File I/O

[fonsp]

One of the reasons to write a notebook system from scratch is to change the default file format. Our wishes are:

• Output is saved separately, optionally.
• The file has nothing but legal Julia syntax.
• The file must be readable in plain form.
• Notebooks are git merge-friendly. This includes:
  • Minimal changes in code are minimal diffs.
  • A merge conflict where two people added a cell can be merged automatically.
• The file should not change when you:
  • Open the file, run cells, save and close the file.
• If your notebook runs without errors on "Run all", it should run when you do julia mynotebook.jl
  • You should be able to include("./yournotebook.jl") in another script/notebook, and use the globally defined variables and functions.
  • This creates a problem with arbitrary cell order.
• Cells that are disconnected dependency-wise, should keep their order.
• Any legal Julia script can be interpreted as a Pluto notebook.

[malyvsen]

My suggestion for saving pure Julia files: Before each cell there would be a comment with its UUID, and at the beginning/end of the file, together with a "made with Pluto.jl" notice, we'd include the UUIDs in notebook order, each in its own line. This is Git merge-friendly: if one person added a cell and another reordered some cells, they can still do an automatic merge

[fonsp]

We now have file I/O, but cells are not yet saved in execution order. For this, we first need to implement "run all" functionality. (#12)

[fonsp]

Should Pluto have a built-in file manager? My pros and cons: Pros:

• For remote access, you no longer need to use a terminal. Good for new programmers.
• Reduces the overhead of starting a Julia+Pluto process for each notebook.

Cons:

• We are duplicating functionality, and we will probably do a worse job than Nautilus, Explorer.exe, etc.
• Effort
• Right now, Pluto is launched inside a Julia environment. Different notebooks might need different environments. (This might only be a problem for experienced users.)

A compromise might be: You can open notebooks from within Pluto, with UI similar to VS Code.

[malyvsen]

I think a compromise is best - just launch the default file explorer to "save as"/load notebooks, with "save" ovewriting the current file. New notebooks could start up a new instance of Pluto if that's possible?

[fonsp]

Oh true! We can use the browser implementation for opening and saving :)

[malyvsen]

Perhaps serve_notebook could start up a container of sorts, optionally running in parallel to the main process? I think this would make for elegant management of multiple notebooks

[fonsp]

I think that different notebooks should be able to use the same port (so that you only need to open one port for remote access), so starting a new Pluto instance with a new HTTP server doesn't work - the HTTP server needs to handle multiple notebooks.

We could use the Notebook struct as this container, containing a reference to its modulemanager workspace and update channel.