You can transform the list, as shown by @LostKobrakai, but you really should consider using a map on the elixir side from the beginning.

A list of maps, one key each feels wrong, especially when you say, that you consider this a single entity at the other end of the application.

For your example Enum.reduce(list, &Map.merge/2) should work, but I’d first consider why you’re having that list in the first place.

This was really the core issue because had they been tuples:

iex(1)> key_values = [
...(1)>   {"next","http://www.example.com/test?foo=bar&page=4"},
...(1)>   {"prev","http://www.example.com/test?foo=bar&page=2"},
...(1)>   {"first","http://www.example.com/test?foo=bar&page=1"},
...(1)>   {"last","http://www.example.com/test?foo=bar&page=5"}
...(1)> ]
[
  {"next", "http://www.example.com/test?foo=bar&page=4"},
  {"prev", "http://www.example.com/test?foo=bar&page=2"},
  {"first", "http://www.example.com/test?foo=bar&page=1"},
  {"last", "http://www.example.com/test?foo=bar&page=5"}
]
iex(2)> my_map = Map.new(key_values)
%{
  "first" => "http://www.example.com/test?foo=bar&page=1",
  "last" => "http://www.example.com/test?foo=bar&page=5",
  "next" => "http://www.example.com/test?foo=bar&page=4",
  "prev" => "http://www.example.com/test?foo=bar&page=2"
}
iex(3)>