diff --git a/Sources/Common/Compiler.swift b/Sources/Common/Compiler.swift
index 329a45a..059ab59 100644
--- a/Sources/Common/Compiler.swift
+++ b/Sources/Common/Compiler.swift
@@ -15,5 +15,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
-public typealias TypeScope = Scope<P4Type>
-public typealias TypeScopes = Scopes<P4Type>
+/// A scope that resolves variable identifiers to their types.
+public typealias VarTypeScope = Scope<P4Type>
+
+/// Scopes that resolve variable identifiers to their types.
+public typealias VarTypeScopes = Scopes<P4Type>
+
+/// A scope that resolves type identifiers to their types.
+public typealias TypeTypeScope = Scope<P4Type>
+
+/// Scopes that resolve type identifiers to their types.
+public typealias TypeTypeScopes = Scopes<P4Type>
+
diff --git a/Sources/Common/Execution.swift b/Sources/Common/Execution.swift
index 33de911..e977281 100644
--- a/Sources/Common/Execution.swift
+++ b/Sources/Common/Execution.swift
@@ -16,8 +16,8 @@
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
 open class ProgramExecution: CustomStringConvertible {
-  public var scopes: ValueScopes = ValueScopes()
-  let initialValues: ValueScopes?
+  public var scopes: VarValueScopes = VarValueScopes()
+  let initialValues: VarValueScopes?
   var error: Error?
   var debug: DebugLevel = DebugLevel.Error
 
@@ -25,7 +25,7 @@ open class ProgramExecution: CustomStringConvertible {
     initialValues = .none
   }
 
-  public init(withGlobalValues values: ValueScopes) {
+  public init(withGlobalValues values: VarValueScopes) {
     initialValues = values
   }
 
@@ -88,10 +88,13 @@ open class ProgramExecution: CustomStringConvertible {
     return new_pe
   }
 
-  public func initial_values() -> ValueScopes? {
+  public func initial_values() -> VarValueScopes? {
     return self.initialValues
   }
 }
 
-public typealias ValueScope = Scope<P4Value>
-public typealias ValueScopes = Scopes<P4Value>
+/// A scope that resolves variable identifiers to their values.
+public typealias VarValueScope = Scope<P4Value>
+
+/// Scopes that resolves variable identifiers to their values.
+public typealias VarValueScopes = Scopes<P4Value>
diff --git a/Sources/P4Compiler/Compiler.swift b/Sources/P4Compiler/Compiler.swift
index 68d752a..e5f2c68 100644
--- a/Sources/P4Compiler/Compiler.swift
+++ b/Sources/P4Compiler/Compiler.swift
@@ -42,15 +42,15 @@ public func ErrorOnNode(node: Node, withError error: String) -> Error {
 
 /// Context for compilation.
 public struct CompilerContext {
-  let names: LexicalScopes
-  let types: LexicalScopes
+  let names: VarTypeScopes
+  let types: TypeTypeScopes
 
-  public init(withNames _names: LexicalScopes) {
+  public init(withNames _names: VarTypeScopes) {
     names = _names
-    types = LexicalScopes()
+    types = TypeTypeScopes()
   }
 
-  public init(withNames _names: LexicalScopes, withTypes _types: LexicalScopes) {
+  public init(withNames _names: VarTypeScopes, withTypes _types: TypeTypeScopes) {
     names = _names
     types = _types
   }
@@ -59,9 +59,9 @@ public struct CompilerContext {
   ///
   /// Create a new compiler context based on the current with the same types and new names.
   ///
-  /// - Parameter names: a ``LexicalScopes`` with the updated names for the newly created compiler context.
+  /// - Parameter names: a ``TypeScopes`` with the updated names for the newly created compiler context.
   /// - Returns: A new compiler context based on the current with the same types and new names.
-  public func update(newNames names: LexicalScopes) -> CompilerContext {
+  public func update(newNames names: VarTypeScopes) -> CompilerContext {
     return CompilerContext(withNames: names, withTypes: self.types)
   }
 
@@ -69,9 +69,9 @@ public struct CompilerContext {
   ///
   /// Create a new compiler context based on the current with the same names and new types.
   ///
-  /// - Parameter types: a ``LexicalScopes`` with the updated types for the newly created compiler context.
+  /// - Parameter types: a ``TypeScopes`` with the updated types for the newly created compiler context.
   /// - Returns: A new compiler context based on the current with the same names and new types.
-  public func update(newTypes types: LexicalScopes) -> CompilerContext {
+  public func update(newTypes types: TypeTypeScopes) -> CompilerContext {
     return CompilerContext(withNames: self.names, withTypes: types)
   }
 
diff --git a/Sources/P4Compiler/LexicalScopes.swift b/Sources/P4Compiler/LexicalScopes.swift
deleted file mode 100644
index ec35f3e..0000000
--- a/Sources/P4Compiler/LexicalScopes.swift
+++ /dev/null
@@ -1,21 +0,0 @@
-// p4rse, Copyright 2026, Will Hawkins
-//
-// This file is part of p4rse.
-//
-// This file is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program. If not, see <https://www.gnu.org/licenses/>.
-
-import Common
-
-public typealias LexicalScope = Scope<P4Type>
-public typealias LexicalScopes = Scopes<P4Type>
diff --git a/Sources/P4Compiler/Program.swift b/Sources/P4Compiler/Program.swift
index 3bc03bf..930b401 100644
--- a/Sources/P4Compiler/Program.swift
+++ b/Sources/P4Compiler/Program.swift
@@ -24,11 +24,15 @@ import TreeSitterP4
 
 public struct Program {
   public static func Compile(_ source: String) -> Result<P4Lang.Program> {
-    return Program.Compile(source, withGlobalTypes: .none)
+    return Program.Compile(source, withGlobalInstances: .none, withGlobalTypes: .none)
+  }
+
+  public static func Compile(_ source: String, withGlobalInstances globalInstances: VarTypeScopes) -> Result<P4Lang.Program> {
+    return Program.Compile(source, withGlobalInstances: globalInstances, withGlobalTypes: .none)
   }
 
   public static func Compile(
-    _ source: String, withGlobalTypes globalTypes: LexicalScopes?
+    _ source: String, withGlobalInstances globalInstances: VarTypeScopes?, withGlobalTypes globalTypes: TypeTypeScopes?
   ) -> Result<P4Lang.Program> {
 
     let maybe_parser = ConfigureP4Parser()
@@ -47,13 +51,18 @@ public struct Program {
     var program = P4Lang.Program()
 
     // Set up a context for parsing.
-    var compilation_context = CompilerContext(withNames: LexicalScopes().enter())
+    var compilation_context = CompilerContext(withNames: VarTypeScopes().enter())
 
     var errors: [Error] = Array()
 
+    // If the caller gave any global instances, add them here.
+    if let globalInstances = globalInstances {
+      compilation_context = compilation_context.update(newNames: globalInstances)
+    }
+
     // If the caller gave any global types, add them here.
     if let globalTypes = globalTypes {
-      compilation_context = compilation_context.update(newNames: globalTypes)
+      compilation_context = compilation_context.update(newTypes: globalTypes)
     }
 
     result?.rootNode?.enumerateNamedChildren { declaration_node in
diff --git a/Sources/P4Runtime/Expressions.swift b/Sources/P4Runtime/Expressions.swift
index 2afb127..733f728 100644
--- a/Sources/P4Runtime/Expressions.swift
+++ b/Sources/P4Runtime/Expressions.swift
@@ -52,36 +52,6 @@ extension SelectExpression: EvaluatableExpression {
   }
 }
 
-extension P4StringValue: EvaluatableExpression {
-  public func evaluate(execution: Common.ProgramExecution) -> Common.Result<any Common.P4Value> {
-    return .Ok(self)
-  }
-}
-
-extension P4BooleanValue: EvaluatableExpression {
-  public func evaluate(execution: Common.ProgramExecution) -> Common.Result<any Common.P4Value> {
-    return .Ok(self)
-  }
-}
-
-extension P4StructValue: EvaluatableExpression {
-  public func evaluate(execution: Common.ProgramExecution) -> Common.Result<any Common.P4Value> {
-    return .Ok(self)
-  }
-}
-
-extension P4IntValue: EvaluatableExpression {
-  public func evaluate(execution: Common.ProgramExecution) -> Common.Result<any Common.P4Value> {
-    return .Ok(self)
-  }
-}
-
-extension P4ArrayValue: EvaluatableExpression {
-  public func evaluate(execution: Common.ProgramExecution) -> Common.Result<any Common.P4Value> {
-    return .Ok(self)
-  }
-}
-
 // Variables are evaluatable because they can be looked up by identifiers.
 extension TypedIdentifier: EvaluatableExpression {
   public func type() -> any Common.P4Type {
@@ -96,8 +66,8 @@ extension TypedIdentifier: EvaluatableExpression {
 // Variables are evaluatable because they can be looked up by identifiers.
 extension TypedIdentifier: EvaluatableLValueExpression {
   public func set(
-    to: any Common.P4Value, inScopes scopes: Common.ValueScopes, duringExecution execution: ProgramExecution
-  ) -> Common.Result<(Common.ValueScopes, P4Value)> {
+    to: any Common.P4Value, inScopes scopes: Common.VarValueScopes, duringExecution execution: ProgramExecution
+  ) -> Common.Result<(Common.VarValueScopes, P4Value)> {
     if case .Error(let e) = scopes.lookup(identifier: self) {
       return .Error(e)
     }
@@ -105,7 +75,7 @@ extension TypedIdentifier: EvaluatableLValueExpression {
     return .Ok((scopes.set(identifier: self, withValue: to), to))
   }
 
-  public func check(to: any Common.EvaluatableExpression, inScopes scopes: Common.TypeScopes) -> Result<()> {
+  public func check(to: any Common.EvaluatableExpression, inScopes scopes: Common.VarTypeScopes) -> Result<()> {
     guard case .Ok(let type) = scopes.lookup(identifier: self) else {
       return .Error(Error(withMessage: "Cannot assign to identifier not in scope"))
     }
@@ -175,8 +145,8 @@ extension ArrayAccessExpression: EvaluatableExpression {
 
 extension ArrayAccessExpression: EvaluatableLValueExpression {
   public func set(
-    to: any Common.P4Value, inScopes scopes: Common.ValueScopes, duringExecution execution: ProgramExecution
-  ) -> Common.Result<(Common.ValueScopes, P4Value)> {
+    to: any Common.P4Value, inScopes scopes: Common.VarValueScopes, duringExecution execution: ProgramExecution
+  ) -> Common.Result<(Common.VarValueScopes, P4Value)> {
     // For purposes of documentation, assume the field access expression we are evaluating is
     // (strct_id)[indexor] = new_value
     // where strct_id expands to
@@ -213,7 +183,7 @@ extension ArrayAccessExpression: EvaluatableLValueExpression {
   }
 
   public func check(
-    to: any Common.EvaluatableExpression, inScopes scopes: Common.TypeScopes
+    to: any Common.EvaluatableExpression, inScopes scopes: Common.VarTypeScopes
   ) -> Common.Result<()> {
 
     if !self.type.value_type().eq(rhs: to.type()) {
@@ -249,8 +219,8 @@ extension FieldAccessExpression: EvaluatableExpression {
 
 extension FieldAccessExpression: EvaluatableLValueExpression {
   public func set(
-    to: any Common.P4Value, inScopes scopes: Common.ValueScopes, duringExecution execution: ProgramExecution
-  ) -> Common.Result<(Common.ValueScopes, P4Value)> {
+    to: any Common.P4Value, inScopes scopes: Common.VarValueScopes, duringExecution execution: ProgramExecution
+  ) -> Common.Result<(Common.VarValueScopes, P4Value)> {
     // For purposes of documentation, assume the field access expression we are evaluating is
     // (strct_id).field_id = new_field_value
     // where strct_id expands to
@@ -282,7 +252,7 @@ extension FieldAccessExpression: EvaluatableLValueExpression {
   }
 
   public func check(
-    to: any Common.EvaluatableExpression, inScopes scopes: Common.TypeScopes
+    to: any Common.EvaluatableExpression, inScopes scopes: Common.VarTypeScopes
   ) -> Common.Result<()> {
 
     if !self.field.type.eq(rhs:to.type()) {
diff --git a/Sources/P4Runtime/Runtime.swift b/Sources/P4Runtime/Runtime.swift
index 680187e..a4abbf9 100644
--- a/Sources/P4Runtime/Runtime.swift
+++ b/Sources/P4Runtime/Runtime.swift
@@ -22,14 +22,14 @@ import P4Lang
 public struct ParserRuntime: CustomStringConvertible {
   public var parser: Parser
 
-  let initialValues: ValueScopes?
+  let initialValues: VarValueScopes?
 
   init(parser: Parser) {
     self.parser = parser
     self.initialValues = .none
   }
 
-  init(parser: Parser, withInitialValues initial: ValueScopes?) {
+  init(parser: Parser, withInitialValues initial: VarValueScopes?) {
     self.parser = parser
     self.initialValues = initial
   }
@@ -40,7 +40,7 @@ public struct ParserRuntime: CustomStringConvertible {
   }
 
   public static func create(
-    program: P4Lang.Program, withInitialValues initial: ValueScopes?
+    program: P4Lang.Program, withInitialValues initial: VarValueScopes?
   ) -> Result<ParserRuntime> {
     return switch program.starting_parser() {
     case .Ok(let parser):
diff --git a/Tests/p4rseTests/ArrayTests.swift b/Tests/p4rseTests/ArrayTests.swift
index 2d2d6bc..8cb41d5 100644
--- a/Tests/p4rseTests/ArrayTests.swift
+++ b/Tests/p4rseTests/ArrayTests.swift
@@ -39,16 +39,16 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
-  test_types = test_types.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
-  var test_values = ValueScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ta"),
     withValue: P4ArrayValue(withType: P4Int(), withValue: [
       P4IntValue(withValue: 1), P4IntValue(withValue: 2), P4IntValue(withValue: 3),
     ]))
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
 
@@ -67,14 +67,14 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
-  test_types = test_types.declare(identifier: Identifier(name: "ta"), withValue: P4Int())
+  var test_declarations = VarTypeScopes().enter()
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ta"), withValue: P4Int())
   #expect(
     #RequireErrorResult(
       Error(
         withMessage: "{49, 22}: Failed to parse a statement element: {65, 2}: ta does not name an array type"
       ),
-      Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+      Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   )
 }
 
@@ -90,16 +90,16 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
-  test_types = test_types.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
-  var test_values = ValueScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ta"),
     withValue: P4ArrayValue(withType: P4Int(), withValue: [
       P4IntValue(withValue: 1), P4IntValue(withValue: 2), P4IntValue(withValue: 3),
     ]))
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
 
@@ -117,16 +117,16 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
-  test_types = test_types.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
-  var test_values = ValueScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ta"),
     withValue: P4ArrayValue(withType: P4Int(), withValue: [
       P4IntValue(withValue: 1), P4IntValue(withValue: 2), P4IntValue(withValue: 3),
     ]))
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
 
@@ -144,16 +144,16 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
-  test_types = test_types.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
-  var test_values = ValueScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ta"),
     withValue: P4ArrayValue(withType: P4Int(), withValue: [
       P4IntValue(withValue: 1), P4IntValue(withValue: 2), P4IntValue(withValue: 3),
     ]))
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
 
@@ -172,9 +172,9 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
-  test_types = test_types.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Array(withValueType: P4Int())))
-  var test_values = ValueScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Array(withValueType: P4Int())))
+  var test_values = VarValueScopes().enter()
 
   let nested = P4ArrayValue(
     withType: P4Int(),
@@ -185,7 +185,7 @@ import TreeSitterP4
     withValue: P4ArrayValue(withType: P4Array(withValueType: P4Int()), withValue: [nested]))
 
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
 
@@ -205,16 +205,16 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
-  test_types = test_types.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
-  var test_values = ValueScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ta"),
     withValue: P4ArrayValue(withType: P4Int(), withValue: [
       P4IntValue(withValue: 1), P4IntValue(withValue: 2), P4IntValue(withValue: 3),
     ]))
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
 
@@ -234,9 +234,9 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
-  test_types = test_types.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Array(withValueType: P4Int())))
-  var test_values = ValueScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Array(withValueType: P4Int())))
+  var test_values = VarValueScopes().enter()
 
   let nested = P4ArrayValue(
     withType: P4Int(),
@@ -247,7 +247,7 @@ import TreeSitterP4
     withValue: P4ArrayValue(withType: P4Array(withValueType: P4Int()), withValue: [nested]))
 
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
 
diff --git a/Tests/p4rseTests/ParserCompilerTests.swift b/Tests/p4rseTests/ParserCompilerTests.swift
index 4e8c2b8..de86ec5 100644
--- a/Tests/p4rseTests/ParserCompilerTests.swift
+++ b/Tests/p4rseTests/ParserCompilerTests.swift
@@ -114,5 +114,5 @@ import P4Lang
     #RequireErrorResult<(EvaluatableStatement, CompilerContext)>(
       Error(withMessage: "{2, 154}: Did not find assignment statement"),
       ParserAssignmentStatement.Compile( // Note: Calling ParserAssignmentStatement compilation directly.
-        node: result.rootNode!, withContext: CompilerContext(withNames: LexicalScopes()))))
+        node: result.rootNode!, withContext: CompilerContext(withNames: VarTypeScopes()))))
 }
diff --git a/Tests/p4rseTests/ScopeTests.swift b/Tests/p4rseTests/ScopeTests.swift
index 62bb0eb..e40a106 100644
--- a/Tests/p4rseTests/ScopeTests.swift
+++ b/Tests/p4rseTests/ScopeTests.swift
@@ -27,7 +27,7 @@ import TreeSitterP4
 @testable import P4Compiler
 
 @Test func test_scope() async throws {
-  let s = LexicalScope()
+  let s = VarTypeScope()
   let s2 = s.declare(identifier: Identifier(name: "first"), withValue: P4Int())
   let found_first = try! #require(s2.lookup(identifier: Identifier(name: "first")))
 
@@ -36,7 +36,7 @@ import TreeSitterP4
 }
 
 @Test func test_scope_no_set() async throws {
-  var ss = LexicalScopes().enter()
+  var ss = VarTypeScopes().enter()
   ss = ss.declare(identifier: Identifier(name: "first"), withValue: P4Int())
   ss = ss.enter()
   ss = ss.declare(identifier: Identifier(name: "second"), withValue: P4Boolean())
@@ -49,7 +49,7 @@ import TreeSitterP4
 }
 
 @Test func test_scope_set() async throws {
-  var ss = LexicalScopes().enter()
+  var ss = VarTypeScopes().enter()
   let id = Identifier(name: "first")
   let id_type = P4Int()
 
diff --git a/Tests/p4rseTests/StructTests.swift b/Tests/p4rseTests/StructTests.swift
index 039673e..8987142 100644
--- a/Tests/p4rseTests/StructTests.swift
+++ b/Tests/p4rseTests/StructTests.swift
@@ -39,15 +39,15 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
   let fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
     P4StructFieldIdentifier(name: "count", withType: P4Int()),
   ])
   let struct_type = P4Struct(withName: Identifier(name: "Testing"), andFields: fields)
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
 
-  var test_values = ValueScopes().enter()
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ts"),
     withValue: P4StructValue(withType: struct_type, andInitializers: [
@@ -56,7 +56,7 @@ import TreeSitterP4
     ]))
 
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
   #expect(state_result == P4Lang.accept)
@@ -74,15 +74,15 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
   let fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
     P4StructFieldIdentifier(name: "count", withType: P4Int()),
   ])
   let struct_type = P4Struct(withName: Identifier(name: "Testing"), andFields: fields)
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
 
-  var test_values = ValueScopes().enter()
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ts"),
     withValue: P4StructValue(withType: struct_type, andInitializers: [
@@ -91,7 +91,7 @@ import TreeSitterP4
     ]))
 
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
   #expect(state_result == P4Lang.reject)
@@ -109,15 +109,15 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
   let fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
     P4StructFieldIdentifier(name: "count", withType: P4Int()),
   ])
   let struct_type = P4Struct(withName: Identifier(name: "Testing"), andFields: fields)
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
 
-  var test_values = ValueScopes().enter()
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ts"),
     withValue: P4StructValue(withType: struct_type, andInitializers: [
@@ -126,7 +126,7 @@ import TreeSitterP4
     ]))
 
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
   #expect(state_result == P4Lang.accept)
@@ -143,15 +143,15 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
   let fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
     P4StructFieldIdentifier(name: "count", withType: P4Int()),
   ])
   let struct_type = P4Struct(withName: Identifier(name: "Testing"), andFields: fields)
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
 
-  var test_values = ValueScopes().enter()
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ts"),
     withValue: P4StructValue(withType: struct_type, andInitializers: [
@@ -160,7 +160,7 @@ import TreeSitterP4
     ]))
 
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
   #expect(state_result == P4Lang.reject)
@@ -178,7 +178,7 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
 
   let ty_fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
@@ -189,9 +189,9 @@ import TreeSitterP4
   let ts_fields = P4StructFields([P4StructFieldIdentifier(name: "ty", withType: ty_struct_type)])
   let ts_struct_type = P4Struct(withName: Identifier(name: "outer"), andFields: ts_fields)
 
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: ts_struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: ts_struct_type)
 
-  var test_values = ValueScopes().enter()
+  var test_values = VarValueScopes().enter()
 
   test_values = test_values.declare(
     identifier: Identifier(name: "ts"),
@@ -206,7 +206,7 @@ import TreeSitterP4
           ])
       ]))
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
   #expect(state_result == P4Lang.accept)
@@ -225,15 +225,15 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
   let fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
     P4StructFieldIdentifier(name: "count", withType: P4Int()),
   ])
   let struct_type = P4Struct(withName: Identifier(name: "Testing"), andFields: fields)
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
 
-  var test_values = ValueScopes().enter()
+  var test_values = VarValueScopes().enter()
   test_values = test_values.declare(
     identifier: Identifier(name: "ts"),
     withValue: P4StructValue(withType: struct_type, andInitializers: [
@@ -242,7 +242,7 @@ import TreeSitterP4
     ]))
 
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
   #expect(state_result == P4Lang.accept)
@@ -257,20 +257,20 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
   let fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
     P4StructFieldIdentifier(name: "count", withType: P4Int()),
   ])
   let struct_type = P4Struct(withName: Identifier(name: "Testing"), andFields: fields)
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: struct_type)
 
   #expect(
     #RequireErrorResult(
       Error(
         withMessage: "{49, 13}: Failed to parse a statement element: {49, 8}: Cannot assign value of type Int to field with type Boolean"
       ),
-      Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+      Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   )
 }
 
@@ -287,7 +287,7 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
 
   let ty_fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
@@ -298,9 +298,9 @@ import TreeSitterP4
   let ts_fields = P4StructFields([P4StructFieldIdentifier(name: "ty", withType: ty_struct_type)])
   let ts_struct_type = P4Struct(withName: Identifier(name: "outer"), andFields: ts_fields)
 
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: ts_struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: ts_struct_type)
 
-  var test_values = ValueScopes().enter()
+  var test_values = VarValueScopes().enter()
 
   test_values = test_values.declare(
     identifier: Identifier(name: "ts"),
@@ -315,7 +315,7 @@ import TreeSitterP4
           ])
       ]))
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
   #expect(state_result == P4Lang.accept)
@@ -335,7 +335,7 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
 
   let ty_fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
@@ -346,9 +346,9 @@ import TreeSitterP4
   let ts_fields = P4StructFields([P4StructFieldIdentifier(name: "ty", withType: ty_struct_type)])
   let ts_struct_type = P4Struct(withName: Identifier(name: "outer"), andFields: ts_fields)
 
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: ts_struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: ts_struct_type)
 
-  var test_values = ValueScopes().enter()
+  var test_values = VarValueScopes().enter()
 
   test_values = test_values.declare(
     identifier: Identifier(name: "ts"),
@@ -363,7 +363,7 @@ import TreeSitterP4
           ])
       ]))
   let program = try #UseOkResult(
-    Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+    Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   let runtime = try #UseOkResult(P4Runtime.ParserRuntime.create(program: program, withInitialValues: test_values))
   let (state_result, _) = try! #UseOkResult(runtime.run())
   #expect(state_result == P4Lang.accept)
@@ -382,7 +382,7 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_declarations = VarTypeScopes().enter()
 
   let ty_fields = P4StructFields([
     P4StructFieldIdentifier(name: "yesno", withType: P4Boolean()),
@@ -393,14 +393,14 @@ import TreeSitterP4
   let ts_fields = P4StructFields([P4StructFieldIdentifier(name: "ty", withType: ty_struct_type)])
   let ts_struct_type = P4Struct(withName: Identifier(name: "outer"), andFields: ts_fields)
 
-  test_types = test_types.declare(identifier: Identifier(name: "ts"), withValue: ts_struct_type)
+  test_declarations = test_declarations.declare(identifier: Identifier(name: "ts"), withValue: ts_struct_type)
 
   #expect(
     #RequireErrorResult(
       Error(
         withMessage: "{49, 20}: Failed to parse a statement element: {49, 11}: Cannot assign value of type Boolean to field with type Int"
       ),
-      Program.Compile(simple_parser_declaration, withGlobalTypes: test_types))
+      Program.Compile(simple_parser_declaration, withGlobalInstances: test_declarations))
   )
 
 }
diff --git a/Tests/p4rseTests/ValueTypeParserTests.swift b/Tests/p4rseTests/ValueTypeParserTests.swift
index bc5d49b..f71586d 100644
--- a/Tests/p4rseTests/ValueTypeParserTests.swift
+++ b/Tests/p4rseTests/ValueTypeParserTests.swift
@@ -29,10 +29,20 @@ import TreeSitterP4
 
 @Test func test_invalid_types() async throws {
   for invalid_type_name in ["boo", "str", "in"] {
-    #expect(
-      #RequireErrorResult(
-        Error(withMessage: "Type name not recognized"),
-        Types.CompileBasicType(type: invalid_type_name)))
+    let simple_parser_declaration = """
+          parser main_parser() {
+            state start {
+              \(invalid_type_name) v = 1;
+              transition reject;
+            }
+          };
+      """;
+
+    let err = Program.Compile(simple_parser_declaration)
+    guard case Result.Error(let e) = err else {
+      assert(false, "Expected an error, but had success")
+    }
+    #expect(e.msg.contains("Failed to parse a statement element: Could not parse a P4 type from \(invalid_type_name)"))
   }
 }
 
@@ -242,7 +252,7 @@ import TreeSitterP4
         }
       };
     """
-  var test_types = LexicalScopes().enter()
+  var test_types = VarTypeScopes().enter()
   test_types = test_types.declare(identifier: Identifier(name: "ta"), withValue: P4Array(withValueType: P4Int()))
   #expect(
     #RequireErrorResult(
@@ -250,5 +260,5 @@ import TreeSitterP4
         withMessage:
           "{49, 22}: Failed to parse a statement element: Cannot initialize where_to (with type Boolean) from rvalue with type Int"
       ),
-      Program.Compile(simple_parser_declaration, withGlobalTypes: test_types)))
+      Program.Compile(simple_parser_declaration, withGlobalInstances: test_types)))
 }