A way to re-order the threading macro

threading.clj

;; The ->> threading macro will normally place the previous form into the last argument position of the next form
;; However, there are times when you are working with functions that don't take the required parameter in the last spot
;; In this example, I'm extracting all path locations before /v
;; re-seq first and second all work with the threading macro
;; However, when it comes time to split the string result, clojure.string/split takes two arguments
;; The first is the string, and the second is the regular expression to split on.  
;; For the threading macro to work as is, these arguments need to be reversed
;; One way of doing this is creating an anonymous function that does this
;; #(clojure.string/split % #"/") This is the function
;; Then you actually evaluate by wrapping it in paranthesis
;; (#(clojure.string/split % #"/")) This returns the anonymous function which takes a single argument, the string
;; The threading macro then threads the previous string into this function, allowing the threading macro to still work

(->>  "/a/file/loc/to/Somewhere/v/dont/include/these/"
  (re-seq #"^[/]([-/_A-Za-z0-9]+)/v/") ; Get all parts before /v
  first ;; Sequence returns in this form ( (total string) (additional sequences match)), first removes the wrapping list
  second ;; So that you can grab the second item in the list
  (#(clojure.string/split % #"/")) ;; Split them into tags using / as a separator
)
;; Returns ["a" "file" "loc" "to" "somewhere"]

;; By using this anonymous function pattern you can use functions that may not normally be useable with the threading macro
;; For example, a function might need the threading argument in the third position of a 5 argument function:
;; (#(some-fn param1 param2 param3 % param4))
;; This pattern will also work with the -> threading macro