Tau

A statically checked unit-aware programming language that prevents dimensional mistakes at compile time. Tau lets you write variables in SI units so that your bad maths gets caught early on.

Why Tau?

Do you remember the time your engineering coursework took 2 hours too long because you wrote the wrong unit on a piece of MATLAB code? Well I do. This problem, among others, can be entirely avoided by using a progamming language that enforces explicitly typed units.

Most languages (MATLAB included) will let you do this:

force = 10  % N? lbs?
mass = 4  % kg? lbs?
acceleration = mass - force % ???

In Tau:

let force: N = 10;
let mass: kg = 4;
let acceleration = force - mass  # Error: Cannot subtract N and kg

Features

• Compile-time unit checking
• Automatic unit inference
• Mutable (let) and immutable (const) bindings

Automatic unit inference

You don't always need to explicitly write the unit:

let force: N = 10;
let mass: kg = 4;
let acceleration = force / mass;  # Result: m/s^2

Inferred dimensions are also checked against any explicit unit:

let force: N = 10;
let mass: kg = 4;
let acceleration: m = force / mass;  # Error: Expected m got m/s^2

Mutable and immutable variables

Some languages will let you change gravity:

g = 9.81
% ...
g = 2  % They wanted 't = 2'
% ...
mass = 4
force = mass*g  % 8 - silent and hard-to-debug error

In Tau this becomes:

const g: m/s^2 = 9.81;
# ...
g = 2;  # Error: Assignment to constant 'g'

Installation

1. Clone the repository; $ git clone git@github.com:JimmyBowcott/tau.git
2. Build the project $ cargo build --release
3. Run some code: $ cargo run test_file.tau

TODO

• Add support for 'const' declaration
• Control flow
• Support for matrices
• String support
• Imperial unit support