[dwringer]

I've always felt ligatures that condense two or more glyphs into something that takes up the space of only one in a monospace font are going beyond what a font should handle and into the realm of what an editor should do. I have several such visual substitutions set up in my .emacs but I don't use fonts that do them on their own.

[trealira]

What about ligatures that make ASCII characters display differently when in proximity, but still use the same number of columns?

For example, when == is written, connect them to be a 2 column wide = instead.

Or when === is written, display a three column equals sign, but it's three bars instead of two.