If you rely on sequential generation then you may still want to have iteration. I think for your "generate a new element" list creation you could use iterate ant take-while. And for the outer for j in range(total): you could use reduce and then terminate early using reduced . Also in Clojure you wouldn't need to do any copies yourself as it's handled for you.

Thanks for the hints! Here is my attempt to rewrite in declarative expression:

(defn calculate [a k decider]
  (let [decider (fn [ [ a b c & rst]]
                  (and (= 1 a) (= 1 b) (= 0 c)))
        f (fn [lst upper]
            (if (empty? lst)
              []
              (let [ [ fst & rst] lst]
                (if (>= fst upper)
                  (concat [0]         (f rst upper))
                  (concat [(inc fst)] rst)))))
        pow (fn  [x n]
              (reduce * (repeat n x)))
        
        n (count a)
        seed (for [i (range n)] 0)
        total (pow n k)]
    (if (or
         (< k 1)
         (> k n))
      (throw (Exception. "IllegalArgument: k."))
      (reduce (fn [a v]
          (let [_last (last a)]
            (if (decider _last)
              (reduced  a)
              (conj a (f _last (dec n))))))
        [seed] (range total)))))
(calculate ['a' 'b' 'c' 'd'] 3 (fn [[fst snd thd & rest]] (and (= fst 1)
                                                              (= snd 1)
                                                              (= thd 0)))

[(0 0 0 0) (1 0 0 0) (2 0 0 0) (3 0 0 0) (0 1 0 0) (1 1 0 0)] 

I suggest to split it into two or three different functions :thinking_face:

You meant take out the inline lambda function as separate ones outside of the function calculate?

@U2QGRCMSM I actually didn't understand what the code should do. Can you explain what it's expected of it, so maybe I can show an option tomorrow?

I have no idea what the function does but what I DO know is that all functions in your let definition should be defined separately and have proper names. And you have three there.

Thanks! I'll try to give them names and move them outside to make it more readable.

The more names the better. A good name is add-numbers or take-out-the-trash or fly-rockets.

(defn decider
  "Determine if the expected element found?"
  [ [ a b c & rst]]
  (and (= 1 a) (= 1 b) (= 0 c)))

(defn from-last-element
  "Generate a new element from the last element of the existing list."
  [lst upper]
  (if (empty? lst)
    []
    (let [ [ fst & rst] lst]
      (if (>= fst upper)
        (concat [0]         (f rst upper))
        (concat [(inc fst)] rst)))))

(defn pow
  "Power of x to the nth"
  [x n]
  (reduce * (repeat n x)))

(defn calculate [a k decider]
  (let [n (count a)
        seed (for [i (range n)] 0)
        total (pow n k)]
    (if (or
         (< k 1)
         (> k n))
      (throw (Exception. "IllegalArgument: k."))
      (reduce (fn [a v]
          (let [_last (last a)]
            (if (decider _last)
              (reduced  a)
              (conj a (from-last-element _last (dec n))))))
        [seed] (range total)))))
(calculate ['a' 'b' 'c' 'd'] 3 (fn [[fst snd thd & rest]] (and (= fst 1)
                                                              (= snd 1)
                                                              (= thd 0))))

What did you use to host the app? AWS is a collection of building blocks and some services that configure them

I currently making my certificate work. Found that I had to make the HTTP load balancer return a redirect to HTTPS. And I'll also create a cerfiticate.

> wget <http://_>._._/ -v

--2022-06-26 21:24:39--  <http://_/>
Resolving _ (_)... _, _
Connecting to _ (_)|_|:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: <https://_:443/> [following]
--2022-06-26 21:24:39--  <https://_/>
Loaded CA certificate '/etc/ssl/certs/ca-certificates.crt'
Connecting to _ (_)|_|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 2211 (2.2K) [text/html]
Saving to: 'index.html'

index.html                                                  100%[==========================================================================================================================================>]   2.16K  --.-KB/s    in 0s      

2022-06-26 21:24:39 (33.5 MB/s) - 'index.html' saved [2211/2211]

If you are hosting on a single instance you can use something like nginx and let's encrypt for your certificate

Currently I start with one instance that does too much stuff and then I'll probably need to split it into several instance types. So I don't want to commit yet.

What if it's a static HTML page? If it's simple and doesn't send or receive data, who cares?

But even if it's HTML page that you can interact with and that doesn't submit data to your backend... it could be a smart-contract page and then it's better to serve it through HTTPS :thinking_face: And then if it's your portfolio page then it's not nice if you get warnings from browser :thinking_face:

HTTPS makes sense even for web 1.0 HTML pages. I'm 90% certain that there have been cases of internet providers incorporating ads into plain HTTP HTML pages - exactly because HTTP does not prevent any MitM attacks.

https://arstechnica.com/tech-policy/2014/09/why-comcasts-javascript-ad-injections-threaten-security-net-neutrality/

That sounds... Terrifying

Only a little MitM attack, as a treat

Is it possible if the website has no js?

Yes, because it's modifying the bare HTML

So it's fairly trivial if you've got the MitM to inject <script> tags

If you configure your browser to run that page without JS they still can include static HTML but then the scripts won't run. But then they can even show "enable JS for full functionality" instead of the original so that you would enable the JS for them. Which would mean they could run the scripts anyway.

No need for JS at all. Just inject a bunch of <p>Your PC is infected, <a href="...">CLICK HERE</a> to fix it</p>.

Change all links to be scam links

Or better, change the entire page to be an invisible <a> tag

If you want to do this then why not return a 302 redirect instead of the content of the HTML... Way simpler.

Perhaps. But in any case, the point is that HTTPS is needed almost everywhere. :) Regardless of the kind of the content. "Almost" because you can use third-party things to check the content, like e.g. it's going on with HTTP Debian repositories.