This is a teensy library that provides some functions to determine the mime-type of a file. As I've had a need for this kind of functionality more than once now and haven't found any suitably lightweight alternative I quickly whipped this up.
(mimes:mime #p"~/something.png")
Upon loading, trivial-mimes builds a mime-type database from the local mime.types file or a copy thereof from its own source directory. This database is a simple association of file extension to mime-type (see mime-lookup). If the mime lookup in the database fails, it will instead try to consult the file shell utility on unix systems (see mime-probe). If that too doesn't work, it falls back onto a default.
