jsource VS Singeli

The one other example I know that morphs the language to that extent and to the detriment of readability by C programmers is the J interpreter[1,2]. But, once again, nobody (that I’ve read) claims it’s good or clear C. (Good C for those who speak J, maybe; I wouldn’t know.)

For a way to morph C syntax that does make things better, see libmill[3].

[1] https://code.jsoftware.com/wiki/Essays/Incunabulum

[2] https://github.com/jsoftware/jsource/tree/master/jsrc

[3] https://250bpm.com/blog:56/

Oh damn Whitney C representation.

I develop J btw

No, it was rhetorical, because it's obviously (to an APL-family programmer), not bad!

Your cultural prejudice is showing. There are good reasons APL is written the way it is, and this example is simply bringing those benefits to C by writing it in the dense APL style. There are other APL derivatives, like J[1] that are written the same way. These projects are well-maintained. They aren't collapsing under a load of technical debt. The style works. To them, it's clean code.

[1]: https://github.com/jsoftware/jsource

Recently, I wanted to write a simple piece of code in J, but immediately found a bug. I went ahead to fetch the source to see if I can fix it. But, hell no. I couldn't believe my eyes. Is this how someone programs, really? I just can't believe it didn't go through some kind of obfuscator.

Here are some samples, but almost anything in the repository is beyond me:

https://github.com/jsoftware/jsource/blob/master/jsrc/xo.c

You can view the code, but is not open source: https://github.com/jsoftware/jsource/blob/master/license.txt

This is the same dense style used in J.

All-in-all this example doesn't seem too bad. It's clear what happens and is easy to follow. If you wan't to see something remarkably terribly, check out Whitney style. It's used in APL/J/K family interpreters. Keep in mind, financial institutions run that code.

I don't put a lot of stock in the "write-only" accusation. I think it's mostly used by those who don't know APL because, first, it's clever, and second, they can't read the code. However, if I remember I implemented something in J 10 years ago, I will definitely dig out the code because that's the fastest way by far for me to remember how it works.

This project specifically looks to be done in a flat array style similar to Co-dfns[0]. It's not a very common way to use APL. However, I've maintained an array-based compiler [1] for several years, and don't find that reading is a particular difficulty. Debugging is significantly easier than a scalar compiler, because the computation works on arrays drawn from the entire source code, and it's easy to inspect these and figure out what doesn't match expectations. I wrote most of [2] using a more traditional compiler architecture and it's easier to write and extend but feels about the same for reading and small tweaks. See also my review [3] of the denser compiler and precursor Co-dfns.

As for being read by others, short snippets are definitely fine. Taking some from the last week or so in the APL Farm, {⍵÷⍨+/|-/¯9 ¯11+.○?2⍵2⍴0} and {(⍸⍣¯1+\⎕IO,⍺)⊂[⎕IO]⍵} seemed to be easily understood. Forum links at [4]; the APL Orchard is viewable without signup and tends to have a lot of code discussion. There are APL codebases with many programmers, but they tend to be very verbose with long names. Something like the YAML parser here with no comments and single-letter names would be hard to get into. I can recognize, say, that c⌿¨⍨←(∨⍀∧∨⍀U⊖)∘(~⊢∊LF⍪WS⍨)¨c trims leading and trailing whitespace from each string in a few seconds, but in other places there are a lot of magic numbers so I get the "what" but not the "why". Eh, as I look over it things are starting to make sense, could probably get through this in an hour or so. But a lot of APLers don't have experience with the patterns used here.

[0] https://github.com/Co-dfns/Co-dfns

[1] https://github.com/mlochbaum/BQN/blob/master/src/c.bqn

[2] https://github.com/mlochbaum/Singeli/blob/master/singeli.bqn

[3] https://mlochbaum.github.io/BQN/implementation/codfns.html

[4] https://aplwiki.com/wiki/Chat_rooms_and_forums

Here's an AVX-2 implementation that assumes it can read up to 31 bytes past the end of the input: https://godbolt.org/z/P7PP1MnK7

Requires -fno-unroll-loops as otherwise clang gets overly unroll-y; the code is fast enough. Tail is dealt with by blending the originally read value with the new one.

(yes, that's autogenerated; from some https://github.com/mlochbaum/singeli code)

It's not ideal, but I've done this in BQN and it took about 15 lines. I didn't need to handle comments or escapes, which would add a little complexity. See functions ParseXml and ParseAttr here: https://github.com/mlochbaum/Singeli/blob/master/data/iintri...

XML is particularly simple though, dealing with something like JPEG would be an entirely different experience.