calcli

A fast terminal calculator (TUI) with an editable history, stored variables and a few helpers engineers reach for. Built with Ratatui.

Type an expression, press Enter, keep going. The previous result is available as ans, every line stays in an editable history (editing a line recomputes everything below it), and results keep full f64 precision internally even when the display is rounded.

Features

• History with recompute – each entry shows the input with its result on the line below (both soft-wrap long content). Edit any earlier line and every line below is re-evaluated, so ans chains stay correct.
• Full precision – the rounded value you see is only for display; further math always uses the exact internal value.
• Variables – save with =name (stores the last answer) or name = expr. Manage them in an overlay: insert, copy, delete, reset all. Persisted.
• Notation – cycle decimal / scientific / SI-prefixed (F2); trailing fractional zeros are dropped by default (12, not 12.000), toggle with F6 or the trim_trailing_zeros config key.
• Angle mode – toggle degrees / radians for trig (F3).
• Lenient input – spaces, _ and the non-decimal one of ./, are accepted as thousands separators; SI prefixes like 3.3k, 100u are expanded. Function arguments use ; (e.g. max(1;2)).
• Clipboard – y copies the plain, full-precision value (no grouping); Y copies it as shown (rounded, grouped).
• Growing input – long expressions soft-wrap and the input field grows (up to input_max_lines); ↑/↓ move the caret across the wrapped lines, ↑ on the first line enters the history.
• Syntax highlighting – functions, constants, operators (bold), numbers, defined variables, parentheses and ans are coloured in the input, the history and while editing. Colours are configurable in the [theme] table; unknown identifiers stay neutral.
• Live feedback – as you type, the input border shows a dim = value preview while the expression is valid and a subtle warning marker when it looks complete but won't parse (silent while still mid-typing). Toggle with live_feedback in the config.
• Persistence – settings, variables and history are saved on exit and restored next time (settings restore is configurable).

Install

From crates.io:

cargo install calcli

Or from a local checkout:

cargo install --path .

Or run without installing:

cargo run --release

Start with --demo to fill the session with sample data (history, variables, unit conversions) for a quick tour – demo mode never writes to your saved session:

calcli --demo

Keys

Input

Key	Action
Enter	evaluate the expression
↑	enter the history
Ctrl+Y	copy the last result (plain)
Ctrl+C / X / V	copy / cut / paste in the input
Esc	clear the input

History (after ↑)

Key	Action
↑ ↓ / PgUp PgDn / Home End	move the selection
Alt+↑ / Alt+↓	move the selected line up / down (recomputes)
o / O	insert a line below / above and edit it
Enter / e	edit the selected line (recomputes below)
d / Del	delete the selected line (asks first)
Shift+D	clear the whole history (asks first)
y	copy the value (plain, full precision)
Y	copy the value (as shown, grouped)
Esc	back to the input

Reordering, inserting and deleting all re-evaluate the affected lines, so ans and variable assignments stay consistent with the new order.

Variables (F4)

Key	Action
↑ ↓	select
Enter	insert the name into the input
y / Y	copy the value
d	delete the variable
R	reset all variables
Esc	close

Global

Key	Action
F1	toggle help
F2	cycle notation (dec / sci / SI)
F3	toggle angle mode (deg / rad)
F4	variables overlay
F5	toggle decimal separator (. / ,)
F6	toggle trailing-zero trimming
Ctrl+Q	quit (saving the session)

Typed commands (in the input)

:d[n], :s[n], :si[n] set notation (and optional decimals); :deg / :rad set the angle mode; :clear clears the history.

Expressions

Backed by meval: + - * / ^ (and ** for power), parentheses, constants pi, e, and functions such as sqrt, exp, ln, abs, sin, cos, tan, asin, acos, atan, sinh/cosh/tanh, floor, ceil, round, min, max, atan2. Trig respects the angle mode.

• ans – the previous result. A line starting with an operator (e.g. +5) continues from it automatically.
• =name – save the previous answer to name.
• name = expr – evaluate and store. ans, pi and e are reserved.
• SI prefixes on numbers: k M G T m µ u n p (e.g. 4.7k → 4700).
• Units, conversion & arithmetic: write a quantity as value unit (space-separated, e.g. 123 MPa) and convert with -> (or to): 123 MPa -> bar, 1 l -> dm^3, 100 km/h -> m/s, ans -> psi, x = 50 kN then x -> N. You can also calculate with units – 20 kN + 300 N → 20.3 kN, 1 m + 50 cm → 1.5 m, 1 m * 2 m → 2 m^2, 2 kN / 4 m^2 -> kN/m^2 → 0.5 kN/m^2. ans and variables keep their unit. Units are powered by rink-core; a conversion is shown in the unit you typed, a derived result in a sensible symbol (pin any other unit with ->). Exponents use ^ (cm^3, m^2).
• Comments: everything after # is ignored by the calculation but kept in the history (e.g. 2*pi*r # circumference). A line that is only a comment is kept as a note (no result); notes don't break the ans chain.

Configuration

calcli reads config.toml from $XDG_CONFIG_HOME/calcli/ (or ~/.config/calcli/). Every key is optional. See examples/config.toml for the full list with defaults (notation, decimals, angle mode, separators, max history, glyph set, the restore_last_settings and live_feedback switches, and the accent and syntax-highlight colours).

The session (settings, variables, history) is stored in state.toml under $XDG_STATE_HOME/calcli/ (or ~/.local/state/calcli/); see examples/state.toml. History values are recomputed on load so the ans chain stays consistent with the active settings.

The glyphs = "ascii" option currently switches the warning marker to ASCII; borders and a few separators use broadly-compatible Unicode box-drawing and middle-dot glyphs.

Architecture

Layered, with the composition root in main.rs:

• domain/ – pure core: evaluation (Evaluator trait + meval), the units engine (rink), expression preprocessing, number formatting, variables, history (and its replay).
• service/ – CalcService: orchestration (submit / edit / delete + recompute, variables, settings).
• storage/ – StateRepository port + TOML implementation (state.toml).
• config/ – Config and its loader.
• tui/ – the Ratatui front-end.
• util/ – paths, logging, clipboard, app metadata.

Dimensionless math runs through the Evaluator trait (meval), keeping full f64 precision and the angle mode; anything involving units is routed to the domain::units wrapper around rink-core, which owns conversion and unit arithmetic.

Development

cargo test                  # unit + integration tests
cargo clippy --all-targets  # must be warning-free

See CLAUDE.md for the coding standards this project follows.