A simple class for storing time-of-day values — hms

The values are stored as a difftime vector with a custom class, and always with "seconds" as unit for robust coercion to numeric. Supports construction from time values, coercion to and from various data types, and formatting. Can be used as a regular column in a data frame. hms() is a high-level constructor that accepts second, minute, hour and day components as numeric vectors. new_hms() is a low-level constructor that only checks that its input has the correct base type, numeric. is_hms() checks if an object is of class hms. as_hms() is a generic that supports conversions beyond casting. The default method forwards to vec_cast().