/usr/lib/ghc-doc/hoogle/libghc-lambdahack-doc.txt is in libghc-lambdahack-doc 0.5.0.0-2build5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-lambdahack-doc/html/LambdaHack.txt