diff --git a/src/irc/types.h b/src/irc/types.h
index 7b0765d..7a4c754 100644
--- a/src/irc/types.h
+++ b/src/irc/types.h
@@ -13,7 +13,7 @@
 namespace nix_irc {
 
 constexpr uint32_t IR_MAGIC = 0x4E495258;
-constexpr uint32_t IR_VERSION = 2;
+constexpr uint32_t IR_VERSION = 3;
 
 enum class NodeType : uint8_t {
   CONST_INT = 0x01,
@@ -41,6 +41,11 @@ enum class NodeType : uint8_t {
   ASSERT = 0x52,
   THUNK = 0x60,
   FORCE = 0x61,
+  LAMBDA_PATTERN = 0x70,
+  INHERIT = 0x71,
+  INHERIT_FROM = 0x72,
+  STRING_INTERPOLATION = 0x73,
+  BUILTIN_CALL = 0x74,
   ERROR = 0xFF
 };
 
@@ -131,6 +136,25 @@ struct LambdaNode {
   LambdaNode(uint32_t a, std::shared_ptr<Node> b, uint32_t l = 0);
 };
 
+struct PatternField {
+  std::string name;
+  std::optional<std::shared_ptr<Node>> default_value;
+
+  PatternField(std::string n, std::optional<std::shared_ptr<Node>> def = std::nullopt)
+      : name(std::move(n)), default_value(std::move(def)) {}
+};
+
+struct LambdaPatternNode {
+  std::vector<PatternField> required_fields;
+  std::vector<PatternField> optional_fields;
+  std::optional<std::string> at_binding;
+  bool allow_extra;
+  std::shared_ptr<Node> body;
+  uint32_t line = 0;
+
+  LambdaPatternNode(std::shared_ptr<Node> b, uint32_t l = 0);
+};
+
 struct AppNode {
   std::shared_ptr<Node> func;
   std::shared_ptr<Node> arg;
@@ -252,14 +276,70 @@ struct ListNode {
       : elements(std::move(elems)), line(l) {}
 };
 
+struct InheritNode {
+  std::vector<std::string> names;
+  uint32_t line = 0;
+
+  InheritNode(std::vector<std::string> n = {}, uint32_t l = 0) : names(std::move(n)), line(l) {}
+};
+
+struct InheritFromNode {
+  std::shared_ptr<Node> source;
+  std::vector<std::string> names;
+  uint32_t line = 0;
+
+  InheritFromNode(std::shared_ptr<Node> src, std::vector<std::string> n, uint32_t l = 0)
+      : source(std::move(src)), names(std::move(n)), line(l) {}
+};
+
+struct StringPart {
+  enum class Type { LITERAL, EXPR };
+  Type type;
+  std::string literal;
+  std::shared_ptr<Node> expr;
+
+  static StringPart make_literal(std::string lit) {
+    StringPart part;
+    part.type = Type::LITERAL;
+    part.literal = std::move(lit);
+    return part;
+  }
+
+  static StringPart make_expr(std::shared_ptr<Node> e) {
+    StringPart part;
+    part.type = Type::EXPR;
+    part.expr = std::move(e);
+    return part;
+  }
+};
+
+struct StringInterpolationNode {
+  std::vector<StringPart> parts;
+  uint32_t line = 0;
+
+  StringInterpolationNode(std::vector<StringPart> p = {}, uint32_t l = 0)
+      : parts(std::move(p)), line(l) {}
+};
+
+struct BuiltinCallNode {
+  std::string builtin_name;
+  std::vector<std::shared_ptr<Node>> args;
+  uint32_t line = 0;
+
+  BuiltinCallNode(std::string name, std::vector<std::shared_ptr<Node>> a = {}, uint32_t l = 0)
+      : builtin_name(std::move(name)), args(std::move(a)), line(l) {}
+};
+
 // Node wraps a variant for type-safe AST
 class Node {
 public:
-  using Variant = std::variant<ConstIntNode, ConstFloatNode, ConstStringNode, ConstPathNode,
-                               ConstBoolNode, ConstNullNode, ConstURINode, ConstLookupPathNode,
-                               VarNode, LambdaNode, AppNode, BinaryOpNode, UnaryOpNode, ImportNode,
-                               AttrsetNode, SelectNode, HasAttrNode, WithNode, IfNode, LetNode,
-                               LetRecNode, AssertNode, ThunkNode, ForceNode, ListNode>;
+  using Variant =
+      std::variant<ConstIntNode, ConstFloatNode, ConstStringNode, ConstPathNode, ConstBoolNode,
+                   ConstNullNode, ConstURINode, ConstLookupPathNode, VarNode, LambdaNode, AppNode,
+                   BinaryOpNode, UnaryOpNode, ImportNode, AttrsetNode, SelectNode, HasAttrNode,
+                   WithNode, IfNode, LetNode, LetRecNode, AssertNode, ThunkNode, ForceNode,
+                   ListNode, LambdaPatternNode, InheritNode, InheritFromNode,
+                   StringInterpolationNode, BuiltinCallNode>;
 
   Variant data;
 
@@ -312,6 +392,9 @@ inline ThunkNode::ThunkNode(std::shared_ptr<Node> e, uint32_t l) : expr(std::mov
 
 inline ForceNode::ForceNode(std::shared_ptr<Node> e, uint32_t l) : expr(std::move(e)), line(l) {}
 
+inline LambdaPatternNode::LambdaPatternNode(std::shared_ptr<Node> b, uint32_t l)
+    : allow_extra(false), body(std::move(b)), line(l) {}
+
 struct SourceFile {
   std::string path;
   std::string content;