Sonnet
TensorFlow-based neural network library
...These modules can hold references to parameters, other modules and methods that apply some function on the user input. There are a number of predefined modules that already ship with Sonnet, making it quite powerful and yet simple at the same time. Users are also encouraged to build their own modules.
Sonnet is designed to be extremely unopinionated about your use of modules. It is simple to understand, and offers clear and focused code.