Clojure equivalent to the Perl "unpack" function

Question

In Perl, unpack can be used to neatly split a string of fixed-length fields into its parts. What follows is an example of it being used to accomplish this:

# get a 5-byte string, skip 3, then grab 2 8-byte strings, then the rest
my ($leading, $s1, $s2, $trailing) = unpack("A5 x3 A8 A8 A*", $data);

Is there an equivalent to unpack in Clojure?

Answer 1

No, and there's no the corresponding pack.

I'd use RegExes. Although I can't really tell how exact of an alternative that is since I don't know Perl and how it handles multibyte characters in strings.

;; If you prefer named groups.
(let [data "xxxxx___yyyyyyyyzzzzzzzz1234awerasdf"
      pattern #"(?<leading>.{5}).{3}(?<s1>.{8})(?<s2>.{8})(?<trailing>.*)"
      matcher (re-matcher pattern data)]
  (re-find matcher)
  (into {}
        (map (fn [[n idx]]
               [(keyword n) (.group matcher ^long idx)]))
        (.namedGroups matcher)))

;; If you prefer to rely on positions.
(let [data "xxxxx___yyyyyyyyzzzzzzzz1234awerasdf"
      pattern #"(.{5}).{3}(.{8})(.{8})(.*)"
      [_ leading s1 s2 trailing] (re-matches pattern data)]
  {:leading  leading
   :s1       s1
   :s2       s2
   :trailing trailing})