I think Elixir is a wonderfully expressive language built on a strong foundation in the ErlangVM. It inherits Erlang's semantics which I've always liked.

Elm on the other hand inherits Javascript as its foundation, and the browser as its target. Javascript has an anemic standard library, and isn't a functional strongly typed language to begin with. Now since the browser is the target, file size is important, preventing Elm from simply shipping its own runtime + standard library.