# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=18

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**Page:** 19

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## [Splitting qml file into several files](https://discourse.julialang.org/t/splitting-qml-file-into-several-files/135553)

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**Author:** [@HVinther](https://discourse.julialang.org/u/HVinther)\
**Replies:** 8\
**Last updated:** [February 18, 2026, 10:17am UTC](https://discourse.julialang.org/t/splitting-qml-file-into-several-files/135553 "2026-02-18T10:17:57Z")

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Following https://stackoverflow.com/questions/45652525/qml-filling-menu-with-model-items I made a menu that behaves similarly to standard Makie menu. To make my project more manageable I am trying to split my files into …

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## [DAE‑safe bounding for CoolProp property calls in Julia](https://discourse.julialang.org/t/dae-safe-bounding-for-coolprop-property-calls-in-julia/135416)

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**Author:** [@TimGyx](https://discourse.julialang.org/u/TimGyx)\
**Replies:** 7\
**Last updated:** [February 18, 2026, 3:38am UTC](https://discourse.julialang.org/t/dae-safe-bounding-for-coolprop-property-calls-in-julia/135416 "2026-02-18T03:38:45Z")

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I am building a large DAE-based vapor‑compression refrigeration loop in Julia using DifferentialEquations.jl and CoolProp for thermodynamic properties, and I am running into repeated CoolProp crashes during DAE initializ…

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## [Equivalent of PreallocationTools.jl for functions](https://discourse.julialang.org/t/equivalent-of-preallocationtools-jl-for-functions/135707)

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**Author:** [@densmojd](https://discourse.julialang.org/u/densmojd)\
**Replies:** 4\
**Last updated:** [February 18, 2026, 1:35am UTC](https://discourse.julialang.org/t/equivalent-of-preallocationtools-jl-for-functions/135707 "2026-02-18T01:35:09Z")

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A Julia design paradigm I often see to avoid allocating temporary arrays in repeated calculations is to use a struct that contains the temporary array and a “functor” for performing the calculation: struct MyStruct …

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## [How do I print hello world in Julia?](https://discourse.julialang.org/t/how-do-i-print-hello-world-in-julia/54691)

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**Author:** [@BridgeBot](https://discourse.julialang.org/u/BridgeBot)\
**Replies:** 3\
**Last updated:** [February 18, 2026, 1:01am UTC](https://discourse.julialang.org/t/how-do-i-print-hello-world-in-julia/54691 "2026-02-18T01:01:02Z")

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How do I print hello world in Julia? I tried doing: julia&gt; hello world ERROR: syntax: extra token "world" after end of expression Stacktrace: \[1\] top-level scope at none:1 \[This is a test\] Note that the original …

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## ["i in 3" is valid and continues to cost me some debug time :(](https://discourse.julialang.org/t/i-in-3-is-valid-and-continues-to-cost-me-some-debug-time/134910)

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**Author:** [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Replies:** 18\
**Last updated:** [February 17, 2026, 2:52pm UTC](https://discourse.julialang.org/t/i-in-3-is-valid-and-continues-to-cost-me-some-debug-time/134910 "2026-02-17T14:52:44Z")

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Hi, I spent a few hours to fix a bug where I was using an integer in place of a range for i in N do\_something\_with\_i(i) end instead of for i in 1:N do\_something\_with\_i(i) end I wish i in 3 wasn’t a valid exp…

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## [Error : MethodError(Core.kwcall, ((reuseaddr = true,), Sockets.send, UDPSocket(init), ip"192.168.10.255", 11000,](https://discourse.julialang.org/t/error-methoderror-core-kwcall-reuseaddr-true-sockets-send-udpsocket-init-ip-192-168-10-255-11000/135698)

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**Author:** [@VinodV](https://discourse.julialang.org/u/VinodV)\
**Replies:** 1\
**Last updated:** [February 17, 2026, 2:51pm UTC](https://discourse.julialang.org/t/error-methoderror-core-kwcall-reuseaddr-true-sockets-send-udpsocket-init-ip-192-168-10-255-11000/135698 "2026-02-17T14:51:13Z")

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Hi friends, From a (windows os) souce IP : 192.168.10.10 a unicasted udp message is coming to (rhel Linux OS) destination IP : 192.168.10.40, dest port : 2000 Line : addr, data = recvfrom(recv\_sock) I have written a …

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## [Simple simulation](https://discourse.julialang.org/t/simple-simulation/135701)

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**Author:** [@Lincoln\_Hannah](https://discourse.julialang.org/u/Lincoln_Hannah)\
**Replies:** 8\
**Last updated:** [February 17, 2026, 11:00am UTC](https://discourse.julialang.org/t/simple-simulation/135701 "2026-02-17T11:00:07Z")

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Is there an easy way to speed this up? sims = 10\_000 T = 1 σ = .1 Δ = .000001 σrΔ = σ√Δ steps = (Int64 ∘ round)(T/Δ) L = .9 H = 1.1 x = ones( sims ) alive = trues( sims ) …

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## [Outputs of JuliaC compiled functions question](https://discourse.julialang.org/t/outputs-of-juliac-compiled-functions-question/135678)

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**Author:** [@JackC](https://discourse.julialang.org/u/JackC)\
**Replies:** 3\
**Last updated:** [February 16, 2026, 11:29pm UTC](https://discourse.julialang.org/t/outputs-of-juliac-compiled-functions-question/135678 "2026-02-16T23:29:41Z")

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I’ve been experimenting with the new JuliaC functionality for generating small binaries introduced in 1.12. I have been able to successfully compile and run example programs (such as the ones provided in this repo). Howe…

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## [Bug in NLSolve](https://discourse.julialang.org/t/bug-in-nlsolve/135660)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 8\
**Last updated:** [February 16, 2026, 6:37pm UTC](https://discourse.julialang.org/t/bug-in-nlsolve/135660 "2026-02-16T18:37:11Z")

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I had a very ugly bug for more than a year. Now, thanks to AI, I found the reason and could fix it. This bug was very ugly at first, because it does not always appear, only for certain numerical values. And secondly, no…

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## [Changing font family in Plots using pythonplot() (globally)](https://discourse.julialang.org/t/changing-font-family-in-plots-using-pythonplot-globally/135679)

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**Author:** [@maltee1](https://discourse.julialang.org/u/maltee1)\
**Replies:** 1\
**Last updated:** [February 16, 2026, 3:01pm UTC](https://discourse.julialang.org/t/changing-font-family-in-plots-using-pythonplot-globally/135679 "2026-02-16T15:01:39Z")

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Specifically to “Latin Modern Roman”, to have it match the LaTeX document the plots will be used in. This seems like a simple issue, just set const PLOTS\_DEFAULTS = Dict( :theme=\>:default, :fontfamily =\> "Latin …

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## [Decrease margins of IJulia in Jupyter notebook?](https://discourse.julialang.org/t/decrease-margins-of-ijulia-in-jupyter-notebook/6912)

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**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 3\
**Last updated:** [February 16, 2026, 11:46am UTC](https://discourse.julialang.org/t/decrease-margins-of-ijulia-in-jupyter-notebook/6912 "2026-02-16T11:46:56Z")

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Is there a way to increase the width of cells in IJulia Jupyer Notebooks?

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## [Registration server-side issue?](https://discourse.julialang.org/t/registration-server-side-issue/135665)

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**Author:** [@technocrat](https://discourse.julialang.org/u/technocrat)\
**Replies:** 3\
**Last updated:** [February 15, 2026, 11:01pm UTC](https://discourse.julialang.org/t/registration-server-side-issue/135665 "2026-02-15T23:01:22Z")

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Anyone else having this problem? The failure in job 63685326871 occurred because Julia’s package manager could not download the registry file from https://pkg.julialang.org/registry/23338594-aafe-5451-b93e-139f81909106…

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## [TransformImages warp error](https://discourse.julialang.org/t/transformimages-warp-error/135663)

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**Author:** [@mekapses](https://discourse.julialang.org/u/mekapses)\
**Replies:** 1\
**Last updated:** [February 15, 2026, 10:46pm UTC](https://discourse.julialang.org/t/transformimages-warp-error/135663 "2026-02-15T22:46:23Z")

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Trying to implement a log polar transform… warp gets a MethodError: no method matching similar(::Type{Array{ColorTypes.Gray{Float64}}}, ::Tuple{StepRangeLen{Float64, Base.TwicePrecision{Float64}, Base.TwicePrecision{Flo…

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## [How do you start julia?](https://discourse.julialang.org/t/how-do-you-start-julia/135644)

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**Author:** [@tp2750](https://discourse.julialang.org/u/tp2750)\
**Replies:** 7\
**Last updated:** [February 15, 2026, 9:35pm UTC](https://discourse.julialang.org/t/how-do-you-start-julia/135644 "2026-02-15T21:35:08Z")

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My preferred spell to summon julia is this: julia --project=. -O0 -t auto what is yours?

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## [Creating Packages tutorial: Precompile error](https://discourse.julialang.org/t/creating-packages-tutorial-precompile-error/134934)

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**Author:** [@nbrantut](https://discourse.julialang.org/u/nbrantut)\
**Replies:** 3\
**Last updated:** [February 14, 2026, 8:28pm UTC](https://discourse.julialang.org/t/creating-packages-tutorial-precompile-error/134934 "2026-02-14T20:28:47Z")

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I am trying to make a new package, using Julia v1.10 on macosx. Coming back to basics and following the tutorial ( 5. Creating Packages · Pkg.jl ), I am running into a precompilation error. (This happens for all external…

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## [Using \`symbol\` in \`ccall\`](https://discourse.julialang.org/t/using-symbol-in-ccall/135608)

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**Author:** [@f-fathurrahman](https://discourse.julialang.org/u/f-fathurrahman)\
**Replies:** 2\
**Last updated:** [February 14, 2026, 12:39pm UTC](https://discourse.julialang.org/t/using-symbol-in-ccall/135608 "2026-02-14T12:39:57Z")

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Dear all Suppose that I have this Fortran module in file named MyModule.f90: MODULE MyModule IMPLICIT NONE ! REAL(8) :: x INTEGER :: Nsize REAL(8), ALLOCATABLE :: v(:) END MODULE !--------------------------…

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## [Update a const defined in a module](https://discourse.julialang.org/t/update-a-const-defined-in-a-module/135548)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 3\
**Last updated:** [February 14, 2026, 7:58am UTC](https://discourse.julialang.org/t/update-a-const-defined-in-a-module/135548 "2026-02-14T07:58:22Z")

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Now we can update a const julia\> const m = 0 0 julia\> const m = 1 1 in a REPL. But in a larger project I may want to wrap all the consts in another module M. # Opening a new julia REPL julia\> module M con…

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## [Time-dependent Hamiltonian for symplectic integrators in DifferentialEquations.jl](https://discourse.julialang.org/t/time-dependent-hamiltonian-for-symplectic-integrators-in-differentialequations-jl/39987)

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**Author:** [@EmadMasroor](https://discourse.julialang.org/u/EmadMasroor)\
**Replies:** 9\
**Last updated:** [February 13, 2026, 8:06pm UTC](https://discourse.julialang.org/t/time-dependent-hamiltonian-for-symplectic-integrators-in-differentialequations-jl/39987 "2026-02-13T20:06:55Z")

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Hello, I am using the DifferentialEquations.jl scaffolding to solve a Hamiltonian dynamical system. It is important to conserve the Hamiltonian to a reasonable accuracy, and so I am using symplectic integrators (Symplec…

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## [How to continue (vector calculus) abuse of notation in Julia?](https://discourse.julialang.org/t/how-to-continue-vector-calculus-abuse-of-notation-in-julia/135593)

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**Author:** [@Abhro](https://discourse.julialang.org/u/Abhro)\
**Replies:** 2\
**Last updated:** [February 13, 2026, 6:24pm UTC](https://discourse.julialang.org/t/how-to-continue-vector-calculus-abuse-of-notation-in-julia/135593 "2026-02-13T18:24:47Z")

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Is there an idiomatic way to get the curl of a symbolic vector field using Symbolics.jl? I’m trying the following using Symbolics, LinearAlgebra @variables x y z @variables A₁(x,y,z) A₂(x,y,z) A₃(x,y,z) ∇ = \[Differentia…

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## [Why is the OSMMakie plot out of bounds?](https://discourse.julialang.org/t/why-is-the-osmmakie-plot-out-of-bounds/135591)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 4\
**Last updated:** [February 13, 2026, 8:30am UTC](https://discourse.julialang.org/t/why-is-the-osmmakie-plot-out-of-bounds/135591 "2026-02-13T08:30:10Z")

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Hello, In the example below, the plotted area (including roadways) is outside of the bounds defined in area. Why is this happening? using GLMakie using LightOSM using OSMMakie file\_name = "woodstock\_illinois\_park.osm"…

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## [Can't add \`General\` registry](https://discourse.julialang.org/t/cant-add-general-registry/135595)

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**Author:** [@PatrickHaecker](https://discourse.julialang.org/u/PatrickHaecker)\
**Replies:** 9\
**Last updated:** [February 12, 2026, 6:25pm UTC](https://discourse.julialang.org/t/cant-add-general-registry/135595 "2026-02-12T18:25:16Z")

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Does anyone else have the problem of not being able to add the General registry? I get (@v1.14) pkg\> registry add General ERROR: could not download https://pkg.julialang.org/registry/23338594-aafe-5451-b93e-139f81909106…

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## [Reconstruct closure?](https://discourse.julialang.org/t/reconstruct-closure/135583)

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**Author:** [@mattsignorelli](https://discourse.julialang.org/u/mattsignorelli)\
**Replies:** 5\
**Last updated:** [February 12, 2026, 1:15pm UTC](https://discourse.julialang.org/t/reconstruct-closure/135583 "2026-02-12T13:15:51Z")

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I have some function like adder(x) = y-\>x+y which is said to lower to roughly struct ##1{T} x::T end (\_::##1)(y) = \_.x + y function adder(x) return ##1(x) end Now if I do g = adder(3) println(typeof(g)) t…

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## [BLAS multithreading on 8 core Apple M2](https://discourse.julialang.org/t/blas-multithreading-on-8-core-apple-m2/135587)

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**Author:** [@sparrowhawk](https://discourse.julialang.org/u/sparrowhawk)\
**Replies:** 2\
**Last updated:** [February 12, 2026, 3:54am UTC](https://discourse.julialang.org/t/blas-multithreading-on-8-core-apple-m2/135587 "2026-02-12T03:54:08Z")

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This seems to suggest that there is no improvement with using more threads with BLAS on my 8 core Apple M2 late 2023 model. \*\*julia\>\*\* using AppleAccelerate \*\*julia\>\*\* using LinearAlgebra \*\*julia\>\*\* BLAS.get\_config() Li…

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## [Glib\_jll usage failure on v1.13.0-beta2 on Windows](https://discourse.julialang.org/t/glib-jll-usage-failure-on-v1-13-0-beta2-on-windows/135565)

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**Author:** [@jackyarndley](https://discourse.julialang.org/u/jackyarndley)\
**Replies:** 10\
**Last updated:** [February 12, 2026, 2:36am UTC](https://discourse.julialang.org/t/glib-jll-usage-failure-on-v1-13-0-beta2-on-windows/135565 "2026-02-12T02:36:46Z")

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I’m trying out the new v1.13.0-beta2 on Windows but cannot use it because of package build failures. In particular I have been trying to use GLMakie.jl but have a build failure of Cairo\_jll.jl, which traces back to a bui…

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## [ODBC querying Snowflake is super slow](https://discourse.julialang.org/t/odbc-querying-snowflake-is-super-slow/131718)

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**Author:** [@Snowy](https://discourse.julialang.org/u/Snowy)\
**Replies:** 4\
**Last updated:** [February 11, 2026, 3:11pm UTC](https://discourse.julialang.org/t/odbc-querying-snowflake-is-super-slow/131718 "2026-02-11T15:11:11Z")

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Hi all, I’m trying to use ODBC.jl to query our enterprise’s Snowflake server. Fortunately, it works. Unfortunately, it’s extremely slow. E.g. pulling 1000 rows via ODBC takes 1.5 minutes. Pulling the same 1000 rows in t…

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## [Multichar variables names in docstring LaTeX](https://discourse.julialang.org/t/multichar-variables-names-in-docstring-latex/135555)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 4\
**Last updated:** [February 11, 2026, 8:09am UTC](https://discourse.julialang.org/t/multichar-variables-names-in-docstring-latex/135555 "2026-02-11T08:09:34Z")

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What’s the recommended way to include a multi-character function or argument name in the LaTeX/math part of a docstring? \\text, \\mathrm, or something else? MWE: @doc """ Test if \`\`x \\\\le \\\\text{abstol}\`\`. """ is\_done(x…

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## [Reactant: how to use it, limititations and opportunities?](https://discourse.julialang.org/t/reactant-how-to-use-it-limititations-and-opportunities/135559)

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**Author:** [@marcobonici](https://discourse.julialang.org/u/marcobonici)\
**Replies:** 1\
**Last updated:** [February 11, 2026, 12:49am UTC](https://discourse.julialang.org/t/reactant-how-to-use-it-limititations-and-opportunities/135559 "2026-02-11T00:49:04Z")

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After reading a few posts (and some suggestion from @wmshen0323 to try Enzyme), Reactant got my attention. My understanding is that, if I manage to compile my code with Reactant, I get for free to run my code on GPUs and…

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## [Problem with Julia1.12 sources section in Project.toml](https://discourse.julialang.org/t/problem-with-julia1-12-sources-section-in-project-toml/134520)

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**Author:** [@Mark\_Nahabedian](https://discourse.julialang.org/u/Mark_Nahabedian)\
**Replies:** 1\
**Last updated:** [February 10, 2026, 10:51pm UTC](https://discourse.julialang.org/t/problem-with-julia1-12-sources-section-in-project-toml/134520 "2026-02-10T22:51:28Z")

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I’m trying to make use of the new sources section of Project.toml provided in Julia 1.12. This is in my project https://github.com/MarkNahabedian/PanelCutting.jl. The only mention of WebScrapingTools is in \[sources\] N…

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## [Parsing structs with computed fields in JSON.jl v1](https://discourse.julialang.org/t/parsing-structs-with-computed-fields-in-json-jl-v1/135551)

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**Author:** [@simsurace](https://discourse.julialang.org/u/simsurace)\
**Replies:** 6\
**Last updated:** [February 10, 2026, 8:02pm UTC](https://discourse.julialang.org/t/parsing-structs-with-computed-fields-in-json-jl-v1/135551 "2026-02-10T20:02:25Z")

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I have the following problem migrating from JSON3.jl to JSON.jl v1: julia\> struct MyStruct a::Int b::String # MyStruct(a::Int) = new(a, string(a)) this won't work even with J…

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## [Basic question about thread interaction](https://discourse.julialang.org/t/basic-question-about-thread-interaction/135532)

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**Author:** [@slwu89](https://discourse.julialang.org/u/slwu89)\
**Replies:** 3\
**Last updated:** [February 10, 2026, 9:39am UTC](https://discourse.julialang.org/t/basic-question-about-thread-interaction/135532 "2026-02-10T09:39:23Z")

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Hi everyone. I’m trying to learn how to use threads in Julia by comparing them to the Python examples from Ramalho’s Fluent Python book Fluent Python, 2nd Edition \[Book\]. The basic Python example is: import itertools i…

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