Firacode: Arrows ambiguity with Unicode arrows

[stevengj]

Copied from https://discourse.julialang.org/t/fira-code-font-and-ligatures-for-julia/9367/13?u=stevengj:

-> => → ⇒ ⟶ ⟹ are all distinct operators in Julia. It seems like your ligatures make the first two look very similar to some of the latter ones, which is problematic:

This illustrates the general danger of mixing fancy ligatures with a language that supports both ASCII and Unicode operators. (Something like <= looking like ≤ is probably okay, because any language like Julia that supports ≤ directly will certainly have it mean the same thing as <=.) Please be conservative about ligatures that make some combination of ASCII characters closely resemble a completely unrelated Unicode character.

[j-f1]

A difference here is that the ligature for -> is two characters wide, whereas → is one character wide.

[tonsky]

Fira Code is for languages that don’t support Unicode and resort to ASCII pseudo-graphics instead, for historical or other reasons. If you can use full Unicode range, I definitely recommend that (I believe that’s the future) and you probably don’t need something like Fira Code