leiroigh

6 ms·

1.
by leiroigh 3mo ago
I'll be interested in seeing the fallout of the (unavoidable) compat issue: If I have a function that has a value `x` that erases to `java.lang.Object` (e.g. a parametric function with no lower bound); then it used to be safe to check
2.
by leiroigh 11mo ago
Yes. O(1) snapshots are awesome! Persistent datastructures are a monumental achievement. But that comes at a performance price, and in the end, you only really need persistent datastructures for niche applications. Good examples are: ZFS mo
3.
by leiroigh 11mo ago
There is nothing counter-intuitive or julia-specific about it: Fastest way is to have your datastructure in a (virtual) register, and that works better with immutable structures (ie memory2ssa has limitations). Second fastest way is to have
4.
by leiroigh 1y ago
Pumping heat from 300K to 900K is not a big gain over heating -- the entire thing is premised on using extremely cheap intermittent electricity during the summer, and your savings are capped at 30%.
5.
by leiroigh 1y ago
"The Planck dive", freely available on Greg Egan's website https://www.gregegan.net/PLANCK/Complete/Planck.html
6.
by leiroigh 1y ago
The bounce is invisible from the outside -- an event horizon means causal decoupling. From outside, the formation of the black hole looks like the good old "frozen star" picture. There will never be observational evidence on what
7.
by leiroigh 1y ago
I have not really looked at the summary, opted to go straight to the source. This identification happens in equations 31-34 on page 7f subsection "Cosmic Acceleration" in https://arxiv.org/abs/2505.23877 The
8.
by leiroigh 1y ago
>in a higher-dimensional parent universe That's incorrect: The parent universe is not higher-dimensional, it's the same good old 3+1 as our universe. What they propose is: Let's take our good old GR, and start with a (larg
9.
by leiroigh 1y ago
>so unfortunately I see a fellow enjoyer of bugs ;) >vmap afaict only exposes push-back and pop-front for mutation what about https://doc.rust-lang.org/nightly/std/io/trait.Write.html#ty... ? >and cr
10.
by leiroigh 1y ago
The main problem with that is that it doesn't play nice with most languages. Consider int foo(int* ptr) { int x = ptr[1<<16]; *ptr += 1; return x + ptr[1<<16]; } Compilers/languages/specs ten
11.
by leiroigh 2y ago
That's pretty cool. Normally it would be the either the programmer's or the compiler's job to unroll a loop and then reduce dependency chain lengths. But its nice if the renamer can do that as well. Presumably intel have real
12.
by leiroigh 3y ago
^this! In garbage-collected languages, please give me gradual / optional annotations that permit deterministic fast freeing of temps, in code that opts in. Basically to relieve GC pressure, at some modest cost of programmer productivit
13.
by leiroigh 3y ago
This is very very well known. Cf https://en.wikipedia.org/wiki/Affine_group I don't see how people should glorify this with the word "algorithm". It is a trivial undergrad homework exercise, once you giv
14.
by leiroigh 3y ago
This is awesome and the first precedent I've ever seen for a standard library doing the right thing on rand floats. Big kudos to the zig people and thanks for brightening my day!
15.
by leiroigh 3y ago
Depends on control registers like e.g. MXCSR. It's an utter mess. Consider e.g. https://news.ycombinator.com/item?id=32738206
16.
by leiroigh 3y ago
Fair enough, if a user asks for a random float between [0, 1e-38f] then subnormals are expected. I was just thinking about the (0,1) case, under the mistaken assumption that one could map it to (a,b) via multiplication/addition, but yo
17.
by leiroigh 3y ago
Comparability between implementations: Say GPU vs CPU, or between languages, or to pseudocode in old papers. Typical example where the badness of the floats bites you is if you do something like log(rand()), or 1/x, or more generally y
18.
by leiroigh 3y ago
You think there might be applications like complex very large simulations where an event with probability 1:10^38 matters? You are aware that the current age of the universe is < 10^27 nanoseconds, just for comparison?
19.
by leiroigh 3y ago
I don't think that would be a good idea -- sticking to positive normals and truncating below is enough for float32 and float64. I mean, consider that 1.1754944f-38 is a normal 32 bit float. The probability that your "perfect"
20.
by leiroigh 3y ago
That thread was in 0.6 days on my long-dead broadwell using DSFMT as a C library with afaiu hand-written intrinsic code for bulk generation of floats. We switched RNG to xoshiro in the meantime which is faster and generates 64 bit numbers n
21.
by leiroigh 3y ago
This problem is much more acute in Float32. Another sample implementation (maybe easier to read?) is in https://discourse.julialang.org/t/output-distribution-of-ran... As far as I remember, the main reasons for not roc
22.
by leiroigh 7y ago
Nobody complains about julia for "shelling out". The imo justified complaint is that julia sucks at "shelling in". (OK, the pipe buffering rules still annoy me) Similar with FFI: Julia has awesome support for calling out
23.
by leiroigh 7y ago
Are startup times really your problem? Consider https://github.com/JuliaLang/julia/issues/30044 You can manually enable buffering of the pipe endpoints. Otherwise julia will be super-duper-slow when part of a
24.
by leiroigh 7y ago
It's not. But people who like the language will invariably use beyond its core competency. Hence it is important to ensure that julia is "kinda mediocre" for CLI scripting (big step up from "absolutely terrible"). P
25.
by leiroigh 7y ago
Speed depends on workload. Fast startup, high throughput, high productivity: Choose two. C/C++/Fortran take fast startup and high throughput, python takes fast startup and high productivity, and julia takes high productivity and h
26.
by leiroigh 7y ago
Some have been partially addressed. But the main point is that the critique is misguided in its generality. If the author cares about running many small scripts that each take a handful of milliseconds, then julia is just not the right tool
27.
by leiroigh 7y ago
I hate how the article waffles between "almost none", "virtually none" and "negligible". There is a word with precise mathematical meaning that matches naive non-mathematical intuition: "almost all" &
28.
by leiroigh 7y ago
We even have a universally agreed upon safe-word for this kind of thing ("sudo").
29.
by leiroigh 7y ago
It's all about better L3 utilization. Cilk is good for using L1 and L2, i.e. caches that are core-local, and suboptimal for using L3, i.e. caches that are shared between cores.
30.
by leiroigh 7y ago
Big difference is that Cilk appears to typically synchronize on function return, while julia needs an explicit wait/fetch (there is also a @sync macro). That is, spawn/wait can be matched from the AST in cilk, while julia demands

More ›