The Rust team seems to not want to write trait impls where it would be inefficient to use those traits. If a method doesn't exist, its often because there is a

The Rust team seems to not want to write trait impls where it would be inefficient to use those traits. If a method doesn't exist, its often because there is a slightly better way. They also insist that memory usage, especially any heap allocations, be very clear and explicit: allocating and attaching a buffer is probably not OK within the internal logic of the library designs. The interface for reading is split into multiple parts. Read is the lower level interface for any stream of bytes, and is what lets you read a specific number of bytes into a preallocated buffer. Seek is implemented for files, but not all streams, because in most cases it makes no sense. There are also a number of file-specific methods directly attached to File for handling permissions and sync and such. BufRead is the trait that lets you read all the lines, but it is explicitly not implemented for File, since using it for a File would be slow, and generally the wrong way to do things. It does have an implementation for Stdin, because that is already buffered, but if you want to associate a buffer with a file, you have to do it yourself by wrapping it in a ReadBuffer. If I were to find a problem with the File documentation, it is that it does not mention BufReader.