josephwilk · July 30, 2013 20:06 · Jul 30, 2013
diff --git a/future.ex b/future.ex
@@ -0,0 +1,38 @@
+defmodule Future do
+  def new(fun) do
+    fn(x) ->
+          spawn_link fn ->
+            value = try do
+              { :ok, fun.(x) }  
+            rescue
+              e -> { :error, e }
+            end
+
+            receive do 
+              pid -> 
+                pid <- {self, value} 
+            end
+          end
+    end 
+  end
+
+  def value(pid, timeout // :infinity, default // {:error, :timeout}) do
+      pid <- self
+      receive do
+          {^pid, {:ok, value}} -> value
+          {^pid, {:error, e}}  -> raise e
+      after 
+          timeout -> default
+      end 
+  end
+end
+
+defmodule Parallel do
+  def pmap(collection, fun) do 
+    collection
+    |> Enum.map(Future.new(fun))
+    |> Enum.map(Future.value(&1, 1000, {:error}))
+  end
+end
+
+IO.inspect Parallel.pmap([1,2,3,4], fn x -> :timer.sleep(1000); x+1 end)