''The ability to have "pockets of imperative mutability"... connected by a "functional tissue," is not only clarifying, but works quite well in practice for bu

''The ability to have "pockets of imperative mutability"... connected by a "functional tissue," is not only clarifying, but works quite well in practice for building large and complex concurrent systems.'' That's always been a winning combination, and if you look for it you'll see that many examples of well-written code hold to the pattern: large swaths of code that are referentially transparent, with smaller chunks of imperative code piping them together. This can be done in almost any language, but of course support from the toolchain is nice to have.