chickadee » transducers » chain-mapping

A transducer that chains all the (key . value) pairs in the relevant mapping / hashmap onto the current transduction.

chain-reverse-mapping chains the mapping in the reverse order of the keys, similar to how reverse-mapping-fold folds over the keys and values in a mapping in reverse order.

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

(transduce mapping-fold
           (chain-hashmap (hashmap (make-default-comparator)
                                   "foo" 'bar
                                   "fzz" 'baz))
           (collect-list)
           (mapping (make-default-comparator)
                    "abc" 'def
                    "eef" 'ghi))

; => (("abc" . def) ("eef" . ghi) ("fzz" . baz) ("foo" . bar))