[racket-users] custom input ports and specials

I'm implementing a tokenizer as a custom input port using `make-input-port`. My thinking is that `peek-char-or-special` and `read-char-or-special` will be the primary interface to the tokenizer; port locations will also be used. In this case, the input port should emitting characters as well

[racket-users] custom input ports

Almost every time I've created a custom input port, I've run up against the rule: "The read-in procedure must not block indefinitely." And each time, I've either: - ignored it (with the suspicion that I've just written code that can block the whole process, though I've never actually verified