ddragon (u/ddragon) - Readit News

ddragon commented on Mojo is available for local download modular.com/blog/mojo-its... · Posted by u/hasheddan

zogrodea · 3 years ago

Richard Feldman states in a video aiming to explain the popularity of OOP that Python initially had a small community for decades, and that Python's increase in popularity followed a slow and steady increase, which is not true of many other languages like Ruby. That's corroborated by the graph in this article. [0]

Based on Python's slow and steady incresae, timing and luck don't seem like good factors for explaining its popularity. The others are debatable though.

[0]

https://flatironschool.com/blog/python-popularity-the-rise-o...

ddragon · 3 years ago

I fail to see how timing and luck isn't a factor. It's more than how popular it was when it launched, many of those languages that are allegedly better had a strong timing disadvantage by either not existing or not being mature once the data science boom occurred (including equivalents to libraries like numpy, scipy, matplotlib and theano), allowing python to be the right option then. Any language that missed the timing must now play catch up with a fraction of the resources and completely unproven in the market.

Luck is harder to quantify, but at the very least competitors like common lisp didn't have much of it.

ddragon commented on Mojo is available for local download modular.com/blog/mojo-its... · Posted by u/hasheddan

gostsamo · 3 years ago

if the better languages were actually good, they wouldn't have allowed python to whip their asses. Python won because it was nice and easy. meet your users where they are, not where you want them to be.

ddragon · 3 years ago

That would be simplifying too much. There are a lot of external factors for something being popular, like timing, luck, support from big enterprises and leading colleges, inertia and sunk costs. You could argue that does make python better regardless of the language itself but that poster was talking about a hypothetical scenario in which those factors were won by a language better designed for those tasks. Would you use python if most libraries, docs and support were elsewhere just for the language design as is today?

ddragon commented on Julia 1.9 julialang.org/blog/2023/0... · Posted by u/kristofferc

ddragon · 3 years ago

I'm quite interested in the interactive thread pool (although I assume it works based on conventions of everyone playing nice). Julia seems to have a powerful parallelism model but it couldn't apply it to responsive GUI and web frameworks that requires low latency, so it is nice if you indeed can have for example the tasks handling HTTP request focusing on handling it as fast as possible while the background working threads dealing with larger computations use all the speed of the Julia language without being constantly interrupted.

ddragon commented on PyTorch: Where we are headed and why it looks a lot like Julia (but not exactly) dev-discuss.pytorch.org/t... · Posted by u/thetwentyone

bjourne · 4 years ago

But that scheme is the same as green threading and has the same faults. Start Julia with one system thread. Run one infinite loop in one green thread and another in another green thread. One of the loops will run while the other will wait until the other completes (which it never does). This is inferior to Java and C# which both uses system threads by default, allowing both infinite loops to run. Erlang/Elixir has the same problem. You can run thousands of green threads, but if one of them is stupid enough to call a blocking C function then all others have to wait.

ddragon · 4 years ago

That issue actually doesn't happen with regular elixir, since it's immutable and stateless, the scheduler doesn't wait for the process to voluntarily wield (it's always safe to switch, so it just gives some fixed time for each process, which makes it very low latency and very reliable but not very efficient at any individual task due to all the switching). Calling other languages from erlang/elixir create dirty processes that can't be scheduled this way and may cause those issues.

Since I didn't use dirty processes in elixir it did make me forget about this obvious issue you pointed out, that for a mutable language like Julia can happen in every thread, but that's not something that limits the expressiveness of the model, but something that requires consideration to avoid while programming and language level mechanisms to protect the thread (at the very least the ability to define timeouts that can throw an exception on any spawned process) or maybe a future framework on top of it that handles this in a safer way (something like Akka). I can only hope Julia can achieve the full potential of it's multithreading model.

ddragon commented on PyTorch: Where we are headed and why it looks a lot like Julia (but not exactly) dev-discuss.pytorch.org/t... · Posted by u/thetwentyone

bjourne · 4 years ago

According to this discussion thread, Julia requires the number of kernel threads to be specified at startup: https://discourse.julialang.org/t/does-multithreading-requir... This seem to be more like pyprocessing and much more limited than the pthreads interface.

ddragon · 4 years ago

I didn't go deep on Julia's multithreading, but what he is saying is that Julia uses an MxN threading (I think nowadays if you don't specify it at startup it will just use one for each cpu thread), which is the same as a language I did most of distributed programming (elixir/erlang), and as far as I know it's the same as Go.

Having 1 kernel thread for each CPU thread means that your program can use all available CPU threads at the same time (so you get all the parallelism available within the machine), and having a language based scheduler for each thread means you can have minimal overhead (no need to do a system call) to create a new concurrent execution (meaning lightweight/green threading similar to what python allows, except being automatically distributed by the language within all kernel/cpu threads). In Elixir this means you can create millions of processes even though the OS will only see one thread per logical cpu thread, and I never felt the limitation of this abstraction over multiprocessing (of course, Julia is definitely nowhere near as mature - and maybe never will due to stuff like preemptive scheduling and parallel garbage collection that is easier to implement in a language with only immutable types, though it seems to be moving along, and in Julia 1.7 the processes being able to move between kernel threads solving the issue mentioned in that discussion you linked).

ddragon commented on Facebook Renames to Meta about.facebook.com/meta/... · Posted by u/TiredOfLife

tekknik · 4 years ago

Way too long to respond to all of it so I’ll just do some highlights. I covered resetting center again. This is a problem for all gyro controllers, not just VR. Splatoon 2 does this great.

Adding 3 additional axises change nothing. Nintendo didn’t do it because it’s very niche to require that. It costs pennie’s more to get a 6DOF gyro vs a 3DOF. The question is the need. Do you need to rotate the yaw of your hand? Nope.

So my statements stand. The VR folks seem to be on a “we’re more superior than thou” kick with gyro controls.

ddragon · 4 years ago

>6DOF gyro

A gyroscope is used to detect orientation/angular velocity (spinning), the sensor to add the other degrees of freedom is already there in most modern controllers and smartphones (the accelerometer). The issue is still accuracy I'm afraid.

>Do you need to rotate the yaw of your hand? Nope.

I'd certainly enjoy to open doors and make a simple goodbye gesture in VR.

ddragon commented on Facebook Renames to Meta about.facebook.com/meta/... · Posted by u/TiredOfLife

tekknik · 4 years ago

Play Splatoon 2, they nailed motion controls. Every time I read people saying they’re not accurate enough I get confused.

ddragon · 4 years ago

I mean, I had a vita and the gyroscope control was more accurate than the stick for shooters but that's because I'll naturally adjust if it overshoots (if I go to above I'll immediately push slightly down in a feedback loop - so here what really matters is the precision, not accuracy and in fact I can even adjust the sensitivity to my preference). That feedback loop with the user doesn't work well in VR, if my hand overshoots I don't have means of resetting the position (I can only compensate, but it's extremely uncomfortable when you feel your hand in position x, look at it and it's at position y and that x-y mapping will keep changing over time - and of course it's even worse with your head PoV not matching your head movements). Of course there are lots of issues as well, how do you get the perfect initial position? After all gyroscope/accelerometers only measure movement, it can't know where it starts (for example for jogging you need a gps to get a measurement of position, just like you need a camera/laser sensor for current VR). For gyroscope in traditional gaming you usually use the stick to adjust a solid start position, which is not possible in VR as well unless you force the user to stay in a perfect pose at the start of every level after inputting arms length and height as an example, which would definitely be annoying quickly if you need to reset frequently).

And finally, you example (splatoon 2) only needs to compute 2 degrees of freedom in movement (rotation left-right - or yawing, rotation down-up - or pitching, since rolling isn't relevant with a dot target), while VR systems depend on 6 degrees of freedom (yawing, pitching, rolling, elevating, strafing and surging - all of these for at least 3 devices at the same time: your head, left hand and right hand). Unfortunately controls in VR are quite complicated, and accelerometers, gyroscopes (and magnetometers which are also used in VR systems to know the reference to the floor) are simply insufficient (but necessary since the positional sensors can't keep track all time with occasional occlusion, such as having one hand passing over the other or leaving the tracking area), which is why the same sensors on the switch are used in every VR headset and controls in addition with even more sensors and algorithms.

EDIT: the camera system also helps a lot with defining gaming boundaries in the room and being able to quickly see if I accidentally leave it, I already punched my monitor once and that's with a barrier that always get visible when I approach something in my room.

ddragon commented on Facebook Renames to Meta about.facebook.com/meta/... · Posted by u/TiredOfLife

elliekelly · 4 years ago

I would imagine the Switch gyro controller must be pretty close to the tech needed to make VR games?

ddragon · 4 years ago

In my experience with a rift s, even though the oculus touch also has gyroscopes and accelerometers, they only help for a few seconds at most when the controllers leave the camera. Those sensors are just not accurate enough (I know little about the details of the sensors, but accelerometers are tracking the second derivative of the position, so any small error will accumulate fast when you want the latter), and you don't want to have your hand all over the place when you're trying to interact with things in VR, which is why, at least for now, you need to measure position directly for it to work, such as the camera/LED devices that are most popular with VR headsets and controllers (and even stuff like the PS Move controller).

ddragon commented on What's bad about Julia? viralinstruction.com/post... · Posted by u/jakobnissen

mint2 · 5 years ago

Wow this is helpful, I’ve had a slowly growing interest in julia due to all the positive threads in HN, but that latency forcing a repl dev or notebook dev is a nonstarter. That’s a big limitation.

And from what I’ve seen of dev done in python notebooks for data analytics, now I’m concerned about the code quality of Julia projects. Does Julia have good linters for notebooks if people are pushed to use them due to the latency?

ddragon · 5 years ago

I don't think there is anyone developing packages on pluto/jupyter, so I wouldn't worry about that. The most common method for that should be using an editor like VSCode (which will have some linting capabilities) with an open REPL and Revise [1]. What it does is every time you save any of your files (with some known restrictions), it will automatically and incrementally update the state of your application in the REPL, allowing you to probe your code whenever you want (with tons of introspection methods, up to interactively inspecting the native code being generated), and since you never leave the session you don't face the compiling latency more than once. I end up preferring this workflow for experimenting and data science stuff since it retains the structure and tooling of an editor with the ability to interact with my application (and really miss it when I'm writing Python applications), but of course each one has a preferred workflow and it'd be nice if Julia supported more of them as well.

[1] https://github.com/timholy/Revise.jl

ddragon commented on Julia 1.6 addresses latency issues lwn.net/SubscriberLink/85... · Posted by u/leephillips

skybrian · 5 years ago

I've only kicked the tires on Julia a bit, but it seems like while methods are less likely to clash, they still might if you happen to use the same name and argument types? Or maybe unexpected method resolution causes a bug?

ddragon · 5 years ago

While that might happen (and probably cause a method redefinition), there is an important convention that helps preventing it: your package must either own the function or at least one of the types used for arguments, otherwise you're practicing type piracy [1]. I've seen an automated scripts that can detect type piracy, so hopefully it could be part of a linting toolset eventually since not everyone might be aware, but at the very least popular packages shouldn't have them - or at least not in a way that may cause bugs (and if any package has it unintentionally it's probably worth creating an issue).

[1] https://docs.julialang.org/en/v1/manual/style-guide/#Avoid-t...