super excited that we have nav and datafy in CLJS now! 😄

hi guys

how could i navigate to specific div in the page from clojurescript?

@abdullahibra what is dommy? are you sure you are calling that right?

@thheller [prismatic/dommy "1.1.0"]

https://github.com/plumatic/dommy/blob/master/src/dommy/core.cljs#L294-L299

that only takes a bool argument. not a js object

[elem ^boolean align-with-top?]

it takes two args

elem and align-with-top? as boolean type

yeah but you are calling it with elem and the clj->js result (which is not a boolean)

oh right

maybe this was old version

you don't really need dommy for this

(defn scroll-to-id
  [target-id]
  (-> (js/document.getElementById target-id)
      (.scrollIntoView #js {:behavior "smooth" :inline "nearest"})))

should do fine

that's good

can i scroll to top of div?

ah

inline "start"

@thheller thanks 🙂

that's the right params {:behavior "smooth" :block "end" :inline "nearest"}

How do we use type hints in Clojurescript and how does it relate with type inference? I am running this code snippet on version 1.10.516:

(defn bar [^number x]
  (inc x))
  (bar "abc")

(inc "abc")

cljs.core/+, all arguments must be numbers, got [string number] instead

@viebel pretty sure that is reserved to special js forms currently and not supported via type hints

@thheller Is there a support for type hints in cljs?

yes, plenty. the numeric stuff just doesn't take those into account (yet)

@viebel ClojureScript doesn’t generally use type information for type checking.

@mfikes Under what conditions a warning about argument type is emitted?

@viebel The core numeric macro-functions do this. Outside of this I’m struggling to think of any other specific examples.

@mfikes I see. Any idea why in my 1st example above no warning is emitted?

@viebel Because ClojureScript doesn't generally use type information to perform type checking. There was an experiment that, as an aside, involved adding generic type checking (https://gist.github.com/mfikes/1e2341b48b882587500547f6ba19279d), but ClojureScript probably isn't pursuing that direction.

Hmmm @mfikes So what is the big story with type inference?

ClojureScript has always had basic type inference, and the algorithms have been improving, so that more types are inferred. This is especially true over the past several releases, IMHO.

I understand that the algorithms are improving. My question is what value does it bring to developers?

Is it in terms of type checking or more efficient transpiled code or something else?

The latter—type information is primarily leveraged to generate efficient JavaScript.

Any interesting example to share?

Look at what gets generated by and if it knows its arguments are Boolean

A silly example: the code generated for (str x) when x is known to be a string

By the way, I’ll be giving a talk about this at Clojure/north

@mfikes excellent. I am looking forward to watch the video of your talk