Allow specializing Anything type variables via isinstance

AGENTS.md

@@ -0,0 +1,18 @@
+This repository contains code for a language transpiler of smart contracts. It is therefore extremely important to write code that generalizes well and to *not* hardcode specific edge cases.
+
+### Testing
+- First write tests that reflect diversely how the language is supposed to work and how not.
+- Check out other tests for language features (esp. test_misc.py) to see how tests are written. They define a program, compile it and then test its behavior against expectations, usually using property based tests. It is fine to start with a fixed example which gives faster feedback (PBT tend to time out when the behavior is violated, feel free to abort test generation)
+- The entire test suite takes > 20 minutes to execute. Only run it at the end, prefer individual relevant tests before.
+
+### Adding features
+For language features
+- Make sure to familiarize yourself with the way the visitor pattern is used for basically everything in the repo.
+- There are three main steps for the compiler: normalization and optimization (in many individual steps in rewrite/ and optimize/), type inference (in type_inference.py) and transpilation (in compiler.py)
+- If you rewrite a feature into existing features, make sure that the existing features are actually supported already. For example, lambda expressions are not supported yet.
+
+For standard library tooling
+- All code in std/ and ledger/ is meant to be interpreted by the opshin compiler. Add code there if it is supposed to extend the standard library of the language
+
+Documentation is autogenerated from function comments.
+- 

opshin/fun_impls.py

@@ -159,8 +159,11 @@ def impl_from_args(self, args: typing.List[Type]) -> plt.AST:
             )
         elif isinstance(target, RecordType):
             # default: all fields in union are records, so we can safely access CONSTR_ID
+            attr_source: ClassType = (
+                target if isinstance(instance.typ, AnyType) else instance.typ
+            )
             node = plt.EqualsInteger(
-                plt.Apply(instance.typ.attribute("CONSTR_ID"), OVar("x")),
+                plt.Apply(attr_source.attribute("CONSTR_ID"), OVar("x")),
                 plt.Integer(target.record.constructor),
             )
 
@@ -202,7 +205,7 @@ def impl_from_args(self, args: typing.List[Type]) -> plt.AST:
             )
         else:
             raise NotImplementedError(
-                f"Only isinstance for byte, int, Plutus Dataclass types are supported"
+                f"Only isinstance for byte, int, Plutus Dataclass, List and Dict types are supported"
             )
 
 

opshin/type_inference.py

@@ -730,8 +730,12 @@ def does_literally_reference_self(arg):
                     stmt.test
                 )
                 # for the time after this assert, the variable has the specialized type
-                prevtyps.update(self.implement_typechecks(typchecks))
-        self.implement_typechecks(prevtyps)
+                wrapped = self.implement_typechecks(typchecks)
+                prevtyps.update(wrapped)
+                self.wrapped.extend(wrapped.keys())
+        if prevtyps:
+            self.wrapped = [x for x in self.wrapped if x not in prevtyps.keys()]
+            self.implement_typechecks(prevtyps)
         return stmts
 
     def visit_ClassDef(self, node: ClassDef) -> TypedClassDef:
@@ -1273,22 +1277,17 @@ def visit_Call(self, node: Call) -> TypedCall:
 
         # might be isinstance
         # Subscripts are not allowed in isinstance calls
-        if (
-            isinstance(tc.func, Name)
-            and tc.func.orig_id == "isinstance"
-            and isinstance(tc.args[1], Subscript)
-        ):
+        is_isinstance_call = (
+            isinstance(tc.func, Name) and tc.func.orig_id == "isinstance"
+        )
+        if is_isinstance_call and isinstance(tc.args[1], Subscript):
             raise TypeError(
                 "Subscripted generics cannot be used with class and instance checks"
             )
 
         # Need to handle the presence of PlutusData classes
-        if (
-            isinstance(tc.func, Name)
-            and tc.func.orig_id == "isinstance"
-            and not isinstance(
-                tc.args[1].typ, (ByteStringType, IntegerType, ListType, DictType)
-            )
+        if is_isinstance_call and not isinstance(
+            tc.args[1].typ, (ByteStringType, IntegerType, ListType, DictType)
         ):
             if (
                 isinstance(tc.args[0].typ, InstanceType)

tests/test_misc.py

@@ -63,6 +63,74 @@ def fib(n):
 
 some_output = st.sampled_from([SomeOutputDatum(b"0"), SomeOutputDatumHash(b"1")])
 
+ASSERT_ANYTHING_CONFIG = DEFAULT_TEST_CONFIG.update(allow_isinstance_anything=True)
+
+
+def _assert_isinstance_anything_int_program():
+    return """
+def validator(x: Anything) -> int:
+    y = x
+    assert isinstance(y, int), "Wrong type"
+    return y + 1
+"""
+
+
+def _assert_isinstance_anything_int_program_cast_if():
+    return """
+def validator(x: Anything) -> int:
+    y = x
+    if isinstance(y, int):
+        return y + 1
+    return 0
+"""
+
+
+def _assert_isinstance_anything_bytes_program():
+    return """
+def validator(x: Anything) -> int:
+    y = x
+    assert isinstance(y, bytes), "Wrong type"
+    return len(y)
+"""
+
+
+def _assert_isinstance_anything_list_program():
+    return """
+from typing import List
+
+def validator(x: Anything) -> int:
+    y = x
+    assert isinstance(y, List), "Wrong type"
+    return len(y)
+"""
+
+
+def _assert_isinstance_anything_dict_program():
+    return """
+from typing import Dict
+
+def validator(x: Anything) -> int:
+    y = x
+    assert isinstance(y, Dict), "Wrong type"
+    return len(y)
+"""
+
+
+def _assert_isinstance_anything_user_defined_program():
+    return """
+from opshin.prelude import *
+
+@dataclass()
+class Foo(PlutusData):
+    CONSTR_ID = 0
+    value: int
+
+def validator(x: Anything) -> int:
+    y = x
+    assert isinstance(y, Foo), "Wrong type"
+    return y.value + 2
+"""
+
 
 class MiscTest(unittest.TestCase):
     def test_assert_sum_contract_succeed(self):
@@ -816,6 +884,81 @@ def validator(x: Anything) -> int:
         ret = eval_uplc_value(source_code, 0)
         self.assertEqual(ret, 0)
 
+    def test_assert_isinstance_anything_int(self):
+        source_code = _assert_isinstance_anything_int_program()
+        ret = eval_uplc_value(source_code, 1, config=ASSERT_ANYTHING_CONFIG)
+        self.assertEqual(ret, 2)
+
+    def test_assert_isinstance_anything_int_cast_if(self):
+        source_code = _assert_isinstance_anything_int_program_cast_if()
+        ret = eval_uplc_value(source_code, 1, config=ASSERT_ANYTHING_CONFIG)
+        self.assertEqual(ret, 2)
+
+    def test_assert_isinstance_anything_int_cast_if_wrong_config(self):
+        source_code = _assert_isinstance_anything_int_program_cast_if()
+        with self.assertRaises(CompilerError):
+            ret = eval_uplc_value(source_code, 1, config=DEFAULT_TEST_CONFIG)
+
+    def test_assert_isinstance_anything_int_wrong_config(self):
+        source_code = _assert_isinstance_anything_int_program()
+        with self.assertRaises(CompilerError):
+            ret = eval_uplc_value(source_code, 1, config=DEFAULT_TEST_CONFIG)
+
+    def test_assert_isinstance_anything_int_illegal(self):
+        source_code = _assert_isinstance_anything_int_program()
+        with self.assertRaises(RuntimeError):
+            eval_uplc_value(source_code, b"\x01", config=ASSERT_ANYTHING_CONFIG)
+
+    def test_assert_isinstance_anything_bytes(self):
+        source_code = _assert_isinstance_anything_bytes_program()
+        ret = eval_uplc_value(source_code, b"abc", config=ASSERT_ANYTHING_CONFIG)
+        self.assertEqual(ret, 3)
+
+    def test_assert_isinstance_anything_bytes_illegal(self):
+        source_code = _assert_isinstance_anything_bytes_program()
+        with self.assertRaises(RuntimeError):
+            eval_uplc_value(source_code, 1, config=ASSERT_ANYTHING_CONFIG)
+
+    def test_assert_isinstance_anything_list(self):
+        source_code = _assert_isinstance_anything_list_program()
+        ret = eval_uplc_value(source_code, [1, 2, 3], config=ASSERT_ANYTHING_CONFIG)
+        self.assertEqual(
+            ret,
+            3,
+        )
+
+    def test_assert_isinstance_anything_list_illegal(self):
+        source_code = _assert_isinstance_anything_list_program()
+        with self.assertRaises(RuntimeError):
+            eval_uplc_value(source_code, {1: 2}, config=ASSERT_ANYTHING_CONFIG)
+
+    def test_assert_isinstance_anything_dict(self):
+        source_code = _assert_isinstance_anything_dict_program()
+        ret = eval_uplc_value(source_code, {1: 2, 3: 4}, config=ASSERT_ANYTHING_CONFIG)
+        self.assertEqual(ret, 2)
+
+    def test_assert_isinstance_anything_dict_illegal(self):
+        source_code = _assert_isinstance_anything_dict_program()
+        with self.assertRaises(RuntimeError):
+            eval_uplc_value(source_code, [1, 2], config=ASSERT_ANYTHING_CONFIG)
+
+    def test_assert_isinstance_anything_user_defined_type(self):
+        source_code = _assert_isinstance_anything_user_defined_program()
+        datum = uplc.PlutusConstr(0, [uplc.PlutusInteger(5)])
+        ret = eval_uplc_value(source_code, datum, config=ASSERT_ANYTHING_CONFIG)
+        self.assertEqual(ret, 7)
+
+    def test_assert_isinstance_anything_user_defined_type_wrong_config(self):
+        source_code = _assert_isinstance_anything_user_defined_program()
+        datum = uplc.PlutusConstr(0, [uplc.PlutusInteger(5)])
+        with self.assertRaises(CompilerError):
+            eval_uplc_value(source_code, datum, config=DEFAULT_TEST_CONFIG)
+
+    def test_assert_isinstance_anything_user_defined_type_illegal(self):
+        source_code = _assert_isinstance_anything_user_defined_program()
+        with self.assertRaises(RuntimeError):
+            eval_uplc_value(source_code, 1, config=ASSERT_ANYTHING_CONFIG)
+
     def test_typecast_int_anything(self):
         # this should compile, it happens implicitly anyways when calling a function with Any parameters
         source_code = """