Fix: projecting calls to Erlang modules like Alice.(:crypto.foo())

Other minor changes: easy improvements to test coverage; mix format

Author: ashton314

README.md

@@ -359,6 +359,10 @@ If you find any bugs or would like to suggest a feature, please [open an issue o
 
 We will collect change descriptions here until we come up with a more stable format when changes get bigger.
 
+ - v0.4.2; 2024-08-07
+ 
+   Bugfix: projecting local expressions that call out to an Erlang module.
+
  - v0.4.1; 2024-08-01
 
    Bugfix: choreographies can now have literal maps in local expressions.

lib/chorex.ex

@@ -392,8 +392,6 @@ defmodule Chorex do
   import Utils
   alias Chorex.Proxy
 
-  defguard is_immediate(x) when is_number(x) or is_atom(x) or is_binary(x)
-
   @doc """
   Start a choreography.
 
@@ -799,7 +797,8 @@ defmodule Chorex do
   end
 
   def project(code, _env, _label, _ctx) do
-    raise ProjectionError, message: "No projection for form: #{Macro.to_string(code)}\n   Stx: #{inspect(code)}"
+    raise ProjectionError,
+      message: "No projection for form: #{Macro.to_string(code)}\n   Stx: #{inspect(code)}"
   end
 
   #
@@ -1133,6 +1132,14 @@ defmodule Chorex do
       match?({:., [{:__aliases__, _, _} | _]}, {funcname, args}) ->
         return(funcall, acc)
 
+      # Calls to functions in Erlang modules also need to get returned
+      # verbatim: something like :crypto.generate_key() for example.
+      match?(
+        {:., [erlang_mod, func_name | _]} when is_atom(erlang_mod) and is_atom(func_name),
+        {funcname, args}
+      ) ->
+        return(funcall, acc)
+
       Enum.member?(variadics, funcname) ->
         return(funcall, acc)
 

mix.exs

@@ -4,7 +4,7 @@ defmodule Chorex.MixProject do
   def project do
     [
       app: :chorex,
-      version: "0.4.1",
+      version: "0.4.2",
       elixir: "~> 1.16",
       start_permanent: Mix.env() == :prod,
       description: description(),

test/chorex_test.exs

@@ -163,6 +163,17 @@ defmodule ChorexTest do
     assert [] = diags
   end
 
+  test "projection error when sending self a message" do
+    stx =
+      quote do
+        Alice.(:whatever) ~> Alice.(whatevs)
+      end
+
+    assert_raise Chorex.ProjectionError, fn ->
+      Chorex.project(stx, __ENV__, Alice, Chorex.empty_ctx())
+    end
+  end
+
   describe "local expression projection" do
     test "single variable" do
       stx =
@@ -330,6 +341,18 @@ defmodule ChorexTest do
                Chorex.project_local_expr(stx, __ENV__, Alice, Chorex.empty_ctx())
     end
 
+    test "call to Erlang library is preserved" do
+      stx =
+        quote do
+          Alice.(:crypto.generate_key(:rsa))
+        end
+
+      call =
+        {{:., [], [:crypto, :generate_key]}, [], [:rsa]}
+
+      assert {^call, [], []} = Chorex.project_local_expr(stx, __ENV__, Alice, Chorex.empty_ctx())
+    end
+
     test "deeply nested pattern" do
       stx =
         quote do

test/utils_test.exs

@@ -1,4 +1,11 @@
 defmodule UtilsTest do
   use ExUnit.Case
   doctest Utils
+
+  test "fresh_atom/1" do
+    a1 = Utils.fresh_atom("foo")
+    a2 = Utils.fresh_atom("foo")
+
+    assert a1 != a2
+  end
 end

test/writer_monad_test.exs

@@ -14,4 +14,13 @@ defmodule WriterMonadTest do
 
     assert {12, ["bar", "foo"], [:baz, :quux]} = foo
   end
+
+  def t1(thing) do
+    thing + 1
+  end
+
+  test "fmap" do
+    assert {2, [1], []} = fmap(return(1, [1]), &t1/1)
+    assert {3, [2], []} = return(2, [2]) <~> &t1/1
+  end
 end