Dhall's lists are homogeneous lists, meaning that every element always has the same type of value. This is true whether or not you annotate list elements with a type or you annotate the list with a type.

You only need to annotate the type of an empty list. Lists with at least one element don't require a type annotation because the type can be inferred from the type of that element.

Dhall does not have buit-in support for homogeneous maps. Dhall does have statically typed heterogeneous records (i.e. something like `{ foo = Bool, bar = "ABC" }` which has type `{ foo : Bool, bar : Text }` for example).

If you want to store different type of values in the same list you wrap them in a union. For example, if you want to store both `Text` values and `Natural` numbers in a list you would do:

        let union = constructors < Left : Natural | Right : Text >

    in  [ union.Left 10, union.Right "ABC", union.Right "DEF", union.Left 4 ]

The closest thing to a homogeneous map in Dhall is an association list of type `[ { mapKey : Text, mapValue : a } ]` but even that is still not an exact fit since it doesn't guarantee uniqueness of keys. However, Dhall's JSON/YAML integration does convert that automatically to a JSON/YAML homogeneous map (i.e. a JSON record where every field has the same type).

In general, Dhall's JSON/YAML integration has several tricks and conventions that translate to weakly typed JSON idioms (such as homogeneous maps, omitting null values, and using tags).