Base expressions on dataclasses

doc/index.rst

@@ -69,13 +69,13 @@ You can also easily define your own objects to use inside an expression:
 
 .. doctest::
 
-    >>> from pymbolic.primitives import Expression
-    >>> class FancyOperator(Expression):
-    ...     def __init__(self, operand):
-    ...         self.operand = operand
-    ...
-    ...     def __getinitargs__(self):
-    ...         return (self.operand,)
+    >>> from pymbolic.primitives import Expression, augment_expression_dataclass
+    >>> from dataclasses import dataclass
+    >>>
+    >>> @augment_expression_dataclass
+    ... @dataclass(frozen=True)
+    ... class FancyOperator(Expression):
+    ...     operand: Expression
     ...
     ...     mapper_method = "map_fancy_operator"
     ...

pymbolic/parser.py

@@ -23,6 +23,8 @@
 from sys import intern
 from typing import ClassVar, Dict, List, Tuple
 
+from immutabledict import immutabledict
+
 import pytools.lex
 from pytools import memoize_method
 
@@ -333,7 +335,8 @@ def parse_postfix(self, pstate, min_precedence, left_exp):
             args, kwargs = self.parse_arglist(pstate)
 
             if kwargs:
-                left_exp = primitives.CallWithKwargs(left_exp, args, kwargs)
+                left_exp = primitives.CallWithKwargs(
+                        left_exp, args, immutabledict(kwargs))
             else:
                 left_exp = primitives.Call(left_exp, args)