[RFC]: support auto-completion and completion previews after function executions in the REPL

[kgryte]

Description

This RFC proposes adding support for auto-completion and completion previews after function executions in the REPL. The idea is that, for side-effect commands, we could eagerly evaluate and support TAB completion and the display of potential completions. E.g., consider

In [1]: [ 'foo', 'bar', 'beep' ].sort().fil<|>

where <|> is the cursor. In this example, after eager evaluation, we know that sort() returns the input array and thus we should be able to auto-complete filter.

One possibility which may not rely on eager evaluation for implementing this RFC is to take advantage of take advantage of our signature database (see https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/repl/signature), where we statically know output values. If a function/method returns a value having a specific type, we can then auto-complete based on the known properties/methods of that type.

Eager evaluation, however, would allow for result previews of chained commands and would also the need to analyze complex static AST graphs.

Related Issues

• Implementing this RFC is dependent on [RFC]: add support for eager evaluation of side-effect free code in the REPL #2073.
• Completion previews: [RFC]: Add auto-completion preview for REPL #1775

Questions

No.

Other

• https://developer.chrome.com/blog/new-in-devtools-68/#eagerevaluation

Checklist

• I have read and understood the Code of Conduct.
• Searched for existing issues and pull requests.
• The issue name begins with RFC:.