If you want to try this out, simply `gem install ripl ripl-multi_line` and add the gist to ~/.riplrc. Since this is a hack, I would open an issue on https://github.com/janlelis/ripl-multi_line/issues if you want it to be done properly.
If you were talking about using readline's multi-line history, I'm not sure if ruby's readline library has an api to it. Would be useful.
You can change the behavior with the Ripl.config[:multi_line_history] option. Possible values: * :compact - transform the last statement into a ; separated one-liner * :block - just join the last multi-line statement to one block ("\n") * :blank - do nothing
Unless of course you mean history through different sessions as that doesn't work for full functions.
Idle is a bit easier to edit the function though.