  Programming models for building large-scale distributed applications assist
the developer in reasoning about consistency and distribution. However, many of
the programming models for weak consistency, which promise the largest
scalability gains, have little in the way of evaluation to demonstrate the
promised scalability. We present an experience report on the implementation and
large-scale evaluation of one of these models, Lasp, originally presented at
PPDP `15, which provides a declarative, functional programming style for
distributed applications. We demonstrate the scalability of Lasp's prototype
runtime implementation up to 1024 nodes in the Amazon cloud computing
environment. It achieves high scalability by uniquely combining hybrid gossip
with a programming model based on convergent computation. We report on the
engineering challenges of this implementation and its evaluation, specifically
related to operating research prototypes in a production cloud environment.
