A fun way to start the fall. (Today is my daughter's first day of "school". This defines the beginning of fall.) Thanks, Iavor, for kicking this off. I initially wrote a long email in this space, with numbered criteria (heavily based on Iavor's suggestions) and my thoughts on the individual extensions proposed. But I realized this would quickly grow unwieldy. I thus have created https://github.com/ghc-proposals/ghc-proposals/wiki/GHC2020, where I propose we track this conversation. Specifically: arguments for or against an individual extension should go right on the wiki, labeled with the author's name/initials. This preserves these arguments for later. Then, to keep the conversation moving, write back to this list just mentioning which extensions you've commented on. Please review the criteria on the wiki page. Do you agree with what I've put forward? I've commented on the following extensions: ApplicativeDo CApiFFI EmptyCase ExplicitNamespaces ForeignFunctionInterface LambdaCase MultiWayIf NamedFieldPuns OverloadedLists OverloadedStrings PatternSynonyms RecordWildCards ScopedTypeVariables StandaloneKindSignatures TupleSections TypeOperators I have added these new extensions for consideration: MultiParamTypeClasses ImplicitParams FlexibleContexts FlexibleInstances GeneralizedNewtypeDeriving DeriveDataTypeable DeriveGeneric DefaultSignatures InstanceSigs ConstrainedClassMethods ExplicitForAll DeriveFunctor DeriveTraversable DeriveFoldable PolyKinds RoleAnnotations NegativeLiterals DeriveAnyClass DeriveLift DerivingStrategies EmptyDataDeriving Looking forward to seeing your thoughts here! Richard