Refactor Type System

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>

README.md

@@ -10,3 +10,20 @@ Very, very alpha:
 2. Limited programs can be evaluated.
 
 Please check back often!
+
+### Building
+
+#### Generating Documentation
+
+To build the documentation:
+
+```console
+$ swift package generate-documentation
+```
+
+To preview the generated documentation:
+```console
+$ swift package swift package --disable-sandbox preview-documentation  --target <some target>
+```
+
+For more information, see the [documentation for the Swift-DocC plugin](https://swiftlang.github.io/swift-docc-plugin/documentation/swiftdoccplugin/).

Sources/Common/ProgramTypes.swift

@@ -15,85 +15,171 @@
 // You should have received a copy of the GNU General Public License
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
-
+/// A P4 identifier
 public class Identifier: CustomStringConvertible, Equatable {
-    var name: String
+  var name: String
 
-    public init(name: String) {
+  public init(name: String) {
-        self.name = name
+    self.name = name
-    }
+  }
 
-    public var description: String {
+  public var description: String {
-        return "\(name)"
+    return "\(name)"
-    }
+  }
 
-    public static func ==(lhs: Identifier, rhs: Identifier) -> Bool {
+  public static func == (lhs: Identifier, rhs: Identifier) -> Bool {
-        return lhs.name == rhs.name
+    return lhs.name == rhs.name
-    }
+  }
 }
 
+/// A P4 variable
 public class Variable: Identifier {
-    var constant: Bool
+  var constant: Bool
-    var value: ValueType
+  var value: P4Value
 
-    public init(name: String, withValue value: ValueType, isConstant constant: Bool) {
+  public init(name: String, withValue value: P4Value, isConstant constant: Bool) {
-        self.constant = constant
+    self.constant = constant
-        self.value = value
+    self.value = value
-        super.init(name: name)
+    super.init(name: name)
-    }
+  }
 
-    public override var description: String {
+  public override var description: String {
-        return "\(super.description) = \(value) \(constant ? "(constant)" : "")"
+    return "\(super.description) = \(value) \(constant ? "(constant)" : "")"
-    }
+  }
 
-    public var value_type: ValueType {
+  public var value_type: P4Value {
-        get {
+    value
-            value
+  }
-        }
-    }
 }
 
-public enum ValueType: CustomStringConvertible, Equatable {
+/// A base for all instances of P4 types
-    case Boolean(Bool)
+open class P4ValueBase<T: P4Type>: P4Value {
-    case Int(Int)
-    case String(String)
 
-    public var description: String {
+  public init() {}
-        switch self {
-            case ValueType.Boolean(let b):
-                return "\(b) of Boolean"
-            case ValueType.Int(let i):
-                return "\(i) of Int"
-            case ValueType.String(let s):
-                return "\(s) of String"
-        }
-    }
-
-    public static func==(lhs: ValueType, rhs: ValueType) -> Bool {
-        switch (lhs,rhs) {
-            case (ValueType.Boolean(let lhsb), ValueType.Boolean(let rhsb)):
-                return lhsb == rhsb
-            case (ValueType.String(let lhsb), ValueType.String(let rhsb)):
-                return lhsb == rhsb
-            case (ValueType.Int(let lhsb), ValueType.Int(let rhsb)):
-                return lhsb == rhsb
-            default: return false
-        }
-    }
 
+  public func type() -> P4Type {
+    return T.create()
+  }
+  public func eq(rhs: P4Value) -> Bool {
+    return false
+  }
 }
 
-public struct Value: CustomStringConvertible {
+/// The type for a P4 struct
-    public var value_type: ValueType
+public struct P4Struct: P4Type {
+  public let name: String
+  // The type of the struct created is always anonymous.
+  public static func create() -> any P4Type {
+    return P4Struct()
+  }
 
-    public init(withValue value: ValueType) {
+  public init(withName name: String) {
-        self.value_type = value
+    self.name = name
+  }
+  public init() {
+    self.name = ""
+  }
+}
+
+/// The field of a P4 struct
+public struct P4StructField {
+  public let name: Identifier
+  public let type: P4Type
+
+  public init(withName name: Identifier, withType type: P4Type) {
+    self.name = name
+    self.type = type
+  }
+}
+
+/// An instance of a P4 struct
+public class P4StructValue: P4ValueBase<P4Struct> {
+  public let fields: [P4StructField]
+  public init(withFields fields: [P4StructField]) {
+    self.fields = fields
+  }
+}
+
+/// A P4 boolean type
+public struct P4Boolean: P4Type {
+  public static func create() -> any P4Type {
+    return P4Boolean()
+  }
+}
+
+/// An instance of a P4 boolean
+public class P4BooleanValue: P4ValueBase<P4Boolean> {
+  let value: Bool
+
+  public init(withValue value: Bool) {
+    self.value = value
+  }
+  public override func eq(rhs: P4Value) -> Bool {
+    guard let bool_rhs = rhs as? P4BooleanValue else {
+      return false
     }
-    public var description: String {
+    return self.value == bool_rhs.value
-        return "\(value_type)"
+  }
+}
+
+/// A P4 int type
+public struct P4Int: P4Type {
+  public static func create() -> any P4Type {
+    return P4Int()
+  }
+}
+
+/// An instance of a P4 integer
+public class P4IntValue: P4ValueBase<P4Int> {
+  let value: Int
+  public init(withValue value: Int) {
+    self.value = value
+  }
+  public override func eq(rhs: P4Value) -> Bool {
+    guard let int_rhs = rhs as? P4IntValue else {
+      return false
     }
+    return self.value == int_rhs.value
+  }
+}
+
+/// A P4 string type
+public struct P4String: P4Type {
+  public static func create() -> any P4Type {
+    return P4String()
+  }
+}
+/// An instance of a P4 string
+public class P4StringValue: P4ValueBase<P4String> {
+  let value: String
+  public init(withValue value: String) {
+    self.value = value
+  }
+  public override func eq(rhs: P4Value) -> Bool {
+    guard let string_rhs = rhs as? P4StringValue else {
+      return false
+    }
+    return self.value == string_rhs.value
+  }
+}
+
+/// A P4 value (with a type)
+public struct Value: CustomStringConvertible, Equatable {
+  public var type: P4Type
+  public var value: P4Value
+
+  public init(withValue value: P4Value, andType type: P4Type) {
+    self.value = value
+    self.type = type
+  }
+  public var description: String {
+    return "\(self.value) of \(self.type)"
+  }
+  public static func == (lhs: Value, rhs: Value) -> Bool {
+    return lhs.value.eq(rhs: rhs.value)
+  }
 }
 
 public class Packet {
-    public init() {}
+  public init() {}
 }

Sources/Common/Protocols.swift

@@ -20,7 +20,7 @@ public protocol EvaluatableExpression {
     /// - Parameters
     ///  - execution: The execution context in which to evaluate the expression
     /// - Returns: The value of expression
-    func evaluate(execution: ProgramExecution) -> ValueType
+    func evaluate(execution: ProgramExecution) -> P4Value
 }
 
 public protocol EvaluatableParserStatement {
@@ -31,3 +31,11 @@ public protocol EvaluatableParserStatement {
     func evaluate(execution: ProgramExecution) -> ProgramExecution
 }
 
+public protocol P4Type {
+    static func create() -> P4Type
+}
+
+public protocol P4Value {
+    func type() -> P4Type
+    func eq(rhs: P4Value) -> Bool
+}

Sources/Lang/Instantiation.swift

@@ -0,0 +1,22 @@
+// 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 struct Instantiation {
+
+}

Sources/Lang/Parser.swift

@@ -85,13 +85,21 @@ public struct ParserStates {
 nonisolated(unsafe) public let accept: ParserState = ParserState(name: "accept")
 nonisolated(unsafe) public let reject: ParserState = ParserState(name: "reject")
 
-public struct Parser {
+public struct Parser: P4Type {
   public var states: [ParserState] = Array()
   public var count: Int {
     states.count
   }
 
-  public init() {}
+  public var name: Identifier
+
+  public init(withName name: Identifier) {
+    self.name = name
+  }
+
+  public static func create() -> any P4Type {
+    return Parser(withName: Identifier(name: ""))
+  }
 
   public func findStartState() -> ParserState? {
     for state in states {
@@ -103,25 +111,25 @@ public struct Parser {
   }
 }
 
-public class ParserExecution: ProgramExecution {
+public class ParserInstance: ProgramExecution {
 
     private init(state: ParserState) {
       self.state = state
       super.init()
     }
 
-    public static func create(_ parser: Parser) -> Result<ParserExecution> {
+    public static func create(_ parser: Parser) -> Result<ParserInstance> {
         guard let start_state = parser.findStartState() else {
             return Result.Error(Error(withMessage: "Could not find the start state"))
         }
-        let new = ParserExecution(state: start_state)
+        let new = ParserInstance(state: start_state)
 
         return Result.Ok(new)
     }
 
     public var state: ParserState
 
-    public func transition(toNextState state: ParserState) -> ParserExecution {
+    public func transition(toNextState state: ParserState) -> ParserInstance {
         let next = self
         next.state = state
         return next

Sources/Lang/Program.swift

@@ -15,7 +15,30 @@
 // 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 struct Program {
-    public var parsers: [Parser] = Array()
+    public var types: [P4Type] = Array()
+
+    /// Find the program's main parser
+    /// 
+    /// Note: For now, the main parser is expected to be named main_parser.
+    public func starting_parser() -> Result<Parser> {
+        return self.find_parser(withName: Identifier(name: "main_parser"))
+    }
+
+    public func find_parser(withName name: Identifier) -> Result<Parser> {
+        for type in self.types {
+            print("type: \(type)")
+            guard let parser = type as? Parser else {
+                continue
+            }
+            if parser.name == name {
+                return .Ok(parser)
+            }
+        }
+        return .Error(Error(withMessage: "Could not find parser named \(name)"))
+    }
+
     public init() {}
 }

Sources/Parser/Parser.swift

@@ -24,45 +24,6 @@ import TreeSitterP4
 
 let p4lang = Language(tree_sitter_p4())
 
-public protocol ParseableValueType {
-  static func Parse(type: String, withValue value: String) -> Result<ValueType>
-}
-
-// This seems unnecessary because all the value types are in a single enum?
-extension ValueType: ParseableValueType {
-  public static func Parse(type: String, withValue value: String) -> Result<ValueType> {
-    if type == "bool" {
-      // Default
-      if value == "" {
-        return .Ok(ValueType.Boolean(false))
-      }
-
-      if value == "true" {
-        return .Ok(ValueType.Boolean(true))
-      } else if value == "false" {
-        return .Ok(ValueType.Boolean(false))
-      }
-      return .Error(Error(withMessage: "Cannot convert \(value) into boolean value"))
-
-    } else if type == "string" {
-      return .Ok(ValueType.String(value))
-
-    } else if type == "int" {
-      // Default
-      if value == "" {
-        return .Ok(ValueType.Int(0))
-      }
-
-      guard let parsed_value = Swift.Int(value) else {
-        return .Error(Error(withMessage: "Cannot convert \(value) into integer value"))
-      }
-      return .Ok(ValueType.Int(parsed_value))
-    }
-
-    return .Error(Error(withMessage: "Invalid type"))
-  }
-}
-
 public protocol ParseableParserStatement {
   static func Parse(node: Node, inTree tree: MutableTree) -> Result<EvaluatableParserStatement?>
 }
@@ -129,7 +90,7 @@ extension VariableDeclarationStatement: ParseableParserStatement {
         ""
       }
 
-    return switch ValueType.Parse(type: type_name, withValue: value) {
+    return switch Parser.ParseValueType(type: type_name, withValue: value) {
     case Result.Ok(let value_type):
       Result.Ok(
         VariableDeclarationStatement(
@@ -141,6 +102,37 @@ extension VariableDeclarationStatement: ParseableParserStatement {
 }
 
 public struct Parser {
+  static func ParseValueType(type: String, withValue value: String) -> Result<P4Value> {
+    if type == "bool" {
+      // Default
+      if value == "" {
+        return .Ok(P4BooleanValue(withValue: false))
+      }
+
+      if value == "true" {
+        return .Ok(P4BooleanValue(withValue: true))
+      } else if value == "false" {
+        return .Ok(P4BooleanValue(withValue: false))
+      }
+      return .Error(Error(withMessage: "Cannot convert \(value) into boolean value"))
+
+    } else if type == "string" {
+      return .Ok(P4StringValue.init(withValue: value))
+
+    } else if type == "int" {
+      // Default
+      if value == "" {
+        return .Ok(P4IntValue.init(withValue: 0))
+      }
+
+      guard let parsed_value = Swift.Int(value) else {
+        return .Error(Error(withMessage: "Cannot convert \(value) into integer value"))
+      }
+      return .Ok(P4IntValue.init(withValue: parsed_value))
+    }
+
+    return .Error(Error(withMessage: "Invalid type"))
+  }
 
   public struct P4Parser {
 
@@ -305,7 +297,7 @@ public struct Parser {
           withTransition: transition_statement))
     }
   }
-  static func Parser(node: Node, inTree tree: MutableTree) -> Result<Lang.Parser> {
+  static func Parser(withName name: Identifier, node: Node, inTree tree: MutableTree) -> Result<Lang.Parser> {
     guard
       let parser_state_query = try? SwiftTreeSitter.Query(
         language: p4lang,
@@ -317,7 +309,7 @@ public struct Parser {
         Error(withMessage: "Could not compile the parser state tree sitter query"))
     }
 
-    var parser = Lang.Parser()
+    var parser = Lang.Parser(withName: name)
 
     // Build a state from each one listed.
     for parser_states in parser_state_query.execute(node: node, in: tree) {
@@ -340,7 +332,8 @@ public struct Parser {
 
     let result = p.parse(source)
     guard let tree = result,
-      !tree.isError(lang: p4lang)
+      !tree.isError(lang: p4lang),
+      !tree.containsMissing(lang: p4lang)
     else {
       return Result.Error(Error(withMessage: "Could not compile the P4 program"))
     }
@@ -349,7 +342,7 @@ public struct Parser {
       let parser_declaration_query = try? SwiftTreeSitter.Query(
         language: p4lang,
         data: String(
-          "(parserDeclaration (parserType) (parserStates) @parser-states)"
+          "(parserDeclaration (parserType parser_name: (identifier) @parser-name) (parserStates) @parser-states)"
         ).data(using: String.Encoding.utf8)!)
     else {
       return Result.Error(
@@ -361,8 +354,8 @@ public struct Parser {
     let parser_qc = parser_declaration_query.execute(in: tree)
 
     for parser_declaration in parser_qc {
-      switch Parser(node: parser_declaration.nodes[0], inTree: tree) {
+      switch Parser(withName: Identifier(name: parser_declaration.nodes[0].text!), node: parser_declaration.nodes[1], inTree: tree) {
-      case Result.Ok(let parser): program.parsers.append(parser)
+      case Result.Ok(let parser): program.types.append(parser)
       case Result.Error(let error): return Result.Error(error)
       }
     }

Sources/Runtime/Runtime.swift

@@ -18,33 +18,39 @@
 import Common
 import Lang
 
+/// The runtime for a parser
 public class ParserRuntime: CustomStringConvertible {
-  var execution: ParserExecution
+  var execution: ParserInstance
 
-  init(execution: ParserExecution) {
+  init(execution: ParserInstance) {
     self.execution = execution
   }
 
-  public static func create(program: Lang.Parser) -> Result<ParserRuntime> {
+  /// Create a parser runtime from a P4 program
-    switch ParserExecution.create(program) {
+  public static func create(program: Lang.Program) -> Result<ParserRuntime> {
-    case .Ok(let execution): return .Ok(Runtime.ParserRuntime(execution: execution))
+    return switch program.starting_parser() {
-    case .Error(let error): return .Error(error)
+    case .Ok(let parser):
-
+      switch ParserInstance.create(parser) {
+      case .Ok(let execution): .Ok(Runtime.ParserRuntime(execution: execution))
+      case .Error(let error): .Error(error)
+      }
+    case .Error(let error): .Error(error)
     }
   }
 
+  /// Run the P4 parser on a given packet
   public func run(input: Packet) -> Result<(ParserState, ProgramExecution)> {
     execution.scopes.enter()
     return .Ok(execution.execute())
   }
 
   public var description: String {
-    //return "\(super.description)\nState: \(execution?.description ?? "N/A")\nError: \(error?.description ?? "None")"
     return "Runtime:\nExecution: \(execution)"
   }
 }
 
-extension ParserExecution: Execution {
+/// Instances of parsers are executable
+extension ParserInstance: Execution {
   public func execute() -> (ParserState, ProgramExecution) {
     var execution = self as ProgramExecution
     var state = self.state

Sources/TreeSitterExtensions/Extensions.swift

@@ -35,5 +35,21 @@ extension MutableTree {
     }
     return false
   }
-}
+  public func containsMissing(lang: Language) -> Bool {
+    guard
+    let parser_error_query = try? SwiftTreeSitter.Query(
+        language: lang,
+        data: String(
+          "(MISSING)"
+        ).data(using: String.Encoding.utf8)!)
+    else {
+      return false
+    }
 
+    let error_qr = parser_error_query.execute(in: self)
+    for _ in error_qr {
+      return true
+    }
+    return false
+  }
+}

Tests/p4lmTests/ParserTests.swift

@@ -29,47 +29,66 @@ import Macros
 
 @Test func test_simple_parser() async throws {
     let simple_parser_declaration = """
-        parser simple() {
+        parser main_parser() {
            state start {
                transition drop;
            }
-        }
+        };
         """
 
     let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
+    let parser = try #UseOkResult(program.find_parser(withName: Identifier(name: "main_parser")))
 
-    #expect(program.parsers.count == 1)
+    #expect(parser.states.count == 1)
-    #expect(program.parsers[0].states.count == 1)
+    #expect(parser.states[0].state_name == "start")
-    #expect(program.parsers[0].states[0].state_name == "start")
+    #expect(parser.states[0].statements.count == 0)
-    #expect(program.parsers[0].states[0].statements.count == 0)
 }
 
 @Test func test_simple_parser_syntax_error() async throws {
     let simple_parser_declaration = """
-        parser simple() {
+        parser main_parser() {
            state
                transition drop;
            }
-        }
+        };
         """
     #expect(#RequireErrorResult(Error(withMessage: "Could not compile the P4 program"), Parser.Program(simple_parser_declaration)))
 }
 
 @Test func test_simple_parser_with_statement() async throws {
     let simple_parser_declaration = """
-        parser simple() {
+        parser main_parser() {
            state start {
                true;
                transition drop;
            }
-        }
+        };
+        """
+
+    let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
+    let parser = try #UseOkResult(program.find_parser(withName: Identifier(name: "main_parser")))
+
+    #expect(parser.states.count == 1)
+    #expect(parser.states[0].state_name == "start")
+    #expect(parser.states[0].statements.count == 1)
+}
+
+@Test func test_simple_parser_with_instantiation() async throws {
+    let simple_parser_declaration = """
+        parser main_parser() {
+           state start {
+               true;
+               transition drop;
+           }
+        };
+        bool() main;
         """
 
     let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
 
-    #expect(program.parsers.count == 1)
+    let parser = try #UseOkResult(program.find_parser(withName: Identifier(name: "main_parser")))
-    #expect(program.parsers[0].states.count == 1)
+    #expect(parser.states.count == 1)
-    #expect(program.parsers[0].states[0].state_name == "start")
+    #expect(parser.states[0].state_name == "start")
-    #expect(program.parsers[0].states[0].statements.count == 1)
+    #expect(parser.states[0].statements.count == 1)
 }
 

Tests/p4lmTests/RuntimeTests.swift

@@ -15,11 +15,11 @@
 // 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 Foundation
-import Runtime
 import Common
+import Foundation
 import Lang
 import Macros
+import Runtime
 import SwiftTreeSitter
 import Testing
 import TreeSitter
@@ -28,77 +28,75 @@ import TreeSitterP4
 @testable import Parser
 
 @Test func test_simple_runtime() async throws {
-    let simple_parser_declaration = """
+  let simple_parser_declaration = """
-        parser simple() {
+    parser main_parser() {
-           state start {
+       state start {
-               true;
+           true;
-               transition reject;
+           transition reject;
-           }
+       }
-        }
+    };
-        """
+    """
 
-    let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
+  let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
-    #expect(#RequireOkResult(Runtime.ParserRuntime.create(program: program.parsers[0])))
+  #expect(#RequireOkResult(Runtime.ParserRuntime.create(program: program)))
 }
 
 @Test func test_simple_runtime_no_start_state() async throws {
-    let simple_parser_declaration = """
+  let simple_parser_declaration = """
-        parser simple() {
+    parser main_parser() {
-           state tart {
+       state tart {
-               true;
+           true;
-               transition reject;
+           transition reject;
-           }
+       }
-        }
+    };
-        """
+    """
 
-    let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
+  let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
-    #expect(
+  #expect(
-        #RequireErrorResult<ParserRuntime>(
+    #RequireErrorResult<ParserRuntime>(
-            Error(withMessage: "Could not find the start state"),
+      Error(withMessage: "Could not find the start state"),
-            Runtime.ParserRuntime.create(program: program.parsers[0])))
+      Runtime.ParserRuntime.create(program: program)))
 }
 
 @Test func test_simple_local_element_variable_declaration() async throws {
-    let simple_parser_declaration = """
+  let simple_parser_declaration = """
-        parser simple() {
+    parser main_parser() {
-           state start {
+       state start {
-               bool b = false;
+           bool b = false;
-               string s = "testing";
+           string s = "testing";
-               true;
+           true;
-               false;
+           false;
-               transition reject;
+           transition reject;
-           }
+       }
-        }
+    };
-        """
+    """
 
-    let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
+  let program = try #UseOkResult(Parser.Program(simple_parser_declaration))
-    let runtime = try #UseOkResult(Runtime.ParserRuntime.create(program: program.parsers[0]))
+  let runtime = try #UseOkResult(Runtime.ParserRuntime.create(program: program))
 
-    // This seems awkward to me!
+  // This seems awkward to me!
-    // TODO: Is there a better way?
+  // TODO: Is there a better way?
-    guard case Common.Result.Ok(let (state_result, execution_result)) = runtime.run(input: Packet()) else {
+  guard case Common.Result.Ok(let (state_result, execution_result)) = runtime.run(input: Packet())
-        assert(false)
+  else {
-    }
+    assert(false)
+  }
 
-    // There should be 1 scope.
+  // There should be 1 scope.
-    #expect(execution_result.scopes.count == 1)
+  #expect(execution_result.scopes.count == 1)
 
-    guard let scope = execution_result.scopes.current else {
+  guard let scope = execution_result.scopes.current else {
-        assert(false)
+    assert(false)
-    }
+  }
-
-    // We should be in the accept state.
-    #expect(state_result == Lang.accept)
-
-    // There are two variables declared.
-    #expect(scope.count == 2)
-
-    // Check the names/values of the variables in scope.
-    let b = try #require(scope.lookup(identifier: Identifier(name: "b")))
-    let s = try #require(scope.lookup(identifier: Identifier(name: "s")))
-    #expect(b.value_type == ValueType.Boolean(false))
-    #expect(s.value_type == ValueType.String("\"testing\""))
 
+  // We should be in the accept state.
+  #expect(state_result == Lang.accept)
 
+  // There are two variables declared.
+  #expect(scope.count == 2)
 
+  // Check the names/values of the variables in scope.
+  let b = try #require(scope.lookup(identifier: Identifier(name: "b")))
+  let s = try #require(scope.lookup(identifier: Identifier(name: "s")))
+  #expect(b.value_type.eq(rhs: P4BooleanValue(withValue: false)))
+  #expect(s.value_type.eq(rhs: P4StringValue(withValue: "\"testing\"")))
 }