Make key combinations with letter keys case-insensitive

[xiaq]

What new feature should Elvish have?

Keybindings in Elvish are case sensitive. For example, Alt-x stands for the key combination Alt + X, while Alt-X stands for the combination Alt + Shift + X. On the other hand, the key combination Ctrl + X has to be spelt as Ctrl-X, not Ctrl-x. These are more of a result of historical quirks than rational choice.

I posit that when we think about key combinations we indeed think about keys (as opposed to characters), so we think of the x and X in Alt-x and Alt-X both as "the X key", not as lower-case and upper-case characters, hence it's more intuitive if both just mean the key combination Alt + X. Elvish making a distinction between the two is counter-intuitive. Instead, Elvish should call the key combination Alt + X Alt-X (or Alt-x, or alt-x), and call the key combination Alt + Shift + X Alt-Shift-X (or Alt-Shift-x, or alt-shift-x).

The discussion so far only touches on key combinations with letter keys, which leaves two other classes:

• Key combinations not involving letter keys, like Alt-!. This should remain unchanged, even though on a US layout keyboard it's typed as Alt + Shift + 1. This is because whether ! is shifted from 1 depends on the keyboard layout, and the problem with case sensitivity doesn't exist here, so hopefully there's no confusion about what Alt-! means, although unfortunately there's still ambiguity around whether the combination should be spelt as Alt-! or Alt-Shift-1.

• Lone letter keys, like just x. I'm a bit ambivalent about whether X should be changed to Shift-X.

Some research into how other terminal applications spell key combinations may also be illuminating.

Output of "elvish -version"

irrelevant

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