Sample code to scan a body of text for @mentions and #tags

mentions_and_tags.clj

;=============================
; a sample body of text
;=============================
(def sample "A mention: @bob and another: \uFF20charlie but not me@home.com and #my_tag should be caught as should #another. Tests passed? #blimey!")

;=============================
; valid at chars are @ and \uFF20
;=============================
(def mention-pattern #"(^|\s)[@\uFF20](\w+)")
(def tag-pattern #"(^|\s)#(\w+)")
(defn extract-group [n] (fn [group] (group n)))

;=============================
; scan comment for mentions
;=============================
(defn scan-for-mentions [comment]
  (let [matches (re-seq  mention-pattern comment)]
       (map (extract-group 2) matches)))

;=============================
; scan comment for hash tags
;=============================
(defn scan-for-tags [comment]
  (let [matches (re-seq  tag-pattern comment)]
       (map (extract-group 2) matches)))


;=============================
; Test the sample
;=============================
(scan-for-mentions sample)
(scan-for-tags sample)


; This renders:
;("bob" "charlie")
; and
;("my_tag" "another" "blimey")