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Co-dfns Live Stream: Compiler Design and Architecture

Aaron Hsu (arcfide) · 20.5K views · 2017-02-13 · 2:03:12

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Overview

A two-hour live stream in which Aaron Hsu explains the architecture, design history and aesthetic of Co-dfns, his parallel APL compiler. He walks through the code and the reasoning behind its dense style.

On Hacker News

HN readers say it changed their view of APL and array languages, with a clear walkthrough of how a compiler can be written in this style.

Recommended by 3 HN people across 5 months · HN mentions 2018–2025

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What people said

Nadya · 2024-06 · Strong recommendation

I thought the same about APL until arcfide made a video about codfns a few years back. Was eye opening. [VIDEO]

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refset · 2024-01 · Strong recommendation

Nothing has ever convinced me about the potential for array languages in practice quite like watching Aaron Hsu describe how he develops his parallel APL compiler [0] using two Notepad.exe windows side-by-side: [VIDEO] He has also written many comments (arcfide on HN) about this stuff before, e.g. discussing "semantic density" [1] > The compiler is designed so that I can see as much as possible with as little indirection as possible, so that when I see a piece of code I not only know how it works in complete detail, but how it connects to the world around it, and every single dependency related to it in basically one single half screen full of code (usually much less than that) without any jumps, paging, scrolling or any movement. [...] The idea of semantic density is critical to this point. The semantic density of the APL code I'm using to solve the problem is at a certain rate. I maintain a consistent density rate by choosing my variable names in such a way that they visually align with the expressivity per character of the built in primitive symbols. And > [...] idiomatic programming methods that are so concise, they can begin to be read as we read and chunk English phrases. By doing so, it becomes actually easier to just write out most algorithms, because the normal name for such an algorithm is basically as long as the algorithm itself written out. This means that I start to learn to chunk idioms as phrases and can read code directly, without the cost of name lookup indi

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Nadya · 2021-07 · Strong recommendation

One of the most memorable and interesting things I've ever seen on HN was an AMA from the creator of the Co-dfns parallel APL compiler. Here is co-dfns [0] and the AMA by the creator [1]. The video may give you some insight and at the very least may be extremely interesting to hear the APL code explained (jump to around 13:30 for the beginning of the explanation behind the structure + what the compiler is doing). He explains it very well - it's quite easy to follow along. [0] [LINK] [1] [VIDEO]

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Sources

Video by Aaron Hsu (arcfide), played through YouTube.

Data and selection notes

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