It’s very easy to reduce lists in Elm, here is an example using Elm REPL.

> List.foldl String.append "" ["a", "b", "c"]
"cba"

This one is a clean equivalent of that dirty one: String.append "c" (String.append "b" (String.append "a" ""))

Same one but going from the right:

> List.foldr String.append "" ["a", "b", "c"]
"abc"

Tested with Elm 0.19.1