How to read a byte from a file in elisp

Question

Elisp has a lot of functions for manipulating buffers opened in the editor, but it doesn't seem to have any raw file operations. Maybe what I need is in there, but I'm missing it.

How do you open a stream and read bytes from it? The Common Lisp equivalent would be:

(defvar stream (open "example.txt" :element-type '(unsigned-byte 8)))
(defvar byte (read-byte stream))

Answer 1

You can't do that directly. Either you read the file into a buffer (with insert-file-contents, which actually can also insert a subrange of the file's bytes), or otherwise you create a process that runs cat on the file.