# Internals & Design

**URL:** https://discourse.julialang.org/c/dev/5.md?page=71

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**Page:** 72

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## [Couldn't find 'jl\_is\_float64' declaration in julia.h](https://discourse.julialang.org/t/couldnt-find-jl-is-float64-declaration-in-julia-h/3818)

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**Author:** [@tastelessjolt](https://discourse.julialang.org/u/tastelessjolt)\
**Replies:** 2\
**Last updated:** [May 20, 2017, 6:56pm UTC](https://discourse.julialang.org/t/couldnt-find-jl-is-float64-declaration-in-julia-h/3818 "2017-05-20T18:56:06Z")

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Why isn’t there a ‘jl\_is\_float64’ declaration? As a result, I’m not able to use it in Embedding Julia in my C program. Is it removed deliberately? Thank you.

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## [Bringing more Abstracts Julia](https://discourse.julialang.org/t/bringing-more-abstracts-julia/3760)

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**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 10\
**Last updated:** [May 18, 2017, 6:03pm UTC](https://discourse.julialang.org/t/bringing-more-abstracts-julia/3760 "2017-05-18T18:03:28Z")

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Some Abstract types are used within Julia base (e.g. AbstractTime, AbstractArray, AbstractToken). Others are in use through substantive packages (e.g. AbstractInterval, AbstractTimeSeries, AbstractModel). It seems to m…

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## [Type system revision (#18457)](https://discourse.julialang.org/t/type-system-revision-18457/512)

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**Author:** [@ScottPJones](https://discourse.julialang.org/u/ScottPJones)\
**Replies:** 6\
**Last updated:** [May 17, 2017, 10:18am UTC](https://discourse.julialang.org/t/type-system-revision-18457/512 "2017-05-17T10:18:09Z")

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At JuliaCon this summer, I’d brought up an issue I’d found, where the expressions for the types of the members were evaluated when type is first created, which isn’t correct if the expressions depend on any of the TypeVa…

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## [Recommended 0.6 API for Dict-like constructors and functions](https://discourse.julialang.org/t/recommended-0-6-api-for-dict-like-constructors-and-functions/3743)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 1\
**Last updated:** [May 16, 2017, 12:14pm UTC](https://discourse.julialang.org/t/recommended-0-6-api-for-dict-like-constructors-and-functions/3743 "2017-05-16T12:14:20Z")

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Suppose I have a function (usually, but not necessarily a constructor) with signature myfun(xs...) and I want it to be able to take a generator, eg myfun(something(x) for x in itr). An example of this style in Base is Di…

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## [Linking libjulia doesn't fail even when llvm-config fails](https://discourse.julialang.org/t/linking-libjulia-doesnt-fail-even-when-llvm-config-fails/3732)

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**Author:** [@singam-sanjay](https://discourse.julialang.org/u/singam-sanjay)\
**Replies:** 0\
**Last updated:** [May 16, 2017, 6:04am UTC](https://discourse.julialang.org/t/linking-libjulia-doesnt-fail-even-when-llvm-config-fails/3732 "2017-05-16T06:04:09Z")

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I had inadvertently deleted all the libLLVMDebugInfoDWARF.so\* files while executing rm \*DWARF\* in llvm\_build/lib. While llvm-config associated with the build exited with errors, the Julia build using the same build did n…

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## [Bool literals redefinition](https://discourse.julialang.org/t/bool-literals-redefinition/3722)

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**Author:** [@cdsousa](https://discourse.julialang.org/u/cdsousa)\
**Replies:** 9\
**Last updated:** [May 15, 2017, 6:31pm UTC](https://discourse.julialang.org/t/bool-literals-redefinition/3722 "2017-05-15T18:31:23Z")

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Hi, shouldn’t this be disallowed, just to play on the safe side? julia\> function f() true = false return true end julia\> f() false

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## [Could fill! be twice as fast?](https://discourse.julialang.org/t/could-fill-be-twice-as-fast/3701)

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**Author:** [@Per](https://discourse.julialang.org/u/Per)\
**Replies:** 13\
**Last updated:** [May 15, 2017, 12:55pm UTC](https://discourse.julialang.org/t/could-fill-be-twice-as-fast/3701 "2017-05-15T12:55:18Z")

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I discovered an interesting thing while trying out some code on Julia 0.6. On my system, I can now fill an array of Float64 with zeros in about half the time that A .= 0.0 or fill!(A, 0.0) does it. The reason seems to b…

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## [0.6 release timeline](https://discourse.julialang.org/t/0-6-release-timeline/836)

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**Author:** [@StefanKarpinski](https://discourse.julialang.org/u/StefanKarpinski)\
**Replies:** 58\
**Last updated:** [May 13, 2017, 3:16am UTC](https://discourse.julialang.org/t/0-6-release-timeline/836 "2017-05-13T03:16:03Z")

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Here’s the 0.6 release timeline: 0.6 feature freeze: Dec 31, 2016 – implement it by then or it’s not going in 0.6 0.6.0-alpha: early Jan, 2017 – great time to update packages to support 0.6! 0.6.0-beta: late Jan, 20…

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## [Low-level IO with libuv](https://discourse.julialang.org/t/low-level-io-with-libuv/3432)

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**Author:** [@wavexx](https://discourse.julialang.org/u/wavexx)\
**Replies:** 4\
**Last updated:** [May 12, 2017, 11:12am UTC](https://discourse.julialang.org/t/low-level-io-with-libuv/3432 "2017-05-12T11:12:10Z")

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Hi, I’m working on the Expect.jl module to interact with external processes under a pty (https://github.com/wavexx/Expect.jl). For those unfamiliar with expect-like modules, the current API looks like this: interac…

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## [Help making gfortran dependency in a package work on Travis-CI (Mac)](https://discourse.julialang.org/t/help-making-gfortran-dependency-in-a-package-work-on-travis-ci-mac/3656)

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**Author:** [@ScottPJones](https://discourse.julialang.org/u/ScottPJones)\
**Replies:** 8\
**Last updated:** [May 12, 2017, 9:46am UTC](https://discourse.julialang.org/t/help-making-gfortran-dependency-in-a-package-work-on-travis-ci-mac/3656 "2017-05-12T09:46:58Z")

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I’ve been trying to figure out why https://github.com/JuliaDiffEq/DASKR.jl doesn’t work on Travis-CI (for Mac). It seems that the problem is that gfortran isn’t available. The .travis.yml file has the following: addon…

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## [Why is julia-debug producing redundant debug intrinsics?](https://discourse.julialang.org/t/why-is-julia-debug-producing-redundant-debug-intrinsics/3655)

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**Author:** [@singam-sanjay](https://discourse.julialang.org/u/singam-sanjay)\
**Replies:** 2\
**Last updated:** [May 12, 2017, 7:49am UTC](https://discourse.julialang.org/t/why-is-julia-debug-producing-redundant-debug-intrinsics/3655 "2017-05-12T07:49:30Z")

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When the following function’s IR is generated by julia-debug, function add\_mat(a,b) ni,nj = size(a) for i=1:ni for j=1:nj a\[i,j\] = a\[i,j\] + b\[i,j\] end end …

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## [Strategies to trim shipped not critical libs](https://discourse.julialang.org/t/strategies-to-trim-shipped-not-critical-libs/3657)

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**Author:** [@musm](https://discourse.julialang.org/u/musm)\
**Replies:** 1\
**Last updated:** [May 12, 2017, 7:38am UTC](https://discourse.julialang.org/t/strategies-to-trim-shipped-not-critical-libs/3657 "2017-05-12T07:38:39Z")

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If you look at the Julia bin directory it includes several packages that are only used for convenience by other packages, in particular 7z and libexpat to name the ones I see as candidates. I’m wondering if it would be b…

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## [Packages failing on Julia 0.6 vs 0.5](https://discourse.julialang.org/t/packages-failing-on-julia-0-6-vs-0-5/3647)

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**Author:** [@tkelman](https://discourse.julialang.org/u/tkelman)\
**Replies:** 3\
**Last updated:** [May 11, 2017, 11:52am UTC](https://discourse.julialang.org/t/packages-failing-on-julia-0-6-vs-0-5/3647 "2017-05-11T11:52:15Z")

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Now that the first release candidate for 0.6 is out, it’s worth taking a quick look at the state of the package ecosystem. The below gist is pulled from the data at http://pkg.julialang.org/pulse.html, running on Package…

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## [Package Structure in Julia Ecosystem](https://discourse.julialang.org/t/package-structure-in-julia-ecosystem/3632)

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**Author:** [@shivin9](https://discourse.julialang.org/u/shivin9)\
**Replies:** 3\
**Last updated:** [May 10, 2017, 5:38pm UTC](https://discourse.julialang.org/t/package-structure-in-julia-ecosystem/3632 "2017-05-10T17:38:17Z")

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Hi, I have noticed that in the Julia Ecosystem, the trend is of maintaining a large number of small packages, quite unlike the Python ecosystem where we have do-it-all libraries like Pandas or sklearn or numpy. Is ther…

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## [Make function paramaters immutable by default](https://discourse.julialang.org/t/make-function-paramaters-immutable-by-default/3611)

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**Author:** [@Ford](https://discourse.julialang.org/u/Ford)\
**Replies:** 31\
**Last updated:** [May 10, 2017, 12:59pm UTC](https://discourse.julialang.org/t/make-function-paramaters-immutable-by-default/3611 "2017-05-10T12:59:09Z")

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Right now Julia has a convention that every function that mutates its parameters is marked with ! but it has several downsides : It is just a convention - we rely on programmer’s good will and we all know what does tha…

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## [Limitations to the fix of #265?](https://discourse.julialang.org/t/limitations-to-the-fix-of-265/3613)

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**Author:** [@GunnarFarneback](https://discourse.julialang.org/u/GunnarFarneback)\
**Replies:** 4\
**Last updated:** [May 10, 2017, 10:51am UTC](https://discourse.julialang.org/t/limitations-to-the-fix-of-265/3613 "2017-05-10T10:51:16Z")

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Are these things still supposed to happen after #265 was fixed? Fine: \_ \_ \_ \_(\_)\_ | A fresh approach to technical computing (\_) | (\_) (\_) | Documentation: https://docs.julialang.o…

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## [Parallel julia - TCP ports and security](https://discourse.julialang.org/t/parallel-julia-tcp-ports-and-security/3618)

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**Author:** [@anon94023334](https://discourse.julialang.org/u/anon94023334)\
**Replies:** 2\
**Last updated:** [May 9, 2017, 8:58pm UTC](https://discourse.julialang.org/t/parallel-julia-tcp-ports-and-security/3618 "2017-05-09T20:58:48Z")

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I noticed that Julia opens up TCP port 9100 when addprocs() is used. Is there a description of how that port is used, along with the security controls surrounding its use (and of the network communication in general)? (M…

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## [Accelerate precompilation of base](https://discourse.julialang.org/t/accelerate-precompilation-of-base/3594)

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**Author:** [@singam-sanjay](https://discourse.julialang.org/u/singam-sanjay)\
**Replies:** 6\
**Last updated:** [May 8, 2017, 3:39pm UTC](https://discourse.julialang.org/t/accelerate-precompilation-of-base/3594 "2017-05-08T15:39:49Z")

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Hello, I’m trying out a feature which requires me re-compile libjulia everytime. Sometimes, even the recompilation of Julia files under base/ is invoked, but this operation has been very time consuming. The compilation …

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## [Dispatch time using \`Val\` is an order of magnitude slower than looking up with \`Dict\`](https://discourse.julialang.org/t/dispatch-time-using-val-is-an-order-of-magnitude-slower-than-looking-up-with-dict/3543)

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**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 4\
**Last updated:** [May 5, 2017, 8:29pm UTC](https://discourse.julialang.org/t/dispatch-time-using-val-is-an-order-of-magnitude-slower-than-looking-up-with-dict/3543 "2017-05-05T20:29:41Z")

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I was going to post this as an issue, but then I reminded myself that I know very little about what’s really going on here, and thought better of it (apologies for any issues I might have posted in the past out of ignora…

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## [Is there a good reason why \`!(Tuple \<: AbstractVector)\`?](https://discourse.julialang.org/t/is-there-a-good-reason-why-tuple-abstractvector/3461)

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**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 16\
**Last updated:** [May 4, 2017, 9:04pm UTC](https://discourse.julialang.org/t/is-there-a-good-reason-why-tuple-abstractvector/3461 "2017-05-04T21:04:27Z")

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I’m assuming there is, but I don’t know what that might be. I’m pretty sure tuples implement everything in the AbstractVector interface except for size (and I see no reason why you couldn’t just do size(t::Tuple)=tuple(…

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## [Make cleanall && make testall broke v0.6.0-pre.beta](https://discourse.julialang.org/t/make-cleanall-make-testall-broke-v0-6-0-pre-beta/3515)

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**Author:** [@Federico\_Calboli](https://discourse.julialang.org/u/Federico_Calboli)\
**Replies:** 1\
**Last updated:** [May 4, 2017, 3:08pm UTC](https://discourse.julialang.org/t/make-cleanall-make-testall-broke-v0-6-0-pre-beta/3515 "2017-05-04T15:08:34Z")

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Specifically on MacOS 10.12.2, all bells and whistles (that is, Apple LLVM version 8.1.0 (clang-802.0.42) from the latest XCode, dev tools), gfortran as GNU Fortran (Homebrew GCC 7.1.0) 7.1.0 Because I homebrew updated …

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## [Precompilation not speeding up startup](https://discourse.julialang.org/t/precompilation-not-speeding-up-startup/3486)

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**Author:** [@peter.derijk](https://discourse.julialang.org/u/peter.derijk)\
**Replies:** 3\
**Last updated:** [May 4, 2017, 8:22am UTC](https://discourse.julialang.org/t/precompilation-not-speeding-up-startup/3486 "2017-05-04T08:22:47Z")

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I was trying to improve the Julia score on the next basic benchmark https://github.com/Microbiology/JuliaPerlBenchmark (where they conclude that Perl is faster than Julia for processing fasta files). I already spotted o…

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## [Blog post: Loop fusion and vectorization in Julia 0.6](https://discourse.julialang.org/t/blog-post-loop-fusion-and-vectorization-in-julia-0-6/1634)

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**Author:** [@stevengj](https://discourse.julialang.org/u/stevengj)\
**Replies:** 28\
**Last updated:** [May 4, 2017, 5:39am UTC](https://discourse.julialang.org/t/blog-post-loop-fusion-and-vectorization-in-julia-0-6/1634 "2017-05-04T05:39:52Z")

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Some of you may be interested in my new post on the Julia blog, discussing the new features for efficient “vectorized” code in Julia 0.6: More Dots - Syntactic Loop Fusion in Julia

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## [Can Julia exploit constant propagation?](https://discourse.julialang.org/t/can-julia-exploit-constant-propagation/3443)

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**Author:** [@singam-sanjay](https://discourse.julialang.org/u/singam-sanjay)\
**Replies:** 2\
**Last updated:** [April 30, 2017, 3:22pm UTC](https://discourse.julialang.org/t/can-julia-exploit-constant-propagation/3443 "2017-04-30T15:22:51Z")

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Say we have a function like, function f\_with\_const\_arg( arr, C ) for iter=1:length(arr) #\[...Something happens...and C is used but not modified...\] end end Can Julia codegenerate functions with instructions with…

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## [How to deal with julia \<= 0.5 issues on packages?](https://discourse.julialang.org/t/how-to-deal-with-julia-0-5-issues-on-packages/3429)

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**Author:** [@lobingera](https://discourse.julialang.org/u/lobingera)\
**Replies:** 1\
**Last updated:** [April 29, 2017, 11:59pm UTC](https://discourse.julialang.org/t/how-to-deal-with-julia-0-5-issues-on-packages/3429 "2017-04-29T23:59:13Z")

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Hello. Due to some misunderstandings, i’m currently maintainer of Cairo.jl (adaptation to a well-known 2D drawing library) which is the infrastructure for some plotting and some painting. Major part of Cairo issues are …

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## [Is there way to make testsets fail after N seconds?](https://discourse.julialang.org/t/is-there-way-to-make-testsets-fail-after-n-seconds/3424)

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**Author:** [@djsegal](https://discourse.julialang.org/u/djsegal)\
**Replies:** 2\
**Last updated:** [April 29, 2017, 11:37pm UTC](https://discourse.julialang.org/t/is-there-way-to-make-testsets-fail-after-n-seconds/3424 "2017-04-29T23:37:12Z")

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Sometimes a @testset ends up with an infinite loop that makes testing a pain. Is there a way to add a timeout param to testsets to treat all codes taking longer than N seconds as failures?

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## [Standard ways to run common commands](https://discourse.julialang.org/t/standard-ways-to-run-common-commands/154)

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**Author:** [@djsegal](https://discourse.julialang.org/u/djsegal)\
**Replies:** 10\
**Last updated:** [April 28, 2017, 9:04pm UTC](https://discourse.julialang.org/t/standard-ways-to-run-common-commands/154 "2017-04-28T21:04:34Z")

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Over the course of developing a project, there are certain commands that get executed all the time. These include running: Tests Subsets of tests The application’s main function How can we introduce standard ways to …

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## [Unusual @code\_warntype behavior in 0.6?](https://discourse.julialang.org/t/unusual-code-warntype-behavior-in-0-6/3414)

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**Author:** [@anon94023334](https://discourse.julialang.org/u/anon94023334)\
**Replies:** 2\
**Last updated:** [April 28, 2017, 12:52am UTC](https://discourse.julialang.org/t/unusual-code-warntype-behavior-in-0-6/3414 "2017-04-28T00:52:33Z")

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eigenvector\_centrality(g::AbstractGraph) = norm.(eigs(adjacency\_matrix(g), nev=1)\[2\]) julia\> @code\_warntype(eigenvector\_centrality(g)) Variables: #self#::LightGraphs.#eigenvector\_centrality g::LightGraphs.SimpleGrap…

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## [Purpose of the "intro-issue" tag](https://discourse.julialang.org/t/purpose-of-the-intro-issue-tag/3398)

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**Author:** [@pkofod](https://discourse.julialang.org/u/pkofod)\
**Replies:** 4\
**Last updated:** [April 27, 2017, 1:43pm UTC](https://discourse.julialang.org/t/purpose-of-the-intro-issue-tag/3398 "2017-04-27T13:43:31Z")

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I’ve been wondering about this for some time. What is the “intro-issue” tag supposed to signal? Just that the issue has a simple fix that would be appropriate even for a Julia beginner to tackle but no-one has gotten aro…

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## [Gallium status](https://discourse.julialang.org/t/gallium-status/3289)

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**Author:** [@Nectarineimp](https://discourse.julialang.org/u/Nectarineimp)\
**Replies:** 2\
**Last updated:** [April 27, 2017, 3:55am UTC](https://discourse.julialang.org/t/gallium-status/3289 "2017-04-27T03:55:59Z")

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I see that Gallium hit some big roadblocks with LLVM in 2016. Will that project come back to life sometime soon or is LLVM development still the major roadblock? I wasn’t able to find a discussion giving an indication of…

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