/usr/lib/ghc-doc/hoogle/libghc-mersenne-random-pure64-doc.txt is in libghc-mersenne-random-pure64-doc 0.2.0.4-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-mersenne-random-pure64-doc/html/mersenne-random-pure64.txt