Elm

Other Elm solutions.

module Etl exposing (transform)

import Dict exposing (Dict)


transform : Dict Int (List String) -> Dict String Int
transform input =
    let
        convertScoreEntry ( score, letters ) =
            letters
                |> List.map (\l -> ( String.toLower l, score ))
    in
    Dict.toList input
        |> List.concatMap convertScoreEntry
        |> Dict.fromList

Roc

Other Roc solutions.

module [transform]

transform : Dict U64 (List U8) -> Dict U8 U64
transform = \legacy ->
    Dict.walk legacy (Dict.empty {}) \acc, score, letters ->
        letters
        |> List.map \letter -> (toLower letter, score)
        |> Dict.fromList
        |> Dict.insertAll acc

toLower = \char -> if char >= 'A' && char <= 'Z' then char + ('a' - 'A') else char