[I cannot find a question tagged emacs-lisp, so let's start, it will be the first on StackOverflow.]
Emacs Lisp has replace-string but I cannot find a replace-char. If I want to replace "typographic" curly quotes (Emacs code for this character is hexa 53979) with regular ASCII quotes, I write:
(replace-string (make-string 1 ?\x53979) "'")
which would certainly be better with replace-char. Any way to improve my code?