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A comment on Single Page Applications using Rust. Parent comment

Re:Single Page Applications using Rust by AlisdairO on Tuesday August 11, 2020 @04:59PM (#24125903)
Well, yes, of course. The thing you could previously rely on being present can no longer be guaranteed to be present - that _should_ require code in the calling function to change.
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Re:Single Page Applications using Rust by nickbauman on Tuesday August 11, 2020 @05:10PM (#24126021)
Not if I loosened the requirement. Stricter adherents shouldn't have to change anything. This is poor language ergonomics.
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Re:Single Page Applications using Rust by setr on Tuesday August 11, 2020 @05:33PM (#24126242)
To be clear, you're talking about the function signature changing from

    fn(a: int)
to

    fn(a: Option<int>)
?

Technically, yes, all callers would have to update, but practically, you'd just define

    fn(a: int) { fn_2(Some(a)) }
to avoid the breakage. That is, you're essentially telling the compiler how to loosen the requirements. Ergonomically, this seems rather fine. Especially if this means you gain (some) protections from the much more problematic case of restricting the requirements.
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Re:Single Page Applications using Rust by mqus on Tuesday August 11, 2020 @07:52PM (#24127285)
There is also the Option of accepting Into<Option<T>>, which does cover both variants and is completely backwards compatible.
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