# \#internals **URL:** https://discourse.julialang.org/tag/internals/984.md [Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md) --- ## [\`SparseArray\` types](https://discourse.julialang.org/t/sparsearray-types/138210)
**Author:** [@rokke](https://discourse.julialang.org/u/rokke)\ **Replies:** 5\ **Last updated:** [July 16, 2026, 6:56am UTC](https://discourse.julialang.org/t/sparsearray-types/138210 "2026-07-16T06:56:38Z")
SparseMatrixCSC currently has a documented type definition of: SparseMatrixCSC{Tv,Ti\<:Integer} \<: AbstractSparseMatrixCSC{Tv,Ti} but, if you try to actually make one, you will find in practice that it only has exactly … --- ## [Good subsystems in Julia internals for new contributors?](https://discourse.julialang.org/t/good-subsystems-in-julia-internals-for-new-contributors/134668)
**Author:** [@Ark\_Gupta](https://discourse.julialang.org/u/Ark_Gupta)\ **Replies:** 2\ **Last updated:** [December 22, 2025, 11:10am UTC](https://discourse.julialang.org/t/good-subsystems-in-julia-internals-for-new-contributors/134668 "2025-12-22T11:10:15Z")
Hi everyone, I’m exploring contributing to Julia internals and recently submitted a small README PR. I’d like to continue contributing more meaningfully and deepen my understanding of the codebase. Are there particula… --- ## [How does \`Base.@locals\` work?](https://discourse.julialang.org/t/how-does-base-locals-work/133483)
**Author:** [@mhauru](https://discourse.julialang.org/u/mhauru)\ **Replies:** 1\ **Last updated:** [October 28, 2025, 3:25pm UTC](https://discourse.julialang.org/t/how-does-base-locals-work/133483 "2025-10-28T15:25:08Z")
Base.@locals has this very curious implementation: macro locals() return Expr(:locals) end How does this work? Is locals some sort of special node type in the AST? I can’t find it documented. I don’t need to know … --- ## [Mutating a flag in a nonmutating struct](https://discourse.julialang.org/t/mutating-a-flag-in-a-nonmutating-struct/132341)
**Author:** [@mesonepigreco](https://discourse.julialang.org/u/mesonepigreco)\ **Replies:** 5\ **Last updated:** [September 13, 2025, 1:04pm UTC](https://discourse.julialang.org/t/mutating-a-flag-in-a-nonmutating-struct/132341 "2025-09-13T13:04:18Z")
Dear Julia Community. I have a struct that contains both Bool flags and arrays. I want to be able to change the value of some of the Bool flags, but I would like to avoid having a mutable struct, which I believe can cr… --- ## [Sea of Nodes IR](https://discourse.julialang.org/t/sea-of-nodes-ir/131171)
**Author:** [@mrufsvold](https://discourse.julialang.org/u/mrufsvold)\ **Replies:** 4\ **Last updated:** [July 30, 2025, 7:45am UTC](https://discourse.julialang.org/t/sea-of-nodes-ir/131171 "2025-07-30T07:45:26Z")
This is a very interesting talk on treeless parsing and IR. The first half about treeless parsing doesn’t apply to Julia what without user facing AST. However, the second half is about using a graph of nodes to represent… --- ## [Invalidating the generator of a \`@generated\` function](https://discourse.julialang.org/t/invalidating-the-generator-of-a-generated-function/125164)
**Author:** [@K11BN367](https://discourse.julialang.org/u/K11BN367)\ **Replies:** 1\ **Last updated:** [January 24, 2025, 1:03pm UTC](https://discourse.julialang.org/t/invalidating-the-generator-of-a-generated-function/125164 "2025-01-24T13:03:18Z")
Hello, i started to investigate the julia internals a bit and toyed around with some code that tries to invalidate the generator of a ‘@generated’ function. I came up with the following code: import Core.Compiler.Meth… --- ## [Why doesn’t Julia offer built-in privacy/encapsulation features?](https://discourse.julialang.org/t/why-doesn-t-julia-offer-built-in-privacy-encapsulation-features/124666)
**Author:** [@younes](https://discourse.julialang.org/u/younes)\ **Replies:** 12\ **Last updated:** [January 13, 2025, 3:15pm UTC](https://discourse.julialang.org/t/why-doesn-t-julia-offer-built-in-privacy-encapsulation-features/124666 "2025-01-13T15:15:00Z")
I would like to understand Julia’s rationale for not including a language-level privacy feature: a way to truly protect the internal state from outside access. I’m aware that we can use closures to emulate encapsulation… --- ## [Can you twiddle bits in a Float64 variable?](https://discourse.julialang.org/t/can-you-twiddle-bits-in-a-float64-variable/121271)
**Author:** [@StevenSiew](https://discourse.julialang.org/u/StevenSiew)\ **Replies:** 6\ **Last updated:** [October 14, 2024, 2:45pm UTC](https://discourse.julialang.org/t/can-you-twiddle-bits-in-a-float64-variable/121271 "2024-10-14T14:45:49Z")
Can you twiddle bits in a Float64 variable? Can you have x = 123.456 then type cast x into UInt64 Twiddle its bits then type cast it back to Float64 to get a different Float64 number? Just wondering. --- ## [Any existing efforts on cross-compiling Julia programs across different platforms?](https://discourse.julialang.org/t/any-existing-efforts-on-cross-compiling-julia-programs-across-different-platforms/118253)
**Author:** [@Barzin](https://discourse.julialang.org/u/Barzin)\ **Replies:** 3\ **Last updated:** [August 17, 2024, 12:03pm UTC](https://discourse.julialang.org/t/any-existing-efforts-on-cross-compiling-julia-programs-across-different-platforms/118253 "2024-08-17T12:03:57Z")
Hi everyone, I’m looking at possibilities for cross-compiling Julia programs, which would enable compiling on one platform to run natively on another without setting up separate environments or relying on emulation. Thi… --- ## [A question about parsing (Markdown) string literals](https://discourse.julialang.org/t/a-question-about-parsing-markdown-string-literals/117442)
**Author:** [@mitiemannn](https://discourse.julialang.org/u/mitiemannn)\ **Replies:** 3\ **Last updated:** [July 25, 2024, 4:57pm UTC](https://discourse.julialang.org/t/a-question-about-parsing-markdown-string-literals/117442 "2024-07-25T16:57:22Z")
Hi everyone, I’ve tried to generate a Markdown.MD object from an computed string and observed something odd (MWE): julia\> using Markdown julia\> md"foo\\ bar" foo bar julia\> md"foo\\\\\\nbar" foo\\\\nbar julia\>… --- ## [Side Effect Analysis on Macros](https://discourse.julialang.org/t/side-effect-analysis-on-macros/106526)
**Author:** [@mrufsvold](https://discourse.julialang.org/u/mrufsvold)\ **Replies:** 10\ **Last updated:** [April 25, 2024, 2:12am UTC](https://discourse.julialang.org/t/side-effect-analysis-on-macros/106526 "2024-04-25T02:12:08Z")
A recurrent challenge for linting Julia is macro mini languages. From chaining with underscores to sum types, there are lots of symbols that get created by macros which are obvious to the human reader but not to LSP. The… --- ## [TimesDates.jl dev for v2](https://discourse.julialang.org/t/timesdates-jl-dev-for-v2/78377)
**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\ **Replies:** 44\ **Last updated:** [September 14, 2023, 3:50am UTC](https://discourse.julialang.org/t/timesdates-jl-dev-for-v2/78377 "2023-09-14T03:50:59Z")
I am working on a new version of TimesDates.jl using advancements that have become part of the Dates stdlib to simplify the implementation. Some of these improvements are accessible through non-exported specific element… --- ## [This month in Julia world - 2023-05](https://discourse.julialang.org/t/this-month-in-julia-world-2023-05/99634)
**Author:** [@Krastanov](https://discourse.julialang.org/u/Krastanov)\ **Replies:** 20\ **Last updated:** [June 9, 2023, 10:04pm UTC](https://discourse.julialang.org/t/this-month-in-julia-world-2023-05/99634 "2023-06-09T22:04:04Z")
There was a call to action for someone to make a newsletter that lists interesting developments in the Julia world, in order to communicate improvements to the language that are not visible unless you track Github and Sl…