Is this related to flang?
LFortran's main advantage is that it is interactive, so the parser and semantics has to be a little different. And also we designed it so that it will be quite approachable for people to write tools on top.
For the really big Fortran systems I worked on in the 1980's (Map Reduce) the edit compile / link process could take several minutes for a single module - we did have a build system written in JCL to help automate this as well.
Here’s a demo of the Jupyter notebook-like interface: https://mybinder.org/v2/gl/lfortran%2Fweb%2Flfortran-binder/...