On: Ask HN: Which tools have made you a much better programmer?

[slim]

you can do that in bash too, and any cli that uses readline library

[kadonoishi → slim]

  set -o vi

Starts you in insert mode. To go back to the usual command-line editing,

  set -o emacs

[chrisweekly → slim]

also zsh (tho it doesn't use readline per se)