refactor: convert is_distinct_from operators to functions

Following PR review feedback, convert IS DISTINCT FROM and IS NOT DISTINCT FROM from operators to functions.

Changes:
- Remove Ash.Query.Operator.DistinctFrom and NotDistinctFrom
- Add Ash.Query.Function.IsDistinctFrom and IsNotDistinctFrom
- Move optimization logic to new() instead of simplify()
- Update test descriptions to reflect eager evaluation behavior

Rationale:
- Functions cannot be overloaded, which is appropriate here since is_distinct_from only needs [:any, :any] signature
- Optimization (converting to != or == when NULL is impossible) happens at creation time in new()
- simplify() is only for filter comparison context, not needed for these functions

Author: jechol

lib/ash/filter/filter.ex

@@ -32,7 +32,9 @@ defmodule Ash.Filter do
     Has,
     If,
     Intersects,
+    IsDistinctFrom,
     IsNil,
+    IsNotDistinctFrom,
     Lazy,
     Length,
     Minus,
@@ -51,14 +53,12 @@ defmodule Ash.Filter do
   }
 
   alias Ash.Query.Operator.{
-    DistinctFrom,
     Eq,
     GreaterThan,
     GreaterThanOrEqual,
     In,
     LessThan,
     LessThanOrEqual,
-    NotDistinctFrom,
     NotEq
   }
 
@@ -78,7 +78,9 @@ defmodule Ash.Filter do
     FromNow,
     GetPath,
     Has,
+    IsDistinctFrom,
     IsNil,
+    IsNotDistinctFrom,
     If,
     Intersects,
     Lazy,
@@ -109,9 +111,7 @@ defmodule Ash.Filter do
                LessThan,
                GreaterThan,
                LessThanOrEqual,
-               GreaterThanOrEqual,
-               DistinctFrom,
-               NotDistinctFrom
+               GreaterThanOrEqual
              ] ++ Ash.Query.Operator.Basic.operator_modules()
 
   @builtins @functions ++ @operators

lib/ash/query/operator/distinct_from.ex …b/ash/query/function/is_distinct_from.exlib/ash/query/operator/distinct_from.ex renamed to lib/ash/query/function/is_distinct_from.ex lib/ash/query/operator/distinct_from.ex renamed to lib/ash/query/function/is_distinct_from.ex

@@ -2,37 +2,34 @@
 #
 # SPDX-License-Identifier: MIT
 
-defmodule Ash.Query.Operator.DistinctFrom do
+defmodule Ash.Query.Function.IsDistinctFrom do
   @moduledoc """
-  left is_distinct_from right
+  is_distinct_from(left, right)
 
   SQL's IS DISTINCT FROM operator.
   Unlike `!=`, this operator treats NULL as a comparable value.
 
   When both sides cannot return NULL, this simplifies to `!=` for better performance.
   """
-  use Ash.Query.Operator,
-    operator: :is_distinct_from,
-    name: :distinct_from,
-    predicate?: true,
-    types: [:same, :any]
-
-  @impl Ash.Query.Operator
-  def new(left, right) do
+  use Ash.Query.Function, name: :is_distinct_from, predicate?: true
+
+  def args, do: [[:any, :any]]
+
+  def returns, do: [:boolean]
+
+  def evaluate_nil_inputs?, do: true
+
+  def new([left, right]) do
     if Ash.Expr.can_return_nil?(left) || Ash.Expr.can_return_nil?(right) do
-      {:ok, struct(__MODULE__, left: left, right: right)}
+      {:ok, struct(__MODULE__, arguments: [left, right])}
     else
       Ash.Query.Operator.new(Ash.Query.Operator.NotEq, left, right)
     end
   end
 
-  @impl Ash.Query.Operator
-  def evaluate(%{left: left, right: right}) do
+  def evaluate(%{arguments: [left, right]}) do
     {:known, Comp.not_equal?(left, right)}
   end
 
-  @impl Ash.Query.Operator
-  def evaluate_nil_inputs?, do: true
-
   def can_return_nil?(_), do: false
 end

…/ash/query/operator/not_distinct_from.ex …h/query/function/is_not_distinct_from.exlib/ash/query/operator/not_distinct_from.ex renamed to lib/ash/query/function/is_not_distinct_from.ex lib/ash/query/operator/not_distinct_from.ex renamed to lib/ash/query/function/is_not_distinct_from.ex

@@ -2,43 +2,34 @@
 #
 # SPDX-License-Identifier: MIT
 
-defmodule Ash.Query.Operator.NotDistinctFrom do
+defmodule Ash.Query.Function.IsNotDistinctFrom do
   @moduledoc """
-  left is_not_distinct_from right
+  is_not_distinct_from(left, right)
 
   SQL's IS NOT DISTINCT FROM operator (NULL-safe equality).
   Unlike `==`, this operator treats NULL as equal to NULL.
 
   When both sides cannot return NULL, this simplifies to `==` for better performance.
   """
-  use Ash.Query.Operator,
-    operator: :is_not_distinct_from,
-    name: :not_distinct_from,
-    predicate?: true,
-    types: [:same, :any]
-
-  @impl Ash.Query.Operator
-  def new(left, right) do
+  use Ash.Query.Function, name: :is_not_distinct_from, predicate?: true
+
+  def args, do: [[:any, :any]]
+
+  def returns, do: [:boolean]
+
+  def evaluate_nil_inputs?, do: true
+
+  def new([left, right]) do
     if Ash.Expr.can_return_nil?(left) || Ash.Expr.can_return_nil?(right) do
-      {:ok, struct(__MODULE__, left: left, right: right)}
+      {:ok, struct(__MODULE__, arguments: [left, right])}
     else
       Ash.Query.Operator.new(Ash.Query.Operator.Eq, left, right)
     end
   end
 
-  @impl Ash.Query.Operator
-  def evaluate(%{left: left, right: right}) do
+  def evaluate(%{arguments: [left, right]}) do
     {:known, Comp.equal?(left, right)}
   end
 
-  @impl Ash.Query.Operator
-  def evaluate_nil_inputs?, do: true
-
-  @impl Ash.Filter.Predicate
-  def simplify(%__MODULE__{left: left, right: right}) do
-    {:ok, op} = Ash.Query.Operator.new(Ash.Query.Operator.DistinctFrom, left, right)
-    Ash.Query.Not.new(op)
-  end
-
   def can_return_nil?(_), do: false
 end

lib/ash/query/operator/operator.ex

@@ -380,9 +380,7 @@ defmodule Ash.Query.Operator do
       Ash.Query.Operator.IsNil,
       Ash.Query.Operator.LessThanOrEqual,
       Ash.Query.Operator.LessThan,
-      Ash.Query.Operator.NotEq,
-      Ash.Query.Operator.DistinctFrom,
-      Ash.Query.Operator.NotDistinctFrom
+      Ash.Query.Operator.NotEq
     ] ++ Ash.Query.Operator.Basic.operator_modules()
   end
 

test/filter/filter_test.exs

@@ -1298,7 +1298,7 @@ defmodule Ash.Test.Filter.FilterTest do
       assert hd(results).id == post1.id
     end
 
-    test "is_distinct_from evaluates to !=" do
+    test "is_distinct_from with literals is eagerly evaluated" do
       assert Image
              |> Ash.Query.filter(is_distinct_from("jpg", "png"))
              |> inspect() =~
@@ -1315,7 +1315,7 @@ defmodule Ash.Test.Filter.FilterTest do
                ~S(filter: #Ash.Filter<false>)
     end
 
-    test "is_not_distinct_from evaluates to ==" do
+    test "is_not_distinct_from with literals is eagerly evaluated" do
       assert Image
              |> Ash.Query.filter(is_not_distinct_from("jpg", "png"))
              |> inspect() =~