just to confirm, smt in clojure (alter) only offers snapshot isolation, and still suffers write skew ?

do you mean stm?

the correct way to use stm is to write code that uses the snapshot value meaningfully (except the null case of unconditional rewrite...), and the retry mechanism plus ref capture will help that function keep things coherent

that won't save you from the sort of error your function could make in a single thread, but makes preventing concurrency errors much easier

@i to directly answer your question, the retry mechanism of transactions means write-skew doesnt' happen if you use it correctly

You can use ‘ensure‘ on reads to prevent write skew if needed

oh yeah, I should have name checked that instead of vaguely mentioning "ref capture", thanks

yup. ensure. I forgot that. so that indicates alter re-tries only if the ref it refers to have been updated, not the world state (all refs in a transaction).

iirc the classic ants demo from Rich Hickey demonstrates that write-skew doesn't happen can be effectively prevented

Correct

write-skew can definitely happen

ensure prevents it but reduces concurrency, but have control to choose

is rand-nth not working on sets intentional or accidental? if intentional what's the reasoning?

I guess "nth" is in the name, but since it's point is to not care about the order, erroring on sets seems like a misfeature

how can we use ns meta to run tests using kaocha for example if I have (ns ^:foo file1-test) (ns ^:foo file2-test) how can I run just both of them using the ns meta There is a :focus-meta config we can specify in tests.edn but the problem I’m facing is it runs only the first match.

Has anyone got an idea what on Earth is going on here?

(require '[co.ytems.model.money-amount])
=> nil

(require '[co.ytems.model.money-amount :as money])
Syntax error compiling at (/private/var/folders/62/3v4gckg15t706bjzkjw155n00000gq/T/form-init6286340574717549821.clj:1:1).
namespace 'co.ytems.model.money-amount' not found

any chance you edited the file and it no longer declares the same ns symbol in the declaration as the one you required?

Is there an idiom for coercing a val to a collection if a collection was not passed?I'm using this at the moment:

(cond (coll? x) x (seq? x) x :default [x]))

coll? is true for everything seq? is true for

:else is the most common constant used for a else case in a cond

Thanks. I got tripped up since (coll? (seq [])) is false. But that is since (seq []) is nil not a seq. I was hoping for something simpler like (into [] x) but into doesn't support that usage.

as mentioned in the thread above, there's also seqable? - depending on how you would treat eg. strings, hash-maps, arrays

org.noisesmith.hammurabi.hold-my-beer=> (pprint (map (juxt identity seqable?) [nil [] "" () #
{} {} (byte-array 10) 1 (reify Object) (fn [])]))
([nil true]
 [[] true]
 ["" true]
 [() true]
 [#{} true]
 [{} true]
 [[0, 0, 0, 0, 0, 0, 0, 0, 0, 0] true]
 [1 false]
 [#object[org.noisesmith.hammurabi.hold_my_beer$eval15945$reify__15946 0x130a3d99 "org.noises
mith.hammurabi.hold_my_beer$eval15945$reify__15946@130a3d99"]
  false]
 [#object[org.noisesmith.hammurabi.hold_my_beer$eval15945$fn__15948 0x22895cca "org.noisesmit
h.hammurabi.hold_my_beer$eval15945$fn__15948@22895cca"]
  false])
nil

Okay so I have this method that applies highlights to hiccup and cannot figure out how to get the highlighted vector to not be in a seq

(defn find-body-text
  [hiccup rule]
  (into []
        (for [element hiccup]
                (cond
                  (string? element) (highlight-text element (:regex rule) (:color rule))
                  (vector? element) (find-body-text element rule)
                  (some? element) element))))

Call=>
(find-body-text (labelmaker.views/playground) {:regex #"quick" :color "#333"})

Returns =>
[:div
 [:span.p-3]
 [:p ("The " [:mark {:style {:background-color "#333"}} "quick"] " brown fox jumps over the lazy dog")]]

I feel like I am missing something on getting the highlighted text from ("The" ...) to just items in the outer vector.

that should blow up and tell you that "The" isn't a function

Sorry edited to show the defn, call, and return

I want the highlight-text to return just "The " [:mark {:style {:background-color "#333"}} "quick"] " brown fox jumps over the lazy dog" instead of ("The " [:mark {:style {:background-color "#333"}} "quick"] " brown fox jumps over the lazy dog")

what does highlight-text do?

you can't return multiple items without some collection around them

Applies a regex to some text string and returns a vector of strings and hiccup :mark items

if you don't want it to be a list, you can use vec to make it a vector instead, which hiccup should do the right thing with here

that's clearly not a vector of strings

perhaps you are using the result of a regex split that is in a list or lazy-seq? anyway, vec in the caller or in the function itself would both suffice surely

The other two cond options only return 1 item which I think is my issue, is there some way to pull each item out into the parent vector?

Yea, you can use (into [:p] children)

@isak my last case was just returning the keywords, but seems like I need to treat them different and start each new vector after seeing one.