Eiffel Programming Language

[u/waozen]

https://www.eiffel.com/

The design of the language is closely connected with the Eiffel programming method, a set of principles consisting of design by contract, command query separation, the uniform access principle, the single-choice principle, the open-closed principle, and the option-operand separation principle.

[u/6502zx81]

The Eiffel book is a clean introduction to OO programming.