Bubble Tea: fun, functional and stateful way to build terminal apps

Command on macOS doesn't work, ctrl+shift doesn't work, ctrl alone doesn't work with most non-letters, etc. Terminals typically let you add explicit key mappings but that's really tedious and you have to map each individual key, and then ensure that the programs you want to use understand the mapped values. And not all terminals allow for freeform key mapping either.

I do see on https://invisible-island.net/xterm/ctlseqs/ctlseqs.html that xterm has a resource modifyOtherKeys that is documented to turn keys like like alt-tab turn into CSI 2 7 ; 3 ; 9 ~, but this doesn't appear to work on Terminal.app, iTerm.app, or Kitty. Similarly there's a documented sequence that's supposed to make xterm set the 8th bit for meta instead of prefixing with ESC, but that also doesn't work on these three terminal emulators. I am not set up right now to try xterm itself (I don't have an X11 server).

Ultimately, the ways keys are sent to terminal processes by default disallow many modifier combinations (and may also have multiple key chords that send the same input). Some terminals may allow for customizing this on a key-by-key basis but most CLI apps won't understand the resulting input, and won't have a way to declare whether or not the terminal should do this. xterm documents a way to do this for most keys, but that isn't supported on the terminals I have access to on macOS.

Interesting, I hadn't seen CSI-u mode before. It looks like it's a toggle for the whole profile though, rather than something the CLI tool can opt in to, which means it will break any tools that expect existing keys like C-M-e to be ^[^E, and that seems rather unfortunate.

It looks like kitty actually has a means of requesting this stuff dynamically with CSI = flags ; mode u (and a push/pop stack). It also says it will use CSI-u mode automatically for keys that don't have a "legacy" escape, but I didn't see this before because stuff like C-M-3 does not in fact echo as CSI-u but instead that inputs as just 3 instead of CSI 5 1 ; 7 u. Even using Kitty's "progressive enhancement" mode to request disambiguation of escape codes leaves C-M-3 broken which is rather confusing. Versus iTerm where its profile-wide CSI-u mode toggle does report C-M-3 correctly.

In any case, Terminal.app doesn't support this, and I'm not sure what else does. Looking at Alacritty right now, I don't see any direct support for this, the closest I've found is some issue comments suggesting setting up custom key bindings to simulate it (which I guess means defining every single combination of modifiers for every single keyboard key?).

As for Command, yes, it should be for actions _to_ my terminal. But for GUI apps they go to that app, and so replacing GUIs with TUIs means losing the ability to use Command for this sort of thing. For example, in MacVim I can press ⌘N to open a new MacVim window. In vim I can't, because that just opens a new Terminal window. Or ⌘A to select all, which doesn't even have an equivalent CLI key shortcut (e.g. in Vim I'd have to type something like ggv, exiting insert mode first if necessary).

And of course proper usability of the terminal typically requires binding Alt to Meta, but doing that means losing the ability to type non-ASCII chars on macOS. This is another thing that GUIs don't have to worry about.

Not directed at you, but here we are in a post about a CLI for Go, discussing Rust. It seems like every discussion of something related to Go requires someone to screech about safety (again, not you) and how Go is a terrible choice.

I use both weekly, for different things. There are numerous people who don't use Go at all that are in Go specific forums. They read Go specific threads here on HN just to make their Rust points. I poke fun at them with my statement. You just gave me the hook.

:) smiley face for you