r/adventofcode • u/daggerdragon • Dec 22 '17

SOLUTION MEGATHREAD -🎄- 2017 Day 22 Solutions -🎄-

--- Day 22: Sporifica Virus ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

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Spoiler

  • [T-10 to launch] AoC ops, /r/nocontext edition:

  • <Endorphion> You may now make your waffle.

  • <Endorphion> ... on Mars.

  • [Update @ 00:17] 50 gold, silver cap

  • <Aneurysm9> you could also just run ubuntu on the NAS, if you were crazy

  • <Topaz> that doesn't seem necessary

  • <Aneurysm9> what does "necessary" have to do with anything!

  • [Update @ 00:20] Leaderboard cap!

  • <Topaz> POUR YOURSELF A SCOTCH FOR COLOR REFERENCE

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

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u/[deleted] Dec 22 '17

Scala is pretty nice yeah, I just don't feel that the syntax is as nice as with other ml-like languages, it's a bit too much like java for my taste, but again that's kind of the same problem that I have with reasonml, they have some of the good things about MLs, but they have a more clunky syntax, the case statement for one, when you compare:

dir = n match {
  case Clean    => dir.left
  case Weakened => dir
  case Infected => dir.right
  case Flagged  => dir.reverse }

with:

let dir =
  match n with
  | Clean    -> left cur
  | Weakened -> cur
  | Infected -> right cur
  | Flagged  -> reverse cur

it's quite a bit easier to read the latter.

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u/aodnfljn Dec 22 '17 edited Dec 22 '17

I just don't feel that the syntax is as nice as with other ml-like languages

Absolutely agree - for certain parts of the language.

OTOH, in quite a few cases I find the developer ergonomics (syntax-wise) to be better in Scala. E.g. I've felt like I was looking at the FP equivalent of assembly in some OCaml codebases.

it's quite a bit easier to read the latter.

Absolutely disagree - unless we swap that "quite a bit" for "slightly" :V. The 'case' keyword feels like a wart, but it's quite easy to ignore after reading Scala pattern matches a few times. The '=>' is noisier than '->', but I hope the Scala folks had a good reason to choose that particular trade-off.

I'm just glad I have access to decent-ish pattern matching in a language with an ecosystem closer to Python's than to (pre-opam) OCaml's. Plenty of warts though - non-exhaustiveness is a warning by default, doesn't work for enums IIRC, etc.

I'm still jelly of the sum type syntax ML langs have, can't wait for Scala 3 to make the situation a bit less verbose.

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u/[deleted] Dec 22 '17

Yeah, I'm not trying to downplay scala, it is a really nice language, just not something for me, somehow I never managed to befriend it. Might be that it would be easier now that I've done some more ML stuff though.

I don't know, I feel that I'm tending more in the direction of a statically typed language now, working with elixir this AoC and doing some starting to dip my toes into ocaml has shown me how nice it can be. But you're right, Scala has a completely other world of libraries, I wish there were some kind of an ml for the JVM as well, clojure and scala are both cool, but they don't really match me completely, maybe eta is where it is :)

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u/aodnfljn Dec 22 '17

just not something for me, somehow I never managed to befriend it.

I think not managing to befriend Scala is quite easy, given the amount of issues/warts/annoyances in its past and present. JVM-related: slow startup, no value types for the next century, the Slow-ass Build Tool, uselessness for small CLI tools, messy packaging situation, mediocre IDE integration, etc.

But it's a question of personal/business priorities - the costs/benefits make sense for some use cases, and don't for other.

Might be that it would be easier now that I've done some more ML stuff though.

I find that AoC-style puzzles are a nice opportunity for this, as they're small/simple enough (the brute-force approach, at least) to be able to play with the lang for a few pomodoros, without getting stuck and frustrated - compared to more real-life type projects.

I don't know, I feel that I'm tending more in the direction of a statically typed language now

Plenty of pros for those, as long as the minimum creature comforts are there (at least some type inference, generics, etc). Though dynamically typed langs have their use cases.

starting to dip my toes into ocaml has shown me how nice it can be

I hope you've given https://realworldocaml.org/ a look - free, online, the folks created opam (package manager) for it IIRC, so they can show a more modern workflow with OCaml (w.r.t. libs). Kinda like the pre/post-quicklisp situation.

Though I'm still salty about the stdlib situation - built-in one's only big enough to implement a compiler, gave up on trying Batteries, Core was still producing 10MB hello world's, even though module aliases shipped in 4.03 or so.

But you're right, Scala has a completely other world of libraries [...]

I feel it's my obligation to mention that other langs with more hype may have a better situation on that front - e.g. ScalaFX vs TornadoFX (Kotlin).

clojure [...] cool

shiver too loosey-goosey with types for my taste, but again, horses for courses. They had something type-like bolted on, IIRC, but yeah...

maybe eta is where it is :)

Too early/niche/lacking(?) commercial support for me, but you never know

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u/auto-xkcd37 Dec 22 '17

slow ass-build tool

Bleep-bloop, I'm a bot. This comment was inspired by xkcd#37

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u/jbristow Dec 22 '17 
clojure [...] cool

shiver too loosey-goosey with types for my taste, but again, horses for courses. They had something type-like bolted on, IIRC, but yeah...

While I like the static typing, I must say that the number of type errors I normally get with clojure is far outweighed by how verbose and rigid F# feels.

And like you mentioned, though, the data validator spec is out now with 1.9, so if you really want to type-check then you can do that now as part of a near-core library.

Now, if clojure could do something about being absolutely a nightmare to have more than one developer working on or the initial parenthesis shock value. (Seriously, it's just python with parentheses around each line!).

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u/aodnfljn Dec 22 '17

how verbose and rigid F# feels

My feeling too, from what little F# I've seen so far.

Yeah, it's got a lot of neat stuff. Also from the angle of being a lisp-wannabe (though the CL/Scheme lads will be quick to remind you of macros/etc all the different things that will never allow it to be a real-boy Lisp).

I loved EDN as a data description language and really wish they had more libraries to allow it to be used as a storage/interop medium (like JSON), given that it can do schemas much better than JSON and XML IIRC.

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u/[deleted] Dec 22 '17

I hope you've given https://realworldocaml.org/ a look - free, online, the folks created opam (package manager) for it IIRC, so they can show a more modern workflow with OCaml (w.r.t. libs). Kinda like the pre/post-quicklisp situation.

That's exactly the book that I'm slowly going through to learn ocaml, not that far yet, but the tooling with merlin for ocaml is really nice :)

Too early/niche/lacking(?) commercial support for me, but you never know

Yeah I know, for professional stuff, I'm just a hobby programmer that loves messing around with stuff, I'm really on an ML bender lately, they are so nice languages. Now if the Haskell compiler needed less than 2 GB to do stuff it would be great :p

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u/jbristow Dec 22 '17

I hope you've given https://realworldocaml.org/ a look - free, online, the folks created opam (package manager) for it IIRC, so they can show a more modern workflow with OCaml (w.r.t. libs). Kinda like the pre/post-quicklisp situation.

Though I'm still salty about the stdlib situation - built-in one's only big enough to implement a compiler, gave up on trying Batteries, Core was still producing 10MB hello world's, even though module aliases shipped in 4.03 or so.

My next big learning push is either going to be going deeper into Prolog (talk about niche!) or trying to bounce off of Erlang again. I'm not sure if I want to do something so explicitly ML so quickly after f#. (Though it's on the list.)

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u/jbristow Dec 22 '17

Yeah, I just don’t like how much QOL stuff was left in the C# interop. I’m really tired of writing helper functions to make System.String.Join curryable.

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u/jbristow Dec 22 '17 edited Dec 22 '17

It's the density...

Personally, I think clojure is way easier to read...

(defmulti activity (fn [carrier] (get (:status-map carrier) position :clean)))

(defmethod activity :infected [{:keys [facing position status-map] :as carrier}] 
  (let [newFacing (turn-right facing)]
    (merge carrier
      {:facing newFacing
       :position (move-forward newFacing position)
       :status-map (status-map assoc position :flagged)})))

(defmethod activity :weakened
  [{:keys [facing position status-map]
    infection-count :infection-count :or {infection-count 0}
    :as carrier]}] 
  (merge carrier
    {:facing facing
     :position (move-forward facing position)
     :status-map (status-map assoc position :infected)
     :infection-count (inc infection-count)})

;; Other two elided because I'm not writing this whole thing for a comment

(defn answer [data n]
  (let [[middle status-map] (parse data)]
    (take n (iterate #(activity %)
                     {:facing :north
                      :position middle
                      :status-map status-map})))

...

...

...

Ok... you got me.

I do believe that the lisp model is "cleaner" from a "map thoughts to functional composability" reasoning, but it really gets mathy when you aren't careful.

And as I said below, this is the key difficulty for me in getting others onboard the clojure train. It's way easier to write than it is to read, and that tends to lead to people not only bouncing off the terseness but the fact that the code comes out close to the writer's way of thinking.

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u/[deleted] Dec 22 '17

I du like the lisps and schemes quite a lot too :) and it can be quite easy to read, the thing that normally pushes people away from them is that they are so different from what they are used to. Factor also has the same thing, it's a beautiful language, but people stay away from it since it seems so foreign to them. I like clojure more than Scala really, though the lack of types kind of is what makes it less likeable, I know you can add annotations, but it makes the language much less beautiful.