Not sure where to triage this issue, starting with Editor, though I assume some VM work is also needed.

I will re-triage this to the VM :) I think the bulk of the work will occur there.

cc @mhausner.
Removed Area-Editor label.
Added Area-VM label.

This comment was originally written by @mhausner

We designed the language and runtime to make load times very fast, so I'm not sure whether there is a problem in the first place. Hot-swapping code probably would mean to invalidate a lot (if not all) compiled code, so the benefit of such a feature would have to be put in perspective to the complexity it adds to the runtime.

cc @iposva-google.

A potential use case:

Game developer working on game and wants to improve a boss AI logic. This logic is limited to a single function. The time it takes to launch the game (loading assets from disk/network, processing them, uploading to GPU, etc) and then load the boss's stage is a high price to pay given the programmer has only changed the logic in one function.

Reloading is fast. However, getting the app back into the correct state is potentially not fast. Not just for games, but for complex apps with many screens that require a user to click through "deep" into the app.

This comment was originally written by @Andersmholmgren

Nothing beats the productivity you get when you have one window showing the browser and another the editor side by side and as you change any source (dart CSS HTML etc) you see the changes immediately in the browser. That would be a big feather in darts cap IMO

Another use case: building a server. Servers often need to connect to various external resources: database servers, memcache servers, etc. Establishing all those connections on startup is non-trivial. I'd love to be able to edit files for the server, and just hit reload, and the VM or framework detect the file is dirty and reload it without having to restart the server.

Changed the title to: "Hot-swap code, reduce full-reload situations".

The VM now supports hot reload. Closing.

Any plans for hot reload in Dartium?

@gnomesley no, Dartium is going to die and be replaced by DDC
There is currently no hot reload for DDC and AFAIK no current plans to support it (that might change eventually when DDC becomes more mature)