Is Nimony supposed to be Nim v3 then?
Eventually, yes that is the plan, but it's really too early to say for sure.
Compile with nimony c -r temp.nim:
proc printf(format: cstring) {.importc: "printf", varargs, header: "<stdio.h>", nodecl.}
printf("Hello, world!\n")
It compiles&runs the code. The build is incremental¶llel. Unfortunately, nothing else works. :D