# Latest

**URL:** https://discourse.julialang.org/latest.md?page=71

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 72

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## [Int -\> Str -\> print(io,\_) without allocations](https://discourse.julialang.org/t/int-str-print-io-without-allocations/134626)

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**Author:** [@Leo\_I](https://discourse.julialang.org/u/Leo_I)\
**Replies:** 16\
**Last updated:** [December 19, 2025, 11:53am UTC](https://discourse.julialang.org/t/int-str-print-io-without-allocations/134626 "2025-12-19T11:53:12Z")

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I have billions of Ints that I wish to write to a file. Something similar to mmwrite() in MatrixMarket.jl. I am already using IOBuffer with a large enough sizehint. When I do print(io, n::Int), behind the scenes, a conve…

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## [Blog post: Rust vs Julia in scientific computing](https://discourse.julialang.org/t/blog-post-rust-vs-julia-in-scientific-computing/101711)

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**Author:** [@Mo8it](https://discourse.julialang.org/u/Mo8it)\
**Replies:** 144\
**Last updated:** [December 18, 2025, 11:08pm UTC](https://discourse.julialang.org/t/blog-post-rust-vs-julia-in-scientific-computing/101711 "2025-12-18T23:08:26Z")

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Why I think that Julia doesn’t solve the two-language problem and when you should use Rust instead. The blog post is the base for my tiny talk at Scientific Computing in Rust 2023 which is now public: T…

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## [Current state of reaction-diffusion solvers with ModelingToolkit](https://discourse.julialang.org/t/current-state-of-reaction-diffusion-solvers-with-modelingtoolkit/118492)

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**Author:** [@Alicanter](https://discourse.julialang.org/u/Alicanter)\
**Replies:** 10\
**Last updated:** [December 18, 2025, 9:49pm UTC](https://discourse.julialang.org/t/current-state-of-reaction-diffusion-solvers-with-modelingtoolkit/118492 "2025-12-18T21:49:48Z")

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I am trying to solve a reaction-diffusion in Julia. I’ve worked with ModelingToolkit and the SciML ecosystem before, but it seems that with PDEs there is not a single best way to solve them. The simplest way I found to…

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## [Problem with concurrent calls to HiGHS solver (via JuMP) on Windows](https://discourse.julialang.org/t/problem-with-concurrent-calls-to-highs-solver-via-jump-on-windows/134631)

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**Author:** [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Replies:** 2\
**Last updated:** [December 18, 2025, 9:16pm UTC](https://discourse.julialang.org/t/problem-with-concurrent-calls-to-highs-solver-via-jump-on-windows/134631 "2025-12-18T21:16:43Z")

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Hi, I wanted to report some crashes observed when solving concurrently (multi-thread) different LP problems via JuMP with HiGHS solver: EXCEPTION\_ACCESS\_VIOLATION dans HighsTaskExecutor… No crashes observed on Linu…

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## [Sparse variables in JuMP](https://discourse.julialang.org/t/sparse-variables-in-jump/134630)

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**Author:** [@Marc\_Sevaux](https://discourse.julialang.org/u/Marc_Sevaux)\
**Replies:** 2\
**Last updated:** [December 18, 2025, 7:56pm UTC](https://discourse.julialang.org/t/sparse-variables-in-jump/134630 "2025-12-18T19:56:19Z")

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Hi all, I’m facing a nice large problem and I would like to reduce the model by creating only the needed variables. Is there anything close to: @variable(model, x\[u in 1:n, v in 1:n; if c\[u,v\] \> 0.0\], Bin) I get the …

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## [Trying to build julia locally after latest macOS Tahoe update: \`lld: error: malformed sdk version\`](https://discourse.julialang.org/t/trying-to-build-julia-locally-after-latest-macos-tahoe-update-lld-error-malformed-sdk-version/134633)

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**Author:** [@NHDaly](https://discourse.julialang.org/u/NHDaly)\
**Replies:** 3\
**Last updated:** [December 18, 2025, 7:44pm UTC](https://discourse.julialang.org/t/trying-to-build-julia-locally-after-latest-macos-tahoe-update-lld-error-malformed-sdk-version/134633 "2025-12-18T19:44:52Z")

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Has anyone else seen an error like this? I think it probably started after updating to the latest macOS. Struggling to build julia from source on my mac. It works fine at first, but fails right at the end of precompili…

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## [What is the correct way to use Base.OncePerThread?](https://discourse.julialang.org/t/what-is-the-correct-way-to-use-base-onceperthread/134597)

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**Author:** [@AwesomeQuest](https://discourse.julialang.org/u/AwesomeQuest)\
**Replies:** 7\
**Last updated:** [December 18, 2025, 4:52pm UTC](https://discourse.julialang.org/t/what-is-the-correct-way-to-use-base-onceperthread/134597 "2025-12-18T16:52:42Z")

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I want to use Base.OncePerThread but it’s not clear what the intended usage is. Is the following a correct / safe / intended way to use Base.OncePerThread ? finalset = Set() tempsets = OncePerThread() do return Set…

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## [Understanding allocations reported by --track-allocation (solved)](https://discourse.julialang.org/t/understanding-allocations-reported-by-track-allocation-solved/134628)

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**Author:** [@paulmelis](https://discourse.julialang.org/u/paulmelis)\
**Replies:** 1\
**Last updated:** [December 18, 2025, 11:48am UTC](https://discourse.julialang.org/t/understanding-allocations-reported-by-track-allocation-solved/134628 "2025-12-18T11:48:21Z")

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I’m trying to understand the output of --track-allocation=user on this very straightforward snippet: mutable struct S n positions end function S(n) return S(n, zeros(Float32,n)) end function (@main)(args) …

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## [Why Atomix.@atomic b\[\] += a\[i\] works and b\[\] = b\[\] + a\[i\] does not](https://discourse.julialang.org/t/why-atomix-atomic-b-a-i-works-and-b-b-a-i-does-not/134627)

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**Author:** [@Tomas\_Pevny](https://discourse.julialang.org/u/Tomas_Pevny)\
**Replies:** 6\
**Last updated:** [December 18, 2025, 10:48am UTC](https://discourse.julialang.org/t/why-atomix-atomic-b-a-i-works-and-b-b-a-i-does-not/134627 "2025-12-18T10:48:02Z")

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Hi all, I am updating my lecture on GPU programming and this year, I would like to have kernels written in CUDA.jl and KernelAbstractions.jl side by side. The idea is to show students, how GPU accelerators are similar a…

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## [Makie - Unable to make colors cycle for new recipe](https://discourse.julialang.org/t/makie-unable-to-make-colors-cycle-for-new-recipe/134625)

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**Author:** [@oskarhs](https://discourse.julialang.org/u/oskarhs)\
**Replies:** 0\
**Last updated:** [December 18, 2025, 6:59am UTC](https://discourse.julialang.org/t/makie-unable-to-make-colors-cycle-for-new-recipe/134625 "2025-12-18T06:59:11Z")

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I am trying to define a new Makie recipe for a custom type, but I am not able to make the plot type cycle colors like normal Makie recipes such as lines or density do. After spending a few hours trying out different solu…

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## [Eigenvectors with the most overlap with v](https://discourse.julialang.org/t/eigenvectors-with-the-most-overlap-with-v/134008)

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**Author:** [@Nichola](https://discourse.julialang.org/u/Nichola)\
**Replies:** 7\
**Last updated:** [December 18, 2025, 1:39am UTC](https://discourse.julialang.org/t/eigenvectors-with-the-most-overlap-with-v/134008 "2025-12-18T01:39:40Z")

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Given a sparse matrix M and a vector v, I would like to get the k eigenvectors of M that have the most overlap with v. Is there an efficient method for doing this with sparse matrices ? All sparse solvers I ran into tar…

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## [How to solve or optimize a mixed problem?](https://discourse.julialang.org/t/how-to-solve-or-optimize-a-mixed-problem/134465)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 2\
**Last updated:** [December 17, 2025, 9:44pm UTC](https://discourse.julialang.org/t/how-to-solve-or-optimize-a-mixed-problem/134465 "2025-12-17T21:44:24Z")

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I have the following problem: a wind farm uncontrolled input: time and location-dependent wind speed control input: time-dependent induction factor set values: time-dependent power demand output: total power For simpl…

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## [Makie - trouble using both a slider and textbox to change a number](https://discourse.julialang.org/t/makie-trouble-using-both-a-slider-and-textbox-to-change-a-number/73276)

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**Author:** [@JoshL](https://discourse.julialang.org/u/JoshL)\
**Replies:** 1\
**Last updated:** [December 17, 2025, 8:29pm UTC](https://discourse.julialang.org/t/makie-trouble-using-both-a-slider-and-textbox-to-change-a-number/73276 "2025-12-17T20:29:34Z")

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I’m running into some issues trying to use Makie to visualize some of my data using Julia 1.6.0. I’ve created a toy example below that illustrates the problem. In the example, I have a number between 0 and 1, and I want …

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## [Convert or Reinterpret Between NamedTuple and SVector](https://discourse.julialang.org/t/convert-or-reinterpret-between-namedtuple-and-svector/134600)

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**Author:** [@cortner](https://discourse.julialang.org/u/cortner)\
**Replies:** 7\
**Last updated:** [December 17, 2025, 7:33pm UTC](https://discourse.julialang.org/t/convert-or-reinterpret-between-namedtuple-and-svector/134600 "2025-12-17T19:33:07Z")

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My question is related to Vector to NamedTuple? Assume my NamedTuple contains only floating point values T and SVector{N, T} entries, e.g., using StaticArrays nt = ( a = rand(), b = SA\[1.0, 2.0 ,3.0\] ) Taking such a N…

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## [Prevent Pkg.test from executing parent's \`@main\` function](https://discourse.julialang.org/t/prevent-pkg-test-from-executing-parents-main-function/134617)

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**Author:** [@alametti](https://discourse.julialang.org/u/alametti)\
**Replies:** 3\
**Last updated:** [December 17, 2025, 7:28pm UTC](https://discourse.julialang.org/t/prevent-pkg-test-from-executing-parents-main-function/134617 "2025-12-17T19:28:06Z")

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When I test a local package using the test instruction in the Pkg REPL, the function called by the @main macro gets executed after the tests. For example: src/Foo.jl: module Foo main() = println("hello from main func…

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## [Why do I get an error when installing iJulia that Conda is missing? I'll duplicate the question here](https://discourse.julialang.org/t/why-do-i-get-an-error-when-installing-ijulia-that-conda-is-missing-ill-duplicate-the-question-here/134587)

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**Author:** [@Kobold](https://discourse.julialang.org/u/Kobold)\
**Replies:** 1\
**Last updated:** [December 17, 2025, 6:34pm UTC](https://discourse.julialang.org/t/why-do-i-get-an-error-when-installing-ijulia-that-conda-is-missing-ill-duplicate-the-question-here/134587 "2025-12-17T18:34:46Z")

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Below I’ll post a copy of what happens when I try to download IJulia; I can’t attach a screenshot. I can download any package that doesn’t require Conda, but as soon as it requires Conda (as far as I understand, it’s a p…

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## [Why do I get an error when installing iJulia that Conda is missing?](https://discourse.julialang.org/t/why-do-i-get-an-error-when-installing-ijulia-that-conda-is-missing/134572)

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**Author:** [@Kobold](https://discourse.julialang.org/u/Kobold)\
**Replies:** 1\
**Last updated:** [December 17, 2025, 5:36pm UTC](https://discourse.julialang.org/t/why-do-i-get-an-error-when-installing-ijulia-that-conda-is-missing/134572 "2025-12-17T17:36:30Z")

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Below I’ll post a copy of what happens when I try to download IJulia; I can’t attach a screenshot. I can download any package that doesn’t require Conda, but as soon as it requires Conda (as far as I understand, it’s a p…

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## [Matrix multiplication fails with Reactant and Lux](https://discourse.julialang.org/t/matrix-multiplication-fails-with-reactant-and-lux/134612)

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**Author:** [@weltenbummler](https://discourse.julialang.org/u/weltenbummler)\
**Replies:** 2\
**Last updated:** [December 17, 2025, 4:34pm UTC](https://discourse.julialang.org/t/matrix-multiplication-fails-with-reactant-and-lux/134612 "2025-12-17T16:34:06Z")

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Hello, I have this simple script: using LinearAlgebra using Reactant using Lux dev = reactant\_device() #dev = cpu\_device() A = dev(rand(Float32, 2, 2)) B = dev(rand(Float32, 2, 3)) A \* B # ERROR: conversion to point…

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## [Is it possible to use the Julia Astro package in VS Code?](https://discourse.julialang.org/t/is-it-possible-to-use-the-julia-astro-package-in-vs-code/134610)

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**Author:** [@Kobold](https://discourse.julialang.org/u/Kobold)\
**Replies:** 3\
**Last updated:** [December 17, 2025, 3:33pm UTC](https://discourse.julialang.org/t/is-it-possible-to-use-the-julia-astro-package-in-vs-code/134610 "2025-12-17T15:33:12Z")

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Hello! I want to start learning this package, and based on my experience with Python, all the code doesn’t have graphics to display function graphs or images. Is there a way to do this?

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## [Possible error on Julia documentation page](https://discourse.julialang.org/t/possible-error-on-julia-documentation-page/134585)

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**Author:** [@xiaoxi](https://discourse.julialang.org/u/xiaoxi)\
**Replies:** 2\
**Last updated:** [December 17, 2025, 3:06pm UTC](https://discourse.julialang.org/t/possible-error-on-julia-documentation-page/134585 "2025-12-17T15:06:55Z")

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Shouldn’t this text be inside the box? It’s from the variable section of the documentation page.

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## [Switching off implicit conversion](https://discourse.julialang.org/t/switching-off-implicit-conversion/134568)

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**Author:** [@sadish-d](https://discourse.julialang.org/u/sadish-d)\
**Replies:** 25\
**Last updated:** [December 17, 2025, 2:04pm UTC](https://discourse.julialang.org/t/switching-off-implicit-conversion/134568 "2025-12-17T14:04:29Z")

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Let’s work with an example. Say I have two different units of length. abstract type Length end struct Meters \<: Length value::Float64 end struct CentiMeters \<: Length value::Float64 end I want to use the existing…

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## [Distributed workflow for MCMC](https://discourse.julialang.org/t/distributed-workflow-for-mcmc/134590)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 5\
**Last updated:** [December 17, 2025, 1:43pm UTC](https://discourse.julialang.org/t/distributed-workflow-for-mcmc/134590 "2025-12-17T13:43:26Z")

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I would like to set up an MCMC workflow using Distributed. I have a Julia script that does the following: load all packages load the data run an MCMC chain, with index i, for i in 1:5 save the result in some\_chain\_$i.…

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## [Two fully funded PhD positions in real-time infectious disease modelling (LSHTM / Imperial / UKHSA)](https://discourse.julialang.org/t/two-fully-funded-phd-positions-in-real-time-infectious-disease-modelling-lshtm-imperial-ukhsa/134609)

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**Author:** [@sbfnk](https://discourse.julialang.org/u/sbfnk)\
**Replies:** 2\
**Last updated:** [December 17, 2025, 12:42pm UTC](https://discourse.julialang.org/t/two-fully-funded-phd-positions-in-real-time-infectious-disease-modelling-lshtm-imperial-ukhsa/134609 "2025-12-17T12:42:47Z")

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Two fully funded PhD positions in real-time infectious disease modelling and forecasting, jointly supervised between the London School of Hygiene & Tropical Medicine, Imperial College London (Anne Cori), and UK Health Se…

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## [Please Guide Newcomers How To Write Typestable Code](https://discourse.julialang.org/t/please-guide-newcomers-how-to-write-typestable-code/134606)

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**Author:** [@ziolai](https://discourse.julialang.org/u/ziolai)\
**Replies:** 1\
**Last updated:** [December 17, 2025, 7:52am UTC](https://discourse.julialang.org/t/please-guide-newcomers-how-to-write-typestable-code/134606 "2025-12-17T07:52:57Z")

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Various students of mine struggle in understanding the issue of type stability and memory allocations. What reading material and tutorials should I give them? Thx!

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## [PicoHTTPParser package](https://discourse.julialang.org/t/picohttpparser-package/134593)

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**Author:** [@AbrJA](https://discourse.julialang.org/u/AbrJA)\
**Replies:** 2\
**Last updated:** [December 17, 2025, 3:11am UTC](https://discourse.julialang.org/t/picohttpparser-package/134593 "2025-12-17T03:11:29Z")

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I’m happy to announce the new package PicoHTTPParser PicoHTTPParser is a minimal, high-performance Julia wrapper around the picohttpparser C library. This package provides extremely fast HTTP request/response/headers pa…

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## [Trouble with installing AlphaShapes package](https://discourse.julialang.org/t/trouble-with-installing-alphashapes-package/134599)

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**Author:** [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Replies:** 6\
**Last updated:** [December 17, 2025, 3:01am UTC](https://discourse.julialang.org/t/trouble-with-installing-alphashapes-package/134599 "2025-12-17T03:01:28Z")

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I am very interested in using the AlphaShapes.jl package. However after installation, I get the following error when I try to load it for the first time. I would appreciate any help with troubleshoorting. julia\> using …

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## [Julia 1.11.8 performance up a notch since 1.11.7 (was: down a notch)](https://discourse.julialang.org/t/julia-1-11-8-performance-up-a-notch-since-1-11-7-was-down-a-notch/134577)

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**Author:** [@JJMerelo](https://discourse.julialang.org/u/JJMerelo)\
**Replies:** 4\
**Last updated:** [December 16, 2025, 11:59pm UTC](https://discourse.julialang.org/t/julia-1-11-8-performance-up-a-notch-since-1-11-7-was-down-a-notch/134577 "2025-12-16T23:59:56Z")

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As you may know, I’m using Julia for performance/energy evaluation here GitHub - cecimerelo/BraveNewAlgorithm.jl I routinely test new versions for improvements… After initially measuring a downgraded performance, I took…

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## [Failed to precompile CUDA](https://discourse.julialang.org/t/failed-to-precompile-cuda/134255)

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**Author:** [@WuSiren](https://discourse.julialang.org/u/WuSiren)\
**Replies:** 14\
**Last updated:** [December 16, 2025, 10:59pm UTC](https://discourse.julialang.org/t/failed-to-precompile-cuda/134255 "2025-12-16T22:59:21Z")

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julia\> using CUDA ┌ Warning: Circular dependency detected. Precompilation will be skipped for: │ SparseArraysExt \[85068d23-b5fb-53f1-8204-05c2aba6942f\] │ AtomixCUDAExt \[13011619-4c7c-5ef0-948f-5fc81565cd05\] │ Linea…

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## [Issues with JuliaFormatter and JET tests on 1.12](https://discourse.julialang.org/t/issues-with-juliaformatter-and-jet-tests-on-1-12/134596)

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**Author:** [@rsenne](https://discourse.julialang.org/u/rsenne)\
**Replies:** 3\
**Last updated:** [December 16, 2025, 10:43pm UTC](https://discourse.julialang.org/t/issues-with-juliaformatter-and-jet-tests-on-1-12/134596 "2025-12-16T22:43:23Z")

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I have tests like this across a few packages: @testset verbose=true "Package Quality" begin @testset "Blue Formatting" begin @test\_broken JuliaFormatter.format(MyPackage; verbose=false, overwr…

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## [The while cycle doesn't work](https://discourse.julialang.org/t/the-while-cycle-doesnt-work/134542)

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**Author:** [@Kobold](https://discourse.julialang.org/u/Kobold)\
**Replies:** 3\
**Last updated:** [December 16, 2025, 8:29pm UTC](https://discourse.julialang.org/t/the-while-cycle-doesnt-work/134542 "2025-12-16T20:29:35Z")

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I wrote a simple program, literally to test how the while cycle works, but it gives the same error, even though I wrote it identically to the one in the training material. x=0 while x\<10 x+=1 println(x) end and the…

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