Pure functional languages, aka Haskell or Idris or whatever, don't have this property. A closure closes over values, and thus is a value, no state mutation invo

Pure functional languages, aka Haskell or Idris or whatever, don't have this property. A closure closes over values, and thus is a value, no state mutation involved. Of course, your point about complex mechanisms to reintroduce mutation into specific contexts stands (usually via monads) but those are a very different Kind of object then the functions.