The post is interesting and highlights a true fact : it is not always easy to chain map/filter/reduce transformations when the processed values are compound and

The post is interesting and highlights a true fact : it is not always easy to chain map/filter/reduce transformations when the processed values are compound and call for processing that are specific to each part. Nonetheless, the proposed solution is most in the component/object realm rather in the functional world. As an evidence the use of nouns rather verbs as in : splitter.input = hi_generator.his lowercaser.input = splitter.left_part uppercaser.input = splitter.right_part This is not a judgement, just a remark. A functional solution would rather use transformation combinators to propagate a transformation on a specific value part. For instance : input |> map split_two_halves |> map_fst to_lower |> map_snd to_upper Or even better, use lenses as a generic way to unpack a specific part of a data structure and to repack an updated value: input |> map split_two_halves |> map_lens fst to_lower |> map_lens snd to_upper