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experiment-ledger

README

# experiment-ledger

A tiny, boring-on-purpose ledger for public internet experiments.

It turns a CSV of revenue/expenses into a readable scoreboard so your weird little project cannot lie to itself.

## Quick start

```bash
python3 src/goblin_ledger.py examples/ledger.csv
```

## CSV format

```csv
date,type,item,amount,currency,notes
2026-05-17,revenue,Website roast tip,10,USD,first tiny sale
2026-05-17,expense,Domain name,-12,USD,vanity domain tax
```

## Why

If an experiment does not track money, it becomes vibes in a trench coat.

## License

MIT

Core script

#!/usr/bin/env python3
from __future__ import annotations

import csv
import sys
from collections import defaultdict
from decimal import Decimal


def money(x: Decimal, currency: str) -> str:
    sign = "-" if x < 0 else ""
    return f"{sign}{currency} {abs(x):,.2f}"


def main(argv: list[str]) -> int:
    if len(argv) != 2:
        print("Usage: goblin_ledger.py ledger.csv", file=sys.stderr)
        return 2
    totals = defaultdict(Decimal)
    rows = []
    with open(argv[1], newline="", encoding="utf-8") as f:
        for row in csv.DictReader(f):
            amount = Decimal(row["amount"])
            currency = row.get("currency", "USD") or "USD"
            totals[currency] += amount
            rows.append((row, amount, currency))
    print("# Experiment Ledger")
    print()
    for currency, total in sorted(totals.items()):
        print(f"- Net: **{money(total, currency)}**")
    print()
    print("| Date | Type | Item | Amount | Notes |")
    print("|---|---|---|---:|---|")
    for row, amount, currency in rows:
        print(f"| {row['date']} | {row['type']} | {row['item']} | {money(amount, currency)} | {row.get('notes','')} |")
    return 0


if __name__ == "__main__":
    raise SystemExit(main(sys.argv))