sfgml\sfgml-dev\Map.hx:8: characters 20-37 : Type not found : haxe.ds.Map

Above is the error I'm receiving when I try to compile. I tried looking at it myself but I just don't know Haxe well enough. 

As far as I know I set everything up correctly and I even tried adding sfgml_native_map to the directives. I tried with and without sfgml-next and I still get the error. 

You'll need a preview build of Haxe - some of the standard classes moved places and sfgml mostly references the up-to-date paths.

Ah that explains it. Thanks for the help!

Encountered this same problem, and to date (Nov 11th 2019) 4.0.0 Preview 5 works with the version of sfgml I downloaded. Anyone reading this in the future should just install versions of Haxe until it works.