Nominating arrayref, which instantly solved a tedious and annoying problem (turning &[T; 16] into (&[T; 8], &[T; 8])) that was holding me up the other day. Tiny crates are the best.
This package contains just four macros, which enable the creation of array references to portions of arrays or slices (or things that can be sliced).
Nominating cargo-about, because it lets you create the file you're legally obliged to ship with your executable according to most licenses' text. Also, it checks crates against your list of approved licenses. Where there's a choice of license, it only includes the license you've approved. By default it generates HTML, but with some fiddling about with the about.hbs it can produce nice plain text output too. Saved me a lot of time.
When you use std::fs, you may get very unhelpful errors like The system cannot find the file specified. (os error 2)
that don't show the path of the file on which the error occured.
fs-err wraps the functions in std::fs and adds the path information to the error while staying compatible with std::io::Error.
Saved me the pain of adding the error context myself everywhere.
That definitely gives me some ideas for the time crate! The formatting is (unsurprisingly) based on the Unicode standard, bit it is something to look at.
Vec but with strongly typed indices, e.g. instead of Vec<CpuUsage> // Indexed by CPU core you can do TiVec<CpuCoreId, CpuUsage>. It prevents accidentally using the wrong index type, which is a common source of bugs.
Despite how useful it is (and IMO should be in std), it has 0 stars and only 300 downloads.