Boot.Pathinclude module type of struct include Env.Path endtype t = Env.Path.tPaths are private, and owned by the functions below
We should gradually add some more functions to handle common dirs here such the theories directories or share files. Abstracting it hereere does allow to use system-specific functionalities
val exists : t -> boolexists file checks if file exists
val to_string : t -> stringString representation