[Haskell-cafe] runhaskell flags: What is going on?

runhaskell -fno-warn-unused-matches Myfile.hs [some compile error]

runhaskell -fno-warn-unused-matches Myfile.hs [no output whatsoever but exit code 127]

runhaskell -asdf Myfile.hs ghc: unrecognised flags: -asdf

runhaskell -fasdf Myfile.hs [no output whatsoever but exit code 127]

Not sure if that's how it should work or missing error reporting? Thanks Niklas