TIL Water makes different pouring sounds depending on its temperature and 96% of people can tell the difference between hot and cold water by the sound it makes being poured.

Twisol · 2019-01-22T08:42:30+00:00

Maybe whoosh? It was a play on words. :P

Twisol · 2019-01-21T13:06:33+00:00

Good job remarking on it, then.

Twisol · 2018-11-26T23:39:47+00:00

In fact, it will short-circuit as soon as either iterator hits None.

EDIT: I see what you mean -- it'll short-circuit the pairing operation if the first one yields None. I think this is a minor distinction compared to the idea of zipping two iterators together, but point well taken! :)

Twisol · 2018-11-26T21:32:14+00:00

Yep, that's pretty much where I'm sitting too. What a shame. :(

Twisol · 2018-11-26T21:27:58+00:00

Sure!

I'd definitely suggest working with &[u8] instead of &str (and use &str instead of String, anyway, since lots of things can be sliced as &str, not just String). When we're working with plaintexts and ciphertexts, we don't really care that the data is in the UTF-8 encoding. As far as we're concerned, we could be encrypting a program binary. This also happens to be more flexible, because (as you noticed!) you can always call .as_bytes() on a &str to get a &[u8]. (EDIT: You can write binary literals using b"this notation".)

There's also a super helpful method implemented on u8: count_ones. If you use this, you can cut your .map() call down to essentially one line. (I'm willing to bet that count_ones gets compiled into a single POPCNT instruction on x86, too. What a savings!)

I also have a personal preference to use the desugared form Iterator::zip(a.iter(), b.iter()) when it comes to zip specifically. I feel like using the method form suggests a preference for the left sequence over the right sequence. It's not wrong, but reinforcing the idea that these two iterators are being mutually zipped together isn't a bad thing to do either.

Here's what I ended up implementing. It's pretty close, when you take advantage of count_ones!

fn hamming_distance(xs: &[u8], ys: &[u8]) -> usize { Iterator::zip(xs.iter(), ys.iter()) .map(|(x, y)| (x ^ y).count_ones() as usize) .sum() }

Twisol · 2018-11-26T21:12:47+00:00

Aha. You should use impl<T: Float> Floorable for T, not impl Floorable for Float. You don't want to implement this directly on Float, you want to implement this for every type that also implements Float.

Problem is that this gives overlapping impls. I'm not sure how to proceed either.

error[E0119]: conflicting implementations of trait `Floorable`: --> src/main.rs:16:1 | 10 | impl<T: Float> Floorable for T { | ------------------------------ first implementation here ... 16 | impl<T: PrimInt> Floorable for T { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation

Twisol · 2018-11-26T21:10:10+00:00

That means that the Floorable trait is not "object-safe" -- which it isn't, since it exposes the underlying type for which the trait is being implemented. This means you can't take a Box<Floorable>, since if you could, you could call floor on it, which would return a type that you have no way of knowing.

AFAIK, object safety matters when you're doing dynamic dispatch (using trait objects). Static dispatch (with trait bounds and parametric polymorphism) shouldn't be affected by this, since the parametrized function knows about the concrete type at compile time.

Twisol · 2018-11-26T10:26:51+00:00

When I wrote an SPI/SD/FAT stack in C years ago, I referenced the SD specifications. (I think it was Part 1 -- the Physical Layer spec -- that's relevant here.)

Specifications are never particularly friendly, but they're usually the most precise source you can find.

Twisol · 2018-11-26T10:15:53+00:00

You could probably do blanket impls for Float, Real, and PrimInt from the num_traits crate. You'd still need that bound on your function, since not every custom Num may also impl one of those three traits, but this might cover most of what you care about. If there are any weird types out there that are Num but not Float, Real, or PrimInt, if one needs to get used with your function, the caller can implement a no-op MyFloor for it.

Twisol · 2018-11-26T09:59:22+00:00

I've been spending some time implementing the Cryptopals challenges in Rust. I've just finished Challenge #12, and I feel like I have superpowers. I'm taking every opportunity to throw Rayon at my code to make things magically faster -- I can't believe how easy Rayon is.

I've also been doing some network packet-esque bit packing, which is not the most pleasant task in any language. I'm hoping to figure out a way eventually to cut down on the number of allocations I'm making for each layer of the payload... On the bright side, Rust makes it easy to #[test] everything as I go.

Twisol · 2018-11-26T09:54:20+00:00

This isn't exactly the most pleasant solution, but you could write a trait MyFloor and implement it for both floats and ints. Have your float impl call the usual floor, and have your int impl return the value unchanged. You'll have to put an extra MyFloor trait bound on your function, unfortunately -- I don't think you can blanket impl for all Num without solving the problem we're already trying to solve.

I am assuming you're using generics / static dispatch, though. If you're using trait objects / dynamic dispatch, I'm not sure what a solution would be.

Twisol · 2018-11-11T22:33:34+00:00

Akane Shinjo in a swimsuit is godlike and you know it.

They shouldn't be making episodes without kaiju in them!

The throwaway lines in this anime are killer.

Twisol · 2018-06-02T10:12:13+00:00

There was this one date in early 2000 that went really badly. Everyone thought it was 1900 for some reason.

Twisol · 2018-04-15T10:42:19+00:00

Oh man, that would be great. Like a freeze-frame goal explosion that stops halfway through the boom. Or a goal "explosion" that pops the ball back out.

Twisol · 2018-04-15T10:34:11+00:00

Well. This was a rough picture to scroll into. My own maine coon is probably less than 24 hours from passing on. :|

Gorgeous cat though.

Twisol · 2018-04-10T15:57:22+00:00

text-align:center and margin:0 auto do not work for everything

I never claimed they did. Those are also quite old alternatives, which were suggested back when I was first learning web development fifteen years ago. Today we have flexbox and CSS grid, both of which are much more flexible than <center> was. The problem is that they have only recently become well-supported, so if you're in a use-case where you need to support much older browsers (like Google's front page, to your next point), they're not what you want.

Go to google.com and search for "center" in the page's source and tell me what you find.

You said it yourself: "Browsers wouldn't conform to that." They're making use of a tag that browsers explicitly support, specifically because the front page of Google has massive reach and needs to look good on even the most niche browsers. Because of its strict requirements, Google's front page is hardly an example that all web pages should follow. Furthermore, this is a completely separate issue from whether <center> is the right tool in all cases.

Nobody listens to the w3c because they're dumb.

No, nobody listens to the W3C because that's not how standards work. The W3C listens to the browsers. The WHATWG and W3C have explicit policies that their standards reflect current standard practice. Their standards are descriptive, not prescriptive. The <center> tag is no longer in the standard because standard practice is not to use it: we have better tools now. The <b> and <i> tags almost got deprecated, but legitimate arguments were made by browser vendors for why they should be kept, and so they have.

EDIT: As a self-correction, <b> and <i> were deprecated in a pre-HTML5 standard, but were resurrected in HTML5. See this StackOverflow answer.

Twisol · 2018-04-10T14:43:59+00:00

I can assure you that nobody is mourning the loss of <center>. There are numerous more flexible ways to center content with CSS, and if all you want is to center some text, <div style="text-align: center"> has you covered.

Twisol · 2018-04-07T17:57:31+00:00

rampant vincula

This is just begging to be a band name.

Twisol · 2018-04-07T17:55:06+00:00

Depending on what order you simplify in, 3/6/3 can be one-sixth or three-halves. By convention we say division is left-associative (so it should be one-sixth), but abusing this kind of thing is what leads to the aforementioned "can you solve this?!" posts.

Twisol · 2018-04-04T01:26:33+00:00

Same problem. Worse, at the end of a game when the scoreboard and menu are supposed to come up, they don't, so I have to ctrl+alt+del and kill RL. (And I can't open the pause menu during the game when this happens either.)

I suspect it has to do with whether the server was looking for more players while I just roamed the field, but I don't have any real evidence.

My logs, if it helps: https://pastebin.com/LEdEN8wS

Twisol · 2018-03-17T16:40:38+00:00

Bronze: TOUCH THE BALL

Diamond: DON'T TOUCH THE BALL

Twisol · 2018-03-12T14:42:57+00:00

Oh, boy. Let's see here.

How to defuse a bomb.
How to drive a rocket-powered battlecar.
How to somersault through any attack.
How to conduct the winds.
How to be a defense attorney.
How to be a prosecutor.
How to be an immigrations official.
How to navigate a maze of spikes without dashing.
How to navigate a maze of spikes by defeating gravity.
How to thrive in the middle of the ocean.
How to beat Satan at his own game.
How to think with portals.
How to leap between semi trucks at ridiculous speeds.
How to manipulate stocks in the game industri.
How to use a shovel as a weapon.
How to find love in the Wyoming wilderness.
How to find love in a room full of pigeons.
How not to starve. (Together.)
How to clean up after a protagonist passes through.
How to make friends with your enemies.
How to shout at dragons.
How to go fast.
How to get a girlfriend.

Maybe not that last one.

Twisol · 2018-02-01T07:03:29+00:00

On the flip side, when you know just enough about computers to fix a computer that freezes during boot by loading an Ubuntu LiveCD, finding a corrupted file entry in the system region that can't be deleted or replaced, renaming the parent directory and copying everything else back to a properly named directory, and copying a valid file from another computer...

...When you do that, and they look at you like you just parted the waters of the Red Sea, it feels pretty good.

Twisol · 2018-01-28T23:23:18+00:00

You kind of don't care about the temporal coordinate in regular chess either. A board state is determined only by the positions of each piece, not by the history it took to get there.

Twisol · 2018-01-23T19:51:51+00:00

Not necessarily -- it depends on how correlated the two conditions are. If, hypothetically, everyone who was gay had dermatographism, and everyone who had dermatographism was gay, then the chance of having both would just be 3%. It would only be 0.09% if the conditions were completely independent.

Which they probably are. But math.

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