# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1518

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

**Page:** 1519

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## [Stuck at please authenticate](https://discourse.julialang.org/t/stuck-at-please-authenticate/53604)

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**Author:** [@Erik](https://discourse.julialang.org/u/Erik)\
**Replies:** 3\
**Last updated:** [January 19, 2021, 1:56pm UTC](https://discourse.julialang.org/t/stuck-at-please-authenticate/53604 "2021-01-19T13:56:45Z")

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I installed JuliaPro yesterday. I’m now trying to install a plotting routine using Pkg.add("Plots"). The Juno/Atom IDE opens an HTML pane and asks me to authenticate. As I signed up with gmail, I click the “gmail” button…

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## [Problem with constrains for consequtive cases](https://discourse.julialang.org/t/problem-with-constrains-for-consequtive-cases/53599)

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**Author:** [@gustav.asbjorn](https://discourse.julialang.org/u/gustav.asbjorn)\
**Replies:** 1\
**Last updated:** [January 19, 2021, 1:15pm UTC](https://discourse.julialang.org/t/problem-with-constrains-for-consequtive-cases/53599 "2021-01-19T13:15:04Z")

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Hello there. I have problems creating some constrains that will satisfy the following case: We have 10 wokers that will work some days of a 14 day period in different timeintervals of the day: daytime, evening and night…

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## [Discourse vs. GitHub for discussing internals](https://discourse.julialang.org/t/discourse-vs-github-for-discussing-internals/53572)

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**Author:** [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Replies:** 1\
**Last updated:** [January 19, 2021, 12:03pm UTC](https://discourse.julialang.org/t/discourse-vs-github-for-discussing-internals/53572 "2021-01-19T12:03:30Z")

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The category “Internals & Design” of Julia’s Discourse is announced as a place for “Discussion of the development of Julia itself: language design, implementation and standard library”. This is of course right, but I thi…

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## [Parameters of the model: free, fixed, constrained](https://discourse.julialang.org/t/parameters-of-the-model-free-fixed-constrained/53501)

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**Author:** [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Replies:** 3\
**Last updated:** [January 19, 2021, 11:57am UTC](https://discourse.julialang.org/t/parameters-of-the-model-free-fixed-constrained/53501 "2021-01-19T11:57:26Z")

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I am seeking advice on the way to store parameters of a model with a metadata free , fixed , or constrained. NamedTuples are already good for the pairs of (:name, :value) p = (a = 1.1, b = 3.3) I am considering two opt…

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## [Base.factorial: Extending and overwriting functions in SpecialFunctions](https://discourse.julialang.org/t/base-factorial-extending-and-overwriting-functions-in-specialfunctions/53486)

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**Author:** [@mr.red](https://discourse.julialang.org/u/mr.red)\
**Replies:** 1\
**Last updated:** [January 19, 2021, 11:46am UTC](https://discourse.julialang.org/t/base-factorial-extending-and-overwriting-functions-in-specialfunctions/53486 "2021-01-19T11:46:14Z")

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The Base.factorial function supplies the following methods julia\> methods(factorial) # 7 methods for generic function "factorial": \[1\] factorial(n::UInt128) in Base at combinatorics.jl:26 \[2\] factorial(n::Int128) in Bas…

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## [Any advice on Stereo Matching in Julia?](https://discourse.julialang.org/t/any-advice-on-stereo-matching-in-julia/53552)

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**Author:** [@Erik\_Engheim](https://discourse.julialang.org/u/Erik_Engheim)\
**Replies:** 2\
**Last updated:** [January 19, 2021, 11:05am UTC](https://discourse.julialang.org/t/any-advice-on-stereo-matching-in-julia/53552 "2021-01-19T11:05:56Z")

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I am looking to do stereo matching in Julia, basically to find the depth in an image by using two images. I am at an early stage and would appreciate some advice on where to look for information, and what libraries are …

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## [Problems with constraint. Alternative for JuMP variable in if statement](https://discourse.julialang.org/t/problems-with-constraint-alternative-for-jump-variable-in-if-statement/53563)

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**Author:** [@gustav.asbjorn](https://discourse.julialang.org/u/gustav.asbjorn)\
**Replies:** 7\
**Last updated:** [January 19, 2021, 11:00am UTC](https://discourse.julialang.org/t/problems-with-constraint-alternative-for-jump-variable-in-if-statement/53563 "2021-01-19T11:00:28Z")

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Hey. So I need to implement the following: Let’s say that we have 10 workers. If they work in the weekend then they want to work both days of the weekend or none. If they work only one day of the weekend then we add a p…

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## [Simple CUDA sum kernel](https://discourse.julialang.org/t/simple-cuda-sum-kernel/53594)

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**Author:** [@jw3126](https://discourse.julialang.org/u/jw3126)\
**Replies:** 0\
**Last updated:** [January 19, 2021, 8:43am UTC](https://discourse.julialang.org/t/simple-cuda-sum-kernel/53594 "2021-01-19T08:43:14Z")

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I am trying to write a simple CUDA.jl sum kernel. However I always get: ERROR: LoadError: CUDA error: an illegal memory access was encountered (code 700, ERROR\_ILLEGAL\_AD DRESS) Any ideas? Here is my code: using CUDA …

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## [How to filter out errors due to alias of Type name when building documentation?](https://discourse.julialang.org/t/how-to-filter-out-errors-due-to-alias-of-type-name-when-building-documentation/53588)

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**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 1\
**Last updated:** [January 19, 2021, 8:30am UTC](https://discourse.julialang.org/t/how-to-filter-out-errors-due-to-alias-of-type-name-when-building-documentation/53588 "2021-01-19T08:30:07Z")

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For example, the summary of objects of type Array{T,1} has been changed to Vector{T} in julia1.6. This makes the documentation build of a package fail on nightly. I wonder if there is a way to insert the correct output i…

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## [Trying to understand sort!(), findfirst()](https://discourse.julialang.org/t/trying-to-understand-sort-findfirst/53585)

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**Author:** [@Jared\_shay](https://discourse.julialang.org/u/Jared_shay)\
**Replies:** 4\
**Last updated:** [January 19, 2021, 7:49am UTC](https://discourse.julialang.org/t/trying-to-understand-sort-findfirst/53585 "2021-01-19T07:49:41Z")

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So far, this community is giving a lot of helps to answer beginner level julialang question. I am still in the early stage of learning julialang, so here I got a few new questions that might need community help. I am a …

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## [MenuAdventures.jl for making menu-based adventures in Julia](https://discourse.julialang.org/t/menuadventures-jl-for-making-menu-based-adventures-in-julia/52848)

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**Author:** [@bramtayl](https://discourse.julialang.org/u/bramtayl)\
**Replies:** 6\
**Last updated:** [January 19, 2021, 7:26am UTC](https://discourse.julialang.org/t/menuadventures-jl-for-making-menu-based-adventures-in-julia/52848 "2021-01-19T07:26:28Z")

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MenuAdventures is a Julia package for writing menu based adventures. MenuAdventures is heavily inspired by Inform7. Inform7 is an astounding achievement in terms of natural language programming. However, I’ve made som…

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## [\[JSON.jl\] About empty structs](https://discourse.julialang.org/t/json-jl-about-empty-structs/53571)

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**Author:** [@TommyXR](https://discourse.julialang.org/u/TommyXR)\
**Replies:** 1\
**Last updated:** [January 19, 2021, 6:50am UTC](https://discourse.julialang.org/t/json-jl-about-empty-structs/53571 "2021-01-19T06:50:53Z")

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Hello. The package JSON.jl made the interesting design decision to make singleton structs unserializable. This behavior is implemented in this function in the source code. function lower(a) if nfields(a) \> 0 …

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## [Understanding few syntax of Julia code](https://discourse.julialang.org/t/understanding-few-syntax-of-julia-code/53514)

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**Author:** [@Jared\_shay](https://discourse.julialang.org/u/Jared_shay)\
**Replies:** 21\
**Last updated:** [January 19, 2021, 7:12am UTC](https://discourse.julialang.org/t/understanding-few-syntax-of-julia-code/53514 "2021-01-19T07:12:45Z")

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I am very new to Julia language, so I started to read the documentation and all builtin functions. Now, I am learning one github project for my work. Since I am more comfortable with Python, I tried to translate Julia’s …

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## [Meta-programming an if-else statement of user-defined length](https://discourse.julialang.org/t/meta-programming-an-if-else-statement-of-user-defined-length/53525)

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**Author:** [@MilesCranmer](https://discourse.julialang.org/u/MilesCranmer)\
**Replies:** 17\
**Last updated:** [January 19, 2021, 7:07am UTC](https://discourse.julialang.org/t/meta-programming-an-if-else-statement-of-user-defined-length/53525 "2021-01-19T07:07:20Z")

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I am trying to optimize the way my package SymbolicRegression.jl (the pure-Julia version of PySR) calls user-passed operators. The user passes a list of operators like so: SymbolicRegression.Options( binary\_operato…

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## [Combine two graphs in lightgraph](https://discourse.julialang.org/t/combine-two-graphs-in-lightgraph/53462)

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**Author:** [@AlexanderChen](https://discourse.julialang.org/u/AlexanderChen)\
**Replies:** 4\
**Last updated:** [January 19, 2021, 6:44am UTC](https://discourse.julialang.org/t/combine-two-graphs-in-lightgraph/53462 "2021-01-19T06:44:40Z")

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Hi, I have two graphs that represent SQL tables : f = star\_graph(5) nodelabel = \["T1","C1","C2","C3","C4"\] h = star\_graph(4) nodelabel = \["T2","C1.2","C2.2","C3.2"\] I want to context both graphs on “C2” and “C3.2” h…

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## [Is spzeros deprecated for creating sparse matrix in Julialang?](https://discourse.julialang.org/t/is-spzeros-deprecated-for-creating-sparse-matrix-in-julialang/53582)

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**Author:** [@Jared\_shay](https://discourse.julialang.org/u/Jared_shay)\
**Replies:** 8\
**Last updated:** [January 19, 2021, 6:25am UTC](https://discourse.julialang.org/t/is-spzeros-deprecated-for-creating-sparse-matrix-in-julialang/53582 "2021-01-19T06:25:51Z")

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I am trying to understand how to create a sparse matrix in Julialang. The example project that I am learning in GitHub, I spotted spzeros() function which I believe it is going to create a sparse matrix. When I test fol…

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## [Macro for partially quoting (or partially evaluating) an expression](https://discourse.julialang.org/t/macro-for-partially-quoting-or-partially-evaluating-an-expression/53519)

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**Author:** [@goretkin](https://discourse.julialang.org/u/goretkin)\
**Replies:** 5\
**Last updated:** [January 19, 2021, 1:35am UTC](https://discourse.julialang.org/t/macro-for-partially-quoting-or-partially-evaluating-an-expression/53519 "2021-01-19T01:35:08Z")

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I would like to quote expressions, but evaluate some Symbols (which ones? see below). It should be possible to accomplish this using macros. I’ve tried to give an idea below of what I’m after: """ e.g. \`\`\`julia julia\> …

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## [Read pdf as image](https://discourse.julialang.org/t/read-pdf-as-image/53573)

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**Author:** [@BMval](https://discourse.julialang.org/u/BMval)\
**Replies:** 1\
**Last updated:** [January 19, 2021, 1:32am UTC](https://discourse.julialang.org/t/read-pdf-as-image/53573 "2021-01-19T01:32:07Z")

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Hi. Would somebody suggest, Can I read pdf as images, please? Thank you so much!!!

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## [\[Makie\] How to plot a polygon with holes?](https://discourse.julialang.org/t/makie-how-to-plot-a-polygon-with-holes/53565)

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**Author:** [@circonflexe](https://discourse.julialang.org/u/circonflexe)\
**Replies:** 2\
**Last updated:** [January 19, 2021, 12:53am UTC](https://discourse.julialang.org/t/makie-how-to-plot-a-polygon-with-holes/53565 "2021-01-19T00:53:25Z")

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I am trying to plot polygons in Makie.jl, using the poly function. The documentation for that function is quite terse, to say the least. Does anybody have an example on hand of plotting custom polygons, or unions of poly…

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## [Changing file on disk not affecting IOStream data, is this a bug?](https://discourse.julialang.org/t/changing-file-on-disk-not-affecting-iostream-data-is-this-a-bug/53359)

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**Author:** [@tlnagy](https://discourse.julialang.org/u/tlnagy)\
**Replies:** 11\
**Last updated:** [January 19, 2021, 12:23am UTC](https://discourse.julialang.org/t/changing-file-on-disk-not-affecting-iostream-data-is-this-a-bug/53359 "2021-01-19T00:23:35Z")

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I’m extending my support for memory-mapped TIFF images in my package TiffImages.jl to support writing in addition to reading. One thing I’m running into is that my structs contain a file handle that I read/write to, but …

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## [Animating the content of a title of a plot in Makie.jl](https://discourse.julialang.org/t/animating-the-content-of-a-title-of-a-plot-in-makie-jl/53564)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 1\
**Last updated:** [January 18, 2021, 9:48pm UTC](https://discourse.julialang.org/t/animating-the-content-of-a-title-of-a-plot-in-makie-jl/53564 "2021-01-18T21:48:58Z")

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My “expected” way of animating the title of a plot does not work. MWE: using GLMakie fig = Figure() ax = fig\[1,1\] = Axis(fig) s = Observable(0) # counter of current step titlestr = lift(x -\> "step = "\*string(x), s) ax.…

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## [Low rank SVD](https://discourse.julialang.org/t/low-rank-svd/53529)

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**Author:** [@gdkrmr](https://discourse.julialang.org/u/gdkrmr)\
**Replies:** 3\
**Last updated:** [January 18, 2021, 8:53pm UTC](https://discourse.julialang.org/t/low-rank-svd/53529 "2021-01-18T20:53:18Z")

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I need to calculate a low rank SVD of a large matrix for a pseudoinverse, but I also need the individual matrices. I currently do I like this: X\_svd = svd(X) r = 20 U = X\_svd.U\[:, 1:r\] Σ = Diagonal(X\_svd.S\[1:r\]) Vt = X…

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## [Error using getvalue](https://discourse.julialang.org/t/error-using-getvalue/53546)

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**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 4\
**Last updated:** [January 18, 2021, 8:35pm UTC](https://discourse.julialang.org/t/error-using-getvalue/53546 "2021-01-18T20:35:09Z")

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Hello!! Whenever I try to use getvalue the following error appears to me: MethodError: no method matches getvalue (:: ConstraintRef {Model, JuMP.GenericRangeConstraint {JuMP.GenericAffExpr {Float64, Variable}}}) Could…

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## [\#Helpdesk channel on Slack (proposal to close the channel)](https://discourse.julialang.org/t/helpdesk-channel-on-slack-proposal-to-close-the-channel/47697)

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**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 61\
**Last updated:** [January 18, 2021, 8:21pm UTC](https://discourse.julialang.org/t/helpdesk-channel-on-slack-proposal-to-close-the-channel/47697 "2021-01-18T20:21:25Z")

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Hey all, This post is going to walk through all the details associated with the archiving of the helpdesk channel on the Julia Language’s Slack. Before we go into why this decision is being made, let’s talk about what o…

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## [I've heard a number of people say Julia is not mainstream because it doesn't have many stackoverflow questions answered but they don't know about discourse](https://discourse.julialang.org/t/ive-heard-a-number-of-people-say-julia-is-not-mainstream-because-it-doesnt-have-many-stackoverflow-questions-answered-but-they-dont-know-about-discourse/53168)

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**Author:** [@samerb](https://discourse.julialang.org/u/samerb)\
**Replies:** 21\
**Last updated:** [January 18, 2021, 8:20pm UTC](https://discourse.julialang.org/t/ive-heard-a-number-of-people-say-julia-is-not-mainstream-because-it-doesnt-have-many-stackoverflow-questions-answered-but-they-dont-know-about-discourse/53168 "2021-01-18T20:20:15Z")

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I’ve heard a number of people say Julia is not mainstream because it doesn’t have many stackoverflow questions answered. I’ve noticed a number of people say things like this and got the impression that they don’t know a…

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## [Kanai-Tajimi Process (seismic simulation)](https://discourse.julialang.org/t/kanai-tajimi-process-seismic-simulation/53553)

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**Author:** [@Frederic\_Gilt](https://discourse.julialang.org/u/Frederic_Gilt)\
**Replies:** 0\
**Last updated:** [January 18, 2021, 6:15pm UTC](https://discourse.julialang.org/t/kanai-tajimi-process-seismic-simulation/53553 "2021-01-18T18:15:25Z")

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Dear All, I am a basic user of Julia and was wondering if it’s possible to achieve simulations of mechanical structures facing seismic input modeled with Kanai-Tajami process There is a cool description of such kind of…

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## [How to add a package as a test dependency from the REPL?](https://discourse.julialang.org/t/how-to-add-a-package-as-a-test-dependency-from-the-repl/14313)

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**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 3\
**Last updated:** [January 18, 2021, 8:04pm UTC](https://discourse.julialang.org/t/how-to-add-a-package-as-a-test-dependency-from-the-repl/14313 "2021-01-18T20:04:48Z")

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To add a dependency ony for testing, I followed the instructions here: Pkg · The Julia Language. But this involves editing Project.toml directly. Can this be done through the REPL (like pkg\> add ... does for a proper de…

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## [JSON list of lists to Julia matrix, preferably fast and with low memory overhead](https://discourse.julialang.org/t/json-list-of-lists-to-julia-matrix-preferably-fast-and-with-low-memory-overhead/53410)

<div class="topic-metadata">

**Author:** [@evanfields](https://discourse.julialang.org/u/evanfields)\
**Replies:** 5\
**Last updated:** [January 18, 2021, 8:01pm UTC](https://discourse.julialang.org/t/json-list-of-lists-to-julia-matrix-preferably-fast-and-with-low-memory-overhead/53410 "2021-01-18T20:01:51Z")

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I have JSON files that contain a list of square matrices. Let’s say each JSON has a single key "mats" which is a list of list of lists. Each element in the outer list—i.e. a list of lists—is a matrix in row major order. …

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## [External talk: "GopherCon 2020: Austin Clements - Pardon the Interruption: Loop Preemption in Go 1.14"](https://discourse.julialang.org/t/external-talk-gophercon-2020-austin-clements-pardon-the-interruption-loop-preemption-in-go-1-14/53555)

<div class="topic-metadata">

**Author:** [@NHDaly](https://discourse.julialang.org/u/NHDaly)\
**Replies:** 0\
**Last updated:** [January 18, 2021, 7:59pm UTC](https://discourse.julialang.org/t/external-talk-gophercon-2020-austin-clements-pardon-the-interruption-loop-preemption-in-go-1-14/53555 "2021-01-18T19:59:43Z")

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I really enjoyed watching this talk about how Go has added preemption to their coroutines to avoid stop-the-world GC latency caused by long-running tight-loops in tasks: GopherCon 2020: Austin Clements - Pardon the Inte…

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## [Question on RefValue](https://discourse.julialang.org/t/question-on-refvalue/53498)

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**Author:** [@TI36XPro](https://discourse.julialang.org/u/TI36XPro)\
**Replies:** 12\
**Last updated:** [January 18, 2021, 3:48pm UTC](https://discourse.julialang.org/t/question-on-refvalue/53498 "2021-01-18T15:48:55Z")

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In this video here the lecturer defines a composite type to hold his model and to step it forward in time. He needs to keep track of the number of iterations but the number of iterations is a field within a struct which…

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