JuliaCon 2025 Hackathon Ideas!

TheCedarPrince · July 22, 2025, 6:55pm

Hi folks!

I was thinking about JuliaCon 2025 Hackathon ideas for this Saturday! Figured I would start a general Discourse post so everyone can post and peruse ideas. Feel free to share ideas below!

~ tcp

giordano · July 22, 2025, 7:41pm

jbytecode · July 22, 2025, 7:42pm

How about writing an initial JVM that runs HelloWorld.class?

adienes · July 22, 2025, 8:09pm

free perf improvement clout

github.com/JuliaLang/julia

BitVector has slow lexicographic compare due to storage order

opened 06:37PM - 31 Aug 18 UTC

chethega

performance arrays good first issue

``` julia> using BenchmarkTools julia> a=BitVector(rand(Bool,1<<10)); b=copy(a…); julia> @btime ==($a,$b) 13.865 ns (0 allocations: 0 bytes) true julia> @btime <($a,$b) 2.252 μs (0 allocations: 0 bytes) false julia> versioninfo() Julia Version 1.0.0 Commit 5d4eaca0c9 (2018-08-08 20:58 UTC) ``` The immediate problem is that lexicographic comparison falls back to `AbstractArray`. However, it is not clear how to write a fast (chunk-wise) comparison with the current layout, because the most significant bit of the bitvector (wrt julia's convention for vector comparison) is stored in the least significant bit of the unterlying UInt64 (wrt hardware integer comparison convention). See: ``` julia> a=BitVector(rand(Bool,1<<6)); julia> a 64-element BitArray{1}: true true false false true ⋮ true false true false julia> bitstring(a.chunks[1]) "0101011000101101010100010100000110100011100101000000101011110011" ``` I'd propose to switch the layout of `BitVector` to match the machine convention. Then, one would need to also replace `trailing_zeros` by `leading_zeros` for iterations, but this has just as good hardware support. Or is there a strong reason for the current layout?

TheCedarPrince · July 22, 2025, 8:35pm

Hardware Hacking

Figure out how to connect a Raspberry Pi to a DHT22 and receive signal output
Develop a system to display components on an e-ink Dashboard (Building a Julia-Powered E-Ink Dashboard: A Dev Log - #3 by TheCedarPrince)
Document and add testing harness for WiringPi.jl
Build CI configuration for Raspberry Pi + Julia

Oh I should mention that I brought all the hardware for this with me!

If you want to hack on this, just reach out! And if you want to borrow the machinery while we are here, happy to lend it to you as well – just get it back to me in time for the Hackathon!

Topic		Replies	Views
BitVector vs Vector{Bool} as default on comparison operations Performance	8	9163	November 2, 2020
Yet another language benchmark Performance benchmark	9	910	June 15, 2025
Array performance Julia 0.6 vs 0.5 Performance	11	1777	March 19, 2018
The Julia Challenge Community	33	3351	November 20, 2018
Programming Language Benchmark 2 Performance	25	3381	April 8, 2024

JuliaCon 2025 Hackathon Ideas!

Hardware Hacking

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