Starting with 5240116f3c we only support
GHC versions 8.4.4 and up (more precisely, the GHC version associated
with stackage lts-12 and up). The imports in question are now in
Prelude and need not be imported explicitly.
I have been using this code locally for years now, and it turned out to
be quite useful in many cases, so I thought it is about time to submit
it to the repository.