# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1643

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

**Page:** 1644

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## [\[ANN\] JSONLines v.2.0.0](https://discourse.julialang.org/t/ann-jsonlines-v-2-0-0/45888)

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**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 0\
**Last updated:** [September 1, 2020, 12:11pm UTC](https://discourse.julialang.org/t/ann-jsonlines-v-2-0-0/45888 "2020-09-01T12:11:25Z")

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I am happy to announce v2 of the JSONLines.jl package. This is basically a complete rewrite but offers much more functionality. There are two main functions: Create an iterator over a JSONLines file (now LineIterator) or…

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## [Available Tables.jl implementations](https://discourse.julialang.org/t/available-tables-jl-implementations/45853)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 6\
**Last updated:** [September 1, 2020, 11:11am UTC](https://discourse.julialang.org/t/available-tables-jl-implementations/45853 "2020-09-01T11:11:01Z")

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Do we have a list of all implementations of Tables.jl in the ecosystem? The README file in Tables.jl points to integrations, but those are not necessarily table types. Do you know any other implementation besides the fo…

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## [Why isn't \`i\` defined inside this while?](https://discourse.julialang.org/t/why-isnt-i-defined-inside-this-while/45882)

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**Author:** [@Somayeh\_Esmaeili](https://discourse.julialang.org/u/Somayeh_Esmaeili)\
**Replies:** 4\
**Last updated:** [September 1, 2020, 10:08am UTC](https://discourse.julialang.org/t/why-isnt-i-defined-inside-this-while/45882 "2020-09-01T10:08:14Z")

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would you please help me why i cant be known inside this while as following in julia v1+? W=(\[1.0825998948767477 9.448347129060197 972.5335271289529; 165.861582812015 4.563134610834678 1.0293311999771995\], 0) i=1; k=siz…

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## [Question about task scheduling order](https://discourse.julialang.org/t/question-about-task-scheduling-order/45875)

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**Author:** [@marius311](https://discourse.julialang.org/u/marius311)\
**Replies:** 4\
**Last updated:** [September 1, 2020, 9:59am UTC](https://discourse.julialang.org/t/question-about-task-scheduling-order/45875 "2020-09-01T09:59:57Z")

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Haven’t done much with Julia Tasks (or coroutines in any language) so maybe a basic question, but can’t seem to find a definite answer. Basically, if I schedule one task before another, does that guarantee that it will s…

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## [AudioSchedules.jl](https://discourse.julialang.org/t/audioschedules-jl/45833)

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**Author:** [@bramtayl](https://discourse.julialang.org/u/bramtayl)\
**Replies:** 7\
**Last updated:** [September 1, 2020, 9:55am UTC](https://discourse.julialang.org/t/audioschedules-jl/45833 "2020-09-01T09:55:19Z")

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I made a Julia package for audio synthesis. It allows you to schedule synthesizers to turn on and off at various times, and record or play the results. I’ve worked pretty hard on performance and it’s multi-threaded, so h…

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## [Flux and cpu cores](https://discourse.julialang.org/t/flux-and-cpu-cores/45318)

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**Author:** [@johnbb](https://discourse.julialang.org/u/johnbb)\
**Replies:** 6\
**Last updated:** [September 1, 2020, 9:29am UTC](https://discourse.julialang.org/t/flux-and-cpu-cores/45318 "2020-09-01T09:29:57Z")

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When I run the following code using Flux n = 100\_000 p = 50 x = rand(Float32, p, n) y = rand(Float32, n) trdata = Flux.Data.DataLoader(x, y, batchsize=100) m = Chain(Dense(p, 100), Dense(100,100), Dense(100,1)) loss…

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## [Vertical errors for historgrams](https://discourse.julialang.org/t/vertical-errors-for-historgrams/45881)

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**Author:** [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Replies:** 2\
**Last updated:** [September 1, 2020, 9:27am UTC](https://discourse.julialang.org/t/vertical-errors-for-historgrams/45881 "2020-09-01T09:27:06Z")

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In my field of research (HEP), the vertical errors for the histograms are widely used. Usually, they are calculated assuming narrow bins and Poisson distribution for the number of entries, i.e. the error is sqrt(Nentri…

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## [Models precompilation and general modelling platform architecture](https://discourse.julialang.org/t/models-precompilation-and-general-modelling-platform-architecture/45599)

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**Author:** [@ivborissov](https://discourse.julialang.org/u/ivborissov)\
**Replies:** 11\
**Last updated:** [September 1, 2020, 9:01am UTC](https://discourse.julialang.org/t/models-precompilation-and-general-modelling-platform-architecture/45599 "2020-09-01T09:01:45Z")

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Hi, could you please help me with the following workflow question. Let’s say I have a simulation platform as julia package X and a number of models as julia .jl files. I would like say using X then precompile and upload…

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## [Julia learning macros / metaprogramming](https://discourse.julialang.org/t/julia-learning-macros-metaprogramming/45753)

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**Author:** [@Marcell\_Havlik](https://discourse.julialang.org/u/Marcell_Havlik)\
**Replies:** 13\
**Last updated:** [September 1, 2020, 8:48am UTC](https://discourse.julialang.org/t/julia-learning-macros-metaprogramming/45753 "2020-09-01T08:48:17Z")

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Hey Julianers, I am trieing to understand the julia macros, but I just can’t understand when do I have to use esc, quote, $, eval or so… Can someone give me the easiest tutorial I can understand? How do you know when t…

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## [Parsing a .gro file](https://discourse.julialang.org/t/parsing-a-gro-file/45375)

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**Author:** [@mastrof](https://discourse.julialang.org/u/mastrof)\
**Replies:** 9\
**Last updated:** [September 1, 2020, 8:02am UTC](https://discourse.julialang.org/t/parsing-a-gro-file/45375 "2020-09-01T08:02:32Z")

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Hello everyone, novice Julia user here. I’m using Julia to write some scripts for data analysis of Molecular Dynamics simulations and I need to parse some .gro files(a concise description of the file format can be found…

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## [Reading data in Julia 1.2.0](https://discourse.julialang.org/t/reading-data-in-julia-1-2-0/45876)

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**Author:** [@Nova](https://discourse.julialang.org/u/Nova)\
**Replies:** 1\
**Last updated:** [September 1, 2020, 7:55am UTC](https://discourse.julialang.org/t/reading-data-in-julia-1-2-0/45876 "2020-09-01T07:55:24Z")

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I have a file (A.nets) storing data in the following format: NetDegree : 4 n0 o197239 I : -0.500000 -6.000000 o197110 O : -1.500000 -3.000000 o85644 I : -6.000000 -2.000000 o0 I : -3.000000 -5.000000 NetDegree : …

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## [How to solve problem with TOML.jl?](https://discourse.julialang.org/t/how-to-solve-problem-with-toml-jl/9319)

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**Author:** [@Liso](https://discourse.julialang.org/u/Liso)\
**Replies:** 48\
**Last updated:** [September 1, 2020, 7:43am UTC](https://discourse.julialang.org/t/how-to-solve-problem-with-toml-jl/9319 "2020-09-01T07:43:31Z")

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I just saw nice dependency graph from @kristoffer.carlsson Code starts with: cd("/Users/kristoffer/julia/stdlib") import TOML So I tried it and get: ERROR: ArgumentError: Module TOML not found in current path. Run \`…

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## [\[ANN\]: PkgVersionHelper.jl - check if your \[deps\] packages are up to date](https://discourse.julialang.org/t/ann-pkgversionhelper-jl-check-if-your-deps-packages-are-up-to-date/45722)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 14\
**Last updated:** [September 1, 2020, 7:05am UTC](https://discourse.julialang.org/t/ann-pkgversionhelper-jl-check-if-your-deps-packages-are-up-to-date/45722 "2020-09-01T07:05:11Z")

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See GitHub - xiaodaigh/PkgVersionHelper.jl When developing packages, I often wonder Do I have the latest version of XYZ.jl? and then going to the github repo to check. Now I can skip that step and just use using PkgVe…

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## [MethodError: no method matching Array(::Type{Int64}, ::Int64) -- New Julia User](https://discourse.julialang.org/t/methoderror-no-method-matching-array-type-int64-int64-new-julia-user/45811)

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**Author:** [@W\_K](https://discourse.julialang.org/u/W_K)\
**Replies:** 4\
**Last updated:** [September 1, 2020, 1:44am UTC](https://discourse.julialang.org/t/methoderror-no-method-matching-array-type-int64-int64-new-julia-user/45811 "2020-09-01T01:44:46Z")

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Hello, I am new here and new to Julia. I can’t figure out how to address this error; I’ve tried the suggestions in similar threads and have been unable to find a solution. Help is appreciated. function(form\_one) p…

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## [Error when trying to install JuMP (or any package)](https://discourse.julialang.org/t/error-when-trying-to-install-jump-or-any-package/45713)

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**Author:** [@Eugenio\_Fischetti](https://discourse.julialang.org/u/Eugenio_Fischetti)\
**Replies:** 3\
**Last updated:** [August 31, 2020, 11:40pm UTC](https://discourse.julialang.org/t/error-when-trying-to-install-jump-or-any-package/45713 "2020-08-31T23:40:36Z")

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Hello there! I have Julia 1.5.1 on Windows 7. When installing JuMP i get the following error, below: Anyone can help me, please?

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## [Best way to initialize a sparse matrix with some non-zero columns](https://discourse.julialang.org/t/best-way-to-initialize-a-sparse-matrix-with-some-non-zero-columns/45856)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 2\
**Last updated:** [August 31, 2020, 10:41pm UTC](https://discourse.julialang.org/t/best-way-to-initialize-a-sparse-matrix-with-some-non-zero-columns/45856 "2020-08-31T22:41:42Z")

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Hello, I would like to initialize a sparse array A of size N \\times Nx, for which only the columns in dims are non-zeros. How can I improve this code? using LinearAlgebra using SparseArrays N = 200 Nx = 20 dim = \[1…

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## [Taking derivative of abstract function pattern in sympy](https://discourse.julialang.org/t/taking-derivative-of-abstract-function-pattern-in-sympy/45870)

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**Author:** [@samerb](https://discourse.julialang.org/u/samerb)\
**Replies:** 1\
**Last updated:** [August 31, 2020, 10:31pm UTC](https://discourse.julialang.org/t/taking-derivative-of-abstract-function-pattern-in-sympy/45870 "2020-08-31T22:31:00Z")

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I want to compute a derivative of an expression involving an abstract function like xg(x) or the mixed partial of xg(x)/(g(x)+g(y)). Based on the original python docs here, I tried: using SymPy x = symbols("x") h = fun…

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## [Package update on Windows 7 and offline use](https://discourse.julialang.org/t/package-update-on-windows-7-and-offline-use/45823)

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**Author:** [@Mikhail\_Kagalenko](https://discourse.julialang.org/u/Mikhail_Kagalenko)\
**Replies:** 16\
**Last updated:** [August 31, 2020, 10:20pm UTC](https://discourse.julialang.org/t/package-update-on-windows-7-and-offline-use/45823 "2020-08-31T22:20:25Z")

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Running \]update on a fresh installation (no .julia folder) of Julia 1.5.1 just took me 35 minutes. Windows defender real-time protection was disabled. Observed this behavior on two separate Win 7 machines. Connected wit…

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## [Using ModelingToolkit to invert a symbolic matrix](https://discourse.julialang.org/t/using-modelingtoolkit-to-invert-a-symbolic-matrix/45642)

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**Author:** [@Bruno\_Mendes](https://discourse.julialang.org/u/Bruno_Mendes)\
**Replies:** 10\
**Last updated:** [August 31, 2020, 9:31pm UTC](https://discourse.julialang.org/t/using-modelingtoolkit-to-invert-a-symbolic-matrix/45642 "2020-08-31T21:31:14Z")

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Hi. I’m trying to invert a mass matrix with the purpose of decoupling the second order derivatives of a dynamic system, using ModelingToolkit.jl. The matrix is something like this: In Julia, the elements of this matr…

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## [Faster small CUDA memory transfers (UnifiedMem?)](https://discourse.julialang.org/t/faster-small-cuda-memory-transfers-unifiedmem/45850)

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**Author:** [@Alex\_Ellison](https://discourse.julialang.org/u/Alex_Ellison)\
**Replies:** 2\
**Last updated:** [August 31, 2020, 8:14pm UTC](https://discourse.julialang.org/t/faster-small-cuda-memory-transfers-unifiedmem/45850 "2020-08-31T20:14:21Z")

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Hey, I’m trying to write a program which launches many kernels, but the launches depend on results of earlier kernels. Sometimes the result means a kernel should not be launched at all. They can be distributed across ma…

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## [Unexpect results constructing a DArray](https://discourse.julialang.org/t/unexpect-results-constructing-a-darray/45861)

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**Author:** [@Leandro\_Bataglia](https://discourse.julialang.org/u/Leandro_Bataglia)\
**Replies:** 0\
**Last updated:** [August 31, 2020, 8:06pm UTC](https://discourse.julialang.org/t/unexpect-results-constructing-a-darray/45861 "2020-08-31T20:06:49Z")

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I have been playing with DistributedArrays recently and found the following result: r1 = @spawnat 2 ones(Int64, 3, 2) r2 = @spawnat 3 fill(5, (3,2)) r3 = @spawnat 2 fill(9, (3,2)) r4 = @spawnat 3 zeros(Int64, (3,2)) Drs…

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## [Speed up sparse matrix multiplication](https://discourse.julialang.org/t/speed-up-sparse-matrix-multiplication/45819)

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**Author:** [@Nova](https://discourse.julialang.org/u/Nova)\
**Replies:** 8\
**Last updated:** [August 31, 2020, 7:55pm UTC](https://discourse.julialang.org/t/speed-up-sparse-matrix-multiplication/45819 "2020-08-31T19:55:56Z")

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I have a sparse matrix multiplication in my code but it’s very slow, is there anyway to make it faster? @btime A2 = D \* A \* D 50.816 s (18 allocations: 5.12 GiB) A: adjacency matrix, 6554063×6554063 SparseMatrixCSC{F…

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## [Order of arguments in mutating functions](https://discourse.julialang.org/t/order-of-arguments-in-mutating-functions/45852)

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**Author:** [@ctkelley](https://discourse.julialang.org/u/ctkelley)\
**Replies:** 3\
**Last updated:** [August 31, 2020, 7:52pm UTC](https://discourse.julialang.org/t/order-of-arguments-in-mutating-functions/45852 "2020-08-31T19:52:24Z")

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I’m sure this has been asked before, but my searches came up empty. I have a function F that takes another function f and an array A as input. The function mutates A. So is the order F!(f,A) or F!(A,f) The manual says …

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## [Conditionally suppress output of @time](https://discourse.julialang.org/t/conditionally-suppress-output-of-time/45851)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 2\
**Last updated:** [August 31, 2020, 7:39pm UTC](https://discourse.julialang.org/t/conditionally-suppress-output-of-time/45851 "2020-08-31T19:39:49Z")

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Is there a parameterized version of @time where I can suppress output unless e.g. ‘log\_level \> k’ ? I would like to make the performance of a sequence of function calls debuggable with minimal repetition of code

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## [Comparing performance of 2 simple averaging functions - why is one faster?](https://discourse.julialang.org/t/comparing-performance-of-2-simple-averaging-functions-why-is-one-faster/45854)

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**Author:** [@lwhitefox](https://discourse.julialang.org/u/lwhitefox)\
**Replies:** 5\
**Last updated:** [August 31, 2020, 7:06pm UTC](https://discourse.julialang.org/t/comparing-performance-of-2-simple-averaging-functions-why-is-one-faster/45854 "2020-08-31T19:06:29Z")

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Below I include code for two simple functions that compute averages of pairs of adjacent values in an input 1D vector. Function f2 is almost twice as fast as f3 - I’d like to understand why! If anything, I would have ex…

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## [copy(::CartesianIndices)](https://discourse.julialang.org/t/copy-cartesianindices/45818)

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**Author:** [@greg\_plowman](https://discourse.julialang.org/u/greg_plowman)\
**Replies:** 10\
**Last updated:** [August 31, 2020, 5:48pm UTC](https://discourse.julialang.org/t/copy-cartesianindices/45818 "2020-08-31T17:48:58Z")

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copy(x::CartesianIndices) and copy(x::LinearIndices) do not return the same type as the input argument. I guess you could argue that it doesn’t make sense to copy an immutable. But perhaps you could also argue that tryi…

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## [Finding and fixing invalidations: now, everyone can help reduce time-to-first-plot](https://discourse.julialang.org/t/finding-and-fixing-invalidations-now-everyone-can-help-reduce-time-to-first-plot/45598)

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**Author:** [@tim.holy](https://discourse.julialang.org/u/tim.holy)\
**Replies:** 9\
**Last updated:** [August 31, 2020, 5:45pm UTC](https://discourse.julialang.org/t/finding-and-fixing-invalidations-now-everyone-can-help-reduce-time-to-first-plot/45598 "2020-08-31T17:45:11Z")

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I just posted a new blog post on recent work reducing Julia’s latency, a.k.a., “time to first plot” and even “time to second plot (after loading more code)”. The blog post describes recent work on diagnosing and eliminat…

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## [Table views](https://discourse.julialang.org/t/table-views/45834)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 7\
**Last updated:** [August 31, 2020, 5:37pm UTC](https://discourse.julialang.org/t/table-views/45834 "2020-08-31T17:37:24Z")

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There are various efforts in the tables ecosystem to create a common language for table operations: Query.jl DataKnots.jl TableOperations.jl Volcanito.jl I couldn’t find in any of these efforts an operation to select …

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## [\[ANN\] Alert.jl - Simple desktop notifications](https://discourse.julialang.org/t/ann-alert-jl-simple-desktop-notifications/40360)

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**Author:** [@haberdashPI](https://discourse.julialang.org/u/haberdashPI)\
**Replies:** 17\
**Last updated:** [August 31, 2020, 4:00pm UTC](https://discourse.julialang.org/t/ann-alert-jl-simple-desktop-notifications/40360 "2020-08-31T16:00:58Z")

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Hi all, I created a very small, simple package (Alert) for getting a desktop notification (a.k.a. “toast”) across platforms. Like so: using Alert for i in 1:10\_000 long\_running\_function() end alert("Your julia sc…

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## [Functor usage for Optim.jl](https://discourse.julialang.org/t/functor-usage-for-optim-jl/45778)

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**Author:** [@stevengogogo](https://discourse.julialang.org/u/stevengogogo)\
**Replies:** 4\
**Last updated:** [August 31, 2020, 3:32pm UTC](https://discourse.julialang.org/t/functor-usage-for-optim-jl/45778 "2020-08-31T15:32:07Z")

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Dear Community, I got a question about functor usage with Optim.jl. I’m currently writing a Julian package for biological modeling. To organize parameters of the biological process, I chose function-like object (funct…

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