...

compiler/NubLang/Generation/QBE/QBEGenerator.cs

@@ -693,6 +693,7 @@ public class QBEGenerator
             StructFuncCallNode expr => EmitStructFuncCall(expr),
             StructInitializerNode expr => EmitStructInitializer(expr),
             UnaryExpressionNode expr => EmitUnaryExpression(expr),
+            SizeCompilerMacroNode expr => $"{SizeOf(expr.TargetType)}",
             _ => throw new ArgumentOutOfRangeException(nameof(rValue))
         };
     }

compiler/NubLang/Modules/ModuleRepository.cs

@@ -42,6 +42,11 @@ public class ModuleRepository
                     module.RegisterStruct(structDef.Exported, structDef.Name, fields, functions);
                     break;
                 }
+                case StructTemplateSyntax structDef:
+                {
+                    // todo(nub31): Include templates in modules
+                    break;
+                }
                 default:
                 {
                     throw new ArgumentOutOfRangeException(nameof(definition));

compiler/NubLang/Parsing/Parser.cs

@@ -163,10 +163,20 @@ public sealed class Parser
         return new FuncSyntax(GetTokens(startIndex), name.Value, exported, externSymbol, signature, body);
     }
 
-    private StructSyntax ParseStruct(int startIndex, bool exported)
+    private DefinitionSyntax ParseStruct(int startIndex, bool exported)
     {
         var name = ExpectIdentifier();
 
+        var templateArguments = new List<string>();
+        if (TryExpectSymbol(Symbol.LessThan))
+        {
+            while (!TryExpectSymbol(Symbol.GreaterThan))
+            {
+                templateArguments.Add(ExpectIdentifier().Value);
+                TryExpectSymbol(Symbol.Comma);
+            }
+        }
+
         ExpectSymbol(Symbol.OpenBrace);
 
         List<StructFieldSyntax> fields = [];
@@ -207,6 +217,11 @@ public sealed class Parser
             }
         }
 
+        if (templateArguments.Count > 0)
+        {
+            return new StructTemplateSyntax(GetTokens(startIndex), templateArguments, name.Value, exported, fields, funcs);
+        }
+
         return new StructSyntax(GetTokens(startIndex), name.Value, exported, fields, funcs);
     }
 
@@ -462,6 +477,7 @@ public sealed class Parser
                 Symbol.OpenBracket => ParseArrayInitializer(startIndex),
                 Symbol.OpenBrace => new StructInitializerSyntax(GetTokens(startIndex), Optional<TypeSyntax>.Empty(), ParseStructInitializerBody()),
                 Symbol.Struct => ParseStructInitializer(startIndex),
+                Symbol.At => ParseCompilerMacro(startIndex),
                 _ => throw new ParseException(Diagnostic
                     .Error($"Unexpected symbol '{symbolToken.Symbol}' in expression")
                     .WithHelp("Expected '(', '-', '!', '[' or '{'")
@@ -478,6 +494,34 @@ public sealed class Parser
         return ParsePostfixOperators(expr);
     }
 
+    private ExpressionSyntax ParseCompilerMacro(int startIndex)
+    {
+        var name = ExpectIdentifier();
+        ExpectSymbol(Symbol.OpenParen);
+
+        switch (name.Value)
+        {
+            case "size":
+            {
+                var type = ParseType();
+                ExpectSymbol(Symbol.CloseParen);
+                return new SizeCompilerMacroSyntax(GetTokens(startIndex), type);
+            }
+            case "interpret":
+            {
+                var type = ParseType();
+                ExpectSymbol(Symbol.Comma);
+                var expression = ParseExpression();
+                ExpectSymbol(Symbol.CloseParen);
+                return new InterpretCompilerMacroSyntax(GetTokens(startIndex), type, expression);
+            }
+            default:
+            {
+                throw new ParseException(Diagnostic.Error("Unknown compiler macro").At(name).Build());
+            }
+        }
+    }
+
     private ExpressionSyntax ParseIdentifier(int startIndex, IdentifierToken identifier)
     {
         if (TryExpectSymbol(Symbol.DoubleColon))
@@ -699,13 +743,31 @@ public sealed class Parser
                     return new BoolTypeSyntax(GetTokens(startIndex));
                 default:
                 {
+                    var module = _moduleName;
+
                     if (TryExpectSymbol(Symbol.DoubleColon))
                     {
-                        var customTypeName = ExpectIdentifier().Value;
+                        var customTypeName = ExpectIdentifier();
-                        return new CustomTypeSyntax(GetTokens(startIndex), name.Value, customTypeName);
+                        module = name.Value;
+                        name = customTypeName;
                     }
 
-                    return new CustomTypeSyntax(GetTokens(startIndex), _moduleName, name.Value);
+                    var templateParameters = new List<TypeSyntax>();
+                    if (TryExpectSymbol(Symbol.LessThan))
+                    {
+                        while (!TryExpectSymbol(Symbol.GreaterThan))
+                        {
+                            templateParameters.Add(ParseType());
+                            TryExpectSymbol(Symbol.Comma);
+                        }
+                    }
+
+                    if (templateParameters.Count > 0)
+                    {
+                        return new TemplateTypeSyntax(GetTokens(startIndex), templateParameters, module, name.Value);
+                    }
+
+                    return new CustomTypeSyntax(GetTokens(startIndex), module, name.Value);
                 }
             }
         }

compiler/NubLang/Parsing/Syntax/DefinitionSyntax.cs

@@ -15,3 +15,5 @@ public record StructFieldSyntax(IEnumerable<Token> Tokens, string Name, TypeSynt
 public record StructFuncSyntax(IEnumerable<Token> Tokens, string Name, string? Hook, FuncSignatureSyntax Signature, BlockSyntax Body) : SyntaxNode(Tokens);
 
 public record StructSyntax(IEnumerable<Token> Tokens, string Name, bool Exported, List<StructFieldSyntax> Fields, List<StructFuncSyntax> Functions) : DefinitionSyntax(Tokens, Name, Exported);
+
+public record StructTemplateSyntax(IEnumerable<Token> Tokens, List<string> TemplateArguments, string Name, bool Exported, List<StructFieldSyntax> Fields, List<StructFuncSyntax> Functions) : DefinitionSyntax(Tokens, Name, Exported);

compiler/NubLang/Parsing/Syntax/ExpressionSyntax.cs

@@ -57,3 +57,7 @@ public record StructFieldAccessSyntax(IEnumerable<Token> Tokens, ExpressionSynta
 public record StructInitializerSyntax(IEnumerable<Token> Tokens, Optional<TypeSyntax> StructType, Dictionary<string, ExpressionSyntax> Initializers) : ExpressionSyntax(Tokens);
 
 public record DereferenceSyntax(IEnumerable<Token> Tokens, ExpressionSyntax Target) : ExpressionSyntax(Tokens);
+
+public record SizeCompilerMacroSyntax(IEnumerable<Token> Tokens, TypeSyntax Type) : ExpressionSyntax(Tokens);
+
+public record InterpretCompilerMacroSyntax(IEnumerable<Token> Tokens, TypeSyntax Type, ExpressionSyntax Target) : ExpressionSyntax(Tokens);

compiler/NubLang/Parsing/Syntax/TypeSyntax.cs

@@ -23,3 +23,5 @@ public record CStringTypeSyntax(IEnumerable<Token> Tokens) : TypeSyntax(Tokens);
 public record ArrayTypeSyntax(IEnumerable<Token> Tokens, TypeSyntax BaseType) : TypeSyntax(Tokens);
 
 public record CustomTypeSyntax(IEnumerable<Token> Tokens, string Module, string Name) : TypeSyntax(Tokens);
+
+public record TemplateTypeSyntax(IEnumerable<Token> Tokens, List<TypeSyntax> TemplateParameters, string Module, string Name) : TypeSyntax(Tokens);

compiler/NubLang/TypeChecking/Node/ExpressionNode.cs

@@ -77,3 +77,5 @@ public record DereferenceNode(TypeNode Type, ExpressionNode Expression) : LValue
 public record ConvertIntNode(TypeNode Type, ExpressionNode Value, IntTypeNode ValueType, IntTypeNode TargetType) : RValueExpressionNode(Type);
 
 public record ConvertFloatNode(TypeNode Type, ExpressionNode Value, FloatTypeNode ValueType, FloatTypeNode TargetType) : RValueExpressionNode(Type);
+
+public record SizeCompilerMacroNode(TypeNode Type, TypeNode TargetType) : RValueExpressionNode(Type);

compiler/NubLang/TypeChecking/Node/TypeNode.cs

@@ -1,4 +1,7 @@
-namespace NubLang.TypeChecking.Node;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace NubLang.TypeChecking.Node;
 
 public abstract class TypeNode : IEquatable<TypeNode>
 {
@@ -157,3 +160,34 @@ public class StringTypeNode : TypeNode
     public override bool Equals(TypeNode? other) => other is StringTypeNode;
     public override int GetHashCode() => HashCode.Combine(typeof(StringTypeNode));
 }
+
+public static class NameMangler
+{
+    public static string Mangle(params IEnumerable<TypeNode> types)
+    {
+        var readable = string.Join("_", types.Select(EncodeType));
+        return ComputeShortHash(readable);
+    }
+
+    private static string EncodeType(TypeNode node) => node switch
+    {
+        VoidTypeNode => "V",
+        BoolTypeNode => "B",
+        IntTypeNode i => (i.Signed ? "I" : "U") + i.Width,
+        FloatTypeNode f => "F" + f.Width,
+        CStringTypeNode => "CS",
+        StringTypeNode => "S",
+        PointerTypeNode p => "P" + EncodeType(p.BaseType),
+        ArrayTypeNode a => "A" + EncodeType(a.ElementType),
+        FuncTypeNode fn => "FN(" + string.Join(",", fn.Parameters.Select(EncodeType)) + ")" + EncodeType(fn.ReturnType),
+        StructTypeNode st => "ST(" + st.Module + "." + st.Name + ")",
+        _ => throw new NotSupportedException($"Cannot encode type: {node}")
+    };
+
+    private static string ComputeShortHash(string input)
+    {
+        var bytes = Encoding.UTF8.GetBytes(input);
+        var hash = SHA256.HashData(bytes);
+        return Convert.ToHexString(hash[..8]).ToLower();
+    }
+}

compiler/NubLang/TypeChecking/TypeChecker.cs

@@ -1,5 +1,6 @@
 using System.Diagnostics;
 using System.Globalization;
+using System.Security.Cryptography;
 using NubLang.Diagnostics;
 using NubLang.Modules;
 using NubLang.Parsing.Syntax;
@@ -15,6 +16,8 @@ public sealed class TypeChecker
 
     private readonly Stack<Scope> _scopes = [];
     private readonly Stack<TypeNode> _funcReturnTypes = [];
+    private readonly Dictionary<(string Module, string Name), TypeNode> _typeCache = new();
+    private readonly HashSet<(string Module, string Name)> _resolvingTypes = [];
 
     private Scope Scope => _scopes.Peek();
 
@@ -38,12 +41,26 @@ public sealed class TypeChecker
         Diagnostics.Clear();
         Definitions.Clear();
         ReferencedStructTypes.Clear();
+        _typeCache.Clear();
+        _resolvingTypes.Clear();
 
         foreach (var definition in _syntaxTree.Definitions)
         {
             try
             {
-                Definitions.Add(CheckDefinition(definition));
+                switch (definition)
+                {
+                    case FuncSyntax funcSyntax:
+                        Definitions.Add(CheckFuncDefinition(funcSyntax));
+                        break;
+                    case StructSyntax structSyntax:
+                        Definitions.Add(CheckStructDefinition(structSyntax));
+                        break;
+                    case StructTemplateSyntax:
+                        break;
+                    default:
+                        throw new ArgumentOutOfRangeException(nameof(definition));
+                }
             }
             catch (TypeCheckerException e)
             {
@@ -52,16 +69,6 @@ public sealed class TypeChecker
         }
     }
 
-    private DefinitionNode CheckDefinition(DefinitionSyntax node)
-    {
-        return node switch
-        {
-            FuncSyntax definition => CheckFuncDefinition(definition),
-            StructSyntax definition => CheckStructDefinition(definition),
-            _ => throw new ArgumentOutOfRangeException(nameof(node))
-        };
-    }
-
     private StructNode CheckStructDefinition(StructSyntax node)
     {
         var fieldTypes = node.Fields
@@ -77,9 +84,29 @@ public sealed class TypeChecker
         }
 
         var type = new StructTypeNode(_syntaxTree.Metadata.ModuleName, node.Name, fieldTypes, functionTypes);
+        var fields = node.Fields.Select(CheckStructField).ToList();
+        var functions = node.Functions.Select(x => CheckStructFunc(type, x)).ToList();
 
-        var fields = new List<StructFieldNode>();
+        return new StructNode(type, _syntaxTree.Metadata.ModuleName, node.Name, fields, functions);
-        foreach (var field in node.Fields)
+    }
+
+    private StructFuncNode CheckStructFunc(StructTypeNode type, StructFuncSyntax function, Scope? scope = null)
+    {
+        scope ??= new Scope();
+        scope.DeclareVariable(new Variable("this", type, VariableKind.FunctionParameter));
+
+        foreach (var parameter in function.Signature.Parameters)
+        {
+            scope.DeclareVariable(new Variable(parameter.Name, ResolveType(parameter.Type), VariableKind.FunctionParameter));
+        }
+
+        _funcReturnTypes.Push(ResolveType(function.Signature.ReturnType));
+        var body = CheckBlock(function.Body, scope);
+        _funcReturnTypes.Pop();
+        return new StructFuncNode(function.Name, CheckFuncSignature(function.Signature), body);
+    }
+
+    private StructFieldNode CheckStructField(StructFieldSyntax field)
     {
         var value = Optional.Empty<ExpressionNode>();
         if (field.Value.HasValue)
@@ -87,27 +114,7 @@ public sealed class TypeChecker
             value = CheckExpression(field.Value.Value, ResolveType(field.Type));
         }
 
-            fields.Add(new StructFieldNode(field.Name, ResolveType(field.Type), value));
+        return new StructFieldNode(field.Name, ResolveType(field.Type), value);
-        }
-
-        var functions = new List<StructFuncNode>();
-        foreach (var function in node.Functions)
-        {
-            var scope = new Scope();
-            scope.Declare(new Identifier("this", type, IdentifierKind.FunctionParameter));
-
-            foreach (var parameter in function.Signature.Parameters)
-            {
-                scope.Declare(new Identifier(parameter.Name, ResolveType(parameter.Type), IdentifierKind.FunctionParameter));
-            }
-
-            _funcReturnTypes.Push(ResolveType(function.Signature.ReturnType));
-            var body = CheckBlock(function.Body, scope);
-            _funcReturnTypes.Pop();
-            functions.Add(new StructFuncNode(function.Name, CheckFuncSignature(function.Signature), body));
-        }
-
-        return new StructNode(type, _syntaxTree.Metadata.ModuleName, node.Name, fields, functions);
     }
 
     private FuncNode CheckFuncDefinition(FuncSyntax node)
@@ -115,7 +122,7 @@ public sealed class TypeChecker
         var scope = new Scope();
         foreach (var parameter in node.Signature.Parameters)
         {
-            scope.Declare(new Identifier(parameter.Name, ResolveType(parameter.Type), IdentifierKind.FunctionParameter));
+            scope.DeclareVariable(new Variable(parameter.Name, ResolveType(parameter.Type), VariableKind.FunctionParameter));
         }
 
         var signature = CheckFuncSignature(node.Signature);
@@ -236,7 +243,7 @@ public sealed class TypeChecker
             throw new TypeCheckerException(Diagnostic.Error($"Cannot infer type of variable {statement.Name}").At(statement).Build());
         }
 
-        Scope.Declare(new Identifier(statement.Name, type, IdentifierKind.Variable));
+        Scope.DeclareVariable(new Variable(statement.Name, type, VariableKind.Variable));
 
         return new VariableDeclarationNode(statement.Name, Optional.OfNullable(assignmentNode), type);
     }
@@ -262,10 +269,10 @@ public sealed class TypeChecker
             case ArrayTypeNode arrayType:
             {
                 var scope = Scope.SubScope();
-                scope.Declare(new Identifier(statement.ElementIdent, arrayType.ElementType, IdentifierKind.FunctionParameter));
+                scope.DeclareVariable(new Variable(statement.ElementIdent, arrayType.ElementType, VariableKind.FunctionParameter));
                 if (statement.IndexIdent != null)
                 {
-                    scope.Declare(new Identifier(statement.ElementIdent, new IntTypeNode(true, 64), IdentifierKind.FunctionParameter));
+                    scope.DeclareVariable(new Variable(statement.ElementIdent, new IntTypeNode(true, 64), VariableKind.FunctionParameter));
                 }
 
                 var body = CheckBlock(statement.Body, scope);
@@ -273,7 +280,7 @@ public sealed class TypeChecker
             }
             default:
             {
-                throw new TypeCheckerException(Diagnostic.Error($"Type {target.Type} is not an iterable target").Build());
+                throw new TypeCheckerException(Diagnostic.Error($"Type {target.Type} is not an iterable target").At(statement.Target).Build());
             }
         }
     }
@@ -306,6 +313,8 @@ public sealed class TypeChecker
             LiteralSyntax expression => CheckLiteral(expression, expectedType),
             StructFieldAccessSyntax expression => CheckStructFieldAccess(expression),
             StructInitializerSyntax expression => CheckStructInitializer(expression, expectedType),
+            InterpretCompilerMacroSyntax expression => CheckExpression(expression.Target) with { Type = ResolveType(expression.Type) },
+            SizeCompilerMacroSyntax expression => new SizeCompilerMacroNode(new IntTypeNode(false, 64), ResolveType(expression.Type)),
             _ => throw new ArgumentOutOfRangeException(nameof(node))
         };
 
@@ -338,7 +347,7 @@ public sealed class TypeChecker
         var target = CheckExpression(expression.Target);
         if (target is not LValueExpressionNode lvalue)
         {
-            throw new TypeCheckerException(Diagnostic.Error("Cannot take address of an rvalue").Build());
+            throw new TypeCheckerException(Diagnostic.Error("Cannot take address of an rvalue").At(expression).Build());
         }
 
         var type = new PointerTypeNode(target.Type);
@@ -469,7 +478,7 @@ public sealed class TypeChecker
                 var operand = CheckExpression(expression.Operand);
                 if (operand.Type is not IntTypeNode { Signed: false } or FloatTypeNode)
                 {
-                    throw new TypeCheckerException(Diagnostic.Error("Negation operator must be used with signed integer or float types").Build());
+                    throw new TypeCheckerException(Diagnostic.Error("Negation operator must be used with signed integer or float types").At(expression).Build());
                 }
 
                 return new UnaryExpressionNode(operand.Type, UnaryOperator.Negate, operand);
@@ -479,7 +488,7 @@ public sealed class TypeChecker
                 var operand = CheckExpression(expression.Operand);
                 if (operand.Type is not BoolTypeNode)
                 {
-                    throw new TypeCheckerException(Diagnostic.Error("Invert operator must be used with booleans").Build());
+                    throw new TypeCheckerException(Diagnostic.Error("Invert operator must be used with booleans").At(expression).Build());
                 }
 
                 return new UnaryExpressionNode(operand.Type, UnaryOperator.Invert, operand);
@@ -580,22 +589,25 @@ public sealed class TypeChecker
             return new StructFuncCallNode(function.Type.ReturnType, expression.Name, structType, target, parameters);
         }
 
-        throw new TypeCheckerException(Diagnostic.Error($"No function {expression.Name} exists on type {target.Type}").Build());
+        throw new TypeCheckerException(Diagnostic
+            .Error($"No function {expression.Name} exists on type {target.Type}")
+            .At(expression)
+            .Build());
     }
 
     private ExpressionNode CheckLocalIdentifier(LocalIdentifierSyntax expression)
     {
         // First, look in the current scope for a matching identifier
-        var scopeIdent = Scope.Lookup(expression.Name);
+        var scopeIdent = Scope.LookupVariable(expression.Name);
         if (scopeIdent != null)
         {
             switch (scopeIdent.Kind)
             {
-                case IdentifierKind.Variable:
+                case VariableKind.Variable:
                 {
                     return new VariableIdentifierNode(scopeIdent.Type, expression.Name);
                 }
-                case IdentifierKind.FunctionParameter:
+                case VariableKind.FunctionParameter:
                 {
                     return new FuncParameterIdentifierNode(scopeIdent.Type, expression.Name);
                 }
@@ -624,7 +636,11 @@ public sealed class TypeChecker
     {
         if (!_visibleModules.TryGetValue(expression.Module, out var module))
         {
-            throw new TypeCheckerException(Diagnostic.Error($"Module {expression.Module} not found").WithHelp($"import \"{expression.Module}\"").At(expression).Build());
+            throw new TypeCheckerException(Diagnostic
+                .Error($"Module {expression.Module} not found")
+                .WithHelp($"import \"{expression.Module}\"")
+                .At(expression)
+                .Build());
         }
 
         var includePrivate = expression.Module == _syntaxTree.Metadata.ModuleName;
@@ -638,7 +654,10 @@ public sealed class TypeChecker
             return new FuncIdentifierNode(type, expression.Module, expression.Name, function.ExternSymbol);
         }
 
-        throw new TypeCheckerException(Diagnostic.Error($"No exported symbol {expression.Name} not found in module {expression.Module}").At(expression).Build());
+        throw new TypeCheckerException(Diagnostic
+            .Error($"No exported symbol {expression.Name} not found in module {expression.Module}")
+            .At(expression)
+            .Build());
     }
 
     private ExpressionNode CheckLiteral(LiteralSyntax expression, TypeNode? expectedType)
@@ -825,16 +844,74 @@ public sealed class TypeChecker
             ArrayTypeSyntax arr => new ArrayTypeNode(ResolveType(arr.BaseType)),
             PointerTypeSyntax ptr => new PointerTypeNode(ResolveType(ptr.BaseType)),
             StringTypeSyntax => new StringTypeNode(),
+            TemplateTypeSyntax template => ResolveTemplateType(template),
             VoidTypeSyntax => new VoidTypeNode(),
             _ => throw new NotSupportedException($"Unknown type syntax: {type}")
         };
     }
 
-    private readonly Dictionary<(string Module, string Name), TypeNode> _typeCache = new();
+    private StructTypeNode ResolveTemplateType(TemplateTypeSyntax template)
-    private readonly HashSet<(string Module, string Name)> _resolvingTypes = [];
+    {
+        // todo(nub31): Add module support for template types
+        var definition = _syntaxTree.Definitions
+            .OfType<StructTemplateSyntax>()
+            .FirstOrDefault(x => x.Name == template.Name);
+
+        if (definition == null)
+        {
+            throw new TypeCheckerException(Diagnostic.Error($"Template {template.Name} does not exist").At(template).Build());
+        }
+
+        if (definition.TemplateArguments.Count != template.TemplateParameters.Count)
+        {
+            throw new TypeCheckerException(Diagnostic
+                .Error($"Template {template.Name} has {definition.TemplateArguments.Count} arguments, but usage only has {template.TemplateParameters.Count} parameters")
+                .At(template)
+                .Build());
+        }
+
+        var scope = new Scope();
+
+        for (var i = 0; i < definition.TemplateArguments.Count; i++)
+        {
+            scope.DeclareGenericType(definition.TemplateArguments[i], ResolveType(template.TemplateParameters[i]));
+        }
+
+        _scopes.Push(scope);
+
+        var fields = definition.Fields
+            .Select(x => new StructTypeField(x.Name, ResolveType(x.Type), x.Value.HasValue))
+            .ToList();
+
+        var functions = definition.Functions
+            .Select(x => new StructTypeFunc(x.Name, x.Hook, new FuncTypeNode(x.Signature.Parameters.Select(y => ResolveType(y.Type)).ToList(), ResolveType(x.Signature.ReturnType))))
+            .ToList();
+
+        var name = $"{template.Name}.{NameMangler.Mangle(template.TemplateParameters.Select(ResolveType))}";
+
+        var type = new StructTypeNode(template.Module, name, fields, functions);
+
+        var checkedFields = definition.Fields.Select(CheckStructField).ToList();
+        var checkedFunctions = definition.Functions.Select(x => CheckStructFunc(type, x, scope)).ToList();
+
+        Definitions.Add(new StructNode(type, template.Module, name, checkedFields, checkedFunctions));
+
+        _scopes.Pop();
+
+        return type;
+    }
 
     private TypeNode ResolveCustomType(CustomTypeSyntax customType)
     {
+        if (_syntaxTree.Metadata.ModuleName == customType.Module && _scopes.TryPeek(out var scope))
+        {
+            var generic = scope.LookupGenericType(customType.Name);
+            if (generic != null)
+            {
+                return generic;
+            }
+        }
+
         var key = (customType.Module, customType.Name);
 
         if (_typeCache.TryGetValue(key, out var cachedType))
@@ -853,7 +930,11 @@ public sealed class TypeChecker
         {
             if (!_visibleModules.TryGetValue(customType.Module, out var module))
             {
-                throw new TypeCheckerException(Diagnostic.Error($"Module {customType.Module} not found").WithHelp($"import \"{customType.Module}\"").At(customType).Build());
+                throw new TypeCheckerException(Diagnostic
+                    .Error($"Module {customType.Module} not found")
+                    .WithHelp($"import \"{customType.Module}\"")
+                    .At(customType)
+                    .Build());
             }
 
             var includePrivate = customType.Module == _syntaxTree.Metadata.ModuleName;
@@ -878,7 +959,10 @@ public sealed class TypeChecker
                 return result;
             }
 
-            throw new TypeCheckerException(Diagnostic.Error($"Type {customType.Name} not found in module {customType.Module}").At(customType).Build());
+            throw new TypeCheckerException(Diagnostic
+                .Error($"Type {customType.Name} not found in module {customType.Module}")
+                .At(customType)
+                .Build());
         }
         finally
         {
@@ -887,19 +971,20 @@ public sealed class TypeChecker
     }
 }
 
-public enum IdentifierKind
+public enum VariableKind
 {
     Variable,
     FunctionParameter
 }
 
-public record Identifier(string Name, TypeNode Type, IdentifierKind Kind);
+public record Variable(string Name, TypeNode Type, VariableKind Kind);
 
 public class Scope(Scope? parent = null)
 {
-    private readonly List<Identifier> _variables = [];
+    private readonly List<Variable> _variables = [];
+    private readonly Dictionary<string, TypeNode> _typeArguments = [];
 
-    public Identifier? Lookup(string name)
+    public Variable? LookupVariable(string name)
     {
         var variable = _variables.FirstOrDefault(x => x.Name == name);
         if (variable != null)
@@ -907,12 +992,22 @@ public class Scope(Scope? parent = null)
             return variable;
         }
 
-        return parent?.Lookup(name);
+        return parent?.LookupVariable(name);
     }
 
-    public void Declare(Identifier identifier)
+    public void DeclareVariable(Variable variable)
     {
-        _variables.Add(identifier);
+        _variables.Add(variable);
+    }
+
+    public void DeclareGenericType(string typeArgument, TypeNode type)
+    {
+        _typeArguments[typeArgument] = type;
+    }
+
+    public TypeNode? LookupGenericType(string typeArgument)
+    {
+        return _typeArguments.GetValueOrDefault(typeArgument);
     }
 
     public Scope SubScope()

example/src/main.nub

@@ -1,8 +1,8 @@
 module "main"
 
 extern "puts" func puts(text: cstring)
-extern "malloc" func malloc(size: u64): ^u64
+extern "malloc" func malloc(size: u64): ^void
-extern "free" func free(address: ^u64)
+extern "free" func free(address: ^void)
 
 struct Human
 {
@@ -11,29 +11,29 @@ struct Human
 
 extern "main" func main(args: []cstring): i64
 {
-    let x: ref = {}
+    let x: ref<Human> = {}
 
     test(x)
 
     return 0
 }
 
-func test(x: ref)
+func test(x: ref<Human>)
 {
 
 }
 
-struct ref
+struct ref<T>
 {
-    value: ^u64
+    value: ^T
     count: ^u64
 
     @oncreate
     func on_create()
     {
         puts("on_create")
-        this.value = malloc(8)
+        this.value = @interpret(^T, malloc(@size(T)))
-        this.count = malloc(8)
+        this.count = @interpret(^u64, malloc(@size(u64)))
         this.count^ = 1
     }
 
@@ -52,8 +52,8 @@ struct ref
         if this.count^ <= 0
         {
             puts("free")
-            free(this.value)
+            free(@interpret(^void, this.value))
-            free(this.count)
+            free(@interpret(^void, this.count))
         }
     }
 }