  We present Ecole, a new library to simplify machine learning research for
combinatorial optimization. Ecole exposes several key decision tasks arising in
general-purpose combinatorial optimization solvers as control problems over
Markov decision processes. Its interface mimics the popular OpenAI Gym library
and is both extensible and intuitive to use. We aim at making this library a
standardized platform that will lower the bar of entry and accelerate
innovation in the field. Documentation and code can be found at
https://www.ecole.ai.
