diff --git a/compiler/language_models/expression.py b/compiler/language_models/expression.py
index dd8f8e0..8f25f02 100644
--- a/compiler/language_models/expression.py
+++ b/compiler/language_models/expression.py
@@ -7,7 +7,7 @@
 import attr
 import immutabledict
 
-from . import declarable, argument_list, namespace as namespace_module
+from . import declarable, argument_list, namespace as namespace_module, string
 from ..libs import parser as parser_module
 
 # pylint: disable=fixme
@@ -130,7 +130,7 @@ def execute(self, namespace):
         # TODO: local variable formatting
         if self.is_binary:
             return b''.join(bytes(value.value) for value in self.values)
-        return ''.join(str(value.value) for value in self.values)
+        return string.String(''.join(str(value.value) for value in self.values))
 
     @classmethod
     def from_string(cls, value):
@@ -287,6 +287,11 @@ def execute(self, namespace):
         try:
             return namespace.lookup(self.name)
         except KeyError as exc:
+            if self.annotation is not None:
+                # If there's an annotation, this is a type declaration.
+                # Put None as the value as a placeholder for now.
+                self.assign(namespace, None)
+                return None
             raise NameError(f'name {self.name!r} is not defined') from exc
 
     @classmethod
@@ -677,7 +682,10 @@ def execute(self, namespace):
             key: arg.execute(namespace)
             for key, arg in self.keyword_arguments.items()
         }
-        return callable_value(*positional_arguments, **keyword_arguments)  # noqa
+        try:
+            return callable_value(*positional_arguments, **keyword_arguments)  # noqa
+        except TypeError as exc:
+            raise TypeError(f'problem with {callable_value!r}(*{positional_arguments!r}, **{keyword_arguments!r})') from exc
 
     @property
     def expressions(self):
diff --git a/compiler/language_models/module.py b/compiler/language_models/module.py
index 7ced3a0..7d20ff4 100644
--- a/compiler/language_models/module.py
+++ b/compiler/language_models/module.py
@@ -7,20 +7,11 @@
 
 from . import (
     statement as statement_module,
-    namespace as namespace_module,
+    namespace as namespace_module, test, string,
 )
 from ..libs import parser as parser_module
 
 
-class _String(str):
-    is_alpha = str.isalpha
-    is_digit = str.isdigit
-    is_numeric = str.isnumeric
-    is_decimal = str.isdecimal
-    is_alphanumeric = str.isalnum
-    is_space = str.isspace
-
-
 builtin_namespace = namespace_module.Namespace()
 builtin_namespace.declare('True', True)
 builtin_namespace.declare('False', False)
@@ -31,8 +22,8 @@ class _String(str):
 builtin_namespace.declare('Exception', Exception)
 builtin_namespace.declare('print', print)
 builtin_namespace.declare('Boolean', bool)
-builtin_namespace.declare('String', _String)
-builtin_namespace.declare('Character', str)
+builtin_namespace.declare('String', string.String)
+builtin_namespace.declare('Character', string.String)
 builtin_namespace.declare('Integer', int)
 builtin_namespace.declare('List', list)
 builtin_namespace.declare('FrozenList', tuple)
@@ -49,6 +40,7 @@ class _String(str):
 builtin_namespace.declare('staticmethod', staticmethod)
 builtin_namespace.declare('classmethod', classmethod)
 builtin_namespace.declare('abstract', lambda x: x)  # don't bother implementing yet
+builtin_namespace.declare('test', test.test)
 
 
 @attr.s(frozen=True, slots=True)
@@ -56,8 +48,8 @@ class Module(parser_module.Symbol):
     statements: typing.Sequence[statement_module.Statement] = attr.ib(converter=tuple)
 
     @classmethod
-    def from_string(cls, code: str) -> Module:
-        cursor = parser_module.Cursor(code.splitlines())
+    def from_string(cls, path: typing.Sequence[str], code: str) -> Module:
+        cursor = parser_module.Cursor(code.splitlines(), path=path)
 
         return cls.parse(cursor).last_symbol  # noqa
 
@@ -101,7 +93,11 @@ def execute(self,
             for statement in self.statements:
                 statement.execute(global_namespace).get_value()
 
-        get_outcome().get_value()  # reraise any exception, with module added to traceback
+        outcome = get_outcome()
+
+        if isinstance(outcome, statement_module.Raise.Outcome):
+            print(outcome)
+            outcome.get_value()  # reraise any exception, with module added to traceback
 
         return global_namespace.as_object()
 
diff --git a/compiler/language_models/program.py b/compiler/language_models/program.py
index 6abdd65..f829533 100644
--- a/compiler/language_models/program.py
+++ b/compiler/language_models/program.py
@@ -20,7 +20,7 @@ def register_module(self, path: typing.Sequence[str], module: module_module.Modu
     def register_module_from_string(self, path: typing.Sequence[str], module_string: str):
         self.register_module(
             path,
-            module_module.Module.from_string(module_string),
+            module_module.Module.from_string(path, module_string),
         )
 
     def register_package(self, path: typing.Sequence[str], root_path: str):
@@ -36,6 +36,10 @@ def register_package(self, path: typing.Sequence[str], root_path: str):
                     path + file_path.relative_to(root_path).parts
                 ] = file_path.read_bytes()
 
+        # Initialize all the modules.
+        for module_path in self.modules:
+            self.get_module(module_path)
+
     def get_module(self, path: typing.Sequence[str]):
         path = tuple(path)
 
@@ -43,7 +47,12 @@ def get_module(self, path: typing.Sequence[str]):
             if path not in self.modules:
                 raise ImportError(f'no such module {path}')
 
-            self.initialized_modules[path] = self.modules[path].execute(self, path)
+            module = self.modules[path]
+
+            if isinstance(module, module_module.Module):
+                module = module.execute(self, path)
+
+            self.initialized_modules[path] = module
 
         return self.initialized_modules[path]
 
diff --git a/compiler/language_models/string.py b/compiler/language_models/string.py
index d1abde1..87f8c28 100644
--- a/compiler/language_models/string.py
+++ b/compiler/language_models/string.py
@@ -3,6 +3,17 @@
 import regex
 
 
+class String(str):
+    is_alpha = str.isalpha
+    is_digit = str.isdigit
+    is_numeric = str.isnumeric
+    is_decimal = str.isdecimal
+    is_alphanumeric = str.isalnum
+    is_space = str.isspace
+
+    length = str.__len__
+
+
 def unescape_text(escaped: str) -> str:
     return _ESCAPE_TEXT_REGEX.sub(
         _unescape_text,
diff --git a/compiler/language_models/test.py b/compiler/language_models/test.py
new file mode 100644
index 0000000..ab18567
--- /dev/null
+++ b/compiler/language_models/test.py
@@ -0,0 +1,23 @@
+import traceback
+import typing
+
+
+def test(test_class):
+    print(f'testing {test_class}')
+    instance = test_class()
+
+    for name in dir(test_class):
+        method = getattr(instance, name)
+        if name.startswith('test_') and isinstance(method, typing.Callable):
+            print(f'    {name}:')
+
+            try:
+                method()
+            except AssertionError:
+                print('        FAILURE')
+                traceback.print_exc()
+            except Exception:  # noqa, pylint: disable=broad-except
+                print('        ERROR')
+                traceback.print_exc()
+            else:
+                print('        SUCCESS')
diff --git a/compiler/libs/parser.py b/compiler/libs/parser.py
index 08fec1f..1a27f1c 100644
--- a/compiler/libs/parser.py
+++ b/compiler/libs/parser.py
@@ -28,6 +28,7 @@ class Cursor:
     column: int = attr.ib(default=0)
     last_symbol: typing.Optional[Symbol] = attr.ib(default=None)
     block_depth: int = attr.ib(default=0)
+    path: str = attr.ib(default=('?',))
 
     def line_text(self, line=None):
         line = self.line if line is None else line
@@ -62,6 +63,7 @@ def new_from_symbol(self, symbol: Symbol):
             column=column,
             last_symbol=symbol,
             block_depth=block_depth,
+            path=self.path,
         )
 
     def parse_one_symbol(self, one_of: typing.Sequence[typing.Type[Symbol]], fail=False) -> Cursor:
@@ -99,7 +101,7 @@ def parse_one_symbol(self, one_of: typing.Sequence[typing.Type[Symbol]], fail=Fa
         )
 
     def __str__(self):
-        heading = f'{self.line + 1}, {self.column + 1}: '
+        heading = f'{".".join(self.path)}:{self.line + 1}:{self.column + 1}: '
         line_text = self.line_text()
         pointer_indent = ' ' * (len(heading) + self.column)
         return f'{heading}{line_text}\n{pointer_indent}^'
diff --git a/compiler/meta/generic.py b/compiler/meta/generic.py
index 77599c5..4427127 100644
--- a/compiler/meta/generic.py
+++ b/compiler/meta/generic.py
@@ -1,6 +1,7 @@
 import typing
 
 import attr
+import immutabledict
 
 
 @attr.s(frozen=True, slots=True)
@@ -8,11 +9,16 @@ class Generic:
     class_factory: typing.Callable = attr.ib()
     _cache: typing.MutableMapping = attr.ib(factory=dict)
 
-    def __getitem__(self, item):
-        if not isinstance(item, tuple):
-            item = (item,)
+    def __getitem__(self, *args, **kwargs):
+        if len(args) == 1 and isinstance(args[0], tuple):
+            args = args[0]
+        kwargs = immutabledict.immutabledict(kwargs)
+        item = (args, kwargs)
 
-        if item not in self._cache:
-            self._cache[item] = self.class_factory(*item)
+        try:
+            if item not in self._cache:
+                self._cache[item] = self.class_factory(*args, **kwargs)
+        except TypeError as exc:
+            raise TypeError(f'problem with {item!r}') from exc
 
         return self._cache[item]
diff --git a/src/sibilance/compiler/parsing/ast.sib b/src/sibilance/compiler/parsing/ast.sib
index 32d55b1..4ab15ef 100644
--- a/src/sibilance/compiler/parsing/ast.sib
+++ b/src/sibilance/compiler/parsing/ast.sib
@@ -77,15 +77,6 @@ class Import(Node):
     path: FrozenList[String]
 
 
-class Statement(Or[
-    Import,
-    ClassDefinition,
-    FunctionDefinition,
-    Expression,
-]):
-    pass
-
-
 class ArgumentsDefinition(Node):
     positional_arguments: FrozenList[VariableDefinition]
     keyword_arguments: FrozenMap[String, VariableDefinition]
@@ -103,6 +94,15 @@ class ClassDefinition(Node):
     statements: FrozenList[Statement]
 
 
+class Statement(Or[
+    Import,
+    ClassDefinition,
+    FunctionDefinition,
+    Expression,
+]):
+    pass
+
+
 class Module(Node):
     statements: FrozenList[Statement]
 
diff --git a/src/sibilance/compiler/parsing/ast_test.sib b/src/sibilance/compiler/parsing/ast_test.sib
new file mode 100644
index 0000000..0a3b16f
--- /dev/null
+++ b/src/sibilance/compiler/parsing/ast_test.sib
@@ -0,0 +1,29 @@
+import .ast
+
+
+@test
+class CursorTest:
+    def test_advance_line(self):
+        cursor = ast.Cursor()
+        assert cursor.line == 1
+
+        cursor = cursor.advance("hello\nworld")
+        assert cursor.line == 2
+        cursor = cursor.advance("\n\n")
+        assert cursor.line == 4
+
+    def test_advance_column(self):
+        cursor = ast.Cursor()
+        assert cursor.column == 1
+
+        cursor = cursor.advance("he")
+        assert cursor.column == 3
+
+        cursor = cursor.advance("llo")
+        assert cursor.column == 6
+
+        cursor = cursor.advance("\nwo")
+        assert cursor.column == 3
+
+        cursor = cursor.advance("rld\n!")
+        assert cursor.column == 2