Elo

Elo is a notepad-style calculator for natural math expressions. Type plain-English arithmetic, unit conversions, percentages, dates, and more — results appear live as you type. This is a re-implementation of Numi - for a long time I really wanted Numi on Linux but and made do with the CLI app but with the advent of Claude, I figured I could probably vibe code an implementation. Turns out yeah, you can!

Note

If you like this, please go buy Numi!

Support the original artist behind this, it's a great app and if you're on Mac on Windows, you don't need this. Numi is better and it's shareware, so if you're financially constrained then you can still use the original!

Features

• Arithmetic and functions — standard math, operator precedence, sqrt, log, sin/cos/tan, factorials, and more
• Word operators — plus, minus, times, divide, multiplied by, etc.
• Number formats — decimal, hex (0xFF), binary (0b1010), octal (0o17), scientific (1.5e3), comma-separated (1,000,000)
• Units — length, area, volume, mass, time, temperature, angle, data, CSS, speed with natural conversion syntax (5 feet in meters)
• Unit sequences — 5 feet 3 inches, 1 meter 20 cm
• Percentages — 15% of 200, 100 + 10%, 25% off 80, X% of what is Y
• Scales — k/thousand, M/million, billion
• Dates and timezones — now, today + 3 days, time in Asia/Tokyo, fromunix()
• Currencies — $100, €50, 100 USD
• Variables and sessions — assign with =, reference prev, sum/total, avg/average
• Labels and comments — # headers, // comments, Label: expr
• Format conversions — as hex, as binary, as octal, in scientific
• Locale support — locale-sensitive number formatting (en, de, fr)
• File operations — save and export notes as Markdown (.md, the default), .txt, or the legacy .elo; all three open seamlessly

Prerequisites

• Rust (2024 edition)
• Node.js and pnpm
• Tauri CLI: cargo install tauri-cli

Building

Build all targets:

make build

Or build individually:

make build-cli      # CLI binary only
make build-macos    # macOS .app bundle
make build-linux    # Linux .deb and .appimage bundles

Outputs go to the build/ directory.

Development

cd elo-tauri && pnpm install
cd .. && cargo tauri dev

CLI

cargo run -p elo-cli -- "2 + 3 * 4"

Testing

make test

License

MIT