# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1857

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

**Page:** 1858

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## [Strange behavior of differentiating constant functions in Zygote](https://discourse.julialang.org/t/strange-behavior-of-differentiating-constant-functions-in-zygote/32593)

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**Author:** [@yuxi.liu](https://discourse.julialang.org/u/yuxi.liu)\
**Replies:** 1\
**Last updated:** [December 23, 2019, 12:40am UTC](https://discourse.julialang.org/t/strange-behavior-of-differentiating-constant-functions-in-zygote/32593 "2019-12-23T00:40:49Z")

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Why is using Zygote: gradient gradient((x -\> 0.0), 1) giving (nothing, ) ?

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## [Unable to install PackageCompiler](https://discourse.julialang.org/t/unable-to-install-packagecompiler/32587)

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**Author:** [@johannspies](https://discourse.julialang.org/u/johannspies)\
**Replies:** 2\
**Last updated:** [December 22, 2019, 11:31pm UTC](https://discourse.julialang.org/t/unable-to-install-packagecompiler/32587 "2019-12-22T23:31:32Z")

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I am not able to install PackageCompiler: (v1.3) pkg\> rm -m PackageCompiler Updating \`~/.julia/environments/v1.3/Project.toml\` \[0cdbb3b1\] - JuliaManager v0.1.1 Updating \`~/.julia/environments/v1.3/Manifest.toml\` …

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## [Amusing thing I found in the Introduction to Flux](https://discourse.julialang.org/t/amusing-thing-i-found-in-the-introduction-to-flux/32589)

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**Author:** [@yuxi.liu](https://discourse.julialang.org/u/yuxi.liu)\
**Replies:** 0\
**Last updated:** [December 22, 2019, 10:29pm UTC](https://discourse.julialang.org/t/amusing-thing-i-found-in-the-introduction-to-flux/32589 "2019-12-22T22:29:22Z")

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Modified from Lecture 1’s file 1300.Intro-to-Flux.jl.ipynb: using CSV, DataFrames apples = DataFrame(CSV.File(datapath("data/apples.dat"), delim='\\t', normalizenames=true)) bananas = DataFrame(CSV.File(datapath("data/b…

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## [Coimbination of categories / nominal features encoding](https://discourse.julialang.org/t/coimbination-of-categories-nominal-features-encoding/32447)

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**Author:** [@sairus7](https://discourse.julialang.org/u/sairus7)\
**Replies:** 12\
**Last updated:** [December 22, 2019, 7:06pm UTC](https://discourse.julialang.org/t/coimbination-of-categories-nominal-features-encoding/32447 "2019-12-22T19:06:13Z")

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There is CategoricalArray that supports only mutually exclusive categories (you can have only one caterory from a dictionary). But what if I need to store a combinations of several binary features, say: “Visible”: tru…

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## [\[ANN\] MakieLayout.jl: A layout manager for Makie.jl](https://discourse.julialang.org/t/ann-makielayout-jl-a-layout-manager-for-makie-jl/31218)

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**Author:** [@jules](https://discourse.julialang.org/u/jules)\
**Replies:** 25\
**Last updated:** [December 22, 2019, 5:14pm UTC](https://discourse.julialang.org/t/ann-makielayout-jl-a-layout-manager-for-makie-jl/31218 "2019-12-22T17:14:22Z")

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If you have used Makie.jl before, you will know that the interactivity with Observables and the GPU-powered plotting is great, but the layouting capabilities are limited and 2D axes suffer from problems like arbitrary fo…

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## [\`show\` methods for types](https://discourse.julialang.org/t/show-methods-for-types/32578)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 1\
**Last updated:** [December 22, 2019, 3:40pm UTC](https://discourse.julialang.org/t/show-methods-for-types/32578 "2019-12-22T15:40:23Z")

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In this issue, @jeff.bezanson advises that we shouldn’t override how types are printed. But in some cases, particularly for type-level representations as @thautwarm is developing (and are used heavily in Soss), the defa…

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## [\[ANN\] Grassmann.jl : Differential geometric algebra](https://discourse.julialang.org/t/ann-grassmann-jl-differential-geometric-algebra/21125)

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**Author:** [@chakravala](https://discourse.julialang.org/u/chakravala)\
**Replies:** 23\
**Last updated:** [December 22, 2019, 2:28pm UTC](https://discourse.julialang.org/t/ann-grassmann-jl-differential-geometric-algebra/21125 "2019-12-22T14:28:55Z")

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Grassmann algebra, Clifford algebra, and conformal geometric algebra are powerful algebraic tools To help bring conformal geometric algebra to julia, the Grassmann library now provides most of the basic tools needed t…

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## [Mutable field in immutable type](https://discourse.julialang.org/t/mutable-field-in-immutable-type/3103)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 7\
**Last updated:** [December 22, 2019, 2:20pm UTC](https://discourse.julialang.org/t/mutable-field-in-immutable-type/3103 "2019-12-22T14:20:43Z")

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I sometimes need to change the value in a single field of an instance of an immutable type. This is especially useful when an instance of this type is spread around different places and I need to update one of its values…

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## [Break Dictionary arrange key](https://discourse.julialang.org/t/break-dictionary-arrange-key/32552)

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**Author:** [@imrankhan\_juliaLang](https://discourse.julialang.org/u/imrankhan_juliaLang)\
**Replies:** 2\
**Last updated:** [December 22, 2019, 12:04pm UTC](https://discourse.julialang.org/t/break-dictionary-arrange-key/32552 "2019-12-22T12:04:52Z")

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my dictionary keys is not same after set Set dictionary after set dictionary Code Result = Dict("Ada Boost" =\> Dict(), "Decision Tree" =\> Dict(), "Linear Model" =\> Dict(), …

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## [Extend the domain of maximum and minimum to include empty collection?](https://discourse.julialang.org/t/extend-the-domain-of-maximum-and-minimum-to-include-empty-collection/5135)

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**Author:** [@klacru](https://discourse.julialang.org/u/klacru)\
**Replies:** 24\
**Last updated:** [December 22, 2019, 6:49am UTC](https://discourse.julialang.org/t/extend-the-domain-of-maximum-and-minimum-to-include-empty-collection/5135 "2019-12-22T06:49:23Z")

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When I ask for the maximum of an empty collection, there is no obvious result in general. For a collection of real numbers, nevertheless I would expect to obtain -Inf and not an exception. Boiling down my use-case gave: …

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## [Installed Flux has wrong types](https://discourse.julialang.org/t/installed-flux-has-wrong-types/32555)

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**Author:** [@yuxi.liu](https://discourse.julialang.org/u/yuxi.liu)\
**Replies:** 2\
**Last updated:** [December 22, 2019, 4:43am UTC](https://discourse.julialang.org/t/installed-flux-has-wrong-types/32555 "2019-12-22T04:43:43Z")

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I installed Flux v0.10.0 and tried the example \> d = Dense(5, 2) \> d(rand(5)) and got 2-element Array{Float32,1}: -0.30700117 -0.7389947 Instead of Tracked 2-element Array{Float64,1}: 0.00257447 -0.00449443 C…

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## [Julia, JuMP, and Gurobi what MUST be cited?](https://discourse.julialang.org/t/julia-jump-and-gurobi-what-must-be-cited/31672)

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**Author:** [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Replies:** 17\
**Last updated:** [December 22, 2019, 2:41am UTC](https://discourse.julialang.org/t/julia-jump-and-gurobi-what-must-be-cited/31672 "2019-12-22T02:41:05Z")

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Sorry if this is not the right place, but community seems to be the category that better fit this question. I am sending a conference paper that has a very strict page limit, they are 10 pages including the references. …

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## [Sorting out FFT Compat Issue - help needed](https://discourse.julialang.org/t/sorting-out-fft-compat-issue-help-needed/32569)

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**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 2\
**Last updated:** [December 22, 2019, 2:38am UTC](https://discourse.julialang.org/t/sorting-out-fft-compat-issue-help-needed/32569 "2019-12-22T02:38:17Z")

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So I am not so fresh on this Compat detection and dependency control flow thing. I really need some help! I tried to push a fix to my package and was met with a CI/CD error. Weird because my push did NOT change any depe…

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## [What replaces \`sympy"eye"\` in version 1.3](https://discourse.julialang.org/t/what-replaces-sympy-eye-in-version-1-3/32567)

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**Author:** [@ea42gh](https://discourse.julialang.org/u/ea42gh)\
**Replies:** 2\
**Last updated:** [December 22, 2019, 12:39am UTC](https://discourse.julialang.org/t/what-replaces-sympy-eye-in-version-1-3/32567 "2019-12-22T00:39:32Z")

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The statement sympy"eye"(3) does not result in a warning in julia version 0.7. In julia version 1.3 however, it elicicts UndefVarError: @sympy\_str not defined How would this function get invoked now? Figured out one …

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## [On the riddle in JuliaAcademy lesson "Representing data in a computer"](https://discourse.julialang.org/t/on-the-riddle-in-juliaacademy-lesson-representing-data-in-a-computer/32566)

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**Author:** [@yuxi.liu](https://discourse.julialang.org/u/yuxi.liu)\
**Replies:** 0\
**Last updated:** [December 21, 2019, 11:47pm UTC](https://discourse.julialang.org/t/on-the-riddle-in-juliaacademy-lesson-representing-data-in-a-computer/32566 "2019-12-21T23:47:16Z")

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I filtered out the white background in apples and bananas, iswhite(pixel) = (Float64( red(pixel) ) \> 0.9 && Float64( green(pixel) ) \> 0.9 && Float64( blue(pixel) ) \> 0.9) applewhitearray…

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## [Allocations with anonymous functions](https://discourse.julialang.org/t/allocations-with-anonymous-functions/32564)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 4\
**Last updated:** [December 21, 2019, 10:56pm UTC](https://discourse.julialang.org/t/allocations-with-anonymous-functions/32564 "2019-12-21T22:56:02Z")

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I was experimenting with StaticArrays.jl, and noticed the following issue with memory allocations. Consider the following example code: using Random using StaticArrays function f1(X, h, D) Y = D.\*X- h; return …

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## [Slack: the chat tool we love to hate?](https://discourse.julialang.org/t/slack-the-chat-tool-we-love-to-hate/14021)

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**Author:** [@anon94023334](https://discourse.julialang.org/u/anon94023334)\
**Replies:** 39\
**Last updated:** [December 21, 2019, 9:54pm UTC](https://discourse.julialang.org/t/slack-the-chat-tool-we-love-to-hate/14021 "2019-12-21T21:54:03Z")

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Every week or so we have a discussion somewhere on Slack in which a member complains about some aspect of the service (this week was the lack of message retention; last week was rendering; the week before was message ret…

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## [Spherical Bessel functions](https://discourse.julialang.org/t/spherical-bessel-functions/32487)

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**Author:** [@urp](https://discourse.julialang.org/u/urp)\
**Replies:** 9\
**Last updated:** [December 21, 2019, 8:21pm UTC](https://discourse.julialang.org/t/spherical-bessel-functions/32487 "2019-12-21T20:21:32Z")

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Is “spherical Bessel function” available in any of the libraries in Julia? I am aware that SpecialFunctions.jl package has Bessel function.

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## [Keeping modules "clean" when including files](https://discourse.julialang.org/t/keeping-modules-clean-when-including-files/32525)

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**Author:** [@csavorgn](https://discourse.julialang.org/u/csavorgn)\
**Replies:** 2\
**Last updated:** [December 21, 2019, 5:11pm UTC](https://discourse.julialang.org/t/keeping-modules-clean-when-including-files/32525 "2019-12-21T17:11:44Z")

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Hi, I’m writing a module to test the code of a project I’m working on. I though of using multiple files containing the input data and then combine them to obtain all the test cases I need. To better explain what I want…

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## [Finalizer only works with mutable structs?](https://discourse.julialang.org/t/finalizer-only-works-with-mutable-structs/28777)

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**Author:** [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Replies:** 74\
**Last updated:** [December 21, 2019, 4:36pm UTC](https://discourse.julialang.org/t/finalizer-only-works-with-mutable-structs/28777 "2019-12-21T16:36:57Z")

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The finalizer function has the following doc string: finalizer(f, x) Register a function f(x) to be called when there are no program-accessible references to x, and return x. The type of x must be a mutable struct, o…

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## [SGD doesn't exist in Flux v0.10.0](https://discourse.julialang.org/t/sgd-doesnt-exist-in-flux-v0-10-0/32556)

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**Author:** [@yuxi.liu](https://discourse.julialang.org/u/yuxi.liu)\
**Replies:** 1\
**Last updated:** [December 21, 2019, 4:35pm UTC](https://discourse.julialang.org/t/sgd-doesnt-exist-in-flux-v0-10-0/32556 "2019-12-21T16:35:05Z")

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Same context as “Installed Flux has wrong types”. I am working through the Deep Learning with Flux.jl and it uses SGD from Flux.jl julia\> ?SGD SGD search: SGD AMSGrad Signed signed Unsigned unsigned sigmoid issetgid lo…

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## [Performance of Float32 exponential](https://discourse.julialang.org/t/performance-of-float32-exponential/32549)

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**Author:** [@ffevotte](https://discourse.julialang.org/u/ffevotte)\
**Replies:** 4\
**Last updated:** [December 21, 2019, 3:07pm UTC](https://discourse.julialang.org/t/performance-of-float32-exponential/32549 "2019-12-21T15:07:28Z")

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@LaurentPlagne and myself recently noticed the following surprising performances: julia\> using BenchmarkTools julia\> N = 100\_000 julia\> x32 = rand(Float32, N); julia\> x64 = Float64.(x32); julia\> sumExpStd(x) = sum(exp,…

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## [Replacement of eigs?](https://discourse.julialang.org/t/replacement-of-eigs/13540)

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**Author:** [@axsk](https://discourse.julialang.org/u/axsk)\
**Replies:** 9\
**Last updated:** [December 21, 2019, 11:58am UTC](https://discourse.julialang.org/t/replacement-of-eigs/13540 "2019-12-21T11:58:07Z")

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Given a matrix A I need to compute the eigenvector matching the dominating eigenvalue. In 0.6 I used v = eigs(A, nev = 1, which=:LM) I cannot find anything similar in 1.0. How do I compute this eigenvector without co…

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## [Unexpectedly long method signature in "Closest candidates" list](https://discourse.julialang.org/t/unexpectedly-long-method-signature-in-closest-candidates-list/32537)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 4\
**Last updated:** [December 21, 2019, 11:04am UTC](https://discourse.julialang.org/t/unexpectedly-long-method-signature-in-closest-candidates-list/32537 "2019-12-21T11:04:31Z")

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I just came across this frighteningly long method signature in the “Closest candidates” list of methods after a MethodError: julia\> x, y = \[1, 2\], \[3, 4\]; julia\> x \* y ERROR: MethodError: no method matching \*(::Array{I…

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## [How can i convert number string array to int array](https://discourse.julialang.org/t/how-can-i-convert-number-string-array-to-int-array/32536)

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**Author:** [@imrankhan\_juliaLang](https://discourse.julialang.org/u/imrankhan_juliaLang)\
**Replies:** 4\
**Last updated:** [December 21, 2019, 10:50am UTC](https://discourse.julialang.org/t/how-can-i-convert-number-string-array-to-int-array/32536 "2019-12-21T10:50:14Z")

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Need help to convert string number array to int array Like \[“0”, “1”, “0”, “1”, “0”, “1”, “1”, “1”\] To \[0, 1, 0, 1, 0, 1, 1, 1\] NB: Without use this code \[parse(Int, x) for x in array\] because this method is too s…

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## [Why is the strange type signature of sqrt so long?](https://discourse.julialang.org/t/why-is-the-strange-type-signature-of-sqrt-so-long/32541)

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**Author:** [@yuxi.liu](https://discourse.julialang.org/u/yuxi.liu)\
**Replies:** 4\
**Last updated:** [December 21, 2019, 9:00am UTC](https://discourse.julialang.org/t/why-is-the-strange-type-signature-of-sqrt-so-long/32541 "2019-12-21T09:00:51Z")

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I typed methods(√) and got, among other entries, this: sqrt(A::Union{DenseArray{#s627,2}, Base.ReinterpretArray{#s627,2,S,A} where S where A\<:Union{SubArray{T,N,A,I,true} where I\<:Union{Tuple{Vararg{Real,N} where N}, T…

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## [A type from the same library passed via different paths is not considered identical](https://discourse.julialang.org/t/a-type-from-the-same-library-passed-via-different-paths-is-not-considered-identical/32528)

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**Author:** [@fjarri](https://discourse.julialang.org/u/fjarri)\
**Replies:** 3\
**Last updated:** [December 21, 2019, 4:05am UTC](https://discourse.julialang.org/t/a-type-from-the-same-library-passed-via-different-paths-is-not-considered-identical/32528 "2019-12-21T04:05:23Z")

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I’ve encountered a strange situation while setting up CI for one of my projects. I have a package LogProof that uses another package, DarkIntegers. DarkIntegers is in the Julia registry, LogProof isn’t. LogProof tests f…

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## [What if I want a simpler IDE for Julia?](https://discourse.julialang.org/t/what-if-i-want-a-simpler-ide-for-julia/31142)

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**Author:** [@anon97116444](https://discourse.julialang.org/u/anon97116444)\
**Replies:** 223\
**Last updated:** [December 20, 2019, 9:13pm UTC](https://discourse.julialang.org/t/what-if-i-want-a-simpler-ide-for-julia/31142 "2019-12-20T21:13:59Z")

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I am a simple fellow and, coming from the simplicity of Idle3 for python, the Atom juno seems to be too cluttered for my taste. SO is there a simpler way to develop Julia. I am looking for an Idle3 experience where I ent…

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## [Empty sums in expressions](https://discourse.julialang.org/t/empty-sums-in-expressions/32454)

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**Author:** [@waumpel](https://discourse.julialang.org/u/waumpel)\
**Replies:** 2\
**Last updated:** [December 20, 2019, 8:00pm UTC](https://discourse.julialang.org/t/empty-sums-in-expressions/32454 "2019-12-20T20:00:36Z")

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When you create an expression that is an empty sum, it evaluates to Val{false}() instead of 0: model = Model() @expression(model, sum(1 for i in 1:0)) julia\> Val{false}() A similar problem was posted in the GitHub issu…

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## [Does julia support chaining of collections methods / function chaining at this point?](https://discourse.julialang.org/t/does-julia-support-chaining-of-collections-methods-function-chaining-at-this-point/32519)

<div class="topic-metadata">

**Author:** [@javadba](https://discourse.julialang.org/u/javadba)\
**Replies:** 1\
**Last updated:** [December 20, 2019, 7:30pm UTC](https://discourse.julialang.org/t/does-julia-support-chaining-of-collections-methods-function-chaining-at-this-point/32519 "2019-12-20T19:30:07Z")

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There is a moderately long JIRA about function chaining https://github.com/JuliaLang/julia/issues/5571 . It is unclear what if anything resulted from that JIRA - and thus in what form chaining is presently supported. Cl…

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