The problem I have with ligatures in source code files is that it makes pairs of codepoints visually indistinguishable from a single codepoint. For example, if

The problem I have with ligatures in source code files is that it makes pairs of codepoints visually indistinguishable from a single codepoint. For example, if I see "fl" in a string, is that "fl" or is it "fl"? That is, is it the codepoint sequence U+0066 U+006C turned into a ligated version visually, or is it U+FB02 the single codepoint? Then I get paranoid: Did my text editor Helpfully convert the sequence of characters into the ligature character? The paranoia is probably unjustified, and would be seen as a bug if it weren't (probably), but a clear visual distinction would banish it entirely.