There's a case to be made that Haskell (or Idris) is not imperative, but 'imperative', at it's core, describes an interface, and Haskell supports that interface

There's a case to be made that Haskell (or Idris) is not imperative, but 'imperative', at it's core, describes an interface, and Haskell supports that interface, basically (and a limited version of the associated semantics -- all good interfaces reduce their detail and surface area, though, no good having an arbitrarily precise interface).