# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1907

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

**Page:** 1908

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## [Code\_native opcode annotations](https://discourse.julialang.org/t/code-native-opcode-annotations/29562)

<div class="topic-metadata">

**Author:** [@milesf](https://discourse.julialang.org/u/milesf)\
**Replies:** 9\
**Last updated:** [October 7, 2019, 12:17pm UTC](https://discourse.julialang.org/t/code-native-opcode-annotations/29562 "2019-10-07T12:17:19Z")

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For those of us not yet fluent in reading assembly, code\_native output could be enhanced with human-readable annotations of what the opcodes represent. This will save us from constantly searching through docs to find mea…

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## [Test with title string](https://discourse.julialang.org/t/test-with-title-string/29566)

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**Author:** [@rveltz](https://discourse.julialang.org/u/rveltz)\
**Replies:** 6\
**Last updated:** [October 7, 2019, 10:20am UTC](https://discourse.julialang.org/t/test-with-title-string/29566 "2019-10-07T10:20:23Z")

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Hi, I am doing some testing for a package and I would like to have a string attached to the test result. Right now, I have to use @testset with a begin keyword. Is there anything like the following? @test "Testing dum…

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## [Compare julia sum to a cpp implementation - julia is extremely slow?!](https://discourse.julialang.org/t/compare-julia-sum-to-a-cpp-implementation-julia-is-extremely-slow/29398)

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**Author:** [@stakaz](https://discourse.julialang.org/u/stakaz)\
**Replies:** 35\
**Last updated:** [October 7, 2019, 9:18am UTC](https://discourse.julialang.org/t/compare-julia-sum-to-a-cpp-implementation-julia-is-extremely-slow/29398 "2019-10-07T09:18:29Z")

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Hello, I am about to test the speed of a simple summation function of a 2D array in cpp and julia. However I see that julia code is becoming slower as the array increases while cpp code remains const in time. Could some…

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## [Segfault while using @threads](https://discourse.julialang.org/t/segfault-while-using-threads/26705)

<div class="topic-metadata">

**Author:** [@mindbound](https://discourse.julialang.org/u/mindbound)\
**Replies:** 6\
**Last updated:** [October 7, 2019, 9:13am UTC](https://discourse.julialang.org/t/segfault-while-using-threads/26705 "2019-10-07T09:13:18Z")

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With Julia v1.1.1 (official Arch Linux installation), I get a segmentation fault when running this example code: Threads.@threads for i = 1:10 println("i = $i on thread $(Threads.threadid())") end The exact message…

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## [Julia Workshop](https://discourse.julialang.org/t/julia-workshop/29551)

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**Author:** [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Replies:** 9\
**Last updated:** [October 7, 2019, 8:36am UTC](https://discourse.julialang.org/t/julia-workshop/29551 "2019-10-07T08:36:14Z")

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Hi all, I gave a voluntary three day Julia workshop (+ Hacktoberfest Hackathon) for undergraduate physicists at the University of Cologne last week and it (once again) has been a great pleasure. Julia is just as much fu…

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## [Extracting Lower Triangular Factor of Sparse Cholesky](https://discourse.julialang.org/t/extracting-lower-triangular-factor-of-sparse-cholesky/23095)

<div class="topic-metadata">

**Author:** [@suchitm](https://discourse.julialang.org/u/suchitm)\
**Replies:** 4\
**Last updated:** [October 7, 2019, 7:35am UTC](https://discourse.julialang.org/t/extracting-lower-triangular-factor-of-sparse-cholesky/23095 "2019-10-07T07:35:20Z")

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This question pertains to issue #26147. I am having the same issues with the sparse cholesky factorization as the user who posted the last comment. The results for the lower triangular matrix from a sparse cholesky are n…

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## [How to sum a vector in accumulated form to another vector?](https://discourse.julialang.org/t/how-to-sum-a-vector-in-accumulated-form-to-another-vector/29552)

<div class="topic-metadata">

**Author:** [@Halor](https://discourse.julialang.org/u/Halor)\
**Replies:** 8\
**Last updated:** [October 7, 2019, 6:57am UTC](https://discourse.julialang.org/t/how-to-sum-a-vector-in-accumulated-form-to-another-vector/29552 "2019-10-07T06:57:30Z")

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Hi. I have been struggling trying to figure it out how to sum a vector. For example, I got those numers: a= Float64\[11\] 0.143816064 0.130130156 0.117746635 0.106541561 0.096402791 0.087228852 0.07892793 0.071416944 0.06…

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## [Trouble creating a module from CxxWrap'ped code](https://discourse.julialang.org/t/trouble-creating-a-module-from-cxxwrapped-code/28770)

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**Author:** [@atombear](https://discourse.julialang.org/u/atombear)\
**Replies:** 18\
**Last updated:** [October 7, 2019, 5:07am UTC](https://discourse.julialang.org/t/trouble-creating-a-module-from-cxxwrapped-code/28770 "2019-10-07T05:07:23Z")

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I am totally baffled by this. I have been wrapping a c++ simulations package using cxxwrap learning plenty of c++, and generally getting everything to work. I prepared tests in the canonical way, and saw that I could r…

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## [Intel Mkl Windows building](https://discourse.julialang.org/t/intel-mkl-windows-building/25033)

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**Author:** [@Amin\_Yahyaabadi](https://discourse.julialang.org/u/Amin_Yahyaabadi)\
**Replies:** 33\
**Last updated:** [October 7, 2019, 4:54am UTC](https://discourse.julialang.org/t/intel-mkl-windows-building/25033 "2019-10-07T04:54:21Z")

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Can anyone give me a step by step tutorial on how I can build Julia to use Intel MKL? Edit: if you read this later follow my steps as I said here: To Install: julia\>\]add https://github.com/JuliaComputing/MKL.jl After…

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## [Parallel loop](https://discourse.julialang.org/t/parallel-loop/29561)

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**Author:** [@donquicote](https://discourse.julialang.org/u/donquicote)\
**Replies:** 1\
**Last updated:** [October 7, 2019, 4:16am UTC](https://discourse.julialang.org/t/parallel-loop/29561 "2019-10-07T04:16:56Z")

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Hi, Can anyone help me to parallelize the following code? I’ve tried to look for how to parallelize nested loops in the documentation but I couldn’t find anything about it. Thank you, using Optim s\_vals = collect(ran…

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## [Plotting derived variables](https://discourse.julialang.org/t/plotting-derived-variables/29556)

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**Author:** [@henry2004y](https://discourse.julialang.org/u/henry2004y)\
**Replies:** 2\
**Last updated:** [October 6, 2019, 4:30pm UTC](https://discourse.julialang.org/t/plotting-derived-variables/29556 "2019-10-06T16:30:30Z")

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Hi, I am writing a function to read data from our simulation code output and plot with PyPlot. The data itself is mostly stored as an array with the 1st dimension as variable index and the rest as spatial indexes (1:nI,…

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## [Code\_native diff](https://discourse.julialang.org/t/code-native-diff/29529)

<div class="topic-metadata">

**Author:** [@milesf](https://discourse.julialang.org/u/milesf)\
**Replies:** 3\
**Last updated:** [October 7, 2019, 1:22am UTC](https://discourse.julialang.org/t/code-native-diff/29529 "2019-10-07T01:22:29Z")

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I’m often curious whether small changes to functions have any effect on the compiled output. This leads to a lot of cursory inspection of @code\_native output, where I’m just looking at the line count and last few lines. …

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## [Why not use @generated?](https://discourse.julialang.org/t/why-not-use-generated/29531)

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**Author:** [@jw3126](https://discourse.julialang.org/u/jw3126)\
**Replies:** 16\
**Last updated:** [October 6, 2019, 8:36pm UTC](https://discourse.julialang.org/t/why-not-use-generated/29531 "2019-10-06T20:36:11Z")

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It seems that using @generated is discouraged by the core devs and I would like to understand better when and why it is discouraged. I am aware of the excellent Keynote by @stevengj which already talks a lot about when (…

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## [AkazeFeatures.jl](https://discourse.julialang.org/t/akazefeatures-jl/29563)

<div class="topic-metadata">

**Author:** [@xor0110](https://discourse.julialang.org/u/xor0110)\
**Replies:** 0\
**Last updated:** [October 6, 2019, 7:53pm UTC](https://discourse.julialang.org/t/akazefeatures-jl/29563 "2019-10-06T19:53:00Z")

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AkazeFeatures.jl is a pure Julia port of the original AKAZE image feature extractor. The original code was made in C++, and is available in OpenCV. I have only recently managed to closely reproduce all feature and descr…

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## [Cxx.jl LLVM error / unresolved external function](https://discourse.julialang.org/t/cxx-jl-llvm-error-unresolved-external-function/29550)

<div class="topic-metadata">

**Author:** [@tamasgal](https://discourse.julialang.org/u/tamasgal)\
**Replies:** 1\
**Last updated:** [October 6, 2019, 2:13pm UTC](https://discourse.julialang.org/t/cxx-jl-llvm-error-unresolved-external-function/29550 "2019-10-06T14:13:40Z")

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Today I though I ruin my day by trying to interface our main DAQ framework (written in C++ and ROOT) in Julia and I think I am quite successful so far (haha). The best thing is, the software is closed source so I cannot …

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## [Developing Julia Packages](https://discourse.julialang.org/t/developing-julia-packages/29541)

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**Author:** [@Alec\_Loudenback](https://discourse.julialang.org/u/Alec_Loudenback)\
**Replies:** 5\
**Last updated:** [October 6, 2019, 1:41pm UTC](https://discourse.julialang.org/t/developing-julia-packages/29541 "2019-10-06T13:41:24Z")

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@ChrisRackauckas made a YouTube tutorial on developing julia packages and some best practices:

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## [What is difference between "a" and 'a'?](https://discourse.julialang.org/t/what-is-difference-between-a-and-a/29546)

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**Author:** [@Dito](https://discourse.julialang.org/u/Dito)\
**Replies:** 6\
**Last updated:** [October 6, 2019, 12:52pm UTC](https://discourse.julialang.org/t/what-is-difference-between-a-and-a/29546 "2019-10-06T12:52:40Z")

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What does function sizeof() do? sizeof("a") 1 julia\> length('a') 1 julia\> sizeof('a') 4 julia\> sizeof("∀") 3 julia\> sizeof('∀') 4 julia\> sizeof("🍎") 4 And if sizeof() gives us the size of used memory in bytes why …

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## [Using zip() with count()](https://discourse.julialang.org/t/using-zip-with-count/29549)

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**Author:** [@j.copsey](https://discourse.julialang.org/u/j.copsey)\
**Replies:** 7\
**Last updated:** [October 6, 2019, 11:55am UTC](https://discourse.julialang.org/t/using-zip-with-count/29549 "2019-10-06T11:55:18Z")

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I’m trying to use count where the iterator is taken from zip. Here is the code I’ve written: function hamming(c, d) count((x,y) -\> (x != y), zip(c,d)) end However, when this is run on any non-empty collections, e.…

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## [Lazy readdir in Julia with libuv](https://discourse.julialang.org/t/lazy-readdir-in-julia-with-libuv/29522)

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**Author:** [@xor0110](https://discourse.julialang.org/u/xor0110)\
**Replies:** 2\
**Last updated:** [October 6, 2019, 9:45am UTC](https://discourse.julialang.org/t/lazy-readdir-in-julia-with-libuv/29522 "2019-10-06T09:45:19Z")

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readdir relies on the libuv scandir function, meaning all the contents of a directory must be read to memory before we do anything. Sometimes it is useful to iterate over contents in a streaming way. Libuv allows this tr…

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## [JuliaBinaryWrappers tracker and issue listing](https://discourse.julialang.org/t/juliabinarywrappers-tracker-and-issue-listing/29547)

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**Author:** [@sambitdash](https://discourse.julialang.org/u/sambitdash)\
**Replies:** 2\
**Last updated:** [October 6, 2019, 8:48am UTC](https://discourse.julialang.org/t/juliabinarywrappers-tracker-and-issue-listing/29547 "2019-10-06T08:48:17Z")

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Hi All, Is there a place to request for new binaries to be built for JuliaBinaryWrappers? For example, I want to request for Tesseract and Leptonica binaries to be included. But there is no easy way to do so as each bin…

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## [Reshaping Arrays (DimensionMismatch)](https://discourse.julialang.org/t/reshaping-arrays-dimensionmismatch/29545)

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**Author:** [@ASF](https://discourse.julialang.org/u/ASF)\
**Replies:** 1\
**Last updated:** [October 6, 2019, 8:35am UTC](https://discourse.julialang.org/t/reshaping-arrays-dimensionmismatch/29545 "2019-10-06T08:35:18Z")

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Hi - I have the following arrays: X = Shape (50562,19) theta = Shape (19,) im trying to do a simple dot product but i get the following error: DimensionMismatch(“first array has length 960678 which does not match the…

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## [MethodError: reduce\_empty is ambiguous](https://discourse.julialang.org/t/methoderror-reduce-empty-is-ambiguous/29527)

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**Author:** [@leiteiro](https://discourse.julialang.org/u/leiteiro)\
**Replies:** 1\
**Last updated:** [October 6, 2019, 6:45am UTC](https://discourse.julialang.org/t/methoderror-reduce-empty-is-ambiguous/29527 "2019-10-06T06:45:54Z")

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(Julia 1.2.0) I have a function which generates a list of integer lists, some of which might be empty. For example L = \[Int, \[1\]\], so L is a 2-element Array{Array{Int64,1},1}. This is how I want things to work. In rea…

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## [How to get a JuliaLang Discourse API token](https://discourse.julialang.org/t/how-to-get-a-julialang-discourse-api-token/29506)

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**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 9\
**Last updated:** [October 6, 2019, 4:51am UTC](https://discourse.julialang.org/t/how-to-get-a-julialang-discourse-api-token/29506 "2019-10-06T04:51:21Z")

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Hey all, who do I contact in order to get a DIscourse API token? @vchuravy are you an admin/moderator on here? I am going to make a discourse-feed channel on Slack.

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## [Efficient way to avoid repetitive functions with multiple methods](https://discourse.julialang.org/t/efficient-way-to-avoid-repetitive-functions-with-multiple-methods/29539)

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**Author:** [@Elmer\_Cusipuma](https://discourse.julialang.org/u/Elmer_Cusipuma)\
**Replies:** 1\
**Last updated:** [October 6, 2019, 2:23am UTC](https://discourse.julialang.org/t/efficient-way-to-avoid-repetitive-functions-with-multiple-methods/29539 "2019-10-06T02:23:06Z")

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I have a structure which has a function with many methods. struct shape type :: Symbol mtl :: String t :: Real A :: Float64 Asy :: Float64 Asz :: Float64 function shape(mtl::St…

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## [Genie file management](https://discourse.julialang.org/t/genie-file-management/29537)

<div class="topic-metadata">

**Author:** [@Amin\_Yahyaabadi](https://discourse.julialang.org/u/Amin_Yahyaabadi)\
**Replies:** 1\
**Last updated:** [October 6, 2019, 12:23am UTC](https://discourse.julialang.org/t/genie-file-management/29537 "2019-10-06T00:23:18Z")

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I am trying to add an app to my static html website using Genie. How can I manage my html template/style files and their path? For example, in my layout file in app.jl.html, there is a style.css that should be called. …

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## [Interpreting Pkg add errors](https://discourse.julialang.org/t/interpreting-pkg-add-errors/29530)

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**Author:** [@Ross\_Boylan](https://discourse.julialang.org/u/Ross_Boylan)\
**Replies:** 1\
**Last updated:** [October 6, 2019, 12:16am UTC](https://discourse.julialang.org/t/interpreting-pkg-add-errors/29530 "2019-10-06T00:16:59Z")

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I’m guessing from the following error that the version of RCall I’m attempting to install (in Julia 1.2) needs a different version of StatsModel than I’m using. But I can’t tell which version(s) it wants. Am I missing …

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## [Situations where mutable struct is more performant than immutable struct](https://discourse.julialang.org/t/situations-where-mutable-struct-is-more-performant-than-immutable-struct/29504)

<div class="topic-metadata">

**Author:** [@milesf](https://discourse.julialang.org/u/milesf)\
**Replies:** 6\
**Last updated:** [October 5, 2019, 8:44pm UTC](https://discourse.julialang.org/t/situations-where-mutable-struct-is-more-performant-than-immutable-struct/29504 "2019-10-05T20:44:08Z")

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Wanted to highlight a situation where mutable structs offer better performance than immutable structs. If sorting an array of structs with many isbits fields, the immutable copy cost outweighs the mutable indirection co…

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## [Parallel Postprocessing](https://discourse.julialang.org/t/parallel-postprocessing/29487)

<div class="topic-metadata">

**Author:** [@henry2004y](https://discourse.julialang.org/u/henry2004y)\
**Replies:** 10\
**Last updated:** [October 5, 2019, 7:00pm UTC](https://discourse.julialang.org/t/parallel-postprocessing/29487 "2019-10-05T19:00:21Z")

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Hi everyone, I am using Julia PyPlot to do postprocessing for simulation data. Here is the sample script for my parallel work: using Distributed @everywhere using PyCall @everywhere matplotlib = pyimport("matplotlib") …

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## [Escape the esc function](https://discourse.julialang.org/t/escape-the-esc-function/29524)

<div class="topic-metadata">

**Author:** [@Chong\_Wang](https://discourse.julialang.org/u/Chong_Wang)\
**Replies:** 1\
**Last updated:** [October 5, 2019, 5:16pm UTC](https://discourse.julialang.org/t/escape-the-esc-function/29524 "2019-10-05T17:16:50Z")

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It is not uncommon that most of the expression returned by a macro needs to be escaped. For example using MacroTools const IGNORE = \[true\] macro foo(f) fdict = MacroTools.splitdef(f) fdict\[:body\] = quote …

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## [JuliaCon 2020 will be in Lisbon, Portugal](https://discourse.julialang.org/t/juliacon-2020-will-be-in-lisbon-portugal/29300)

<div class="topic-metadata">

**Author:** [@avik](https://discourse.julialang.org/u/avik)\
**Replies:** 13\
**Last updated:** [October 5, 2019, 4:11pm UTC](https://discourse.julialang.org/t/juliacon-2020-will-be-in-lisbon-portugal/29300 "2019-10-05T16:11:32Z")

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It gives us immense pleasure to announce that JuliaCon 2020 will be held at ISCTE - Instituto Universitário de Lisboa (ISCTE-IUL) in Lisbon, Portugal, from the 27th to the 31st of July. Please mark your calendars, and…

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