Rank tab-completions and suggestions using type information

[sharkdp]

This might be hard to implement, but …

It would be great if we could rank/filter tab-completions and suggestions using type information. For example, if someone types 3 cm -> [Tab], we could ideally only show suggestions that would type-check (e.g. matching units).

To implement this, we would essentially have to run the compiler up to the type-checker phase on a substring of the user input (the left-hand-side of the conversion operator in the example above). Because running it on the full input would lead to a parse error.

Another example:

>>> Atan(2,3)
error: while type checking
  ┌─ <input:4>:1:1
  │
1 │ Atan(2,3)
  │ ^^^^ unknown callable
  │
  = Did you mean 'atan'?>>> Atan(2,3)

could be improved by returning atan2 as a suggestion, even if it's further away in terms of edit-distance.