I've had a program where some R code stuffs some input in an URL, fires it at a server, then reads the returned CSV. No error handling or validation is attempted.

As it happens, basically anything is a valid CSV.

If the input is wrong, the server responds with an XML error. This got interpreted as a CSV. Every line became a record, but no column headers were found so every expected field is null/NA. All these nulls get nicely sorted and processed, which causes more string errors, etc ... Mayhem ensues when thst stuff ends up in a database.

CSV is not a format, its a vague idea, https://www.youtube.com/watch?v=YrqSp8m7fmk - this is a great video on how to make it fast, and how its pretty bad

Can't agree more. I've dealt with a CSV where multiple CSVs were cat'ted together, but the originals were not in the same dialect and differed even in charset encoding. Wrote a statists based parser that decided which part of the file had to be decoded which way. Interesting technical challenge, but my god the reasons for its existence were dumb.

Falsehoods programmers believe about CSV: "Yeah, sure it's a mess and there are like, a gazillion different dialects of it, but at least once you know the dialect of a file, you can decode it"...

Claude decode this.

"How to use a billion dollar GPU cluster to parse commas, in 5 easy steps"

It would be free

My god. I love CSVs because the lack of any standardization makes them incredibly flexible, but combining CSVs is just a wild idea. What was that person thinking?

Nobody was thinking anything. A bunch of managers of a group of frenemy corporations was condemned by the governement to share date. Every company sent the data to a trusted third party. This party removed the source company, anonymangled things a bit, taped them all together, and sent the result back to everyone. Managers wanted CSV as it was easy to open in excel, and they were going to let their underlings process them manually. Then it turned out to be a few 10s of millions of records and excel couldn't yet deal with >64k rows, so IT got to deal with it.

Comma Separated Values, in which commas, separations, and values are all optional.