...

src/compiler/NubLang/Generation/QBE/QBEGenerator.Expression.cs

@@ -48,7 +48,7 @@ public partial class QBEGenerator
         var elementType = ((ArrayTypeNode)arrayIndexAccess.Target.Type).ElementType;
 
         var pointer = TmpName();
-        _writer.Indented($"{pointer} =l mul {index}, {elementType.Size(_definitionTable)}");
+        _writer.Indented($"{pointer} =l mul {index}, {SizeOf(elementType)}");
         _writer.Indented($"{pointer} =l add {pointer}, 8");
         _writer.Indented($"{pointer} =l add {array}, {pointer}");
         return new Val(pointer, arrayIndexAccess.Type, ValKind.Pointer);
@@ -81,7 +81,7 @@ public partial class QBEGenerator
     private Val EmitArrayInitializer(ArrayInitializerNode arrayInitializer)
     {
         var capacity = EmitUnwrap(EmitExpression(arrayInitializer.Capacity));
-        var elementSize = arrayInitializer.ElementType.Size(_definitionTable);
+        var elementSize = SizeOf(arrayInitializer.ElementType);
 
         var capacityInBytes = TmpName();
         _writer.Indented($"{capacityInBytes} =l mul {capacity}, {elementSize}");
@@ -291,7 +291,7 @@ public partial class QBEGenerator
             }
             case LiteralKind.String:
             {
-                if (literal.Type is NubStringTypeNode)
+                if (literal.Type is StringTypeNode)
                 {
                     var stringLiteral = new StringLiteral(literal.Value, StringName());
                     _stringLiterals.Add(stringLiteral);
@@ -328,7 +328,7 @@ public partial class QBEGenerator
         if (destination == null)
         {
             destination = TmpName();
-            var size = structInitializer.StructType.Size(_definitionTable);
+            var size = SizeOf(structInitializer.StructType);
 
             if (structDef.InterfaceImplementations.Any())
             {
@@ -413,7 +413,7 @@ public partial class QBEGenerator
         _writer.Indented($"{output} =l add {target}, {offset}");
 
         // If the accessed member is an inline struct, it will not be a pointer
-        if (structFieldAccess.Type is CustomTypeNode customType && customType.Kind(_definitionTable) == CustomTypeKind.Struct)
+        if (structFieldAccess.Type is StructTypeNode)
         {
             return new Val(output, structFieldAccess.Type, ValKind.Direct);
         }

src/compiler/NubLang/Generation/QBE/QBEGenerator.cs

@@ -189,7 +189,7 @@ public partial class QBEGenerator
     {
         var size = TmpName();
         _writer.Indented($"{size} =l loadl {array}");
-        _writer.Indented($"{size} =l mul {size}, {type.ElementType.Size(_definitionTable)}");
+        _writer.Indented($"{size} =l mul {size}, {SizeOf(type.ElementType)}");
         _writer.Indented($"{size} =l add {size}, 8");
         return size;
     }
@@ -250,9 +250,9 @@ public partial class QBEGenerator
         }
         else
         {
-            if (complexType is CustomTypeNode customType)
+            if (complexType is StructTypeNode structType)
             {
-                EmitMemcpy(value, destinationPointer, customType.Size(_definitionTable).ToString());
+                EmitMemcpy(value, destinationPointer, SizeOf(structType).ToString());
             }
             else
             {
@@ -260,7 +260,8 @@ public partial class QBEGenerator
                 {
                     ArrayTypeNode arrayType => EmitArraySizeInBytes(arrayType, value),
                     CStringTypeNode => EmitCStringSizeInBytes(value),
-                    NubStringTypeNode => EmitStringSizeInBytes(value),
+                    StringTypeNode => EmitStringSizeInBytes(value),
+                    InterfaceTypeNode => 16.ToString(),
                     _ => throw new ArgumentOutOfRangeException(nameof(source.Type))
                 };
 
@@ -309,8 +310,9 @@ public partial class QBEGenerator
         {
             ArrayTypeNode arrayType => EmitArraySizeInBytes(arrayType, value),
             CStringTypeNode => EmitCStringSizeInBytes(value),
-            NubStringTypeNode => EmitStringSizeInBytes(value),
-            CustomTypeNode customType => customType.Size(_definitionTable).ToString(),
+            StringTypeNode => EmitStringSizeInBytes(value),
+            InterfaceTypeNode => 16.ToString(),
+            StructTypeNode structType => SizeOf(structType).ToString(),
             _ => throw new ArgumentOutOfRangeException(nameof(source.Type))
         };
 
@@ -339,9 +341,14 @@ public partial class QBEGenerator
             };
         }
 
-        if (complexType is CustomTypeNode customType)
+        if (complexType is StructTypeNode structType)
         {
-            return CustomTypeName(customType.Name);
+            return StructTypeName(structType.Name);
+        }
+
+        if (complexType is InterfaceTypeNode interfaceType)
+        {
+            return InterfaceTypeName(interfaceType.Name);
         }
 
         return "l";
@@ -387,7 +394,7 @@ public partial class QBEGenerator
 
     private void EmitStructTypeDefinition(StructNode structDef)
     {
-        _writer.WriteLine($"type {CustomTypeName(structDef.Name)} = {{ ");
+        _writer.WriteLine($"type {StructTypeName(structDef.Name)} = {{ ");
 
         var types = new Dictionary<string, string>();
 
@@ -422,9 +429,14 @@ public partial class QBEGenerator
                 };
             }
 
-            if (complexType is CustomTypeNode customType)
+            if (complexType is StructTypeNode structType)
             {
-                return CustomTypeName(customType.Name);
+                return StructTypeName(structType.Name);
+            }
+
+            if (complexType is InterfaceTypeNode interfaceType)
+            {
+                return InterfaceTypeName(interfaceType.Name);
             }
 
             return "l";
@@ -458,6 +470,93 @@ public partial class QBEGenerator
         };
     }
 
+    private static int SizeOf(TypeNode type)
+    {
+        return type switch
+        {
+            SimpleTypeNode simple => simple.StorageSize switch
+            {
+                StorageSize.Void => 0,
+                StorageSize.I8 or StorageSize.U8 => 1,
+                StorageSize.I16 or StorageSize.U16 => 2,
+                StorageSize.I32 or StorageSize.U32 or StorageSize.F32 => 4,
+                StorageSize.I64 or StorageSize.U64 or StorageSize.F64 => 8,
+                _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown storage size: {simple.StorageSize}")
+            },
+            CStringTypeNode => 8,
+            StringTypeNode => 8,
+            ArrayTypeNode => 8,
+            StructTypeNode structType => CalculateStructSize(structType),
+            InterfaceTypeNode => 16,
+            _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown type: {type.GetType()}")
+        };
+    }
+
+    private static int CalculateStructSize(StructTypeNode structType)
+    {
+        var offset = 0;
+
+        if (structType.InterfaceImplementations.Any())
+        {
+            offset = 8;
+        }
+
+        foreach (var field in structType.Fields)
+        {
+            var fieldAlignment = AlignmentOf(field);
+            offset = AlignTo(offset, fieldAlignment);
+            offset += SizeOf(field);
+        }
+
+        var structAlignment = CalculateStructAlignment(structType);
+        return AlignTo(offset, structAlignment);
+    }
+
+    private static int AlignmentOf(TypeNode type)
+    {
+        return type switch
+        {
+            SimpleTypeNode simple => simple.StorageSize switch
+            {
+                StorageSize.Void => 1,
+                StorageSize.I8 or StorageSize.U8 => 1,
+                StorageSize.I16 or StorageSize.U16 => 2,
+                StorageSize.I32 or StorageSize.U32 or StorageSize.F32 => 4,
+                StorageSize.I64 or StorageSize.U64 or StorageSize.F64 => 8,
+                _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown storage size: {simple.StorageSize}")
+            },
+            CStringTypeNode => 8,
+            StringTypeNode => 8,
+            ArrayTypeNode => 8,
+            StructTypeNode structType => CalculateStructAlignment(structType),
+            InterfaceTypeNode => 8,
+            _ => throw new ArgumentOutOfRangeException(nameof(type), $"Unknown type: {type.GetType()}")
+        };
+    }
+
+    private static int CalculateStructAlignment(StructTypeNode structType)
+    {
+        var maxAlignment = 1;
+
+        if (structType.InterfaceImplementations.Any())
+        {
+            maxAlignment = Math.Max(maxAlignment, 8);
+        }
+
+        foreach (var field in structType.Fields)
+        {
+            var fieldAlignment = AlignmentOf(field);
+            maxAlignment = Math.Max(maxAlignment, fieldAlignment);
+        }
+
+        return maxAlignment;
+    }
+
+    private static int AlignTo(int offset, int alignment)
+    {
+        return (offset + alignment - 1) & ~(alignment - 1);
+    }
+
     private int OffsetOf(StructNode structDef, string member)
     {
         var offset = 0;
@@ -474,10 +573,10 @@ public partial class QBEGenerator
                 return offset;
             }
 
-            var fieldAlignment = field.Type.Alignment(_definitionTable);
+            var fieldAlignment = AlignmentOf(field.Type);
 
-            offset = TypeNode.AlignTo(offset, fieldAlignment);
-            offset += field.Type.Size(_definitionTable);
+            offset = AlignTo(offset, fieldAlignment);
+            offset += SizeOf(field.Type);
         }
 
         throw new UnreachableException($"Member '{member}' not found in struct");
@@ -515,7 +614,12 @@ public partial class QBEGenerator
         return $"${funcDef.CallName}";
     }
 
-    private string CustomTypeName(string name)
+    private string StructTypeName(string name)
+    {
+        return $":{name}";
+    }
+
+    private string InterfaceTypeName(string name)
     {
         return $":{name}";
     }

src/compiler/NubLang/TypeChecking/DefinitionTable.cs

@@ -26,11 +26,11 @@ public class DefinitionTable
             .Where(x => x.Name == name);
     }
 
-    public IEnumerable<StructSyntax> LookupStruct(CustomTypeNode type)
+    public IEnumerable<StructSyntax> LookupStruct(string name)
     {
         return _definitions
             .OfType<StructSyntax>()
-            .Where(x => x.Name == type.Name);
+            .Where(x => x.Name == name);
     }
 
     public IEnumerable<StructFieldSyntax> LookupStructField(StructSyntax @struct, string field)
@@ -43,11 +43,11 @@ public class DefinitionTable
         return @struct.Functions.Where(x => x.Name == func);
     }
 
-    public IEnumerable<InterfaceSyntax> LookupInterface(CustomTypeNode type)
+    public IEnumerable<InterfaceSyntax> LookupInterface(string name)
     {
         return _definitions
             .OfType<InterfaceSyntax>()
-            .Where(x => x.Name == type.Name);
+            .Where(x => x.Name == name);
     }
 
     public IEnumerable<InterfaceFuncSyntax> LookupInterfaceFunc(InterfaceSyntax @interface, string name)

src/compiler/NubLang/TypeChecking/Node/DefinitionNode.cs

@@ -14,7 +14,7 @@ public record StructFieldNode(int Index, string Name, TypeNode Type, Optional<Ex
 
 public record StructFuncNode(string Name, FuncSignatureNode Signature, BlockNode Body) : Node;
 
-public record StructNode(string Name, IReadOnlyList<StructFieldNode> Fields, IReadOnlyList<StructFuncNode> Functions, IReadOnlyList<CustomTypeNode> InterfaceImplementations) : DefinitionNode;
+public record StructNode(string Name, IReadOnlyList<StructFieldNode> Fields, IReadOnlyList<StructFuncNode> Functions, IReadOnlyList<InterfaceTypeNode> InterfaceImplementations) : DefinitionNode;
 
 public record InterfaceFuncNode(string Name, FuncSignatureNode Signature) : Node;
 

src/compiler/NubLang/TypeChecking/Node/ExpressionNode.cs

@@ -46,12 +46,12 @@ public record AddressOfNode(TypeNode Type, ExpressionNode Expression) : Expressi
 
 public record LiteralNode(TypeNode Type, string Value, LiteralKind Kind) : ExpressionNode(Type);
 
-public record StructFieldAccessNode(TypeNode Type, CustomTypeNode StructType, ExpressionNode Target, string Field) : ExpressionNode(Type);
+public record StructFieldAccessNode(TypeNode Type, StructTypeNode StructType, ExpressionNode Target, string Field) : ExpressionNode(Type);
 
-public record StructFuncAccessNode(TypeNode Type, CustomTypeNode StructType, ExpressionNode Target, string Func) : ExpressionNode(Type);
+public record StructFuncAccessNode(TypeNode Type, StructTypeNode StructType, ExpressionNode Target, string Func) : ExpressionNode(Type);
 
-public record InterfaceFuncAccessNode(TypeNode Type, CustomTypeNode InterfaceType, ExpressionNode Target, string FuncName) : ExpressionNode(Type);
+public record InterfaceFuncAccessNode(TypeNode Type, InterfaceTypeNode InterfaceType, ExpressionNode Target, string FuncName) : ExpressionNode(Type);
 
-public record StructInitializerNode(CustomTypeNode StructType, Dictionary<string, ExpressionNode> Initializers) : ExpressionNode(StructType);
+public record StructInitializerNode(StructTypeNode StructType, Dictionary<string, ExpressionNode> Initializers) : ExpressionNode(StructType);
 
 public record DereferenceNode(TypeNode Type, ExpressionNode Expression) : ExpressionNode(Type);

src/compiler/NubLang/TypeChecking/Node/TypeNode.cs

@@ -1,11 +1,10 @@
 using System.Diagnostics.CodeAnalysis;
-using NubLang.Generation;
 
 namespace NubLang.TypeChecking.Node;
 
 public abstract class TypeNode : IEquatable<TypeNode>
 {
-    public bool IsSimpleType([NotNullWhen(true)] out SimpleTypeNode? simpleType, [NotNullWhen(false)] out NubComplexTypeNode? complexType)
+    public bool IsSimpleType([NotNullWhen(true)] out SimpleTypeNode? simpleType, [NotNullWhen(false)] out ComplexTypeNode? complexType)
     {
         if (this is SimpleTypeNode st)
         {
@@ -14,7 +13,7 @@ public abstract class TypeNode : IEquatable<TypeNode>
             return true;
         }
 
-        if (this is NubComplexTypeNode ct)
+        if (this is ComplexTypeNode ct)
         {
             complexType = ct;
             simpleType = null;
@@ -24,14 +23,6 @@ public abstract class TypeNode : IEquatable<TypeNode>
         throw new ArgumentException($"Type {this} is not a simple type nor a complex type");
     }
 
-    public abstract int Size(TypedDefinitionTable definitionTable);
-    public abstract int Alignment(TypedDefinitionTable definitionTable);
-
-    public static int AlignTo(int offset, int alignment)
-    {
-        return (offset + alignment - 1) & ~(alignment - 1);
-    }
-
     public override bool Equals(object? obj) => obj is TypeNode other && Equals(other);
 
     public abstract bool Equals(TypeNode? other);
@@ -60,23 +51,6 @@ public enum StorageSize
 public abstract class SimpleTypeNode : TypeNode
 {
     public abstract StorageSize StorageSize { get; }
-
-    public override int Size(TypedDefinitionTable definitionTable)
-    {
-        return StorageSize switch
-        {
-            StorageSize.I64 or StorageSize.U64 or StorageSize.F64 => 8,
-            StorageSize.I32 or StorageSize.U32 or StorageSize.F32 => 4,
-            StorageSize.I16 or StorageSize.U16 => 2,
-            StorageSize.I8 or StorageSize.U8 => 1,
-            _ => throw new ArgumentOutOfRangeException(nameof(StorageSize))
-        };
-    }
-
-    public override int Alignment(TypedDefinitionTable definitionTable)
-    {
-        return Size(definitionTable);
-    }
 }
 
 #region Simple types
@@ -136,7 +110,7 @@ public class BoolTypeNode : SimpleTypeNode
     public override int GetHashCode() => HashCode.Combine(typeof(BoolTypeNode));
 }
 
-public class FuncTypeNode(List<TypeNode> parameters, TypeNode returnType) : SimpleTypeNode
+public class FuncTypeNode(IReadOnlyList<TypeNode> parameters, TypeNode returnType) : SimpleTypeNode
 {
     public IReadOnlyList<TypeNode> Parameters { get; } = parameters;
     public TypeNode ReturnType { get; } = returnType;
@@ -182,110 +156,50 @@ public class VoidTypeNode : SimpleTypeNode
 
 #endregion
 
-public abstract class NubComplexTypeNode : TypeNode;
+public abstract class ComplexTypeNode : TypeNode;
 
 #region Complex types
 
-public class CStringTypeNode : NubComplexTypeNode
+public class CStringTypeNode : ComplexTypeNode
 {
-    public override int Size(TypedDefinitionTable definitionTable) => 8;
-    public override int Alignment(TypedDefinitionTable definitionTable) => Size(definitionTable);
-
     public override string ToString() => "cstring";
     public override bool Equals(TypeNode? other) => other is CStringTypeNode;
     public override int GetHashCode() => HashCode.Combine(typeof(CStringTypeNode));
 }
 
-public class NubStringTypeNode : NubComplexTypeNode
+public class StringTypeNode : ComplexTypeNode
 {
-    public override int Size(TypedDefinitionTable definitionTable) => 8;
-    public override int Alignment(TypedDefinitionTable definitionTable) => Size(definitionTable);
-
     public override string ToString() => "string";
-    public override bool Equals(TypeNode? other) => other is NubStringTypeNode;
-    public override int GetHashCode() => HashCode.Combine(typeof(NubStringTypeNode));
+    public override bool Equals(TypeNode? other) => other is StringTypeNode;
+    public override int GetHashCode() => HashCode.Combine(typeof(StringTypeNode));
 }
 
-public class CustomTypeNode(string name) : NubComplexTypeNode
+public class StructTypeNode(string name, IReadOnlyList<TypeNode> fields, IReadOnlyList<FuncTypeNode> functions, IReadOnlyList<InterfaceTypeNode> interfaceImplementations) : ComplexTypeNode
 {
     public string Name { get; } = name;
-
-    public CustomTypeKind Kind(TypedDefinitionTable definitionTable)
-    {
-        if (definitionTable.GetStructs().Any(x => x.Name == Name))
-        {
-            return CustomTypeKind.Struct;
-        }
-
-        if (definitionTable.GetInterfaces().Any(x => x.Name == Name))
-        {
-            return CustomTypeKind.Interface;
-        }
-
-        throw new ArgumentException($"Definition table does not have any type information for {this}");
-    }
-
-    public override int Size(TypedDefinitionTable definitionTable)
-    {
-        switch (Kind(definitionTable))
-        {
-            case CustomTypeKind.Struct:
-            {
-                var structDef = definitionTable.LookupStruct(Name);
-                var size = 0;
-                var maxAlignment = 1;
-
-                foreach (var field in structDef.Fields)
-                {
-                    var fieldAlignment = field.Type.Alignment(definitionTable);
-                    maxAlignment = Math.Max(maxAlignment, fieldAlignment);
-
-                    size = AlignTo(size, fieldAlignment);
-                    size += field.Type.Size(definitionTable);
-                }
-
-                return AlignTo(size, maxAlignment);
-            }
-            case CustomTypeKind.Interface:
-            {
-                return 16;
-            }
-            default:
-                throw new ArgumentOutOfRangeException();
-        }
-    }
-
-    public override int Alignment(TypedDefinitionTable definitionTable)
-    {
-        switch (Kind(definitionTable))
-        {
-            case CustomTypeKind.Struct:
-                return definitionTable.LookupStruct(Name).Fields.Max(f => f.Type.Alignment(definitionTable));
-            case CustomTypeKind.Interface:
-                return 8;
-            default:
-                throw new ArgumentOutOfRangeException();
-        }
-    }
+    public IReadOnlyList<TypeNode> Fields { get; } = fields;
+    public IReadOnlyList<FuncTypeNode> Functions { get; } = functions;
+    public IReadOnlyList<InterfaceTypeNode> InterfaceImplementations { get; } = interfaceImplementations;
 
     public override string ToString() => Name;
-    public override bool Equals(TypeNode? other) => other is CustomTypeNode custom && Name == custom.Name;
-    public override int GetHashCode() => HashCode.Combine(typeof(CustomTypeNode), Name);
+    public override bool Equals(TypeNode? other) => other is StructTypeNode custom && Name == custom.Name;
+    public override int GetHashCode() => HashCode.Combine(typeof(StructTypeNode), Name);
 }
 
-public enum CustomTypeKind
+public class InterfaceTypeNode(string name, IReadOnlyList<FuncTypeNode> funcs) : ComplexTypeNode
 {
-    Struct,
-    Interface
+    public string Name { get; } = name;
+    public IReadOnlyList<FuncTypeNode> Funcs { get; } = funcs;
+
+    public override string ToString() => Name;
+    public override bool Equals(TypeNode? other) => other is InterfaceTypeNode custom && Name == custom.Name;
+    public override int GetHashCode() => HashCode.Combine(typeof(InterfaceTypeNode), Name);
 }
 
-public class ArrayTypeNode(TypeNode elementType) : NubComplexTypeNode
+public class ArrayTypeNode(TypeNode elementType) : ComplexTypeNode
 {
     public TypeNode ElementType { get; } = elementType;
 
-    public override int Size(TypedDefinitionTable definitionTable) => 8;
-    public override int Alignment(TypedDefinitionTable definitionTable) => Size(definitionTable);
-
     public override string ToString() => "[]" + ElementType;
 
     public override bool Equals(TypeNode? other) => other is ArrayTypeNode array && ElementType.Equals(array.ElementType);

src/compiler/NubLang/TypeChecking/TypeChecker.cs

@@ -38,7 +38,7 @@ public sealed class TypeChecker
             {
                 definitions.Add(CheckDefinition(definition));
             }
-            catch (CheckException e)
+            catch (TypeCheckerException e)
             {
                 _diagnostics.Add(e.Diagnostic);
             }
@@ -100,32 +100,32 @@ public sealed class TypeChecker
             funcs.Add(new StructFuncNode(func.Name, CheckFuncSignature(func.Signature), CheckFuncBody(func.Body, CheckType(func.Signature.ReturnType), parameters)));
         }
 
-        var interfaceImplementations = new List<CustomTypeNode>();
+        var interfaceImplementations = new List<InterfaceTypeNode>();
 
         foreach (var interfaceImplementation in node.InterfaceImplementations)
         {
-            var interfaceType = CheckType(interfaceImplementation);
-            if (interfaceType is not CustomTypeNode customType)
+            var type = CheckType(interfaceImplementation);
+            if (type is not InterfaceTypeNode interfaceType)
             {
                 _diagnostics.Add(Diagnostic.Error("Interface implementation is not a custom type").Build());
                 continue;
             }
 
-            var interfaceDefs = _definitionTable.LookupInterface(customType).ToArray();
+            var interfaceDefs = _definitionTable.LookupInterface(interfaceType.Name).ToArray();
 
             if (interfaceDefs.Length == 0)
             {
-                _diagnostics.Add(Diagnostic.Error($"Interface {customType.Name} is not defined").Build());
+                _diagnostics.Add(Diagnostic.Error($"Interface {interfaceType.Name} is not defined").Build());
                 continue;
             }
 
             if (interfaceDefs.Length > 1)
             {
-                _diagnostics.Add(Diagnostic.Error($"Interface {customType.Name} has multiple definitions").Build());
+                _diagnostics.Add(Diagnostic.Error($"Interface {interfaceType.Name} has multiple definitions").Build());
                 continue;
             }
 
-            interfaceImplementations.Add(customType);
+            interfaceImplementations.Add(interfaceType);
         }
 
         return new StructNode(node.Name, structFields, funcs, interfaceImplementations);
@@ -262,12 +262,12 @@ public sealed class TypeChecker
     {
         if (expectedType == null)
         {
-            throw new CheckException(Diagnostic.Error("Cannot infer argument types for arrow function").Build());
+            throw new TypeCheckerException(Diagnostic.Error("Cannot infer argument types for arrow function").Build());
         }
 
         if (expectedType is not FuncTypeNode funcType)
         {
-            throw new CheckException(Diagnostic.Error($"Expected {expectedType}, but got arrow function").Build());
+            throw new TypeCheckerException(Diagnostic.Error($"Expected {expectedType}, but got arrow function").Build());
         }
 
         var parameters = new List<FuncParameterNode>();
@@ -276,7 +276,7 @@ public sealed class TypeChecker
         {
             if (i >= funcType.Parameters.Count)
             {
-                throw new CheckException(Diagnostic.Error($"Arrow function expected a maximum of {funcType.Parameters.Count} arguments").Build());
+                throw new TypeCheckerException(Diagnostic.Error($"Arrow function expected a maximum of {funcType.Parameters.Count} arguments").Build());
             }
 
             var expectedParameterType = funcType.Parameters[i];
@@ -353,7 +353,7 @@ public sealed class TypeChecker
         {
             if (localFuncs.Length > 1)
             {
-                throw new CheckException(Diagnostic.Error($"Extern func {expression.Name} has multiple definitions").Build());
+                throw new TypeCheckerException(Diagnostic.Error($"Extern func {expression.Name} has multiple definitions").Build());
             }
 
             var localFunc = localFuncs[0];
@@ -369,7 +369,7 @@ public sealed class TypeChecker
         {
             if (externFuncs.Length > 1)
             {
-                throw new CheckException(Diagnostic.Error($"Extern func {expression.Name} has multiple definitions").Build());
+                throw new TypeCheckerException(Diagnostic.Error($"Extern func {expression.Name} has multiple definitions").Build());
             }
 
             var externFunc = externFuncs[0];
@@ -380,7 +380,7 @@ public sealed class TypeChecker
             return new ExternFuncIdentNode(type, expression.Name);
         }
 
-        throw new CheckException(Diagnostic.Error($"No identifier with the name {expression.Name} exists").Build());
+        throw new TypeCheckerException(Diagnostic.Error($"No identifier with the name {expression.Name} exists").Build());
     }
 
     private LiteralNode CheckLiteral(LiteralSyntax expression, TypeNode? expectedType = null)
@@ -389,7 +389,7 @@ public sealed class TypeChecker
         {
             LiteralKind.Integer => new IntTypeNode(true, 64),
             LiteralKind.Float => new FloatTypeNode(64),
-            LiteralKind.String => new NubStringTypeNode(),
+            LiteralKind.String => new StringTypeNode(),
             LiteralKind.Bool => new BoolTypeNode(),
             _ => throw new ArgumentOutOfRangeException()
         };
@@ -401,14 +401,14 @@ public sealed class TypeChecker
     {
         var boundExpression = CheckExpression(expression.Target);
 
-        if (boundExpression.Type is CustomTypeNode customType)
+        if (boundExpression.Type is InterfaceTypeNode customType)
         {
-            var interfaces = _definitionTable.LookupInterface(customType).ToArray();
+            var interfaces = _definitionTable.LookupInterface(customType.Name).ToArray();
             if (interfaces.Length > 0)
             {
                 if (interfaces.Length > 1)
                 {
-                    throw new CheckException(Diagnostic.Error($"Interface {customType} has multiple definitions").Build());
+                    throw new TypeCheckerException(Diagnostic.Error($"Interface {customType} has multiple definitions").Build());
                 }
 
                 var @interface = interfaces[0];
@@ -418,7 +418,7 @@ public sealed class TypeChecker
                 {
                     if (interfaceFuncs.Length > 1)
                     {
-                        throw new CheckException(Diagnostic.Error($"Interface {customType} has multiple functions with the name {expression.Member}").Build());
+                        throw new TypeCheckerException(Diagnostic.Error($"Interface {customType} has multiple functions with the name {expression.Member}").Build());
                     }
 
                     var interfaceFunc = interfaceFuncs[0];
@@ -429,13 +429,16 @@ public sealed class TypeChecker
                     return new InterfaceFuncAccessNode(type, customType, boundExpression, expression.Member);
                 }
             }
+        }
 
-            var structs = _definitionTable.LookupStruct(customType).ToArray();
+        if (boundExpression.Type is StructTypeNode structType)
+        {
+            var structs = _definitionTable.LookupStruct(structType.Name).ToArray();
             if (structs.Length > 0)
             {
                 if (structs.Length > 1)
                 {
-                    throw new CheckException(Diagnostic.Error($"Struct {customType} has multiple definitions").Build());
+                    throw new TypeCheckerException(Diagnostic.Error($"Struct {structType} has multiple definitions").Build());
                 }
 
                 var @struct = structs[0];
@@ -445,12 +448,12 @@ public sealed class TypeChecker
                 {
                     if (fields.Length > 1)
                     {
-                        throw new CheckException(Diagnostic.Error($"Struct {customType} has multiple fields with the name {expression.Member}").Build());
+                        throw new TypeCheckerException(Diagnostic.Error($"Struct {structType} has multiple fields with the name {expression.Member}").Build());
                     }
 
                     var field = fields[0];
 
-                    return new StructFieldAccessNode(CheckType(field.Type), customType, boundExpression, expression.Member);
+                    return new StructFieldAccessNode(CheckType(field.Type), structType, boundExpression, expression.Member);
                 }
 
                 var funcs = _definitionTable.LookupStructFunc(@struct, expression.Member).ToArray();
@@ -458,40 +461,40 @@ public sealed class TypeChecker
                 {
                     if (funcs.Length > 1)
                     {
-                        throw new CheckException(Diagnostic.Error($"Struct {customType} has multiple functions with the name {expression.Member}").Build());
+                        throw new TypeCheckerException(Diagnostic.Error($"Struct {structType} has multiple functions with the name {expression.Member}").Build());
                     }
 
                     var func = funcs[0];
 
                     var parameters = func.Signature.Parameters.Select(x => CheckType(x.Type)).ToList();
                     var returnType = CheckType(func.Signature.ReturnType);
-                    return new StructFuncAccessNode(new FuncTypeNode(parameters, returnType), customType, boundExpression, expression.Member);
+                    return new StructFuncAccessNode(new FuncTypeNode(parameters, returnType), structType, boundExpression, expression.Member);
                 }
             }
         }
 
-        throw new CheckException(Diagnostic.Error($"{boundExpression.Type} does not have a member with the name {expression.Member}").Build());
+        throw new TypeCheckerException(Diagnostic.Error($"{boundExpression.Type} does not have a member with the name {expression.Member}").Build());
     }
 
     private StructInitializerNode CheckStructInitializer(StructInitializerSyntax expression)
     {
         var boundType = CheckType(expression.StructType);
 
-        if (boundType is not CustomTypeNode structType)
+        if (boundType is not StructTypeNode structType)
         {
-            throw new CheckException(Diagnostic.Error($"Cannot initialize non-struct type {expression.StructType}").Build());
+            throw new TypeCheckerException(Diagnostic.Error($"Cannot initialize non-struct type {expression.StructType}").Build());
         }
 
-        var structs = _definitionTable.LookupStruct(structType).ToArray();
+        var structs = _definitionTable.LookupStruct(structType.Name).ToArray();
 
         if (structs.Length == 0)
         {
-            throw new CheckException(Diagnostic.Error($"Struct {structType} is not defined").Build());
+            throw new TypeCheckerException(Diagnostic.Error($"Struct {structType} is not defined").Build());
         }
 
         if (structs.Length > 1)
         {
-            throw new CheckException(Diagnostic.Error($"Struct {structType} has multiple definitions").Build());
+            throw new TypeCheckerException(Diagnostic.Error($"Struct {structType} has multiple definitions").Build());
         }
 
         var @struct = structs[0];
@@ -504,12 +507,12 @@ public sealed class TypeChecker
 
             if (fields.Length == 0)
             {
-                throw new CheckException(Diagnostic.Error($"Struct {structType} does not have a field with the name {field}").Build());
+                throw new TypeCheckerException(Diagnostic.Error($"Struct {structType} does not have a field with the name {field}").Build());
             }
 
             if (fields.Length > 1)
             {
-                throw new CheckException(Diagnostic.Error($"Struct {structType} has multiple fields with the name {field}").Build());
+                throw new TypeCheckerException(Diagnostic.Error($"Struct {structType} has multiple fields with the name {field}").Build());
             }
 
             initializers[field] = CheckExpression(initializer, CheckType(fields[0].Type));
@@ -632,16 +635,69 @@ public sealed class TypeChecker
             ArrayTypeSyntax type => new ArrayTypeNode(CheckType(type.BaseType)),
             BoolTypeSyntax => new BoolTypeNode(),
             CStringTypeSyntax => new CStringTypeNode(),
-            CustomTypeSyntax type => new CustomTypeNode(type.Name),
+            CustomTypeSyntax type => CheckCustomType(type),
             FloatTypeSyntax @float => new FloatTypeNode(@float.Width),
             FuncTypeSyntax type => new FuncTypeNode(type.Parameters.Select(CheckType).ToList(), CheckType(type.ReturnType)),
             IntTypeSyntax @int => new IntTypeNode(@int.Signed, @int.Width),
             PointerTypeSyntax type => new PointerTypeNode(CheckType(type.BaseType)),
-            StringTypeSyntax => new NubStringTypeNode(),
+            StringTypeSyntax => new StringTypeNode(),
             VoidTypeSyntax => new VoidTypeNode(),
             _ => throw new ArgumentOutOfRangeException(nameof(node))
         };
     }
+
+    private TypeNode CheckCustomType(CustomTypeSyntax type)
+    {
+        var structs = _definitionTable.LookupStruct(type.Name).ToArray();
+        if (structs.Length > 0)
+        {
+            if (structs.Length > 1)
+            {
+                throw new TypeCheckerException(Diagnostic.Error($"Struct {type.Name} has multiple definitions").Build());
+            }
+
+            var @struct = structs[0];
+
+            var fields = @struct.Fields.Select(x => CheckType(x.Type)).ToList();
+
+            var funcs = @struct.Functions
+                .Select(x => new FuncTypeNode(x.Signature.Parameters.Select(p => CheckType(p.Type)).ToList(), CheckType(x.Signature.ReturnType)))
+                .ToList();
+
+            var interfaceImplementations = new List<InterfaceTypeNode>();
+
+            foreach (var structInterfaceImplementation in @struct.InterfaceImplementations)
+            {
+                var checkedInterfaceType = CheckType(structInterfaceImplementation);
+                if (checkedInterfaceType is not InterfaceTypeNode interfaceType)
+                {
+                    throw new TypeCheckerException(Diagnostic.Error($"{type.Name} cannot implement non-interface type {checkedInterfaceType}").Build());
+                }
+
+                interfaceImplementations.Add(interfaceType);
+            }
+
+            return new StructTypeNode(type.Name, fields, funcs, interfaceImplementations);
+        }
+
+        var interfaces = _definitionTable.LookupInterface(type.Name).ToArray();
+        if (interfaces.Length > 0)
+        {
+            if (interfaces.Length > 1)
+            {
+                throw new TypeCheckerException(Diagnostic.Error($"Interface {type.Name} has multiple definitions").Build());
+            }
+
+            var @interface = interfaces[0];
+            var functions = @interface.Functions
+                .Select(x => new FuncTypeNode(x.Signature.Parameters.Select(y => CheckType(y.Type)).ToList(), CheckType(x.Signature.ReturnType)))
+                .ToList();
+
+            return new InterfaceTypeNode(type.Name, functions);
+        }
+
+        throw new TypeCheckerException(Diagnostic.Error($"Type {type.Name} is not defined").Build());
+    }
 }
 
 public record Variable(string Name, TypeNode Type);
@@ -672,11 +728,11 @@ public class Scope(Scope? parent = null)
     }
 }
 
-public class CheckException : Exception
+public class TypeCheckerException : Exception
 {
     public Diagnostic Diagnostic { get; }
 
-    public CheckException(Diagnostic diagnostic) : base(diagnostic.Message)
+    public TypeCheckerException(Diagnostic diagnostic) : base(diagnostic.Message)
     {
         Diagnostic = diagnostic;
     }