Every ten years it's discovered that another idea PL researchers have been harping on about about for forty years is very nice and practical once people get used to it :)

I remember when anonymous functions (indeed, first-class functions at all) were considered academic nonsense that just obfuscated problems. After all, who can keep track of all that complexity of functions calling functions?

> I remember when anonymous functions (indeed, first-class functions at all) were considered academic nonsense that just obfuscated problems.

I've been programming since the mid-90s. I've used both Lisp and Haskell.

I don't ever remember even crusty old C greybeards considering anonymous functions to be academic nonsense.

I've honestly had people say this to me within the last year!

There are many practical examples already in Haskell. Pure functional programming is not necessarily about avoiding effects, but about controlling, tracking and managing them. This enables better reasoning and more safety guarantees. For example, software transactional memory, the STM monad, allows optimistic updates to shared mutable state by safely supporting rollbacks.