Haskell has do notation and monads (F# has computation expressions, which are similar). These allow you to implement things as libraries that in most other lang

Haskell has do notation and monads (F# has computation expressions, which are similar). These allow you to implement things as libraries that in most other languages would require changes to the compiler. Lisp macros can do it too. You could push the reactivity monad right down to the core of your application to get the benefits of this reactive language.