Add REPL hook to prompt to install missing packages, if available in registry

[IanButterworth]

Paired with JuliaLang/julia#39026

Adds hooks into REPL to prompt to install packages if missing, and available in registry

[IanButterworth]

The base hook and handler support is now available given JuliaLang/julia#39026 has been merged.

The formatting in this PR now looks like

[fredrikekre]

CSV vs "CSV" looks a bit strange.

[IanButterworth]

My thinking is that..

On the load side: Julia currently prints the load error message like ERROR: ArgumentError: Package CSV not found in current path:.
So on the load side it's unquoted

On the registry side: Julia/Pkg can't guarantee that the package in the registry is the same package the user wants by name alone, so the "CSV" hints that the user should check that it's the one they want

I've been going back and forth on this though..

[fredrikekre]

I don't really see how it hints to that. Perhaps the message can be tweaked somehow instead.

[IanButterworth]

How about

julia> using CSV, ImageIO, DoesNotExist
 │ Packages [CSV, ImageIO, DoesNotExist] not found, but packages named [CSV, ImageIO] are available from a registry.
 │ Project `~/.julia/environments/v1.7/Project.toml`
 └ Add [CSV, ImageIO] to the active project and load? (y/n) [n]: 

[fredrikekre]

Yea that looks good. Perhaps printing the project path is not needed either? Or instead print

julia> using CSV, ImageIO, DoesNotExist
 │ Packages [CSV, ImageIO, DoesNotExist] not found, but packages named [CSV, ImageIO] are available from a registry.
 └ Add [CSV, ImageIO] to the active project (`~/.julia/environments/v1.7/Project.toml`) and retry? (y/n) [n]: 

Perhaps "retry" instead of "load"?

[IanButterworth]

Ok. Updated to this.
I don't love adding the project to the prompt line. It makes the prompt line much longer which makes it a bit less visually obvious that it's waiting on user input

[fredrikekre]

Perhaps it doesn't have to be included at all? I guess in general you either don't care about environments and it will mostly confuse you, or you know about environments, and then you know which one you run in .

[IanButterworth]

In the discussions that lead to the base PR a few people mentioned that showing the active project was important for not confusing the user, given they're not in Pkg mode, and hence don't have the env prefix visible on this action.

If I was to vote I'd go for the original style with a 2nd line devoted to the project

[fredrikekre]

In the discussions that lead to the base PR a few people mentioned that showing the active project was important for not confusing the user, given they're not in Pkg mode, and hence don't have the env prefix visible on this action.

I see no discussion about this at all in JuliaLang/julia#39026. Honestly I don't quite understand why it would be important. The fact that you typed using CSV seems to suggest that you expected CSV to already be installed in the current environmen (or the stack).

[IanButterworth]

It's from your notes in JuliaLang/julia#26469 (comment) plus slack discussions.

The fact that you typed using CSV seems to suggest that you expected CSV to already be installed in the current environmen (or the stack).

True, but I see another use model for this.. people wanting to install packages without switching to pkg> mode. It's actually quite a slick way of doing it, because all you type is using Foo then y [return] and the package is installed, precompiled quickly and loaded.

I've added the single line project print back. Not to be forceful, but to present it alongside the other changes. Happy to revert if the consensus is something else

Current form:

[IanButterworth]

Two more options

[carstenbauer]

I was just about to suggest the same: i.e. why not show it in a similar style as in the Pkg REPL mode. So +1 for this solution from me.

[IanButterworth]

It does feel minimal but informative. I've pushed the last one of those two

[IanButterworth]

@fredrikekre what do you think about that last example? Given this isn't being backported, perhaps the formatting could be trialled and adjusted based on use up to 1.7?

[IanButterworth]

The discussion is still open here but I’m thinking it’s better to merge sooner rather than too close to the 1.7 feature freeze, to see how it goes. I think I’ll merge but happily work with any formatting/info feedback. I’ll merge and update Pkg on master in an hour or so if no one has objection

[fredrikekre]

How about making it look kinda like the Pkg REPL mode syntax?

(@v1) pkg> add CSV ImageIO

[IanButterworth]

Yeah there's a really nice elegance to that, but I think the triage discussion was that the default action when the user hits return should be not to install.

So it would have to be something like

julia> using CSV, ImageIO, DoesNotExist
 │ Packages [CSV, ImageIO, DoesNotExist] not found, but packages named [CSV, ImageIO] are available from a registry.
 └ (@v1) pkg> add CSV ImageIO <- Run and retry? (y/n) [n]: 

[IanButterworth]

Or perhaps just

julia> using CSV, ImageIO, DoesNotExist
 │ Packages [CSV, ImageIO, DoesNotExist] not found, but packages named [CSV, ImageIO] are available from a registry.
 └ (@v1) pkg> add CSV ImageIO ? (y/n) [n]: 

[fredrikekre]

Yea, I meant something like the latter.

[IanButterworth]

With offline help from @fredrikekre we arrived at this, which seems quite nice