I have a project setup with deps.edn . I have an alias for nrepl (from Sean Corfield’s guide). I can start the nrepl with clj -A:nrepl , how do I get it to auto-load my project like lein repl does?

@ryan072 Do you mean the "main" ns that lein repl loads and starts you in?

If you were starting a regular Clojure CLI REPL, you could use -e "(require 'my.main)" -e "(in-ns 'my.main)" -r and it would run those commands and then present a REPL.

But the :nrepl alias uses :main-opts and they do not combine across aliases so I'm not sure if that will work...

I guess what’s your recommendation for “loading” my project into the nrepl?

just go execute the “main” manually file and have it load everything else?

I never type into the REPL. When I evaluate forms from the editor, it auto-selects the correct ns for the evaluation.

when you fire up your repl, is your project “loaded” already, or do you load it yourself?

loaded/parsed/whatever the term is

evaluated

The "project" isn't loaded. Each namespace is loaded/compiled when it is required.

and you do that yourself? (as in you personally evaluated the what you need to get started). unless i”m crazy, doesn’t lein repl already evaluated your entire project?

not that I need it to be like lein repl just want to make sure I’m not setting stuff up incorrectly?

I haven't used lein for years so I don't really remember how it works. I don't use nREPL either.

what do you use?

The Clojure CLI. And a plain Socket REPL.

What editor do you use?

vscode/calva

OK, so you start an nREPL server, then you connect Calva to it...

Then you evaluate the current file into the REPL? Load file?

typically just eval a form

and it switches ns and does it correctly

just felt like the project should be ‘pre-evaled’

on startup

I wouldn't want the REPL to load stuff on its own.

I would want control over what gets loaded.

I work with a large project that has many main entry points -- there's no single namespace that could be required at startup to load "everything".

makes sense

I really hadn't given any thought to the idea of a namespace being auto-required at startup, since the editor always uses the right ns for evaluation. The only caveat is that you have to eval the ns form first in order to have all the other nses compiled that your namespace uses.

Or you could just "load file" whatever that is for your editor.

I have ctrl-; f bound to "load file" and ctrl-; B for "eval top-level form" (and ctrl-; b for "eval current form").

If I'm not mistaken, lein repl only evaluates whatever namespace you put in :main on the project.clj file. On most projects, that main namespace's requires will eventually load all/most of your code, unless it's a big project with multiple entry points.

Yeah, that sounds likely. I suppose it saves a keystroke on small projects when you're first starting your REPL. My REPL tends to run for days, sometimes weeks, so it's not much of a saving.

thanks for the responses @seancorfield!

glad to know that I’m not missing something obvious too

I guess it's another one of those ways that lein makes things "easy" (without being "simple") 🙂

(after paying attention to how I work for a few minutes, apparently I've gotten into the habit of hitting ctrl-; f pretty much every time I open a file... and since my REPL doesn't have a prompt I don't even see what ns it is in...)

Just joined. Enjoying Clojure so far. I’m working in an ML class, and thought Clojure would be a good way to explore some ML in the Java world. I didn’t find any Clojure specific ML libraries, so I ended up using SMILE which has some Clojure bindings. Did I miss anything during my Google searches? Are there more interesting libraries than SMILE for data analysis/ML in Clojure? I’m running clojupyter and it’s pretty good. Not as well integrated as Python of course, but overall it’s pretty handy, and Oz/Vega-Lite is producing decent graphs.

@jkint Have you seen https://mxnet.apache.org/api/clojure

You'll probably also find this guy's stuff interesting https://dragan.rocks/

There's a #data-science channel here as well (although I think a lot of the data science folks are more active on the Clojurians Zulip chat setup?)

I'd recommend asking in #data-science This is also a good resource: https://scicloj.github.io/pages/libraries/

@ryan072 check out https://calva.io/try-first/ , if you haven't. Note that it starts out by the user loading the current namespace. It could seem silly you have to do this yourself, but as @seancorfield points out, you should be in control of what is being evaluated, when. (Calva could be a bit more helpful in reminding you about evaluating forms and files, but anyway.)

Question on Clojure installation om MacOS (unsure if there is a better channel). Installed with Homebrew a while back and now get warnings like: “Warning: Calling 'devel' blocks in formulae is deprecated!...”.

Is it my install or something that will be fixed elsewhere? Thanks 🙂

Not sure if this is the correct way to ask this question, but here it goes: Within the Java API is it possible to compile a Clojure program from a string?

I have converted a js object to clj using (js->clj obj). This is what I get back: {"foo" nil, "bar" #object[com$core$test]} . How do I get the value of foo and bar?

Can someone suggest me a good Mark Down Editor which can be easily integrated with cljs? If possible can you give me some examples also about how to use it. A bit new to Clojure.

I want to create a spec that validates variable length vectors with different predicates based on their first element. These vectors are commands expressed as data What would be the best way to define these specs? (fake) example: • [:add 1 2] would have a spec that validates that values at index > 0 with int? • [:print "Hello world"] would validate with string? (and perhaps assert only one value)

use an s/multi-spec keyed off the first element of the vector

I've done similar things a few times, works well

b/c it's based on a multimethod, it's also open to later extension (which was the whole point behind s/multi-spec)

hm nifty, I've only used multimethods with maps, not vectors, but I suppose a multimethod like

(defmulti command-type first)

yes

Really cool, this works great. Thanks @alexmiller

Is there a spec shorthand to match a literal keyword? (s/tuple #(= % :add) int? int? works, but is a little verbose?

#{:add}

enumerated set as a function

doh, of course, one of the first things you learn with spec. I guess I haven't matched literal values that often

NB that works for all values but false, nil, and NaN

false and nil because match returns falsey, NaN because it won't match

What's the recommended Clojure stack for a CRUD web app? I'm looking to create a site which allows people to add location data to an API map, track the locations the user added, and allow other users to see the locations

Hi guys, I'm trying to test some functions that are implementation of a protocol while stubbing other functions of the same protocol. The scenario is like the following:

(ns my.app.protocol.service)

(defprotocol Service
 (foo? [service args]) ;; Predicate function.
 (bar [service args]))

(ns my.app.impl.service)

(defrecord ServiceImpl [,,,]
  (foo? [service args] (return-true-or-false))

  (bar [service args]
    (if (foo? service args)
      (do-something-if-true)
      (do-something-if-false))))

@yokoyama.km This is why it is common practice to wrap protocol functions so that you can stub the wrapper instead. You cannot instrument a protocol function either, so you have to use a wrapper function in order to leverage instrument.

See, for example, https://github.com/seancorfield/next-jdbc/blob/develop/src/next/jdbc.clj where the API is all wrapper functions around calls to protocol functions -- a common pattern in Clojure.

In this particular case, you can make a proxy of sorts. Say you have an x satisfying Service, you can create a function taking that x and reifying Service and forwards all calls to x but the ones you wish to stub. Not to undermine the advice Sean already gave you ^^

can I pass a conditional into a threaded macro? I'm trying to do this:

->> data
    (if (= "something" "something") 
        function-a
        function-b)
    print

Hello, I have a question about how to cleanly structure code in clojure coming from a Object Oriented background. Let's say I have two function f1 and f2. > f1 uses f1_auxA and f1_auxB. f1 is the only one to use them > f2 uses f2_auxA and f2_auxB. As for f1, f2 is the only one that uses f2_auxA and f2_auxB From what I understand I have to define all these functions in the same file. That's okay for me as long as there are not that many functions. However is there a way to structure the code so I can easilly know that f1_auxA and f2_auxB are only related to f1 and the same thing for f2? I understand I can put them in different files/namespaces, but it might lead to a lot of files for a big project. In OO I would just group related functions in the same class. Are other good practices that you use for this kind of purpose? Thank you for your feedbacks Rabie

Is there a channel to discuss clojure videos?

I've been looking without much luck for discussion about the suggestion in the docstring for empty?:

dev=> (source empty?)
(defn empty?
  "Returns true if coll has no items - same as (not (seq coll)).
  Please use the idiom (seq x) rather than (not (empty? x))"
  {:added "1.0"
   :static true}
  [coll] (not (seq coll)))

the idiom of seq returning a falsey result for an empty input is considered core to the language

it enables direct translation of common-lisp code where an empty list compares false

so to some degree it could be called "historical reasons" from lisp history, but regardless, it's a lot easier to understand clojure if you internalize seq returning falsey for empty input

it's a similar to the reason behind a similar idiom in python, https://stackoverflow.com/questions/53513/how-do-i-check-if-a-list-is-empty

basically, what noisesmith said. seqs are core to clojure and conveying idiomatic usage and behavior of core parts of the language is useful

Sure, I am on board with that in principle. I'm choosing some battles in terms of style in order to make code approachable and this is one I'm willing to cede on, but wanted to make sure there wasn't some other reason behind it

@robertfrederickwarner nb. you can use not-empty to get falsey on empty like seq gives, but not changing the data type if non-empty

(ins)user=> (seq "hi")
(\h \i)
(ins)user=> (defn foo [c] (or (not-empty c) :default))
#'user/foo
(ins)user=> (foo "hi")
"hi"
(cmd)user=> (foo "")
:default

Thanks, I'll have a peek at our uses and see if any can benefit from that