#math #calculator #cli #command-line

app kalk_cli

A calculator that supports user-defined functions, variables and units, and can handle fairly ambiguous syntax

31 releases

0.5.4 May 31, 2021
0.4.1 May 18, 2021
0.3.14 Feb 22, 2021
0.3.9 Dec 28, 2020
0.2.0 Jun 18, 2020

#63 in Math

Download history 48/week @ 2021-02-20 13/week @ 2021-02-27 29/week @ 2021-03-06 59/week @ 2021-03-13 52/week @ 2021-03-20 51/week @ 2021-03-27 52/week @ 2021-04-03 42/week @ 2021-04-10 59/week @ 2021-04-17 6/week @ 2021-04-24 32/week @ 2021-05-01 13/week @ 2021-05-08 72/week @ 2021-05-15 71/week @ 2021-05-22 179/week @ 2021-05-29 45/week @ 2021-06-05

217 downloads per month

MIT and LGPL-3.0+

269 lines

Kalk is a calculator (both program and library) that supports user-defined variables, functions, derivation, and integration. It runs on Windows, macOS, Linux, Android, and in web browsers (with WebAssembly).

Crates.ionpm GitHub Docs.rs Build status

Kanban | Website - Try it out here!


  • Operators: +, -, *, /, !
  • Groups: (), ⌈⌉, ⌋⌊
  • Pre-defined functions and constants
  • User-defined functions and variables. f(x, y) = xy, x = 5
  • User-defined units (experimental). unit m = cm/100, 2m/50cm, 50cm to m
  • Derivative of functions (derivatives of higher order can be a bit inaccurate). f'(2), sin'(-pi)
  • Integration. (0, pi, sin(x) dx) or (0, π, sin(x) dx)
  • Understands fairly ambiguous syntax. Eg. 2sin50 + 2xy
  • Syntax highlighting
  • Special-symbol completion on tab. Eg. write sqrt and press tab. It will be turned into .
  • Sum function: sum(start, to, expression) Eg. sum(1, 3, 2n+1) is the same as 2*1+1 + 2*2+1 + 2*3+1 = 15
  • Load a file including predefined functions and constants. For example, if you're going to use Kalk for physics, you load up your file with physics functions/constants when starting Kalk. -i file
  • Misc: separate expressions by a semicolon to write them on the same line, use the ans variable to get the value of the previously calculated expression.


There are currently three different libraries related to kalk.

  • kalk: The Rust crate that powers it all.
  • @paddim8/kalk: JavaScript bindings for kalk. This lets you use it in the browser thanks to WebAssembly.
  • @paddim8/kalk-component: A web component that runs @paddim8/kalk, which let's you use kalk in the browser with a command line-like interface.



Pre-compiled binaries for Linux, Windows, and macOS (64-bit) are available in the releases page.


Minimum rust version: v1.36.0. Make sure you have diffutils gcc make and m4 installed. If you use windows: follow the instructions here (don't forget to install mingw-w64-x86_64-rust in MSYS2).


Run cargo install kalk_cli


  1. Go into the kalk_cli directory.
  2. Run cargo build --release
  3. Grab the binary from targets/release


A more complete reference can be found on the website


Defining: name(parameter1, parameter2, ...) = expression
Example: f(x) = 2x+3

Using: name(argument1, argument2)
Example: f(2)


Defining: name = expression
Example: x = 3

Using: name
Example: x


kalk and kalk_cli (Rust)

After making changes to the kalk library (in kalk/), you can easily try them out by going to the root of the project directory, and doing cargo run. This will start kalk_cli, with the new changes. If you're using Windows, you will need to follow the instructions here, but also make sure to install mingw-w64-x86_64-rust in MSYS2.

kalk_web (Svelte, TypeScript, Sass)


  1. npm install
  2. npm run dev - this will automatically re-compile the project when changes are made

kalk_mobile (Android)


  1. npm install
  2. npx cap sync
  3. Build the project using Android Studio, or Gradle directly.


~508K SLoC