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Lady, EVOLVED 
which is more efficient:
• writing the software library once, making it portable across many platforms, and then dealing with the ensuing portability concerns for decades to come
• writing the software library multiple times
(original post wasn’t about Swift, but i was just thinking about it versus such languages as Zig and Rust which target much larger sets of platforms)
it does bother me that Swift isn’t more portable but i also understand that the reason Swift isn’t more portable is because it supports such advanced features as “Unicode”
and i would take “there are just multiple interoperable Swift implementations”; that would be better actually