ABSTRACT We report on our experiences in synthesizing a fully-featured autopilot from embedded domain-specific languages (EDSLs) hosted in Haskell. The autopilot was built for the DARPA High-Assurance Cyber-Military Systems (HACMS) program. After an independent red-team assessment, one government official remarked that it was likely "the most secure UAV in the world". We will also describe our experiences in transitioning the EDSLs to Boeing for use in large-scale platforms. The EDSLs and autopilot are both open-source.