Sorry, I got the last argument wrong:
download_artifact(Base.SHA1("f296f1c3f770aaade98d2f1dfa960c89dee06318"), "https://github.com/dhall-lang/dhall-haskell/releases/download/1.30.0/dhall-1.30.0-x86_64-linux.tar.bz2", "6845421de9c3cc40f4140a1278c408df8ef49bf8086ee7f37730d2eda8ce9402"; verbose=true)