Json to string, no newlines, no spaces.

str : String
str =
    compact <| Array
        [ Object [ "name" => String "Hugo" ]
        , Object [ "name" => String "Manuel" ]
        , Object [ "name" => String "Eva" ]
        ]


str == """[{"name":"Hugo"},{"name":"Manuel"},{"name":"Eva"}]"""

Json to string, with an indentation style close to elm-format's.

str : String
str =
    """[{"name":"Hugo"},{"name":"Manuel"},{"name":"Eva"}]"""
        |> fromString
        |> Result.withDefault Null
        |> pretty


str ==
    """[
        { "name": "Hugo"
        }
    ,
        { "name": "Manuel"
        }
    ,
        { "name": "Eva"
        }
    ]"""