See the second link I posted. Even the most basic 3 functionalities are bad designed. If X is your input space and Y your output space then fit should (after ea

See the second link I posted. Even the most basic 3 functionalities are bad designed. If X is your input space and Y your output space then fit should (after each call) return a function X->Y and not modify some internal state. Have you ever tried looked at the pipeline cross validation, where you have to pass a dict of parameters to the function with underscore prefixes for each stage in the pipeline? Do this and you never call the API design amazing again. There are examples for other bad design choices as well. You are right, there is no alternative at the moment. Maybe julia lang will do better job, we will see.