# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1672

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

**Page:** 1673

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## [No Julia in Jupyter](https://discourse.julialang.org/t/no-julia-in-jupyter/44141)

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**Author:** [@alfasst](https://discourse.julialang.org/u/alfasst)\
**Replies:** 1\
**Last updated:** [August 2, 2020, 5:11pm UTC](https://discourse.julialang.org/t/no-julia-in-jupyter/44141 "2020-08-02T17:11:20Z")

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I’m using Fedora 29 and I have installed Jupyter into root directory. And I have installed JuliaPro to local directory. Then I installed IJulia package and it was a success and if I enter notebook() , Jupyter opens in my…

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## [Can this code be made faster](https://discourse.julialang.org/t/can-this-code-be-made-faster/44122)

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**Author:** [@Sanji\_Vinsmoke](https://discourse.julialang.org/u/Sanji_Vinsmoke)\
**Replies:** 9\
**Last updated:** [August 2, 2020, 4:58pm UTC](https://discourse.julialang.org/t/can-this-code-be-made-faster/44122 "2020-08-02T16:58:45Z")

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I attempted the Advent od Code 2015 day 9 solution in julia and here is my code for the first part (for this input 9.txt file refer to the link to the problem): using Combinatorics, BenchmarkTools distances = readlines…

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## [10 min Paper Discussion + Flux Impl.: Towards Learning Convolutions from Scratch](https://discourse.julialang.org/t/10-min-paper-discussion-flux-impl-towards-learning-convolutions-from-scratch/44114)

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**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 0\
**Last updated:** [August 2, 2020, 1:45am UTC](https://discourse.julialang.org/t/10-min-paper-discussion-flux-impl-towards-learning-convolutions-from-scratch/44114 "2020-08-02T01:45:57Z")

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Do we do paper discussions for fun? Figured I’d try it out to see who does CV here and maybe make some new friends. I’m not doing any professional CV work now, did some professionally a few years back, but am getting bac…

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## [JuMP on repl.it (Julia 1.3)](https://discourse.julialang.org/t/jump-on-repl-it-julia-1-3/42662)

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**Author:** [@elalaouifaris](https://discourse.julialang.org/u/elalaouifaris)\
**Replies:** 7\
**Last updated:** [August 2, 2020, 2:11pm UTC](https://discourse.julialang.org/t/jump-on-repl-it-julia-1-3/42662 "2020-08-02T14:11:47Z")

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Hi, Just trying to use Julia on the repl.it website. There you can spin up an instance with Julia 1.3 pre-configured. using JuMP in it results in a compilation error. Is this a known problem? is there a way to make Ju…

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## [\`issubset(::BitSet,::BitSet)\` is slow and allocates unnecessarily](https://discourse.julialang.org/t/issubset-bitset-bitset-is-slow-and-allocates-unnecessarily/43828)

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**Author:** [@guyvdb](https://discourse.julialang.org/u/guyvdb)\
**Replies:** 1\
**Last updated:** [August 2, 2020, 1:28pm UTC](https://discourse.julialang.org/t/issubset-bitset-bitset-is-slow-and-allocates-unnecessarily/43828 "2020-08-02T13:28:10Z")

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The implementation of issubset between two BitSet: https://github.com/JuliaLang/julia/blob/3909294e78d223c740b7e7a4d00eb2d4771055a7/base/bitset.jl#L419 first intersects the sets. This unnecessarily allocates memory to c…

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## [How to define laplacian in Flux or Zygote?](https://discourse.julialang.org/t/how-to-define-laplacian-in-flux-or-zygote/44121)

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**Author:** [@DeepQ](https://discourse.julialang.org/u/DeepQ)\
**Replies:** 0\
**Last updated:** [August 2, 2020, 7:05am UTC](https://discourse.julialang.org/t/how-to-define-laplacian-in-flux-or-zygote/44121 "2020-08-02T07:05:21Z")

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I want to solve a PDE using a neural network and I need to calculate the laplacian of my network.

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## [Quick probably basic question on Floats](https://discourse.julialang.org/t/quick-probably-basic-question-on-floats/44117)

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**Author:** [@clinton](https://discourse.julialang.org/u/clinton)\
**Replies:** 5\
**Last updated:** [August 2, 2020, 6:21am UTC](https://discourse.julialang.org/t/quick-probably-basic-question-on-floats/44117 "2020-08-02T06:21:05Z")

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I was wondering if someone could explain what is going in with the below code to me: function f3264() v32 = rand(Float32, 3) @info v32 v64 = Float64.(v32) @info v64 Δv = v64 .- v32 @info Δv @assert sum(Δv)…

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## [Alternatives to pipelining Table operations like "filter" and "columns"? How to speed this up?](https://discourse.julialang.org/t/alternatives-to-pipelining-table-operations-like-filter-and-columns-how-to-speed-this-up/44100)

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**Author:** [@kai](https://discourse.julialang.org/u/kai)\
**Replies:** 3\
**Last updated:** [August 2, 2020, 6:04am UTC](https://discourse.julialang.org/t/alternatives-to-pipelining-table-operations-like-filter-and-columns-how-to-speed-this-up/44100 "2020-08-02T06:04:33Z")

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Hi all, I found that the following chunk is the major bottleneck in my code. For each “id” (subject), it uses pipelines to filter out the data for that “id”, creates the columns object, and then build the MyObs type. I…

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## [How to extract the most populated bin from a histogram](https://discourse.julialang.org/t/how-to-extract-the-most-populated-bin-from-a-histogram/44081)

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**Author:** [@Tofi](https://discourse.julialang.org/u/Tofi)\
**Replies:** 3\
**Last updated:** [August 2, 2020, 4:42am UTC](https://discourse.julialang.org/t/how-to-extract-the-most-populated-bin-from-a-histogram/44081 "2020-08-02T04:42:42Z")

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Hello, I am using the fit function from the StatsBase package in order to calculate the histogram for an array of numbers. For example: l = rand(100) hist = fit(Histogram, l) Is there a way to extract the most populat…

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## [A suggestion for package maintainers](https://discourse.julialang.org/t/a-suggestion-for-package-maintainers/44111)

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**Author:** [@anon37204545](https://discourse.julialang.org/u/anon37204545)\
**Replies:** 2\
**Last updated:** [August 2, 2020, 12:59am UTC](https://discourse.julialang.org/t/a-suggestion-for-package-maintainers/44111 "2020-08-02T00:59:10Z")

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If your Julia package has any form of online documentation (e.g. docs generated by Documenter.jl), please please put the link to it in the repository’s description. For example, just like in the Documenter.jl repository …

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## [\`TypeVar\` or \`eltype\`, which is faster?](https://discourse.julialang.org/t/typevar-or-eltype-which-is-faster/44113)

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**Author:** [@singularitti](https://discourse.julialang.org/u/singularitti)\
**Replies:** 1\
**Last updated:** [August 1, 2020, 11:50pm UTC](https://discourse.julialang.org/t/typevar-or-eltype-which-is-faster/44113 "2020-08-01T23:50:52Z")

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Consider the following code using Unitful function f(arr::AbstractArray{T}) where {T} N = length(arr) return NTuple{N,T}(arr) end or function g(arr::AbstractArray) N, T = length(arr), eltype(arr) retu…

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## [Trying to speed-up Laplace Equation Solver](https://discourse.julialang.org/t/trying-to-speed-up-laplace-equation-solver/43862)

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**Author:** [@SambitMishra98](https://discourse.julialang.org/u/SambitMishra98)\
**Replies:** 36\
**Last updated:** [August 1, 2020, 10:14pm UTC](https://discourse.julialang.org/t/trying-to-speed-up-laplace-equation-solver/43862 "2020-08-01T22:14:26Z")

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I am trying to speedup my code for Laplace Equation Solver. Based on code profiling, most of the time goes in the function given below. I have tried to optimise the functions as much as possible but the performance still…

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## [How to export names from a lower level module without explicitly listing all of them?](https://discourse.julialang.org/t/how-to-export-names-from-a-lower-level-module-without-explicitly-listing-all-of-them/44104)

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**Author:** [@Zhong\_Pan](https://discourse.julialang.org/u/Zhong_Pan)\
**Replies:** 1\
**Last updated:** [August 1, 2020, 10:11pm UTC](https://discourse.julialang.org/t/how-to-export-names-from-a-lower-level-module-without-explicitly-listing-all-of-them/44104 "2020-08-01T22:11:09Z")

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I often organize code into modules inside a single package. Let’s say I have a pacakge named AB.jl, and inside I have modules A.jl, B.jl, all in the src folder. A nice way to organize them is demonstrated by Jacob Quin…

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## [NeuralPDE.jl vs NeuralNetDiffEq.jl](https://discourse.julialang.org/t/neuralpde-jl-vs-neuralnetdiffeq-jl/43934)

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**Author:** [@Peter\_Uhl](https://discourse.julialang.org/u/Peter_Uhl)\
**Replies:** 4\
**Last updated:** [August 1, 2020, 9:14pm UTC](https://discourse.julialang.org/t/neuralpde-jl-vs-neuralnetdiffeq-jl/43934 "2020-08-01T21:14:35Z")

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Hi all, I’m trying to use the NeuralPDE package, but when I run ‘import Pkg; Pkg.add(“NeuralPDE”)’ I get the error: ERROR: The following package names could not be resolved: NeuralPDE (not found in project, manifest …

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## [Import xlsx file](https://discourse.julialang.org/t/import-xlsx-file/44096)

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**Author:** [@dty](https://discourse.julialang.org/u/dty)\
**Replies:** 1\
**Last updated:** [August 1, 2020, 5:55pm UTC](https://discourse.julialang.org/t/import-xlsx-file/44096 "2020-08-01T17:55:01Z")

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After importing xlsx file, how to read the data according to the original matrix form? Although it was imported, it was not presented in the matrix form of 24 \* 3 in the original excel.

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## [Non-diagonal noise](https://discourse.julialang.org/t/non-diagonal-noise/44004)

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**Author:** [@mzhai2](https://discourse.julialang.org/u/mzhai2)\
**Replies:** 2\
**Last updated:** [August 1, 2020, 5:13pm UTC](https://discourse.julialang.org/t/non-diagonal-noise/44004 "2020-08-01T17:13:11Z")

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How am I supposed to use non-diagonal noise when du is a matrix? When I run the example below I get: BoundsError: attempt to access 2-element Array{Float64,1} at index \[1, 2\] using DifferentialEquations, LinearAlgebra …

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## [Parsing high precision timestamps?](https://discourse.julialang.org/t/parsing-high-precision-timestamps/44061)

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**Author:** [@crbinz](https://discourse.julialang.org/u/crbinz)\
**Replies:** 2\
**Last updated:** [August 1, 2020, 5:09pm UTC](https://discourse.julialang.org/t/parsing-high-precision-timestamps/44061 "2020-08-01T17:09:08Z")

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I have a series of timestamps like 2020-01-01T12:34:56.789123Z. Trying to parse it with DateTime("2020-01-01T12:34:56.789123Z", dateformat"Y-m-dTH:M:S.ssssssZ") results in ERROR: LoadError: InexactError: convert(Dates.De…

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## [ERROR: could not find project file in package at https://github.com/](https://discourse.julialang.org/t/error-could-not-find-project-file-in-package-at-https-github-com/44059)

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**Author:** [@Ken\_Lin](https://discourse.julialang.org/u/Ken_Lin)\
**Replies:** 3\
**Last updated:** [August 1, 2020, 3:41pm UTC](https://discourse.julialang.org/t/error-could-not-find-project-file-in-package-at-https-github-com/44059 "2020-08-01T15:41:41Z")

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Hello! I tried to install some packages on Julia 1.4.2 and I got errors of the following format: ERROR: could not find project file in package at https://github.com/... I was able to install these packages on Julia 1.3…

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## [Replace char vs string](https://discourse.julialang.org/t/replace-char-vs-string/44083)

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**Author:** [@anon37204545](https://discourse.julialang.org/u/anon37204545)\
**Replies:** 3\
**Last updated:** [August 1, 2020, 12:54pm UTC](https://discourse.julialang.org/t/replace-char-vs-string/44083 "2020-08-01T12:54:05Z")

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julia\> @btime replace(" a "^1000, ' ' =\> "a") 120.199 μs (7 allocations: 6.94 KiB) "..." julia\> @btime replace(" a "^1000, " " =\> "a") 193.500 μs (7 allocations: 6.94 KiB) "..." julia\> @btime replace(" a "^1000, ' …

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## [bilevelJuMP](https://discourse.julialang.org/t/bileveljump/44088)

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**Author:** [@dty](https://discourse.julialang.org/u/dty)\
**Replies:** 1\
**Last updated:** [August 1, 2020, 3:06pm UTC](https://discourse.julialang.org/t/bileveljump/44088 "2020-08-01T15:06:25Z")

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@joaquimg I’m sorry to disturb you. Please tell me something about bilevel jump. When defining objective functions in the bilevel jump package, is it not allowed to minimize the sum of multiple objective functions? In …

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## [How to set histogram alignment in Plots.jl](https://discourse.julialang.org/t/how-to-set-histogram-alignment-in-plots-jl/4273)

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**Author:** [@mbeltagy](https://discourse.julialang.org/u/mbeltagy)\
**Replies:** 13\
**Last updated:** [August 1, 2020, 2:47pm UTC](https://discourse.julialang.org/t/how-to-set-histogram-alignment-in-plots-jl/4273 "2020-08-01T14:47:11Z")

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In matplotlib.pyplot.hist their is an align keyword that changes alignment of the histogram from “mid”, “left”, or “right”. This keyword in currently not supported on Plots.jl. It there a way I could force pass it to the…

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## [Syntax for custom cost function for ODE parameter estimation](https://discourse.julialang.org/t/syntax-for-custom-cost-function-for-ode-parameter-estimation/43467)

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**Author:** [@vaglino](https://discourse.julialang.org/u/vaglino)\
**Replies:** 3\
**Last updated:** [August 1, 2020, 12:04pm UTC](https://discourse.julialang.org/t/syntax-for-custom-cost-function-for-ode-parameter-estimation/43467 "2020-08-01T12:04:55Z")

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Hi, I’m trying to write my own cost function for parameter estimation of an ode model. I am trying to weight the loss by the time t. Based on the documentation I came up with the following, but I’m unsure about the cor…

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## [Animation Rendering Package](https://discourse.julialang.org/t/animation-rendering-package/44064)

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**Author:** [@Renan\_Rabelo](https://discourse.julialang.org/u/Renan_Rabelo)\
**Replies:** 1\
**Last updated:** [August 1, 2020, 8:58am UTC](https://discourse.julialang.org/t/animation-rendering-package/44064 "2020-08-01T08:58:41Z")

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Hi everyone! I’m new to Julia language and I need one specific type of package. I use programming to visualize mathematical stuff (fractals, complex behaviors etc) and for a while I used Processing language (Java based…

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## [Flux - Batch data loop in callback causing GPU Memory Error](https://discourse.julialang.org/t/flux-batch-data-loop-in-callback-causing-gpu-memory-error/33292)

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**Author:** [@GdMacmillan](https://discourse.julialang.org/u/GdMacmillan)\
**Replies:** 5\
**Last updated:** [August 1, 2020, 11:15am UTC](https://discourse.julialang.org/t/flux-batch-data-loop-in-callback-causing-gpu-memory-error/33292 "2020-08-01T11:15:53Z")

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I’m trying to build a general tutorial for the basic build of an image classifier in flux on a Colab notebook.. The dataset is Fashion MNIST. Building it out more and more I have found a problem with my code, Recently I…

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## [How to change field names and types of a DataFrame](https://discourse.julialang.org/t/how-to-change-field-names-and-types-of-a-dataframe/43991)

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**Author:** [@sbacelar](https://discourse.julialang.org/u/sbacelar)\
**Replies:** 14\
**Last updated:** [August 1, 2020, 10:31am UTC](https://discourse.julialang.org/t/how-to-change-field-names-and-types-of-a-dataframe/43991 "2020-08-01T10:31:06Z")

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I imported a xlsx file to an array a using XLSX.jl. But now I have no real names for the fields in df and the types are all Any. I changed names using rename! but I don’t know how to change types respectively to String,…

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## [Allocation with in-place sum of a transposed matrix](https://discourse.julialang.org/t/allocation-with-in-place-sum-of-a-transposed-matrix/44066)

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**Author:** [@aaraujo71](https://discourse.julialang.org/u/aaraujo71)\
**Replies:** 4\
**Last updated:** [August 1, 2020, 10:05am UTC](https://discourse.julialang.org/t/allocation-with-in-place-sum-of-a-transposed-matrix/44066 "2020-08-01T10:05:08Z")

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I need to do in-place summations of a transposed matrix and I get memory allocation in the process. For example, running function test of the following code function test\_sum\_transpose(b, a) sum!(b, a') end functio…

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## [Why they are not equivalent?](https://discourse.julialang.org/t/why-they-are-not-equivalent/44078)

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**Author:** [@Hawk](https://discourse.julialang.org/u/Hawk)\
**Replies:** 5\
**Last updated:** [August 1, 2020, 9:55am UTC](https://discourse.julialang.org/t/why-they-are-not-equivalent/44078 "2020-08-01T09:55:35Z")

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A try like below: Expr(:$,:(1+2)) == :($(1+2)) gives false. Why they are not equivalent? I suppose the righthand side has been evaluated to 3. Is this the real reason? Thanks!

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## [How to fix this error (first installation)?](https://discourse.julialang.org/t/how-to-fix-this-error-first-installation/44033)

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**Author:** [@billninja](https://discourse.julialang.org/u/billninja)\
**Replies:** 3\
**Last updated:** [August 1, 2020, 9:50am UTC](https://discourse.julialang.org/t/how-to-fix-this-error-first-installation/44033 "2020-08-01T09:50:41Z")

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I want to use Julia 0.6 with latest version of Atom/Juno. However, there is a below error during installation. Starting Julia… INFO: Precompiling module Atom. ERROR: LoadError: HttpParser not properly installed. Pleas…

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## [Help with Threading](https://discourse.julialang.org/t/help-with-threading/42357)

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**Author:** [@ok\_ok](https://discourse.julialang.org/u/ok_ok)\
**Replies:** 10\
**Last updated:** [July 4, 2020, 3:00pm UTC](https://discourse.julialang.org/t/help-with-threading/42357 "2020-07-04T15:00:07Z")

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Hello Guys, im not sure if im at the Right Place to ask those kind off Questions, if not im really sorry. So my Question is about Threadding. I have got a Julia-Script where im using a lot of Recurssion, and in side th…

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## [Use julia-vscode with upcoming release of Julia](https://discourse.julialang.org/t/use-julia-vscode-with-upcoming-release-of-julia/43961)

<div class="topic-metadata">

**Author:** [@DOT](https://discourse.julialang.org/u/DOT)\
**Replies:** 2\
**Last updated:** [August 1, 2020, 9:33am UTC](https://discourse.julialang.org/t/use-julia-vscode-with-upcoming-release-of-julia/43961 "2020-08-01T09:33:46Z")

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Hi I would like to switch to the upcoming release of Julia (1.15-rc-2) and use, e.g., @NamedTuple. Currently, the linter will complain about @NamedTuple{a:Int, b:Int} saying that a,b are missing references. (1) I’m su…

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