Detect which packages are used. Automatically install them via `{webr}`

[schloerke]

If renv::dependencies("path/to/app") can be used to detect dependencies, then we can preload app dependencies for users.

There should not be a requirement for users to call webr::install("FOO") to load a precompiled FOO package.

[coatless]

@schloerke this should be handled by an internal webR API calling R code. I mocked up something for library()/require() c.f. https://github.com/r-wasm/webr/issues/280

[georgestagg]

I think (where possible) I would lean towards using the tools that already exist in renv for discovering dependencies, rather than replicating the work in webR.

I am currently working on the next iteration of the webR package building process, and investigating Emscripten's FS.mount() API. In principle I think it should be possible to pre-build a Wasm filesystem image containing an R library (defined by renv, or a package list, or similar) ready to pre-load into the environment for a given shinylive/webR app.

This should have the additional benefit of being much quicker than downloading, decompressing, and writing many packages from the public package repo to the virtual disk.

[schloerke]

r-shinylive seems like the wrong place to do this.

• Altering the app code to have extra lines seems wrong.
• Even if it worked the first time, it won't automatically work if a new package is added in a shinylive editor.

Seems like it needs to be run in the shinylive R process if the feature is enabled.

[schloerke]

Bug fixed in https://github.com/posit-dev/shinylive/pull/68

Shinylive asset support updated in #21

Closing