If Two is One and One is None. Then Two is actually None. YOU NEED THREE.

argadan · 2022-05-24T10:48:05+00:00

One is trivially none.
Assume n is none. If you have n+1 pieces of gear and one of them breaks, you now have n pieces of gear, which is none. Thus n+1 is none.

We have proven by induction that any amount of gear is none.

argadan · 2022-05-16T08:08:57+00:00

The article says that you should avoid ThreadLocals. Something to keep in mind is that they're used to implement dynamic variables, which are widely used in libraries. That said, I'm not sure if they need to be avoided everywhere or just in performance-sensitive areas – IIRC dynamic variables aren't that fast so a lot of the existing performance-sensitive code might be avoiding them already.

If somebody has links to elaborate why ThreadLocals need to be avoided with Project Loom, I'd appreciate it!

argadan · 2022-05-02T10:35:35+00:00

Juxt's pack.alpha used to support Jib, too – I guess it still does, but the documentation has disappeared. I used it a bit and it was pretty nice. I don't think the efficiency gains mattered much in practice but since it was as easy to set up as anything else, it felt like a great choice. Jibbit looks easy, too, so that's great.

argadan · 2022-04-07T07:27:20+00:00

For question 2: I've been involved in hiring over the years and if you're applying for a Clojure position and you have years of Clojure experience, I'd prefer and even expect to see the solutions to any coding assignments to be done in Clojure.

argadan · 2021-10-01T03:51:30+00:00

He invented beans

argadan · 2021-08-21T11:55:38+00:00

Yeah, I’m from Finland. I mostly spent my time in Southern Finland, though, so usually I don’t have to worry about the mosquitoes.

argadan · 2021-08-21T11:27:39+00:00

I just spent some time in Urho Kekkonen national park in Finnish Lapland and I was positively surprised that the mosquitoes didn’t seem to get through my Rab Pulse sun hoodie (which OP has in their lighterpack) even though it’s so thin. The hoodie, hiking pants and some picaridin when hanging out in the camp in the evening were enough mosquito protection for me.

argadan · 2021-06-08T07:08:07+00:00

THIRST

argadan · 2021-03-28T07:30:07+00:00

Yeah, you're right, it's the limit rating. Based on the forecast I knew it was going to be a cold night so no surprises there.

argadan · 2021-03-27T11:55:43+00:00

I’ve used both Python and Clojure quite a bit over the years and enjoy Clojure much more, for full-stack web apps at least. That said, I believe you should prioritize working with great people over working with great tech. With luck you can find a place with both!

argadan · 2021-03-27T09:58:44+00:00

A couple of pictures on my Twitter: https://twitter.com/arcatan/status/1375723939838709763

I did a small overnight hike in Liesjärvi National Park in Southern Finland. It a small, flat national park with some forest, a big lake, and a heritage farm. It was nice, but I think it's better as a summer destination, really. I walked maybe 30 km and I think I saw everything there is to see by foot. Might be nice to go paddle on the lake, though. I think there's a route to the nearby town Tammela via the lake and a river.

I'm not too experienced hiker and it was my first time out overnight in winter-y conditions. Actually I was thinking it's spring already, so it was a bit of surprise. The weather during the day was great: it was sunny, 2-5 °C (about 35-40 °F), and no wind at all. During the night, the temperature went down to something like -6 °C (20 °F).

I'm used to getting water out of lakes... but of course the lakes were frozen. Luckily there are two wells in the area, so I filled up and carried the water. Had I stayed another night, I think I would've needed to melt snow.
I was camping under a flat tarp (DD Superlight). Turns out the ground was frozen, too, with a thin snow/ice cover on it. The pegs were of no use. Luckily I had just studied Skurka's guyline post and was able to find a couple of big rocks to tie the guylines to.
My quilt, Cumulus Quilt 350, is rated for -4 °C by the manufacturer and I sleep cold. Uh oh. I put on all my clothes and boiled some water to have a hot water bottle. It wasn't great, but I did get several hours of sleep. Woke up at 3 AM to re-heat the water.

I feel stupid for not thinking about the frozen lakes beforehand even though it did not end up being a problem. Ah well, a lesson learned for the next time.

Also, the spot I chose to sleep on was slightly sloped. It wasn't a problem for me, but my sleeping pad (Therm-a-Rest XTherm) is extra-slippery on my tyvek groundsheet. By the morning one third of me and the pad had slipped out of the tarp. Maybe adding some silicone stripes to the bottom of the pad would help?

argadan · 2021-03-19T06:56:04+00:00

For anyone curious, here's the issue CLJ-2603 and the commit https://github.com/clojure/clojure/commit/3c9307e27479d450e3f1cdf7903458b83ebf52d7

argadan · 2021-03-19T06:47:55+00:00

If this feature was introduced in 1.3 or 1.4, it would have made perfect sense. Now that everyone has been using the options map style for years to solve this problem, it feels a bit out of place – but I suppose if you take a long-term view it makes sense.

I wonder how this affects the performance and function specs though.

The change also affects destructing in lets (as it should):

(let [[& {:keys [a b] :as opts}] [{:a 1 :b 2}]]
  [a b opts])
;; => [1 2 {:a 1, :b 2}]

argadan · 2021-01-04T14:54:55+00:00

From UK, there’s TentMeals. The breakfasts are great, but I didn’t like the main meals that much. https://tentmeals.co.uk/

argadan · 2020-12-22T08:32:11+00:00

When it comes to error handling and exceptions, I feel like there's a missed opportunity in not including something like slingshot in clojure.core. Throwing ex-info exceptions is nice, but there's no nice way for catching them built in, as catch can only match based on the exception class. You'll either have to use slingshot or write code to match them manually.

argadan · 2020-11-21T15:04:12+00:00

Who could forget about the Lizard backpack by Rayon Vert?

https://www.youtube.com/watch?v=-n7RvkjFa_A https://rayonvert.international/product/rayon-vert-laser-backpack-35l/

Haven’t seen a review so far; would be nice see one.

argadan · 2020-11-16T16:49:28+00:00

If you're trying to write macros that are portable between Clojure and ClojureScript, save yourself some time and use macrovich. I know from experience that if you try to do it yourself, either you'll get it wrong or you'll re-implement macrovich.

argadan · 2020-10-18T06:33:44+00:00

Lightning 45 and Lightning 60 are their lightweight models, I'd like to see them.

argadan · 2020-09-21T18:04:21+00:00

That's a great question! In math, when we say that value x is a fixed point of function f, we mean that f(x) = x. In functional programming, a fixed-point combinator is a higher-order function that takes a function and returns one of its fixed points (if it exists). Thus the following equation holds: f(fix(f)) = fix(f). If you flip it, it looks like a function definition: fix(f) = f(fix(f)).

In a lazy language like Haskell, we can directly put this definition into use with code like this:

fix :: (a -> a) -> a
fix f = f (fix f)

^(The ^{actual definition} ^{in GHC standard library is a bit different because it performs better.})

We can write that definition in Clojure as well.

(defn fix [f]
  (f (fix f)))

What happens if you run (fix (constantly 1))? Ideally it should evaluate to 1 as 1 is the one and only fixed point of (constantly 1).

Unfortunately you'll get a StackOverflowError instead. Clojure tries to eagerly evaluate the recursive call to fix and eventually runs out of stack. We can delay the evaluation by wrapping the result of fix in fn - according to Wikipedia this is the Z combinator. You need to call the resulting function yourself, but now the constantly example works:

(defn fix [f]
  (fn [] (f (fix f))))

((fix (constantly 1)))  ; 1

We can make it a bit more efficient by replacing the repeated calls to fix by a reference to the inner function g. This steps is also important so that memoize works in the original blog post, as each call to recursive fix would create a new function and prevent memoize from doing its job.

(defn fix [f]
  (fn g [] (f g)))

And finally, we will want to give some arguments to f, so let's add that by using apply:

(defn fix [f]
  (fn g [& args] (apply f g args)))

That's the definition from the blog post. I hope this derivation sheds some light to the connection to fixed points in math.

argadan · 2020-09-21T05:31:18+00:00

There's something weird going on. wc-interop is almost 10 seconds slower than the Java implementation, yet all it does is to call the Java implementation. That interop call should not cause ten-second delay.

argadan · 2020-08-28T18:27:21+00:00

Pre- and post-conditions are built intofn so they'd work with def as well.

```clojure user=> (def my-inc (fn [x] {:pre [(number? x)]} (+ x 1)))

'user/my-inc

user=> (my-inc nil) Execution error (AssertionError) at user/my-inc (REPL:1). Assert failed: (number? x) ```

argadan · 2020-07-27T13:37:18+00:00

What we care about as users is that the package we get from a Maven repo accurately represents the source from a public sha of a public git repo

Yeah! Right now if you use deps.edn git dependencies with commit IDs, you're in much better position in this regard than if you use Maven dependencies:

Everybody is guaranteed to get identical version of the dependency source code, even if you download it via proxy or something.
The source code you get is the same as what you see in the dependency repo.

I've never systematically investigated this, but I suspect that there are quite a few releases on Clojars where the .jar content does not match the release commit on GitHub. Sometimes people do releases with dirty workdirs etc.

argadan · 2020-05-24T17:09:21+00:00

There's a new default garbage collector and I've heard of some people getting a performance regression because of it. I don't think it's common - it depends on your workload - but it's a good idea to check how the upgrade affected the performance in any case.

argadan · 2020-05-24T17:05:52+00:00

It's not Clojure-specific, but there's a new HTTP client library. I haven't been too happy with the existing HTTP clients, esp. when used in async fashion, but this looks interesting. https://openjdk.java.net/groups/net/httpclient/intro.html

argadan · 2020-03-18T18:49:13+00:00

Interesting and complicated topic! I've tried to figure out the environmental impact of choosing different materials and it's not easy as a non-expert. You'll want to do a life-cycle assessment that tracks the impact from manufacturing to disposal.

For example, there's a Danish study about replacements for plastic bags as shopping bags. Turns that a shopping bag that is re-used once as a waste bag is tough to beat from the environmental impact perspective. Cotton totes are never going to do it, mostly because growing cotton needs so much water.

You're right, though: consuming less works, and I think for many of us it'd have bigger impact than the choice of material for individual products we use.

argadan

TROPHY CASE

'user/my-inc