe a dumb question, but keen to see how others’ view on this: From a pure functional approach perspective, should a map over a structure, like a vector or a set, return the same structure? In Clojure, obviously (map inc #{1 2}) returns a seq rather than a set.

I'm not sure what you mean by "From a pure functional approach perspective"? If you give Clojure map a pure function, then map's operation is also a pure function.

Are you asking whether other functional programming languages have an operation like map that returns the same collection type that it is given as input?

If I map over a set I’d expect to have one result per item in the set. For example, if I did (map (fn [x] (odd? x)) #{1 3 5 8}) I’m not sure I’d want the result #{true false} as opposed to (true true true false)

You can find fmap implementations that do this though

part of the deal with map is that it is lazy, which is extremely handy. For instance, you can map over an infinite sequence (useful for when you're dealing with input from a server/user) and for deferred computation. Most of the other datatypes are eager, so they can't be used this way.

@alfred.xiao I find it useful to think of the seq functions to have the “type” seqable? to seqable?. Seq functions (like map) call seq on their arguments and don’t bother converting the return value back into a concrete type, since that’s a waste when you are composing lots of seq functions

If you want to transform concrete types you’re often better off using transducers

Random thought

Could spark be monkey patched to accept clojure forms on workers instead of serialized bytecode?

That way the requirement that code be serializable wouldn't exist for clojure code

And you could make an incredibly interactive spark session

@emccue Probably worth checking out powderkeg https://github.com/HCADatalab/powderkeg

hi, if I repl into a running jar to execute a long running command. would that continue to run if my ssh connection to the box dies, and thus the repl connection dies?

it probably stops right?

oh it doesn’t stop

😄 ok

rephrase command as in: just call a function, not something in a separate thread or go loop

I’m looking to add server sent events to an existing application that uses ring and good old blocking I/O… However, I clearly don’t want to serve the events from the existing server with long poll requests eating a thread per connection. I only need to send a few simple events from the app, so I’d like something pretty minimal. Ideally with relatively few dependencies (to minimise conflicts), and to be relatively lightweight in terms of overall size. I’d also like to run both the existing jetty server and the SSE server in the same JVM process. Last time I did SSE in clojure was many years ago; so not sure what people would recommend these days… http-kit, aleph, pedestal?

ahh interesting pedestal can work with a jetty backend… was wondering if I might be able to leverage the async capabilities of the current jetty server

@rickmoynihan My experience about 2 years ago with pedestal SSE was fantastic. Lots of things like replaying events to catch a client up after a dropped connection "Just Worked".

i have a strange question, is it possible for clojure to work on really low level architectures in the future? what's the minimum amount of architectural complexity required to provide the luxury of map, filter, and reduce?

a lot

having map, filter and reduce doesn’t mean you have clojure. The minimum required for the luxury of map, filter and reduce is essentially something like the 7 special forms, and high order functions. So you probably want to look into minimal lisp dialects that target small machines.

https://clojure.org/about/rationale#_languages_and_platforms is a good kind of summary of the facilities that clojure rests on top of

There are some very low-level "almost-clojure" implementations though: https://ferret-lang.org/

And languages like carp also go in the direction of high performance, low level code from a high level lisp, didn't do too much with it to judge though

https://github.com/carp-lang/Carp

It takes some inspiration from Clojures syntax

Ferret can run on 2KB of ram! what!

so cool

"real low level architectures" is also very hand wavy

the jvm was originally created for embedded devices, and a computer with gigs of ram and multiple cores fits in your pocket today

My dev workflow involves hosting a socket repl and then piping code to the repl via my editor using ncat. I get an exception if I run the following code twice in a row via my repl: Is this a bug/known-issue?

(ns socket-test.core-test)
  (do
   (require 'socket-test.core-test :reload)
   (run-tests))

socket-test.core-test=> Execution error (SocketException) at java.net.SocketOutputStream/socketWrite (SocketOutputStream.java:118).
Socket closed

Essentially, it seems clojure.test/run-tests and/or (require 'ns :reload) don't seem to be compatible with the socket-repl

that execution error means that nc is exiting while the java process is trying to write its output back right?

yes potentially, but why does nc exit early?

if I recall there is some option you need to pass to nc

-k maybe

no I am thinking of something else

my guess is you are not stopping the jvm from exiting

the socket repl starts up, which if I recall spins up the future threadpool, which can stop the jvm for exiting from a minute or two, but unless you have something keeping some main threads running it will exit

(some non-daemon threads)

ahh, so you could fix it with the @(promise) trick or something

yep

the socket repl doesn't spin up the future threadpool

(.join (Thread/currentThread)) ;)

but something else likely is, or something else is stopping the jvm from immediately exiting

and the threads the socket repl creates are specifically marked as daemon threads, so they don't stop the jvm from exiting if nothing else is going on

I'm so sorry, I lie: a vanilla lein repl with socket enabled doesn't reproduce the issue The issue seems to be an interaction with rebel-readline

lein repl starts a non-daemon nrepl server thread

What’s a “canonical” way to deal with a problem where there [f1 f2 f3...] are functions that need to be applied to [v1 v2 v3] ? Assume that none of those f1… are in a list but you need the result of all those applications in order to compute a final result? Is it better to just stick a let [a (f1 v1) b (f2 v2)] or use a (map #(%1 %2) fs vs)

This happens a lot. juxt for instance applies multiple functions to one argument(s). What if I want a parallel set of functions applied to a parallel set of arguments If you know what I mean…?

@srijayanth one approach is to use juxt

@noisesmith - juxt doesn’t solve this problem

nothing stops you from mapping juxt across args

But I want each of those functions applied to different args

Meaning f1 v1, f2 v2 etc

Not (f1 v1 v2 v3) etc

oh, then your map example is how I usually do that

@noisesmith - that’s what I resort to as well, however, is there a word we can give it? Its a pattern that occurs too commonly

zip-apply might be a decent name, or zip-invoke

Yeah. I think some apply variant indeed. zip-apply sounds nice. I’ve dabbled with apply-against and apply-to

In fact, if we name the #(%1 %2) then we get a lot of benefits. The (map apply-to) would turn into a transducer that can be quite pliable

except we don't have many transducing contexts that zip together multiple collections

sequence is the only one I can think of

it is the only one

Which is still useful.

Any idea why I get an unbound Var when i def the result of a call?

(def _r (cci/concordion-run (org.concordion.api.Resource. "/UsageCharges.md") "./UsageCharges.md"))
=> #'charges-test/_r
charges-test/_r ;; eval the just created var
=> #object[clojure.lang.Var$Unbound ...

(def _r (bean (cci/concordion-run (org.concordion.api.Resource. "/UsageCharges.md") "./UsageCharges.md")))
=> #'charges-test/_r
_r 
=> {:forExample false, ...}

the only thing I can think is that cci/concordion-run might be returning the value of an unbound var, but that seems like a strange behavior

or that you are evaluating _r before the cci//concoridion-run returns

(eg. if using clojure via editor tooling)

I have a coll like [1 2 3] and I want to verify that every element in the vector is a pos-int? so I am doing (every? pos-int? [1 2 3]). I noticed though that (every? pos-int? []) would also yield true. Is there a built in that does this, but would return false because the vector is empty? Just curious if I am missing something.

according to logic, every member of [] is pos-int?, you can just use (and (seq %) (every (pos-int? %))

no, don't do that

oh sorry, I read that as a spec, that's fine

(the every spec has built-in support for min-count)

to be cute, it could be (and (pos-int? (count %)) (every? pos-int? %))

too many parens around pos-int?

good catch

the every? vacuous truth

😱

What is the functionality that makes Boot and Leiningen look better than Maven?

people don't like editing xml

people want to define build tasks using clojure

What build tasks are commonly defined?

compiling to aot, test running, compiling cljs to js, linting

also compare how to specify a dependency in maven versus lein

in boot or lein it's easy to pull in clojure code for those tasks (and that's how it's typically done via plugins or libraries)

oh yeah, the clojure versions are more compact too

CLI seems to beat lein for dependency management.

you can use deps.edn in lein via a plugin to replace it's regular dep management

lein still defines a lot of tasks / plugins with no cli equivalent (but that's changing fast as more teams adopt cli)

I wish there was a lein 3 that required the project.clj file not be evaluable but more static like deps.edn

or, I wonder if this would kinda unify the lein and deps.edn workflows

do that many projects end up using evaluated inline code?

via what plugin

i doubt it but i thought that was the fundamental mismatch between the two

i know cider-nrepl's does for simple things like def'ing the version

but that only matters at your current project - code in your deps isn't run

you just load their pom

@norilinoriginal the plugin https://github.com/RickMoynihan/lein-tools-deps

although it looks like cider-nrepl has had a "static" project.clj since january

doesn't cider-nrepl's project.clj only matter if you are building cider-nrepl? it shouldn't effect a project using it as a dep or plugin? - or is it injecting executed code into the project.clj via the plugin?

i meant if you wanted to target it with tools.deps

i think that's what's preventing them from being targets like that. the description of the project must be evaled

and that's a fundamental issue with any boot or lein project

lein doesn't run code from your deps though - I must be misunderstanding you

sorry i was being unclear. I mean why deps.edn can't target them as git deps etc.

oh, right, it can only use it via the pom / deployed artifact

You can always specify :deps/manifest :deps to "force" tools.deps to treat it as a deps.edn project with an empty list of dependencies, and then provide any transitive deps yourself manually.

(but cider-nrepl has a deps.edn file -- so what repo are you talking about?)

ah i forgot someone added that recently and the def inside the project.clj is gone. it was just an example. i think maybe my last job had some evaluation stuff in one of the project.cljs

Yeah, we used to do some calculations in project.clj back when we still used Leiningen... coming up on four years ago 🙂