fix(vars): accept a frozenset as an array literal

packages/reflex-base/news/+frozenset-literal.bugfix.md

@@ -0,0 +1 @@
+`LiteralVar.create` now accepts a `frozenset`, rendered as an array like a `set`, with its element type inferred so `rx.foreach` and array operations over it are typed.

packages/reflex-base/src/reflex_base/vars/base.py

@@ -2185,7 +2185,7 @@ def figure_out_type(value: Any) -> types.GenericType:
     Returns:
         The type of the value.
     """
-    if isinstance(value, (list, set, tuple, Mapping, Var)):
+    if isinstance(value, (list, set, frozenset, tuple, Mapping, Var)):
         if isinstance(value, Var):
             return value._var_type
         if has_args(value_type := type(value)):
@@ -2194,8 +2194,11 @@ def figure_out_type(value: Any) -> types.GenericType:
             if not value:
                 return Sequence[NoReturn]
             return Sequence[unionize(*{figure_out_type(v) for v in value[:100]})]
-        if isinstance(value, set):
-            return set[unionize(*{figure_out_type(v) for v in value})]
+        if isinstance(value, (set, frozenset)):
+            element_type = unionize(*{figure_out_type(v) for v in value})
+            if isinstance(value, frozenset):
+                return frozenset[element_type]
+            return set[element_type]
         if isinstance(value, tuple):
             if not value:
                 return tuple[NoReturn, ...]

packages/reflex-base/src/reflex_base/vars/sequence.py

@@ -63,7 +63,7 @@
 VALUE_TYPE = TypeVar("VALUE_TYPE")
 
 
-class ArrayVar(Var[ARRAY_VAR_TYPE], python_types=(Sequence, set)):
+class ArrayVar(Var[ARRAY_VAR_TYPE], python_types=(Sequence, set, frozenset)):
     """Base class for immutable array vars."""
 
     def join(self, sep: StringVar | str = "") -> StringVar:
@@ -1920,6 +1920,7 @@ def _determine_value_of_array_index(
         Iterable,
         list,
         set,
+        frozenset,
         collections.abc.Sequence,
         collections.abc.Iterable,
     ]:

tests/units/test_var.py

@@ -51,6 +51,7 @@
     ConcatVarOperation,
     LiteralArrayVar,
     LiteralStringVar,
+    StringVar,
 )
 
 import reflex as rx
@@ -421,6 +422,19 @@ def test_date_comparison_uses_compare_datetime():
     assert str(lhs == rhs) == '(compareDatetime("2024-01-01", "2024-01-02") === 0)'
 
 
+def test_frozenset_literal_types_its_elements():
+    """A frozen set literal infers its element type like a set does."""
+    # The static array bound is Sequence, which no set satisfies; see the PR.
+    var = cast(ArrayVar, v(frozenset({"a"})))
+
+    assert var._var_type == frozenset[str]
+    assert isinstance(var[0], StringVar)
+    assert re.fullmatch(
+        r'\["a"\]\.map\(\(\((\w+)\) => \1\.toUpperCase\(\)\)\)',
+        str(var.map(lambda item: item.upper())),
+    )
+
+
 def test_datetime_equality_with_other_type_uses_default_comparison():
     value = v(datetime(2024, 1, 1))
     expected_equality = (
@@ -436,6 +450,7 @@ def test_datetime_equality_with_other_type_uses_default_comparison():
     [
         (v([1, 2, 3]), "[1, 2, 3]"),
         (v({1, 2, 3}), "[1, 2, 3]"),
+        (v(frozenset({1, 2, 3})), "[1, 2, 3]"),
         (v(["1", "2", "3"]), '["1", "2", "3"]'),
         (
             Var(_js_expr="foo")._var_set_state("state").to(list),