Does Darcs support Cygwin on Windows?
Not officially (sorry!). The Darcs binary on Windows is a normal Windows executable that does not understand Cygwin paths. You could try, at your own risk, a wrapper script (which does the job of converting Cygwin paths like /home/foo to Windows paths) provided by the darcs user community; see WindowsConfiguration for more details. Note that we would be happy to reconsider Cygwin support if somebody is willing to add Cygwin support for GHC.