perform returns a map instead of a list

lib/conductor.ex

@@ -9,10 +9,13 @@ defmodule Grengine.Conductor do
 
   def perform do
     get_performances()
-    |> Enum.map( fn perf ->
-      do_performance(perf)
+    |> Enum.reduce(%{}, fn perf, acc ->
+      {name, val} = do_performance(perf)
+      case name do
+        nil -> acc
+        _   -> Map.put(acc, name, val)
+      end
     end)
-    |> Enum.reject( fn val -> is_nil(val) end)
   end
 
 
@@ -27,8 +30,8 @@ defmodule Grengine.Conductor do
     [{_n, _l, {:performance, name}}, _pid, :undefined] = perf
     values = Performance.get_values(name)
     case length( Map.keys(values)) do
-      0  -> nil
-      _  ->  %{name => Performance.get_values(name)}
+      0  -> {nil, nil}
+      _  -> {name, Performance.get_values(name)}
     end
   end
 

test/conductor_test.exs

@@ -24,8 +24,8 @@ defmodule ConductorTest do
 
     test "handle single performance" do
       values = Conductor.perform()
-      assert is_list(values)
-      assert length(values) == 1
+      assert is_map(values)
+      assert length(Map.keys(values)) == 1
     end
 
   end