Post #3609677

2026-07-05 17:37 UTC

When I started writing my accounting software in 2021, I took a shortcut that has served unexpectedly well. I wanted it to be able to read all the various CSVs and whatnot that banks and credit card companies produce, in addition to files with my own additions. The obvious choice would be "importing" these into some sort of formal database, for speed of access. But for simplicity I decided to just re-parse all of the source files -- a year or more of statements and downloads -- every time a command was run, generating an in-memory data structure. I was sure this wouldn't make it past the initial version. But here we are in 2026, and the load-and-parse step is still under 20ms on my cheap laptop. No perceptible delay. (Having everything written in Rust helps, of course.) Sometimes, the simple approach works out.

Replies (3)

@cliffle@hachyderm.io 2026-07-05 17:42

I haven't published my accounting tools because they're probably the most idiosyncratic software I maintain, and I'm not sure they'd be useful to anyone else! Ways in which I am a weirdo here: - I balance all of my accounts every month because financial trauma from growing up in an endless series of recessions. - I do my personal books with double-entry accounting, mark-to-market, and a large portion of GAAP rules. (I studied accounting at community college during my first startup, thinking it would help; it didn't really.) - My tools are entirely command-line and generate nicely formatted ASCII financial reports. - All records are kept in git. "Received" records are stored as immutable files (CSV, PDF, whatever). Adjustments are typically expressed in text files containing RON, or as "sidecar" CSV files adding metadata (thanks for that name, photography tools). - Adding a new financial institution, or handling a change in their output format, requires writing Rust. Now, all this being said, the uxn ecosystem demonstrates that sometimes releasing a very individual, very idiosyncratic toolset can be inspirational. Though I think accounting is less of an attractor than gamedev.

Open ##3609676
@cliffle@hachyderm.io 2026-07-05 17:53

Probably the closest thing to a "pre-processing" step right now is: there are a few institutions who only let me download monthly data in PDF format. (Looking at you, Betterment.) I use the standard-ish Unix pdftotext tool to convert these into text files, and then parse them with an annoying-to-maintain PEG grammar. But I don't want to depend on tools like that being in the path, _or_ on their output being stable, so I do the conversion to text when the PDF file appears and then check it into the repo alongside the original PDF (in case I need to regenerate it due to a bug). ...also I don't necessarily recommend parsing statement PDFs. Sometimes they change arbitrarily. Betterment used to provide CSV and I just haven't had the spoons to migrate away yet.

Open ##4477307
@zrail@hachyderm.io 2026-07-05 17:40

@cliffle@hachyderm.io huh! That makes a ton of sense.

Open ##4477310