> 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?