hi. Just started with hoplon getting started

seeing this when I ran boot dev

tarting file watcher (CTRL-C to quit)... Retrieving clojure-1.3.0-alpha6.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.3.0-alpha7.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.3.0-alpha8.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.3.0-beta2.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.3.0-beta3.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.3.0-RC0.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.4.0-alpha1.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.4.0-alpha2.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.4.0-alpha3.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.4.0-alpha4.pom from https://repo1.maven.org/maven2/ (5k) Retrieving clojure-1.4.0-alpha5.pom from https://repo1.maven.org/maven2/ (5

is this normal ?

What does your dependency list look like?

wistb that's a little unusual but doesn't necessarily indicate a problem, notice how it's downloading just .poms.

is there a nice solution to having a cell act as a reference in one forumla and as a cell in another?

For example, let’s say I have

(defc indicator 1)
(defc= bad? (> indicator 5))

(defc= alert (when bad? (println "BAD: " indicator)))

it’s easy to do by making another ref (e.g. atom) indicator* which watches and changes together with the indicator

but that’s boilerplate, right? 🙂

may be interesting to have a concept of an “active” vs “passive” source cell

or simply getting a read-only ref view of a cell, something like

(defc= alert (when bad? (println "BAD: " (->ref indicator))))

obviously the above won’t work without hoisting macro support

i think the closest thing is do-watch

i can imagine a cell= variant that takes a do-watch function, kind of like the way refs already take validation fns

don’t follow the last approach

cell= takes an optional update function

oh, by cell= i mean, a macro/function you create and name for yourself :-)

didn't mean overload cell= more

@dm3 usually I just use and within my cells

Which solves the "trigger by watching other cell"

@flyboarder not sure how that helps

@dm3 maybe i dont understand the question, what is the problem with your example?

you could be using an anonymous cell instead

I only want alert triggered off bad? cell but also contain the latest value of indicator

does this not work for you:

(cell= (when bad? (println "BAD: " indicator)))

no, because this will trigger every time indicator changes if bad? is true

ah so you want a debounce cell

one that only triggers once or so but when your conditions have changed

i think we wrote that somewhere previously

I really want a concept of a passive cell

which doesn’t trigger formulas

which makes sense to be determined at the use-site

as per my example - the indicator cell is active when determining the value of bad? but passive when used inside the alert

so you dont want indicator to change once bad? is true?

@dm3 ^

yes, when used inside the alert formula

I want the latest value, but I don’t want indicator to trigger the change

another possible name - mute

(defc= alert (when bad? (println "BAD: " (muted indicator))))

I’m following now, I dont think this is currently possible due to how the formula is walked

@dm3 ^

I know 🙂

hence thinking whether it makes sense to introduce a new concept

can I ask what the issue is with the indicator triggering the formula?

I want it to trigger only on state change, but report the latest value

I’m basically doing https://prometheus.io/docs/alerting/rules/ via Javelin

the use case might be rare enough to be solved without introducing additional concepts to Javelin

@dm3 can the indicator continue to change once the alert function is called?

is that why you only want one value?

personally I use your example all the time

sure, it’s constantly changing

but I only want alert when bad? changes

alert is a formula cell

(def alert ((formula #(when % (println "BAD: " @indicator))) bad?)) just came to mind

yep

i guess formula-of cleans that up a tad

yeah, the only issue is with the macro where you have to introduce something to affect hoisting

I guess I can live without that

maybe ~ in cell= can achieve it somehow?

i've forgotten again how that works

that will embed the value

ah yes

actually not, sorry 🙂

if you just say ~cell it won’t do anythin

so ~@indicator is what you want?

no, that would bring the dereffed value into the formula

more like ~(->ref indicator)

where ->ref creates an atom with a watch on the indicator

then actually @~(->ref indicator)

this works:

(defn ->ref [c] (let [a (atom @c)] (add-watch c (gensym) (fn [_ _ _ n] (reset! a n))) a))
(defc indicator 1)
(defc= bad? (> indicator 5))
(defc= alert (when bad? (println "BAD" @~(->ref indicator))))

thx for the help

are you sure you need the intermediate atom?

i wonder about (defn ->ref [c] (deref c))

the quoted thing will become an argument to the formula

and then (->ref ~indicator)

won’t help as formula looks for arguments which are cells

so it must not be a cell in order to be muted

it either needs to be 1) embedded within the formula with @indicator 2) passed in a way where it’s not recognized by cell? predicate

maybe cell= could understand some meta on symbols

so you could do like (cell= {:x x :y ^passive y})

i'm kind of into it because then it becomes the inverse of formula-of hehe

formula-of-not

...formula-except

yeah, formula-NOT makes sense 🙂

hm, i need to update the templates i think

:thumbsup: