Does JS and/or ClojureScript provide a way to restrict oneself to exact integer arithmetic, i.e. wrapping or exceptions are OK, but auto-promoting to floating point numbers is not?

no

ClojureScript is just JS arithmetic - so semantically doubles

VM of course attempt to do integer arithmetic for performance and we rely on that - but there's no way to do anything that wouldn't damage perf

So even all the JS stuff like (num | 0) doesn't prevent arithmetic ops from promoting to floats?

nope

that just clamps to int

but semantically N.N... to N.0

I think AppleSoft BASIC was the last language I used that did that. Maybe Perl, I guess.

People that implement bignum arithmetic libs in JS are just really careful with their arithmetic expressions I guess?

no

you have to implement your own arithmetic

foo.add etc.

could have probably done things that way in the beginning but probably would have needed to do a lot of stuff to recover perf

but time has shown it to be a very low value add for most users - JavaScript thus ClojureScript aren't used much for numerics

makes sense. Just trying to familiarize myself with the differences. Thx for the quick info.

It's a fundamental JS issue - so if / when it gets sorted out there - we'll probably follow along

I asked this here before but I'm going to ask again in hope to get some more input: Does anyone have experience with embedded databases in ClojureScript (Electron)? I'm trying to figure out what I'd best use for a small amount of entities with few relations but possibly a lot of datapoints/rows for each entity. I want the data to be persistent on the users computer and don't want that the user needs to install additional tools (ex. MongoDB). My current contestants I found are: LevelDB (Through LevelUp), Sqlite3 (embedded) and NeDB (embedded MongoDB-like DB). Any experience report / suggestions / inputs are welcome 🙂

I should maybe add that I'd like to implement text-search features at some point which might make a difference

how can I start a repl-env such that I can run (cljs.repl/-evaluate repl-env "<NO_SOURCE_FILE>" 1 "console.log('hi');")?

Hello! Can I get js array element by index in more js-y way, than (-> arr js->clj first)? Js arrays have not get or at magic methods, but I dont know how to use [] in cljs interop 🙂

(aget arr idx)

Thanks!

in fact you can use nth

(nth #js [1 2] 1)

as well as first

oh, just directly with js objects?

yep

JS Array to be precise

magic! :male_mage:

if you know you are working with js array it is better to use aget directly

nth always needs to check the coll it is working with first

How can i force the execution order of these three things in clojurescript world? The second one is blocking (right now testing with js/timeout for some ms):

:on-click (fn []
                          (reset! updating? true)
                          (edit-complete-handler-fn @updated-value)
                          (reset! updating? false))

the first and third run immediately, even before second is completed

what does edit-complete-handler-fn look like?

@dpsutton right now:

(fn [] (timeout (reset! edit-mode? false) 3000))

timeout is just (js/setTimeout f ms) ..

.... and looks like i found the bug

the reset function is supposed to be a lambda :face_with_rolling_eyes:

that you're calling reset! immediately. yup 🙂

hmm, that fixed the dialogbox immediately closing, but updating? ratom is not changing the actual button to "disabled"

I think those three expressions are still executed in async

Why schedule resetting it to false if you immediately swap it back to false?

they are different ones. edit-mode is local to parent component, setting it true opens up dialog, the`on-click` handler is in "update" button of dialog. I wanted to disable the button while it is updating, so updating? is component local for the dialog (not the parent component). What needs to be done for "updating" is handled by the parent, thus edit-complete-handler-fn is a callback to parent with the updated value

I guess I could just skip setting udpating? to false as well since the dialog is going to go away once the value is updated

(reset! updating? true) ;; disables button
(edit-complete-handler-fn @updated-value)
(reset! updating? false) ;; reenables button?

yes

then that's so quick you shouldn't really see the button as disabled

yes, but edit-complete-handler-fn takes 2 seconds to complete (js/timeout), it should have disabled it and then in 2 seconds enable it but it is async so both get fired before the actual handler function is completed. For now I think i can skip the last expression altogether.

it doesn't

it completes immediately

it schedules something to run in 2 seconds

aah.. that is where I misunderstood

how can i make that function to take 2 seconds? sort of like (Thread/sleep 2000) in java/clojure ?

that doesn't exist in js

yikes!

How do you simulate long running process in clojurescript/js ?

promises, core.async, callbacks. there are several tools

@neupsh

on-click (fn []
                          (reset! updating? true)
                          (js/setTimeout (fn [] (reset! updating? false)) 2000))

Anyone know why Clojure keeps 0.0 as 0.0, but CLJS changes it to 0?

In ClojureScript, numbers that happen to be integers are rendered as such. (ClojureScript uses the one JavaScript numeric type.)

In, short, it is just a rendering concern.

try 0.0 in a browser console and you'll observe the same behavior

Ahh, TIL

$ jsc
>>> 0.0
0
>>> 0.1
0.1

(Node and GraalJS behave similarly; perhaps this is specified? Cool.)

I think that js just has “number” there aren’t integers at all. So js doesn’t (and cant) distinguish an integer zero from a float zero

Right. The specific thing I'm wondering about: Does JavaScript specify how numbers are rendered, thus causing the console and all of the JavaScript REPLs above to print zero as 0.

I can’t imagine any way to do it without tagging all numbers with precision. How would it print 0.0, 0.00, etc

But your question is about specification and not implementation right?

Yes, probably 7.1.12.1 step 2 which says > If m is +0 or -0, return the String "0".

http://www.ecma-international.org/ecma-262/10.0/index.html#sec-tostring-applied-to-the-number-type