Elixir service

test.ex

    
     Users.newusers
     |> elem(1)
     |> Map.get("Items")
     |> Poison.encode 
     |> elem(1)
     |> File.write("/dir/users.json")
   
    #response from dynamodb after first function
 {:ok,
 %{"Count" => 691,
   "Items" => [%{"accountStatus" => %{"S" => "active"},
      "createdDate" => %{"N" => "1452199374896"},
      "emailAddress" => %{"S" => "test@email.com"},
      "fullName" => %{"S" => "Tim Madams"},
      "userId" => %{"S" => "b0aaa703093deeb4b68275a801db5940"}},
    %{"accountStatus" => %{"S" => "active"},
      "createdDate" => %{"N" => "1452203121748"},
      "emailAddress" => %{"S" => "test@email.com"},
      "fullName" => %{"S" => "kc"},
      "userId" => %{"S" => "3dc9b67a039c4af061cfd9b505cd5bcf"}},
    %{"accountStatus" => %{"S" => "active"},
      "createdDate" => %{"N" => "1452204318593"},
      "emailAddress" => %{"S" => "test@email.com"},
      "fullName" => %{"S" => "Fernando"},
      "userId" => %{"S" => "91e63f80a8d7e9cb4692d1b26bce7cfd"}},
    %{"accountStatus" => %{"S" => "active"},
      "createdDate" => %{"N" => "1452208426812"},
      "emailAddress" => %{"S" => "test@email.com"}}]}}

This should work. You are currently piping the json in as the first argument of File.write and it's trying to use the json as the file name

     json = Users.newusers
     |> elem(1)
     |> Map.get("Items")
     |> Poison.encode 
     |> elem(1)


     File.write("/dir/users.json", json)