[lucideer]

They aren't implicitly decided by the font, they are supported (or not supported) by the font and explicitly decided by the editor, so your recommendation is the case in practice.

i.e. OpenType fonts optionally accept a range of settings flags to toggle various features. For standard ligatures this is the `liga` flag, this flag is off by default and an editor sets the flag to display ligatures (if the particular font supports that flag).

[captainmuon]

Really? That would be nice. Last time I checked, Atom was one of the only editors that supported it anyway, and it just applied ligatures indiscriminately. Same for the terminals that supported ligatures, I don't even know how e.g. vim would signal to a terminal to use a ligature.