elixir/lib/mal/env.ex

   1 defmodule Mal.Env do
   2   def initialize(outer \\ nil) do
   3     Agent.start_link(fn ->
   4       %{outer: outer, env: %{}}
   5     end)
   6   end
   7
   8   def set(pid, key, value) do
   9     Agent.update(pid, fn map ->
  10       %{map | :env => Map.put(map.env, key, value)}
  11     end)
  12   end
  13
  14   def merge(pid, env_values) do
  15     Agent.update(pid, fn map ->
  16       %{map | :env => Map.merge(map.env, env_values)}
  17     end)
  18   end
  19
  20   def find(pid, key) do
  21     Agent.get(pid, fn map ->
  22       case Map.has_key?(map.env, key) do
  23         true -> pid
  24         false -> map.outer && find(map.outer, key)
  25       end
  26     end)
  27   end
  28
  29   def retrieve_key(pid, key) do
  30     Agent.get(pid, fn map ->
  31       case Map.fetch(map.env, key) do
  32         {:ok, value} -> {:ok, value}
  33         :error -> :not_found
  34       end
  35     end)
  36   end
  37
  38   def get(pid, key) do
  39     case find(pid, key) do
  40       nil -> :not_found
  41       env -> retrieve_key(env, key)
  42     end
  43   end
  44 end