API for modifying history

[huiyiqun]

So that we could import histories from other shells.

[zhsj]

And then we can implement completer with history in pure elvish lang.

[huiyiqun]

I found a maybe useful function here.

https://github.com/elves/elvish/blob/3f987e286736cfb6d26085459ce7b45b24eb4afc/edit/history.go

[huiyiqun]

However, history is a concept only available in line editor currently, I'm not sure how should I expose this concept in eval gracefully. Maybe a new separate go package?

@xiaq

[huiyiqun]

@zhsj you could use the history builtin

[huiyiqun]

There is already store package.

[huiyiqun]

We could use store/cmd.go directly. I will try to fix #263 first.

[xiaq]

The variable $le:history allows reading the history, so what lacks is a API for modifying history. I have changed the title of the issue.

[krader1961]

See also issue #1205 where I pointed out that dir-history should not be in the builtin: namespace and manipulating the interactive history should be possible independent of whether the shell is interactive.

[xiaq]

This is now supported by store:add-cmd \o/