checkpoint before next attempt at recursive types - noice debugging here

new.exs

@@ -575,7 +575,6 @@ defmodule Tdd.Variable do
   # @spec v_list_all_elements_are(TypeSpec.t()) :: term()
   # def v_list_all_elements_are(element_spec), do: {5, :a_all_elements, element_spec, nil}
 
-
   @doc "Predicate: The list is the empty list `[]`."
   @spec v_list_is_empty() :: term()
   def v_list_is_empty, do: {5, :b_is_empty, nil, nil}
@@ -1093,7 +1092,7 @@ defmodule Tdd.Algo do
   end
 
   # The private helper now takes a `context` to detect infinite recursion.
-    # The private helper now takes a `context` to detect infinite recursion.
+  # The private helper now takes a `context` to detect infinite recursion.
   defp do_simplify(tdd_id, sorted_assumptions, context) do
     current_state = {tdd_id, sorted_assumptions}
 
@@ -1369,7 +1368,6 @@ defmodule Tdd.Compiler do
   @doc "The main entry point. Takes a spec and returns its TDD ID."
   @spec spec_to_id(TypeSpec.t()) :: non_neg_integer()
   def spec_to_id(spec) do
-    # Memoization wrapper for the entire compilation process.
     normalized_spec = TypeSpec.normalize(spec)
     cache_key = {:spec_to_id, normalized_spec}
 
@@ -1378,125 +1376,76 @@ defmodule Tdd.Compiler do
         id
 
       :not_found ->
-        id = do_spec_to_id(normalized_spec)
+        # Do the raw compilation first.
+        raw_id = do_spec_to_id(normalized_spec)
+        # THEN, do a final semantic simplification pass. This is the fix.
+        id = Algo.simplify(raw_id)
         Store.put_op_cache(cache_key, id)
         id
     end
   end
 
-  # The core compilation logic.
+  # This helper does the raw, structural compilation. It does NOT call simplify.
   defp do_spec_to_id(spec) do
-    raw_id =
+    case spec do
-      case spec do
+      :any -> Store.true_node_id()
-        # --- Base Types ---
+      :none -> Store.false_node_id()
-        :any ->
+      :atom -> create_base_type_tdd(Variable.v_is_atom())
-          Store.true_node_id()
+      :integer -> create_base_type_tdd(Variable.v_is_integer())
+      :list -> create_base_type_tdd(Variable.v_is_list())
+      :tuple -> create_base_type_tdd(Variable.v_is_tuple())
+      {:literal, val} when is_atom(val) -> compile_value_equality(:atom, Variable.v_atom_eq(val))
+      {:literal, val} when is_integer(val) -> compile_value_equality(:integer, Variable.v_int_eq(val))
+      {:literal, []} -> compile_value_equality(:list, Variable.v_list_is_empty())
+      {:integer_range, min, max} -> compile_integer_range(min, max)
 
-        :none ->
+      {:union, specs} ->
-          Store.false_node_id()
+        Enum.map(specs, &spec_to_id/1)
+        |> Enum.reduce(Store.false_node_id(), fn id, acc ->
+          Algo.apply(:sum, &op_union_terminals/2, id, acc)
+        end)
 
-        :atom ->
+      {:intersect, specs} ->
-          create_base_type_tdd(Variable.v_is_atom())
+        Enum.map(specs, &spec_to_id/1)
+        |> Enum.reduce(Store.true_node_id(), fn id, acc ->
+          Algo.apply(:intersect, &op_intersect_terminals/2, id, acc)
+        end)
 
-        :integer ->
+      {:negation, sub_spec} ->
-          create_base_type_tdd(Variable.v_is_integer())
+        Algo.negate(spec_to_id(sub_spec))
 
-        :list ->
+      {:cons, head_spec, tail_spec} ->
-          create_base_type_tdd(Variable.v_is_list())
+        id_head = spec_to_id(head_spec)
+        id_tail = spec_to_id(tail_spec)
+        compile_cons_from_ids(id_head, id_tail)
 
-        :tuple ->
+      {:tuple, elements} ->
-          create_base_type_tdd(Variable.v_is_tuple())
+        compile_tuple(elements)
 
-        # --- Literal Types ---
+      {:list_of, element_spec} ->
-        {:literal, val} when is_atom(val) ->
+        compile_list_of(element_spec)
-          compile_value_equality(:atom, Variable.v_atom_eq(val))
 
-        {:literal, val} when is_integer(val) ->
+      _ ->
-          compile_value_equality(:integer, Variable.v_int_eq(val))
+        raise "Tdd.Compiler: Cannot compile unknown spec: #{inspect(spec)}"
-
+    end
-        {:literal, []} ->
-          compile_value_equality(:list, Variable.v_list_is_empty())
-
-        # --- Integer Range ---
-        {:integer_range, min, max} ->
-          compile_integer_range(min, max)
-
-        # --- Set-Theoretic Combinators ---
-        {:union, specs} ->
-          ids = Enum.map(specs, &spec_to_id/1)
-
-          Enum.reduce(ids, Store.false_node_id(), fn id, acc ->
-            Algo.apply(:sum, &op_union_terminals/2, id, acc)
-          end)
-
-        {:intersect, specs} ->
-          ids = Enum.map(specs, &spec_to_id/1)
-
-          Enum.reduce(ids, Store.true_node_id(), fn id, acc ->
-            Algo.apply(:intersect, &op_intersect_terminals/2, id, acc)
-          end)
-
-        {:negation, sub_spec} ->
-          Algo.negate(spec_to_id(sub_spec))
-
-        # --- RECURSIVE TYPES ---
-        #
-        # {:list_of, element_spec} ->
-        #   id_list = spec_to_id(:list)
-        #   # The element_spec MUST be normalized to be a canonical part of the variable.
-          norm_elem_spec = TypeSpec.normalize(element_spec)
-          var = Variable.v_list_all_elements_are(norm_elem_spec)
-        #   id_check = create_base_type_tdd(var)
-        #   Algo.apply(:intersect, &op_intersect_terminals/2, id_list, id_check)
-        {:cons, head_spec, tail_spec} ->
-          id_head = spec_to_id(head_spec)
-          id_tail = spec_to_id(tail_spec)
-          compile_cons_from_ids(id_head, id_tail)
-
-        {:tuple, elements} ->
-          compile_tuple(elements)
-
-
-        # --- Default ---
-        _ ->
-          raise "Tdd.Compiler: Cannot compile unknown spec: #{inspect(spec)}"
-      end
-
-    # CRUCIAL: Every constructed TDD must be passed through simplify
-    # to ensure it's in its canonical, semantically-reduced form.
-    Algo.simplify(raw_id)
   end
 
-  # ------------------------------------------------------------------
+  # --- Private Helpers ---
-  # Private Compilation Helpers
-  # ------------------------------------------------------------------
 
-  defp create_base_type_tdd(var) do
+  defp create_base_type_tdd(var), do: Store.find_or_create_node(var, Store.true_node_id(), Store.false_node_id(), Store.false_node_id())
-    Store.find_or_create_node(
-      var,
-      Store.true_node_id(),
-      Store.false_node_id(),
-      Store.false_node_id()
-    )
-  end
 
   defp compile_value_equality(base_type_spec, value_var) do
     eq_node = create_base_type_tdd(value_var)
+    # Note: spec_to_id is safe here because it's on non-recursive base types.
     base_node_id = spec_to_id(base_type_spec)
     Algo.apply(:intersect, &op_intersect_terminals/2, base_node_id, eq_node)
   end
 
   defp compile_integer_range(min, max) do
     base_id = spec_to_id(:integer)
-
+    lt_min_tdd = if min != :neg_inf, do: create_base_type_tdd(Variable.v_int_lt(min))
-    id_with_min =
+    gte_min_tdd = if lt_min_tdd, do: Algo.negate(lt_min_tdd), else: spec_to_id(:any)
-      if min == :neg_inf do
+    id_with_min = Algo.apply(:intersect, &op_intersect_terminals/2, base_id, gte_min_tdd)
-        base_id
-      else
-        lt_min_tdd = create_base_type_tdd(Variable.v_int_lt(min))
-        gte_min_tdd = Algo.negate(lt_min_tdd)
-        Algo.apply(:intersect, &op_intersect_terminals/2, base_id, gte_min_tdd)
-      end
 
     if max == :pos_inf do
       id_with_min
@@ -1506,49 +1455,18 @@ defmodule Tdd.Compiler do
     end
   end
 
-  # ------------------------------------------------------------------
-  # Helpers for Compositional Recursive Types (`cons`, `tuple`)
-  # ------------------------------------------------------------------
-
-  defp sub_problem(sub_key_constructor, tdd_id) do
-    cache_key = {:sub_problem, sub_key_constructor, tdd_id}
-
-    case Store.get_op_cache(cache_key) do
-      {:ok, result_id} ->
-        result_id
-
-      :not_found ->
-        result_id = do_sub_problem(sub_key_constructor, tdd_id)
-        Store.put_op_cache(cache_key, result_id)
-        result_id
-    end
-  end
-
-  defp do_sub_problem(sub_key_constructor, tdd_id) do
-    case Store.get_node(tdd_id) do
-      {:ok, :true_terminal} ->
-        Store.true_node_id()
-
-      {:ok, :false_terminal} ->
-        Store.false_node_id()
-
-      {:ok, {var, y, n, d}} ->
-        lifted_var = sub_key_constructor.(var)
-        lifted_y = sub_problem(sub_key_constructor, y)
-        lifted_n = sub_problem(sub_key_constructor, n)
-        lifted_d = sub_problem(sub_key_constructor, d)
-        Store.find_or_create_node(lifted_var, lifted_y, lifted_n, lifted_d)
-    end
-  end
-
   defp compile_cons_from_ids(h_id, t_id) do
-    non_empty_list_id = spec_to_id({:intersect, [:list, {:negation, {:literal, []}}]})
+    # Build `list & !is_empty` manually and safely.
+    id_list = create_base_type_tdd(Variable.v_is_list())
+    id_is_empty = create_base_type_tdd(Variable.v_list_is_empty())
+    id_not_is_empty = Algo.negate(id_is_empty)
+    non_empty_list_id = Algo.apply(:intersect, &op_intersect_terminals/2, id_list, id_not_is_empty)
+
     head_checker = sub_problem(&Variable.v_list_head_pred/1, h_id)
     tail_checker = sub_problem(&Variable.v_list_tail_pred/1, t_id)
 
-    ids_to_intersect = [non_empty_list_id, head_checker, tail_checker]
+    [non_empty_list_id, head_checker, tail_checker]
-
+    |> Enum.reduce(Store.true_node_id(), fn id, acc ->
-    Enum.reduce(ids_to_intersect, Store.true_node_id(), fn id, acc ->
       Algo.apply(:intersect, &op_intersect_terminals/2, id, acc)
     end)
   end
@@ -1569,19 +1487,38 @@ defmodule Tdd.Compiler do
     end)
   end
 
-  # ------------------------------------------------------------------
+  defp sub_problem(sub_key_constructor, tdd_id) do
-  # Helper for Self-Recursive Types (`list_of`) via Fixed-Point Iteration
+    cache_key = {:sub_problem, sub_key_constructor, tdd_id}
-  # ------------------------------------------------------------------
+    case Store.get_op_cache(cache_key) do
+      {:ok, result_id} -> result_id
+      :not_found ->
+        result_id = do_sub_problem(sub_key_constructor, tdd_id)
+        Store.put_op_cache(cache_key, result_id)
+        result_id
+    end
+  end
+
+  defp do_sub_problem(sub_key_constructor, tdd_id) do
+    case Store.get_node(tdd_id) do
+      {:ok, :true_terminal} -> Store.true_node_id()
+      {:ok, :false_terminal} -> Store.false_node_id()
+      {:ok, {var, y, n, d}} ->
+        Store.find_or_create_node(
+          sub_key_constructor.(var),
+          sub_problem(sub_key_constructor, y),
+          sub_problem(sub_key_constructor, n),
+          sub_problem(sub_key_constructor, d)
+        )
+    end
+  end
 
   defp compile_list_of(element_spec) do
-    cache_key = {:compile_list_of, element_spec}
+    norm_elem_spec = TypeSpec.normalize(element_spec)
-
+    cache_key = {:compile_list_of, norm_elem_spec}
     case Store.get_op_cache(cache_key) do
-      {:ok, id} ->
+      {:ok, id} -> id
-        id
-
       :not_found ->
-        id = do_compile_list_of(element_spec)
+        id = do_compile_list_of(norm_elem_spec)
         Store.put_op_cache(cache_key, id)
         id
     end
@@ -1590,50 +1527,50 @@ defmodule Tdd.Compiler do
   defp do_compile_list_of(element_spec) do
     id_elem = spec_to_id(element_spec)
     id_empty_list = spec_to_id({:literal, []})
-
     step_function = fn id_x ->
       id_cons = compile_cons_from_ids(id_elem, id_x)
       Algo.apply(:sum, &op_union_terminals/2, id_empty_list, id_cons)
     end
-
     loop_until_stable(Store.false_node_id(), step_function)
   end
 
-  # --- THIS IS THE FIX ---
+  # THIS IS THE FINAL, CORRECTED LOOP
-  defp loop_until_stable(prev_id, step_function) do
+defp loop_until_stable(prev_id, step_function, iteration \\ 0) do
-    # At each step, we must simplify the result to get its canonical form.
+  IO.puts("\n--- Fixed-Point Iteration: #{iteration} ---")
-    # This ensures we are comparing semantic equality, not just structural.
+  IO.inspect(prev_id, label: "prev_id")
-    raw_next_id = step_function.(prev_id)
+  # Tdd.Debug.print(prev_id) # Optional: uncomment for full graph
-    next_id = Algo.simplify(raw_next_id)
 
-    if next_id == prev_id do
+  raw_next_id = step_function.(prev_id)
-      next_id
+  IO.inspect(raw_next_id, label: "raw_next_id (after step_function)")
-    else
+  Tdd.Debug.print(raw_next_id) # Let's see the raw graph
-      loop_until_stable(next_id, step_function)
+
+  # Crucially, simplify after each step for canonical comparison.
+  next_id = Algo.simplify(raw_next_id)
+  IO.inspect(next_id, label: "next_id (after simplify)")
+  Tdd.Debug.print(next_id) # Let's see the simplified graph
+
+  if next_id == prev_id do
+    IO.puts("--- Fixed-Point Reached! ---")
+    next_id
+  else
+    # Add a safety break for debugging
+    if iteration > 2 do
+      IO.inspect Process.info(self(), :current_stacktrace)
+      raise "Fixed-point iteration did not converge after 2 steps. Halting."
     end
+    loop_until_stable(next_id, step_function, iteration + 1)
   end
+end
 
-  # ------------------------------------------------------------------
+  # --- Private Functions for Terminal Logic ---
-  # Private Functions for Terminal Logic
+  defp op_union_terminals(:true_terminal, _), do: :true_terminal
-  # ------------------------------------------------------------------
+  defp op_union_terminals(_, :true_terminal), do: :true_terminal
-
+  defp op_union_terminals(t, :false_terminal), do: t
-  defp op_union_terminals(u1_details, u2_details) do
+  defp op_union_terminals(:false_terminal, t), do: t
-    case {u1_details, u2_details} do
+  defp op_intersect_terminals(:false_terminal, _), do: :false_terminal
-      {:true_terminal, _} -> :true_terminal
+  defp op_intersect_terminals(_, :false_terminal), do: :false_terminal
-      {_, :true_terminal} -> :true_terminal
+  defp op_intersect_terminals(t, :true_terminal), do: t
-      {:false_terminal, t2} -> t2
+  defp op_intersect_terminals(:true_terminal, t), do: t
-      {t1, :false_terminal} -> t1
-    end
-  end
-
-  defp op_intersect_terminals(u1_details, u2_details) do
-    case {u1_details, u2_details} do
-      {:false_terminal, _} -> :false_terminal
-      {_, :false_terminal} -> :false_terminal
-      {:true_terminal, t2} -> t2
-      {t1, :true_terminal} -> t1
-    end
-  end
 end
 
 ####