Clojurians Log v2

the syntax is different from calling a method and getting a property value, the latter requiring a hyphen, i.e. (-.width canvas)

the JS one is fine

Is that all that's wrong with my JS and CLJS attempts? OK, I'll try .-width instead of .width in both.

That little change (adding hyphens) made my CLJS commands work (Great! Thanks!), but didn't work for my JS ones. Actually I am starting to think I may be doing JS interop incorrectly by using the square brackets. Am I? I'm sure I've successfully followed examples of that form before, but I just consulted the main CLJS cheatsheet and it shows #js [] as just something to do with vectors and not general interop.

the #js [...]syntax is not a macro for writing arbitrary code, it is a syntax for constructing data literals (hash-maps or arrays) at compile time

You also need to be sure your REPL is in the namespace that the var is defined. Or if you want to qualify you can do namespace/var-name

If I'm just doing something similar to in the CLJS Quick Start Guide, which REPL am I getting? (with [...]java clj -M --main cljs.main --compile program-name.core --repl )

I think that would drop you in the ClojureScript page repl.

That command would drop you in the cljs.user namespace. So if you have code files, those won't be in that namespace. To access a top-level def variable you'd need to fully qualify it. Say you have a file:

(ns my-app.core)

(def foo :bar)

my-app.core/foo

(require '[my-app.core] :reload)

my-app.core/foo

So far I've been closing the browser tab and hitting [Ctrl]+[c] in the console every time I change something in my code, for a fresh reload every time. I'm running into so many errors trying different coding things that I think I have to do it that way for now, but hopefully once I start getting to just changing working code I can figure out how to get automatic ("hot") reloading going.

An easy-ish thing is just add --watch src to your command that starts the repl, before the --compile Or wherever your source files are, this assumes they are in ./src

Then all you need to do is refresh the browser page. You won't need to restart the REPL command, because it'll auto-watch changed files in that folder for you

The next level is full hot-reload, where it takes it further and you don't even need to refresh the page. But that's more complex to setup.

I have tried adding --watch src but that never seems to work, even after manual page reloads.

Strange. And your source files are indeed inside a ./src folder relative to where you run the command?

I recently noticed that some things are reflected upon a browser refresh, but that just seems to be variable values. If I do anything else, like define new variables or change variable names or, I think, add new code, that doesn't seem to be reflected.

your source files are indeed inside a ./src folder relative to where you run the command?

Good question. vec is a function that creates a new vector of elements taken from its first argument (presumably a collection) vector is a function that creates a new vector containing any arguments you pass it.

user> (vec '(1 2 3))
[1 2 3]
user> (vector 1 2 3)
[1 2 3]

user> (repeatedly 5 rand)
(0.5152826437266472
 0.4053865377084437
 0.9155620586178584
 0.10192533067569265
 0.495269150963787)

I was just returning here to say that I stumbled upon repeatedly and it worked. Thank you. That was a big part of the answer. I think I had to change one other thing as well At first, even after trying repeatedly, I was doing (def v-function-returns (vec (repeatedly 5 (function-with-return-value)))) but needed to not have that function call in its own set of parens (delete them) and do (def v-function-returns (vec (repeatedly 5 function-with-return-value)))

Correct. repeatedly is a so-called higher-order function, which means it expects a function as an argument. The documentation is very good: https://clojuredocs.org/clojure.core/repeatedly "Takes a function of no args ..."

simple_smile

user> (repeatedly 5 rand)
(0.7602804464330288
 0.864122043140823
 0.6044681901148566
 0.7320016864023152
 0.3025718327754262)
user> (repeat 5 (rand))
(0.7487885600966923
 0.7487885600966923
 0.7487885600966923
 0.7487885600966923
 0.7487885600966923)

In the beginning, if it's helpful, you can think 'the innermost parentheses happen first' (like in math).

> but I’m not clear on the difference between vec and vector yet

user=> (doc vec)
-------------------------
clojure.core/vec
([coll])
  Creates a new vector containing the contents of coll. Java arrays
  will be aliased and should not be modified.
nil
user=> (doc vector)
-------------------------
clojure.core/vector
([] [a] [a b] [a b c] [a b c d] [a b c d e] [a b c d e f] [a b c d e f & args])
  Creates a new vector containing the args.
nil

I just watched a video mentioning being able to call up info on functions directly from the REPL being a great feature of clj/cljs too. I'll try to use it more. I did read that difference between vec and vector already, though, on https://cljs.info/cheatsheet/, and it just wasn't clear to me until more recently that "coll" meant the items had to be actually pre-grouped into something like a vector (yes, that seems silly in retrospect).