Add support for dataclass in evaluate

effectful/ops/semantics.py

@@ -1,5 +1,6 @@
 import collections.abc
 import contextlib
+import dataclasses
 import functools
 import types
 import typing
@@ -276,8 +277,19 @@ def evaluate[T](expr: Expr[T], *, intp: Interpretation | None = None) -> Expr[T]
             return type(expr)(evaluate(item) for item in expr)  # type: ignore
     elif isinstance(expr, collections.abc.ValuesView):
         return [evaluate(item) for item in expr]  # type: ignore
+    elif dataclasses.is_dataclass(expr) and not isinstance(expr, type):
+        return typing.cast(
+            T,
+            dataclasses.replace(
+                expr,
+                **{
+                    field.name: evaluate(getattr(expr, field.name))
+                    for field in dataclasses.fields(expr)
+                },
+            ),
+        )
     else:
-        return expr
+        return typing.cast(T, expr)
 
 
 def typeof[T](term: Expr[T]) -> type[T]:

effectful/ops/syntax.py

@@ -1140,6 +1140,19 @@ def syntactic_eq[T](x: Expr[T], other: Expr[T]) -> bool:
         return len(x) == len(other) and all(
             syntactic_eq(a, b) for a, b in zip(x, other)
         )
+    elif (
+        dataclasses.is_dataclass(x)
+        and not isinstance(x, type)
+        and dataclasses.is_dataclass(other)
+        and not isinstance(other, type)
+    ):
+        return type(x) == type(other) and syntactic_eq(
+            {field.name: getattr(x, field.name) for field in dataclasses.fields(x)},
+            {
+                field.name: getattr(other, field.name)
+                for field in dataclasses.fields(other)
+            },
+        )
     else:
         return x == other
 

tests/test_ops_syntax.py

@@ -1,3 +1,4 @@
+import dataclasses
 import functools
 import inspect
 from collections.abc import Callable, Iterable, Iterator, Mapping
@@ -541,3 +542,39 @@ def test_defstream_1():
     # assert isinstance(tm_iter_next, numbers.Number)  # TODO
     # assert issubclass(typeof(tm_iter_next), numbers.Number)
     assert tm_iter_next.op is next_
+
+
+def test_eval_dataclass():
+    @dataclasses.dataclass
+    class Point:
+        x: int
+        y: int
+
+    @dataclasses.dataclass
+    class Line:
+        start: Point
+        end: Point
+
+    @dataclasses.dataclass
+    class Lines:
+        origin: Point
+        lines: list[Line]
+
+    x, y = defop(int, name="x"), defop(int, name="y")
+    p1 = Point(x(), y())
+    p2 = Point(x() + 1, y() + 1)
+    line = Line(p1, p2)
+    lines = Lines(p1, [line])
+
+    assert {x, y} <= fvsof(lines)
+
+    assert p1 == lines.origin
+
+    with handler({x: lambda: 3, y: lambda: 4}):
+        evaluated_lines = evaluate(lines)
+
+    assert isinstance(evaluated_lines, Lines)
+    assert evaluated_lines == Lines(
+        origin=Point(3, 4),
+        lines=[Line(Point(3, 4), Point(4, 5))],
+    )