chickadee » transducers » flatten-hashmap

A transducer that flattens any and all mappings or hashmaps (recursively) that it encounters, forwarding (key . value) pairs onto future transducers.

 
(import (only (srfi 128)
              make-default-comparator)
        (srfi 146)
        transducers)

(define comp (make-default-comparator))

(transduce list-fold
           flatten-mapping
           (collect-list)
           (list (alist->mapping comp '((a . 1) (b . 2) (c . 3)))
                 (alist->mapping comp '((d . 4) (e . 5) (f . 6)))
                 (alist->mapping comp '((g . 7) (h . 8) (i . 9)))))

; => ((a . 1) (b . 2) (c . 3) (d . 4) (e . 5) (f . 6) (g . 7) (h . 8) (i . 9))