type t is lazy. Construction functions (of_rx, quote, ...) don't construct the Emacs regexp until it is needed. Idiomatic use of a Regexp.t looks like:

  let some_function =
    let regexp = Regexp.of_rx ... in
    fun a b c ->
      ... Regexp.match_ regexp ...

This idiom only constructs the Emacs regexp when it is needed, and avoids reconstructing it every time it is used.

Rx.t is the preferred way to construct regexps, especially when the alternative involves string manipulation in OCaml. of_rx is lazy, and doesn't construct the Emacs regexp until it is needed.

(Info-goto-node "(elisp)Syntax of Regexps").

any is lazy, and doesn't construct the Emacs regexp until it is needed.

any_pattern is lazy, and doesn't construct the Emacs regexp until it is needed.

quote string matches string and nothing else. quote is lazy, and doesn't construct the Emacs regexp until it is needed. (describe-function 'regexp-quote) (Info-goto-node "(elisp)Regexp Functions")

any_quote strings matches every string in strings, and nothing else. any_quote is lazy, and doesn't construct the Emacs regexp until it is needed. (describe-function 'regexp-opt) (Info-goto-node "(elisp)Regexp Functions")

Supplying ~update_last_match:true to a searching function causes Emacs to keep track of the "last match", i.e. the start and end positions of the segments of text found during the search. One can access parts of the last match via the Last_match functions. subexp is one based. (Info-goto-node "(elisp)Match Data")

match_ t text finds the first match of t in text, returns the index of the start of the match. (describe-function 'string-match) (describe-function 'string-match-p) (Info-goto-node "(elisp)Regexp Search")

does_match t text is is_some (match_ t text)

(describe-function 'replace-regexp-in-string)

(describe-function 'save-match-data)