Module engine 

What a pocket calculator does, without any interface. Operations run in the order they are pressed, so 2 + 3 × 4 = is 20.

Structs

Engine

The calculator’s memory.

Enums

Op

An operation between two numbers.

Press

A key of the calculator.

Functions

format_number

Shows a number the way a person expects: without the noise of binary fractions, so 0.1 + 0.2 is 0.3, and in scientific notation when it does not fit.