Hey team, I am playing with writing an implementation for https://sep.yimg.com/ty/cdn/paulgraham/bellanguage.txt?t=1595850613& The first challenge, is parsing a string of bel code.

(bel-parse "(foo bar)")) -> '(foo bar)

(bel-parse "\abc") -> \abc (this is a "character" in Bel)

(bel-parse "`(foo ~x)") -> # TODO: need some way to get the information about "`" and "~", without clojure's reader consuming it

Instaparse

We use Instaparse at work @stopachka to turn an English-like search rule language into a data structure that we then turn in JSON to send to Elastic Search.

oo — that sounds awesome, thanks @seancorfield! Will play with it

I have problem getting the intermediate values with the combination of (map & recursion). I would like to add span (hiccup) according to the nested level of a vector. you could see the level result printed in the repl is correct, but how can I get the evaluation of for loop as well. If I move for loop behind the recursion, because do will evaluate to the last form and this will break the receiving value of the map function of the previous level of recursion. Should I add an external source (like atom) to save my intermediate for loop result there or there exists more elegant way to do this? (code is added in the thread)

@s0930161 Screenshots are hard for us to read. Using a code snippet is easier -- and for a small piece of code like that you could just paste it in between triple backticks so it formats as code. As for the code and your problem, it's unclear what output you're expecting so it's hard to say what the code should do. Your (lazy) for in that code won't do anything because, as you figured, do returns the last expression -- the result of map.

For that input -- [[[[]]] []] -- what output do you want?

👋 I’m here! What’d I miss?

Hi, I have a question about reloading with ring. I’ve used wrap-reload for hot-reloading. It seems if file was changed, reload modified-namespaces. But when I added wrap-reload without main-entry and run it with REPL but It’s not working. I got an error “address in use”. so I added main-entry to run reloadable app and run the program using main-entry, and It’s working. Why do wrap-reload need main-entry? and How can I know it need this?

here is the code that is working

(ns hello-world.core
      (:require [ :refer [copy file]]
                [clojure.core :refer [bean]]
                [ring.adapter.jetty :refer [run-jetty]]
                [ring.middleware.reload :refer [wrap-reload]]
                [ring.middleware.params :refer [wrap-params]]
                [ring.middleware.multipart-params :refer [wrap-multipart-params]]
                [ring.util.response :refer [response]]))

(defn handler [{params :params}]
  (prn "test")
  (response ""))

(def reloadable-app (wrap-reload (-> handler
                                     wrap-params
                                     wrap-multipart-params)))

(defn -main []
  (run-jetty #'reloadable-app {:port 3000
                               :join? false}))

not working one is without (defn -main [] ()) and I loaded file in REPL

"not working one is" may be because port 3000 was already in use when you try to run from REPL. In second case it just reloads the changed file.

Check here > https://github.com/ring-clojure/ring/wiki/Setup-for-development

I expected same thing between REPL and main-entry like reloading changed without restart (REPL or main). I’ve just run only in REPL but same.

(ns hello-world.core
      (:require [ :refer [copy file]]
                [clojure.core :refer [bean]]
                [ring.adapter.jetty :refer [run-jetty]]
                [ring.middleware.reload :refer [wrap-reload]]
                [ring.util.response :refer [response]]))

(defn handler [{params :params}]
  (prn "test2323")
  (response ""))

(def reloadable-app
  (-> handler
      wrap-reload))

(run-jetty #'reloadable-app {:port 3000
                             :join? false})

"test"
2021-08-20 15:06:24.932:INFO:oejs.Server:qtp1546265708-28: jetty-9.4.40.v20210413; built: 2021-04-13T20:42:42.668Z; git: b881a572662e1943a14ae12e7e1207989f218b74; jvm 16.0.1+9-jvmci-21.1-b05
2021-08-20 15:06:24.944:INFO:oejs.AbstractConnector:qtp1546265708-28: Stopped ServerConnector@912a3bf{HTTP/1.1, (http/1.1)}{0.0.0.0:3000}
2021-08-20 15:06:24.950:WARN:oejs.HttpChannel:qtp1546265708-28: handleException / java.io.IOException: Failed to bind to 0.0.0.0/0.0.0.0:3000
"test123"

I've got a

sorry just learning to use slack

I've got a function (defn xmlToString [elem params contents] and if I pass in a vector with apply, that works: (apply xmlToString [:div {:style "color: blue;"} "boembabies"]) but if I pass in a vector of vectors with apply, things break: (apply xmlToString [:div {style "color: blue;"} [:p {} "boembabies"]) then I get "; ArityException Wrong number of args (4) passed to: makeworkflow/xmlToString clojure.lang.AFn.throwArity (AFn.java:429)"

Also: (apply xmlToString [:p {:style "color: blue"} [:div {:style "color: blue"} "boembabies"]]) Gives: ; IllegalArgumentException Don't know how to create ISeq from: clojure.lang.Keyword clojure.lang.RT.seqFrom (RT.java:542)

What is the idiomatic way to make the hash-map {:a [1 2] :b [3]} from [[:a 1] [:a 2] [:b 3]]?

When clojure gives an error message how can I get the closest expression to the error ?

I am trying to learn re-frame and I am getting confused looking at the templates source

(defn ^:dev/after-load mount-root []
  (re-frame/clear-subscription-cache!)
  (let [root-el (.getElementById js/document "app")]
    (rdom/unmount-component-at-node root-el)
    (rdom/render [views/main-panel] root-el)))

I don't understand ^:dev/after-load. I believe it is a reader macro to add meta information, but I don't understand the point of meta information. who uses it/consumes it?

shadow-cljs i believe:

the gist is "my code has changed, react should rerender the application again with the new code"

but here is the init function

(defn init []
  (routes/start!)
  (re-frame/dispatch-sync [::events/initialize-db])
  (re-frame/dispatch-sync [::rp/add-keyboard-event-listener "keydown"])
  (re-frame/dispatch-sync [::bp/set-breakpoints
                           {:breakpoints [:mobile
                                          768
                                          :tablet
                                          992
                                          :small-monitor
                                          1200
                                          :large-monitor]
                            :debounce-ms 166}])
  (dev-setup)
  (mount-root))

i don't think i said that? the metadata on mount-root is what will ensure that it runs after every compiliation

@dpsutton I didn't mean to say you said that, I just understood you as saying that meta information can modify when a function gets called

its just information. shadow runs the compiler, outputs new js, presumably syncs it over a websocket to the browser, and then calls the function that has the metadata that says to call if after loading

it's not magic that somehow happens. that metdata is information to a clojure program, shadow-cljs, and indicates it should call it after loading code

so in this specific case, the ^:dev/after-load is a reader macro that acts like advice? https://en.wikipedia.org/wiki/Advice_(programming)

no. it is just a bit of information associated with the var mount-root. It has no inherent value and doesn't affect the runtime or anything

@dpsutton okay, thank you for helping me understand it

@dpsuttion how do you use meta in your experience with clojure?

sparingly. and i think this is a fantastic use of it here. It's a bit of a special case, but you mark a var as a function you want called. If you are a beginner metadata really isn't something you need to worry about at the moment. It has uses and is easily over-relied upon.

@dpsutton meta seems extremely powerful, but when I was looking at it I just thought "oh, so you can use meta to say this always returns a string" or something very simple and one-use

if genprotobuf.clj in the current folder has a "(defn prototext ..." how do I import this? I'm trying to "(ns somens (:require genprotobuf :refer [prototext])" but this results in "; IllegalAccessError prototext does not exist clojure.core/refer (core.clj:4119)"

@oelewapperke What is the ns in genprotobug.clj? The :require needs the full ns name -- also needs [..`]` around the arguments: (:require [genprotobuf :refer [prototext]])

(ns genprotobuf (:require [clojure.string :only [join split replace]]))

and the ns in the program file is: (ns makeit (:require [clojure.string :refer [join split split-lines]]) (:require [genprotobuf :refer [prototext]]))

If you change :only to :refer in genprotobuf, does that make a difference?

no

I have seen below code , which returns a key, where or when such function will be helpful?

(defn client
  []
  :clinet-key)

Hey all, can't tell if this is better in beginner or reagent, but here goes: Have a react component that needs JSON tree data, passed in as a prop, whats the best way to go about that?

do you have the data already? is it behind an api call?

Step 1 is pass it static data and get the component rendering 🙂

for now I've def'd it and am trying to call it

like

[:> Tree {:source list-mock}]

the EDN is def'd to list-mock

ok so if it is edn and you are using a react component like :> Tree you probably need the data to be javascript objects and not clojurescript data. And we're talking a bit loose here because EDN is a string format but i'm assuming we're actually dealing with the clojurescript values from that string

Yeah makes sense

Is this the part where I pick from one of probably 3 fairly popular libraries for doing this? or have I lucked out and there's only 1? 🙂 or is the real true way to roll my own because it's probably only 4 lines of clojurescript anyway

(clj-js list-mock) should accomplish it

(clj->js list-mock) sorry

Awesome, I always manage to pick the wrong one when there's a choice 😉

Awesome, I see tree data. Thanks so much!