In /usr/bin/hpc line 5:
datadir="/usr/share"
^-----^ SC2034: datadir appears unused. Verify use (or export if used externally).


In /usr/bin/hpc line 6:
bindir="/usr/bin"
^----^ SC2034: bindir appears unused. Verify use (or export if used externally).


In /usr/bin/hpc line 7:
topdir="/usr/lib/ghc"
^----^ SC2034: topdir appears unused. Verify use (or export if used externally).

For more information:
  https://www.shellcheck.net/wiki/SC2034 -- bindir appears unused. Verify use...