errset is a trivial golang package that implements a slice of errors.

The typical go idiom is to return an error or a tuple of (thing, error) from functions. This works well if a function performs exactly one task, but when a function does work which can reasonably partially fail, I found myself writing the same code over and over again. For example:

// CommitBatch commits as many things as it can.
func CommitBatch(things []Thing) error {
    errs := errset.ErrSet{}
    for _, thing := range things {
        err := Commit(thing)
        if err != nil {
            errs = append(errs, err)
        }
    }
    return errs.ReturnValue()   // nil if there were no errors
}