How to learn any programming language (or start with it)

Many people asked me: how do i learn a programming language? My answer usually is: start by reading documentation and trying to figure things out.

That approach is not always the best, so i made a small exercise that can teach the basics of pretty much every language.

The Exercise

Make a small calculator app that can handle basic functions like addition, subtraction, multiplication, division and exponentiation and has a CLI interface like this:

{Language} CLI calc V1.0
choose a function
1 - Add        3 - Multiply   5 - Exponentiation
2 - Subtract   4 - Divide
>>> 5

{function} - Please choose two numbers a and b to calculate {expression}
a: {num_a}
b: {num_b}
result: {result}
Press enter to restart...

Requirements

• It must have the above interface
• it must use functions/methods
• builtins are not allowed unless it is to interact with the terminal
• it must have a loop that waits for enter to restart
• it must handle keyboard interrupts without error
• it must not error out
• it must have comments

Optional

• use as few if-statements as possible
• make it efficient (space, time, length)
• make it fancy (color, slight UI change, whatever)
• add docstrings
• do it in as few formatted lines as possible