flatMap<B> method
Used to chain multiple functions that return a ReaderTask.
You can extract the value inside the ReaderTask without actually running it.
Implementation
@override
ReaderTask<E, B> flatMap<B>(covariant ReaderTask<E, B> Function(A a) f) =>
ReaderTask(
(env) => run(env).then(
(v) => f(v).run(env),
),
);