Support methods like __array_function__ on expressions

docs/changelog.md

@@ -4,6 +4,7 @@ _This project uses semantic versioning_
 
 ## UNRELEASED
 
+- Support methods like  on expressions [#315](https://github.com/egraphs-good/egglog-python/pull/315)
 - Automatically Create Changelog Entry for PRs [#313](https://github.com/egraphs-good/egglog-python/pull/313)
 - Upgrade egglog which includes new backend.
   - Fixes implementation of the Python Object sort to work with objects with dupliating hashes but the same value.

docs/reference/python-integration.md

@@ -303,6 +303,11 @@ Note that the following list of methods are only supported as "preserved" since
 - `__iter_`
 - `__index__`
 
+If you want to register additional methods as always preserved and defined on the `Expr` class itself, if needed
+instead of the normal mechanism which relies on `__getattr__`, you can call `egglog.define_expr_method(name: str)`,
+with the name of a method. This is only needed for third party code that inspects the type object itself to see if a
+method is defined instead of just attempting to call it.
+
 ### Reflected methods
 
 Note that reflected methods (i.e. `__radd__`) are handled as a special case. If defined, they won't create their own egglog functions.

python/egglog/__init__.py

@@ -5,7 +5,8 @@
 from . import config, ipython_magic  # noqa: F401
 from .bindings import EggSmolError  # noqa: F401
 from .builtins import *  # noqa: UP029
-from .conversion import ConvertError, convert, converter, get_type_args  # noqa: F401
+from .conversion import *
 from .egraph import *
+from .runtime import define_expr_method as define_expr_method  # noqa: PLC0414
 
 del ipython_magic

python/egglog/conversion.py

@@ -1,10 +1,11 @@
 from __future__ import annotations
 
 from collections import defaultdict
+from collections.abc import Callable
 from contextlib import contextmanager
 from contextvars import ContextVar
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, TypeVar, cast
+from typing import TYPE_CHECKING, Any, TypeVar, cast
 
 from .declarations import *
 from .pretty import *
@@ -13,22 +14,22 @@
 from .type_constraint_solver import TypeConstraintError
 
 if TYPE_CHECKING:
-    from collections.abc import Callable, Generator
+    from collections.abc import Generator
 
     from .egraph import BaseExpr
     from .type_constraint_solver import TypeConstraintSolver
 
-__all__ = ["ConvertError", "convert", "convert_to_same_type", "converter", "resolve_literal"]
+__all__ = ["ConvertError", "convert", "converter", "get_type_args"]
 # Mapping from (source type, target type) to and function which takes in the runtimes values of the source and return the target
-CONVERSIONS: dict[tuple[type | JustTypeRef, JustTypeRef], tuple[int, Callable]] = {}
+CONVERSIONS: dict[tuple[type | JustTypeRef, JustTypeRef], tuple[int, Callable[[Any], RuntimeExpr]]] = {}
 # Global declerations to store all convertable types so we can query if they have certain methods or not
 _CONVERSION_DECLS = Declarations.create()
 # Defer a list of declerations to be added to the global declerations, so that we can not trigger them procesing
 # until we need them
 _TO_PROCESS_DECLS: list[DeclerationsLike] = []
 
 
-def _retrieve_conversion_decls() -> Declarations:
+def retrieve_conversion_decls() -> Declarations:
     _CONVERSION_DECLS.update(*_TO_PROCESS_DECLS)
     _TO_PROCESS_DECLS.clear()
     return _CONVERSION_DECLS
@@ -49,10 +50,10 @@ def converter(from_type: type[T], to_type: type[V], fn: Callable[[T], V], cost:
     to_type_name = process_tp(to_type)
     if not isinstance(to_type_name, JustTypeRef):
         raise TypeError(f"Expected return type to be a egglog type, got {to_type_name}")
-    _register_converter(process_tp(from_type), to_type_name, fn, cost)
+    _register_converter(process_tp(from_type), to_type_name, cast("Callable[[Any], RuntimeExpr]", fn), cost)
 
 
-def _register_converter(a: type | JustTypeRef, b: JustTypeRef, a_b: Callable, cost: int) -> None:
+def _register_converter(a: type | JustTypeRef, b: JustTypeRef, a_b: Callable[[Any], RuntimeExpr], cost: int) -> None:
     """
     Registers a converter from some type to an egglog type, if not already registered.
 
@@ -97,15 +98,15 @@ class _ComposedConverter:
     We use the dataclass instead of the lambda to make it easier to debug.
     """
 
-    a_b: Callable
-    b_c: Callable
+    a_b: Callable[[Any], RuntimeExpr]
+    b_c: Callable[[Any], RuntimeExpr]
     b_args: tuple[JustTypeRef, ...]
 
-    def __call__(self, x: object) -> object:
+    def __call__(self, x: Any) -> RuntimeExpr:
         # if we have A -> B and B[C] -> D then we should use (C,) as the type args
         # when converting from A -> B
         if self.b_args:
-            with with_type_args(self.b_args, _retrieve_conversion_decls):
+            with with_type_args(self.b_args, retrieve_conversion_decls):
                 first_res = self.a_b(x)
         else:
             first_res = self.a_b(x)
@@ -142,33 +143,38 @@ def process_tp(tp: type | RuntimeClass) -> JustTypeRef | type:
     return tp
 
 
-def min_convertable_tp(a: object, b: object, name: str) -> JustTypeRef:
-    """
-    Returns the minimum convertable type between a and b, that has a method `name`, raising a ConvertError if no such type exists.
-    """
-    decls = _retrieve_conversion_decls()
-    a_tp = _get_tp(a)
-    b_tp = _get_tp(b)
-    # Make sure at least one of the types has the method, to avoid issue with == upcasting improperly
-    if not (
-        (isinstance(a_tp, JustTypeRef) and decls.has_method(a_tp.name, name))
-        or (isinstance(b_tp, JustTypeRef) and decls.has_method(b_tp.name, name))
-    ):
-        raise ConvertError(f"Neither {a_tp} nor {b_tp} has method {name}")
-    a_converts_to = {
-        to: c for ((from_, to), (c, _)) in CONVERSIONS.items() if from_ == a_tp and decls.has_method(to.name, name)
-    }
-    b_converts_to = {
-        to: c for ((from_, to), (c, _)) in CONVERSIONS.items() if from_ == b_tp and decls.has_method(to.name, name)
-    }
-    if isinstance(a_tp, JustTypeRef) and decls.has_method(a_tp.name, name):
-        a_converts_to[a_tp] = 0
-    if isinstance(b_tp, JustTypeRef) and decls.has_method(b_tp.name, name):
-        b_converts_to[b_tp] = 0
-    common = set(a_converts_to) & set(b_converts_to)
-    if not common:
-        raise ConvertError(f"Cannot convert {a_tp} and {b_tp} to a common type")
-    return min(common, key=lambda tp: a_converts_to[tp] + b_converts_to[tp])
+# def min_convertable_tp(a: object, b: object, name: str) -> JustTypeRef:
+#     """
+#     Returns the minimum convertable type between a and b, that has a method `name`, raising a ConvertError if no such type exists.
+#     """
+#     decls = _retrieve_conversion_decls().copy()
+#     if isinstance(a, RuntimeExpr):
+#         decls |= a
+#     if isinstance(b, RuntimeExpr):
+#         decls |= b
+
+#     a_tp = _get_tp(a)
+#     b_tp = _get_tp(b)
+#     # Make sure at least one of the types has the method, to avoid issue with == upcasting improperly
+#     if not (
+#         (isinstance(a_tp, JustTypeRef) and decls.has_method(a_tp.name, name))
+#         or (isinstance(b_tp, JustTypeRef) and decls.has_method(b_tp.name, name))
+#     ):
+#         raise ConvertError(f"Neither {a_tp} nor {b_tp} has method {name}")
+#     a_converts_to = {
+#         to: c for ((from_, to), (c, _)) in CONVERSIONS.items() if from_ == a_tp and decls.has_method(to.name, name)
+#     }
+#     b_converts_to = {
+#         to: c for ((from_, to), (c, _)) in CONVERSIONS.items() if from_ == b_tp and decls.has_method(to.name, name)
+#     }
+#     if isinstance(a_tp, JustTypeRef) and decls.has_method(a_tp.name, name):
+#         a_converts_to[a_tp] = 0
+#     if isinstance(b_tp, JustTypeRef) and decls.has_method(b_tp.name, name):
+#         b_converts_to[b_tp] = 0
+#     common = set(a_converts_to) & set(b_converts_to)
+#     if not common:
+#         raise ConvertError(f"Cannot convert {a_tp} and {b_tp} to a common type")
+#     return min(common, key=lambda tp: a_converts_to[tp] + b_converts_to[tp])
 
 
 def identity(x: object) -> object:
@@ -197,7 +203,7 @@ def with_type_args(args: tuple[JustTypeRef, ...], decls: Callable[[], Declaratio
 def resolve_literal(
     tp: TypeOrVarRef,
     arg: object,
-    decls: Callable[[], Declarations] = _retrieve_conversion_decls,
+    decls: Callable[[], Declarations] = retrieve_conversion_decls,
     tcs: TypeConstraintSolver | None = None,
     cls_name: str | None = None,
 ) -> RuntimeExpr:
@@ -208,12 +214,12 @@ def resolve_literal(
 
     If it cannot be resolved, we assume that the value passed in will resolve it.
     """
-    arg_type = _get_tp(arg)
+    arg_type = resolve_type(arg)
 
     # If we have any type variables, dont bother trying to resolve the literal, just return the arg
     try:
         tp_just = tp.to_just()
-    except NotImplementedError:
+    except TypeVarError:
         # If this is a generic arg but passed in a non runtime expression, try to resolve the generic
         # args first based on the existing type constraint solver
         if tcs:
@@ -258,7 +264,7 @@ def _debug_print_converers():
         source_to_targets[source].append(target)
 
 
-def _get_tp(x: object) -> JustTypeRef | type:
+def resolve_type(x: object) -> JustTypeRef | type:
     if isinstance(x, RuntimeExpr):
         return x.__egg_typed_expr__.tp
     tp = type(x)

python/egglog/declarations.py

@@ -73,6 +73,7 @@
     "SpecialFunctions",
     "TypeOrVarRef",
     "TypeRefWithVars",
+    "TypeVarError",
     "TypedExprDecl",
     "UnboundVarDecl",
     "UnionDecl",
@@ -95,7 +96,7 @@ def __egg_decls__(self) -> Declarations:
         # Catch attribute error, so that it isn't bubbled up as a missing attribute and fallbacks on `__getattr__`
         # instead raise explicitly
         except AttributeError as err:
-            msg = f"Cannot resolve declarations for {self}"
+            msg = f"Cannot resolve declarations for {self}: {err}"
             raise RuntimeError(msg) from err
 
 
@@ -225,14 +226,43 @@ def set_function_decl(
             case _:
                 assert_never(ref)
 
-    def has_method(self, class_name: str, method_name: str) -> bool | None:
+    def check_binary_method_with_types(self, method_name: str, self_type: JustTypeRef, other_type: JustTypeRef) -> bool:
         """
-        Returns whether the given class has the given method, or None if we cant find the class.
+        Checks if the class has a binary method compatible with the given types.
         """
-        if class_name in self._classes:
-            return method_name in self._classes[class_name].methods
+        vars: dict[ClassTypeVarRef, JustTypeRef] = {}
+        if callable_decl := self._classes[self_type.name].methods.get(method_name):
+            match callable_decl.signature:
+                case FunctionSignature((self_arg_type, other_arg_type)) if self_arg_type.matches_just(
+                    vars, self_type
+                ) and other_arg_type.matches_just(vars, other_type):
+                    return True
+        return False
+
+    def check_binary_method_with_self_type(self, method_name: str, self_type: JustTypeRef) -> JustTypeRef | None:
+        """
+        Checks if the class has a binary method with the given name and self type. Returns the other type if it exists.
+        """
+        vars: dict[ClassTypeVarRef, JustTypeRef] = {}
+        if callable_decl := self._classes[self_type.name].methods.get(method_name):
+            match callable_decl.signature:
+                case FunctionSignature((self_arg_type, other_arg_type)) if self_arg_type.matches_just(vars, self_type):
+                    return other_arg_type.to_just(vars)
         return None
 
+    def check_binary_method_with_other_type(self, method_name: str, other_type: JustTypeRef) -> Iterable[JustTypeRef]:
+        """
+        Returns the types which are compatible with the given binary method name and other type.
+        """
+        for class_decl in self._classes.values():
+            vars: dict[ClassTypeVarRef, JustTypeRef] = {}
+            if callable_decl := class_decl.methods.get(method_name):
+                match callable_decl.signature:
+                    case FunctionSignature((self_arg_type, other_arg_type)) if other_arg_type.matches_just(
+                        vars, other_type
+                    ):
+                        yield self_arg_type.to_just(vars)
+
     def get_class_decl(self, name: str) -> ClassDecl:
         return self._classes[name]
 
@@ -300,6 +330,10 @@ def __str__(self) -> str:
 _RESOLVED_TYPEVARS: dict[ClassTypeVarRef, TypeVar] = {}
 
 
+class TypeVarError(RuntimeError):
+    """Error when trying to resolve a type variable that doesn't exist."""
+
+
 @dataclass(frozen=True)
 class ClassTypeVarRef:
     """
@@ -309,9 +343,10 @@ class ClassTypeVarRef:
     name: str
     module: str
 
-    def to_just(self) -> JustTypeRef:
-        msg = f"{self}: egglog does not support generic classes yet."
-        raise NotImplementedError(msg)
+    def to_just(self, vars: dict[ClassTypeVarRef, JustTypeRef] | None = None) -> JustTypeRef:
+        if vars is None or self not in vars:
+            raise TypeVarError(f"Cannot convert type variable {self} to concrete type without variable bindings")
+        return vars[self]
 
     def __str__(self) -> str:
         return str(self.to_type_var())
@@ -325,20 +360,39 @@ def from_type_var(cls, typevar: TypeVar) -> ClassTypeVarRef:
     def to_type_var(self) -> TypeVar:
         return _RESOLVED_TYPEVARS[self]
 
+    def matches_just(self, vars: dict[ClassTypeVarRef, JustTypeRef], other: JustTypeRef) -> bool:
+        """
+        Checks if this type variable matches the given JustTypeRef, including type variables.
+        """
+        if self in vars:
+            return vars[self] == other
+        vars[self] = other
+        return True
+
 
 @dataclass(frozen=True)
 class TypeRefWithVars:
     name: str
     args: tuple[TypeOrVarRef, ...] = ()
 
-    def to_just(self) -> JustTypeRef:
-        return JustTypeRef(self.name, tuple(a.to_just() for a in self.args))
+    def to_just(self, vars: dict[ClassTypeVarRef, JustTypeRef] | None = None) -> JustTypeRef:
+        return JustTypeRef(self.name, tuple(a.to_just(vars) for a in self.args))
 
     def __str__(self) -> str:
         if self.args:
             return f"{self.name}[{', '.join(str(a) for a in self.args)}]"
         return self.name
 
+    def matches_just(self, vars: dict[ClassTypeVarRef, JustTypeRef], other: JustTypeRef) -> bool:
+        """
+        Checks if this type reference matches the given JustTypeRef, including type variables.
+        """
+        return (
+            self.name == other.name
+            and len(self.args) == len(other.args)
+            and all(a.matches_just(vars, b) for a, b in zip(self.args, other.args, strict=True))
+        )
+
 
 TypeOrVarRef: TypeAlias = ClassTypeVarRef | TypeRefWithVars
 

python/egglog/egraph.py

@@ -115,7 +115,7 @@
     "__firstlineno__",
     "__static_attributes__",
     # Ignore all reflected binary method
-    *REFLECTED_BINARY_METHODS.keys(),
+    *(f"__r{m[2:]}" for m in NUMERIC_BINARY_METHODS),
 }