chickadee » transducers » enumerate

conses an ordered index starting at 0 and incrementing by 1 to the front of the value.

 
(import transducers)

(transduce list-fold
           enumerate
           (collect-list)
           (list 'a 'b 'c 'd))

; => ((0 . a) (1 . b) (2 . c) (3 . d))