If I knew the shape of what you had and what you wanted, I might be able to make a suggestion.

well i started with something like line 581 except using [] instead of .get(), then i realised everything needed to be Option<>al, so I used bare .get(), then the compiler complained at me for doing 0usize - 1usize so i put one of the if{}else{}s back github.com/fanf2/leapsecs/bl…

Hmm, gimme a tic to think about what you're doing here.

i want something like a backwards .peek()

hmm but i can do a backwards peek with a mutable prev variable and now my problem is that slice::Iter isn’t peekable

but it is if i slap a .peekable() on it

I'm just trying to grok what you actually need in terms of data. Is it that for each entry in the list you want (prev,this,next) where at the start that'd be (None,entry,Some(next)) and a the end it'd be (Some(prev),entry,None) ?

exactly i tried a version with .peek() and it turned out to be more annoying play.rust-lang.org/?version=…

This isn't *quite* what you're after, but it's close (Option,Option,Option) rather than (Option,value,Option) -- play.rust-lang.org/?version=…

ah i thought there might be something in itertools 🤓