Problem

It would be nice to be able for widget crates to rely just on the widget / buffer / etc. types instead of the whole library.
Additionally by extracting a widget crate out of the library we might be able to have quicker incremental build times.
It would also be nice to be able to release non-breaking widget updates in point releases immediately rather than waiting for a library release.

Solution

Decompose Ratatui into several crates:

• ratatui: the main core library, feature flags to include the parts
• ratatui-core: Widget, WidgetRef, StatefulWidget, StatefulWidgetRef, Terminal, Frame, Backend etc.
• ratatui-{crossterm,termion,termwiz}: backends
• ratatui-widgets: all the existing built-in widgets (currently this is something else, but I'd move the current library to a new name)

It's possible that we could also go more granular than this and have a crate per widget, but I think it's worth doing the first part and evaluating whether doing more is worthwhile.

This will be implemented by making the repo into a cargo workspace, moving the current source under /ratatui/src, and creating several more crates at the root. I know it may be tempting to not do a monorepo for this, but the administrative overhead of having a repo per crate seem prohibitive, while I've had reasonable success using mono-repos (e.g. tui-widgets crate).

The work to do this will be:

• make the actual refactoring changes
• make the CI / CD changes
• make the doc changes (fixup website links etc. to examples)
• test changes in various widget libraries

@ratatui/maintainers what do you think?

Plan

• move the folder, create the workspace chore: move ratatui crate into workspace folder #1459
• move the main types to ratatui-core chore: move core types to ratatui-core #1460
• Move widgets into ratatui-widgets chore: move widgets into ratatui-widgets crate #1474
• refactor: move {Stateful,}Widget{,Ref} types into individual files #1479
• docs: improve docs for workspace crates #1490
• chore: move unstable widget refs to ratatui #1491
• refactor: modularize backends #1508
• Move examples into /examples - there's a good approach that tokio uses for this where each example gets a crate, and so can have their own dependencies listed etc rather than these being all smooshed into a single dev-dependencies lists.
• Update / make sure that git cliff and release automation are working fine
• Make an alpha release and then test ratatui-core with some widget libraries
• decide on whether to move frame / terminal to core, or leave them in Ratatui (I'm not certain about this right now, probably should go to core, but there's an argument against it too