On GHC 9.0.1, ParallelArrays
doesn't seem to do anything. Searching through codebase (https://github.com/ghc/ghc/search?q=ParallelArrays&type=code), it seems like related functionality was dropped few years ago (https://github.com/ghc/ghc/commit/faee23bb69ca813296da484bc177f4480bcaee9f), but the flag itself persisted. Is that intentional or was it simply missed?