REPL Without a Pause: Bringing VimBindings.jl to the Julia REPL

VimBindings.jl is a Julia package that emulates vim, the popular text editor, directly in the Julia REPL. This talk will illuminate the context in which a REPL-hacking package runs by taking a deep dive into the Julia REPL code, and articulate the modifications VimBindings.jl makes to introduce novel functionality. The talk will also describe design problems that emerge at the intersection of the REPL and vim paradigms, and the choices made to attempt a coherent fusion of the two.

Vim is a ubiquitous text editor found on almost every modern operating system. Vim (and its predecessor vi) has a storied history as a primary contender in the “editor wars”, its modal editing paradigm often pinned against the modeless, extensibility-oriented Emacs.

Vim users often tout its speed and ease of use, at least after stomaching a steep learning curve. Once a user has learned vim they might question why their fingers should leave home-row, even when they aren’t using vim. Their muscle memory can be applied across many applications by using vim emulation plugins or packages: browsers (vimium and vim vixen), email clients (mutt), IDE plugins (vscode-neovim for vs-code, ideavim for IntelliJ), and shell modes (zsh, bash, fish). Vim emulation can even be used to interact with an operating system: sway for Linux users, AppGrid for MacOS users, or evil mode for Emacs users.

Finally, users can use vim emulation in the Julia REPL. In this talk I will describe how VimBindings.jl works, as well as the design considerations borrowed from other vim emulation implementations in its development. I will take a deep dive into the Julia REPL code and describe how the package introduces new functionality to the REPL, I will also discuss the unique challenges faced during the creation of VimBindings.jl, and the not-so-elegant solutions developed to solve them.

Github repo: https://github.com/caleb-allen/VimBindings.jl