Is there a simple way to load extra packages to ghci when invoked via cabal repl?

cabal repl --ghc-option='-package xyz'

This will load the package you are calling cabal repl from and the package xyz.

To do that after the fact, i.e. when you’re already in the REPL and want to load an extra helper module from another package:

GHCi> :set -package xyz
GHCi> :m +XYZ.Module.You.Suddenly.Need