can't we have a to_string in many modules

[UnixJunkie]

List.to_string, Array.to_string, Set.to_string.

BatList.print uses IO, I would prefer not to use this.

The implementation I have in mind would rely on the Buffer module.

The goal I have in mind is to print things in a human-readable form on disk.
Of course, the representation must be parseable back to the original data structure.

[UnixJunkie]

time to revive the to_seq proposal from @c-cube ?
Then just have a Seq.to_string ?

[UnixJunkie]

And hope there is a Seq.of_string also.

[UnixJunkie]

related to #819