diff --git a/src/prettyPrinter/PrettyPrinter.cj b/src/prettyPrinter/PrettyPrinter.cj
index 001c2ef..c334914 100644
--- a/src/prettyPrinter/PrettyPrinter.cj
+++ b/src/prettyPrinter/PrettyPrinter.cj
@@ -1,6 +1,7 @@
 package cjcj.prettyPrinter
 
 public class PrettyPrinter {
+    public PrettyPrinter(let tabSize!: Int64 = 4) {}
     private var indentation: Int64 = 0
     private let builder: StringBuilder = StringBuilder()
 
@@ -13,13 +14,10 @@ public class PrettyPrinter {
     }
 
     public func append(val: String): Unit {
-        val.runes().forEach(
-            {
-                r =>
-                    builder.append(r)
-                    if (r == r"\n") {
-                        builder.append(StringBuilder(r' ', 4 * indentation))
-                    }
+        val.runes().forEach({
+            r => builder.append(r)
+            if (r == r"\n") {
+                builder.append(StringBuilder(r' ', tabSize * indentation))
             }
         )
     }
diff --git a/src/prettyPrinter/YamlPrinter.cj b/src/prettyPrinter/YamlPrinter.cj
new file mode 100644
index 0000000..40f823b
--- /dev/null
+++ b/src/prettyPrinter/YamlPrinter.cj
@@ -0,0 +1,110 @@
+package cjcj.prettyPrinter
+
+import cjcj.scanner.{Token, TokenKind}
+import std.ast.Position
+
+public interface YamlPrintable {
+    func yamlPrint(printer: YamlPrinter): Unit
+}
+
+public class YamlPrinter {
+    private var indentation: Int64 = 0
+    private let printer: PrettyPrinter = PrettyPrinter(tabSize: 2)
+    private var atObjectStart: Bool = true
+    private var atListItemStart: Bool = false
+
+    private func printlnIfNeeded(): Unit {
+        if (atObjectStart) {
+            atObjectStart = false
+            if (atListItemStart) {
+                atListItemStart = false
+                printer.indent()
+            }
+        } else {
+            printer.append("\n")
+        }
+    }
+
+    public func printObject(key: String, obj: YamlPrintable): Unit {
+        printlnIfNeeded()
+        printer.append(key + ":")
+        printer.indent()
+        printer.append("\n")
+        atObjectStart = true
+        obj.yamlPrint(this)
+        atObjectStart = false
+        printer.unindent()
+    }
+
+    public func printOptionalObject<T>(key: String, obj: ?T): Unit where T <: YamlPrintable {
+        if (let Some(o) <- obj) {
+            printObject(key, o)
+        } else {
+            printlnIfNeeded()
+            printer.append(key + ": null")
+        }
+    }
+
+    public func printList<T>(key: String, objs: Iterable<T>): Unit where T <: YamlPrintable {
+        printlnIfNeeded()
+        if (objs.iterator().isEmpty()) {
+            printer.append(key + ": []")
+            return
+        }
+        printer.append(key + ":")
+        objs.iterator().forEach(
+            {
+                o =>
+                    printer.append("\n- ")
+                    atObjectStart = true
+                    atListItemStart = true
+                    o.yamlPrint(this)
+                    if (atListItemStart) {
+                        printer.append("{}")
+                        atListItemStart = false
+                    } else {
+                        printer.unindent()
+                    }
+                    atObjectStart = false
+            }
+        )
+    }
+
+    public func print(key: String, token: Token): Unit {
+        print(key, token.value)
+        printPosition(token.pos)
+    }
+
+    public func print(key: String, value: ToString, enforceQuoting!: Bool = false): Unit {
+        let valueString = value.toString()
+        let formattedValue = if (!enforceQuoting && valueString.runes().all({r => r.isAsciiNumberOrLetter()})) {
+            valueString
+        } else if (valueString.contains("\n") || valueString.contains("\t") || valueString.contains("'")) {
+            '\"${valueString.replace("\\", "\\\\").replace("\n", "\\n").replace("\t", "\\t").replace('"', '\\"')}\"'
+        } else {
+            "'${valueString}'"
+        }
+        printRaw(key, formattedValue)
+    }
+
+    public func printLiteral(key: String, literal: Token): Unit {
+        match (literal.kind) {
+            case TokenKind.STRING_LITERAL => print(key, literal.value, enforceQuoting: true)
+            case _ => print(key, literal.value)
+        }
+        printPosition(literal.pos)
+    }
+
+    private func printRaw(key: String, rawValue: String): Unit {
+        printlnIfNeeded()
+        printer.append("${key}: ${rawValue}")
+    }
+
+    private func printPosition(pos: Position): Unit {
+        printer.append(" # Position: ${pos.line}:${pos.column}")
+    }
+
+    public func toString(): String {
+        printer.toString()
+    }
+}
diff --git a/src/visitor/Decls.cj b/src/visitor/Decls.cj
index ddce7df..b7d1b47 100644
--- a/src/visitor/Decls.cj
+++ b/src/visitor/Decls.cj
@@ -1,6 +1,6 @@
 package cjcj.visitor
 
-import cjcj.prettyPrinter.PrettyPrinter
+import cjcj.prettyPrinter.{PrettyPrinter, YamlPrinter}
 import cjcj.scanner.Token
 import cjcj.scanner.TokenKind
 import std.collection.ArrayList
@@ -87,6 +87,16 @@ public abstract class Decl <: Node & Equatable<Decl> {
         }
     }
 
+    public open override func yamlPrint(printer: YamlPrinter): Unit {
+        if (keyword.kind != TokenKind.ILLEGAL) {
+            printer.print("keyword", keyword)
+        }
+        if (keyword.kind != TokenKind.ILLEGAL) {
+            printer.print("identifier", identifier)
+        }
+        printer.printOptionalObject("declType", declType)
+    }
+
     public override operator func ==(other: Decl) {
         id == other.id
     }
@@ -140,6 +150,12 @@ public open class VarDecl <: Decl {
             ini.prettyPrint(printer)
         }
     }
+
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "VarDecl")
+        super.yamlPrint(printer)
+        printer.printOptionalObject("initializer", initializer)
+    }
 }
 
 public open class MainDecl <: Decl {
@@ -177,6 +193,13 @@ public open class MainDecl <: Decl {
         block_.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "MainDecl")
+        super.yamlPrint(printer)
+        printer.printOptionalObject("param", param)
+        printer.printObject("block", block)
+    }
+
     public mut prop block: Block {
         get() {
             block_
@@ -222,6 +245,13 @@ public class FuncParam <: Decl {
         paramType.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "FuncParam")
+        super.yamlPrint(printer)
+        printer.print("name", name)
+        printer.printObject("paramType", paramType)
+    }
+
     public mut prop paramType: TypeNode {
         get() {
             paramType_
@@ -287,6 +317,13 @@ public open class FuncDecl <: Decl {
         }
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "FuncDecl")
+        super.yamlPrint(printer)
+        printer.printList("params", params)
+        printer.printOptionalObject("block", block)
+    }
+
     public mut prop block: ?Block {
         get() {
             block_
@@ -331,6 +368,13 @@ public open class ClassDecl <: Decl {
         body.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "ClassDecl")
+        super.yamlPrint(printer)
+        printer.printList("superTypes", superTypes)
+        printer.printObject("body", body)
+    }
+
     public open override func traverse<R>(v: Visitor<R>): R {
         v.visit(this)
     }
@@ -374,6 +418,13 @@ public open class InterfaceDecl <: Decl {
         body.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "InterfaceDecl")
+        super.yamlPrint(printer)
+        printer.printList("superTypes", superTypes)
+        printer.printObject("body", body)
+    }
+
     public open override func traverse<R>(v: Visitor<R>): R {
         v.visit(this)
     }
diff --git a/src/visitor/Exprs.cj b/src/visitor/Exprs.cj
index 99d1b3e..f535b72 100644
--- a/src/visitor/Exprs.cj
+++ b/src/visitor/Exprs.cj
@@ -1,6 +1,6 @@
 package cjcj.visitor
 
-import cjcj.prettyPrinter.PrettyPrinter
+import cjcj.prettyPrinter.{PrettyPrinter, YamlPrinter}
 import cjcj.scanner.Token
 import cjcj.scanner.TokenKind
 import std.collection.ArrayList
@@ -19,6 +19,13 @@ public open class Expr <: Node {
     }
 
     public open override func prettyPrint(_: PrettyPrinter): Unit {}
+
+    public open func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "Expr")
+        let valuePrinter = PrettyPrinter()
+        prettyPrint(valuePrinter)
+        printer.print("value", '"' + valuePrinter.toString() + '"')
+    }
 }
 
 public class BinaryExpr <: Expr {
@@ -47,6 +54,13 @@ public class BinaryExpr <: Expr {
         right.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "BinaryExpr")
+        printer.printObject("left", left)
+        printer.print("oper", oper)
+        printer.printObject("right", right)
+    }
+
     public mut prop left: Node {
         get() {
             left_
@@ -97,6 +111,11 @@ public class ParenExpr <: Expr {
         printer.append(")")
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "ParenExpr")
+        printer.printObject("parenthesizedExpr", parenthesizedExpr)
+    }
+
     public mut prop parenthesizedExpr: Expr {
         get() {
             parenthesizedExpr_
@@ -130,6 +149,12 @@ public class LitConstExpr <: Expr {
         }
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "LitConstExpr")
+        printer.print("kind", literal.kind)
+        printer.printLiteral("literal", literal)
+    }
+
     public mut prop literal: Token {
         get() {
             literal_
@@ -163,6 +188,12 @@ public class UnaryExpr <: Expr {
         right.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "UnaryExpr")
+        printer.print("oper", oper)
+        printer.printObject("right", right)
+    }
+
     public mut prop oper: Token {
         get() {
             oper_
@@ -206,6 +237,12 @@ public class AssignExpr <: Expr {
         right.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "AssignExpr")
+        printer.printObject("left", left)
+        printer.printObject("right", right)
+    }
+
     public mut prop left: Expr {
         get() {
             left_
@@ -249,6 +286,11 @@ public open class RefExpr <: Expr {
     public override func prettyPrint(printer: PrettyPrinter): Unit {
         printer.append(identifier.value)
     }
+
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "RefExpr")
+        printer.print("identifier", identifier)
+    }
 }
 
 public class Block <: Expr {
@@ -285,6 +327,11 @@ public class Block <: Expr {
         printer.append("\n}\n")
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "Block")
+        printer.printList("nodes", nodes)
+    }
+
     public mut prop nodes: ArrayList<Node> {
         get() {
             nodes_
@@ -328,6 +375,13 @@ public class IfExpr <: Expr {
         elseBranch.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "IfExpr")
+        printer.printObject("condition", condition)
+        printer.printObject("ifBlock", ifBlock)
+        printer.printObject("elseBranch", elseBranch)
+    }
+
     public mut prop condition: Expr {
         get() {
             condition_
@@ -381,6 +435,12 @@ public class WhileExpr <: Expr {
         block.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "WhileExpr")
+        printer.printObject("condition", condition)
+        printer.printObject("block", block)
+    }
+
     public mut prop condition: Expr {
         get() {
             condition_
@@ -434,6 +494,12 @@ public open class CallExpr <: Expr {
         printer.append(")")
     }
 
+    public open override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "CallExpr")
+        printer.printObject("callee", callee)
+        printer.printList("arguments", arguments)
+    }
+
     public prop callee: Node {
         get() {
             callee_
@@ -474,6 +540,12 @@ public class ReturnExpr <: Expr {
         }
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "ReturnExpr")
+        printer.printOptionalObject("expr", expr)
+        printer.print("keyword", keyword)
+    }
+
     public mut prop expr: ?Expr {
         get() {
             expr_
@@ -513,6 +585,11 @@ public class JumpExpr <: Expr {
         printer.append(keyword.value)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "JumpExpr")
+        printer.print("keyword", keyword)
+    }
+
     public mut prop keyword: Token {
         get() {
             keyword_
@@ -542,6 +619,12 @@ public open class MemberAccess <: Expr {
         printer.append(".${field.value}")
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "MemberAccess")
+        printer.printObject("baseExpr", baseExpr)
+        printer.print("field", field)
+    }
+
     public open override func traverse<R>(v: Visitor<R>): R {
         v.visit(this)
     }
@@ -581,6 +664,11 @@ public class PrimitiveTypeExpr <: Expr {
         printer.append(keyword.value)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "PrimitiveTypeExpr")
+        printer.print("keyword", keyword)
+    }
+
     public override func traverse<R>(v: Visitor<R>): R {
         v.visit(this)
     }
@@ -611,6 +699,11 @@ public class ThisSuperExpr <: Expr {
         printer.append(keyword.value)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "ThisSuperExpr")
+        printer.print("keyword", keyword)
+    }
+
     public override func traverse<R>(v: Visitor<R>): R {
         v.visit(this)
     }
diff --git a/src/visitor/Node.cj b/src/visitor/Node.cj
index 8097d95..d2cdee4 100644
--- a/src/visitor/Node.cj
+++ b/src/visitor/Node.cj
@@ -1,6 +1,6 @@
 package cjcj.visitor
 
-import cjcj.prettyPrinter.PrettyPrinter
+import cjcj.prettyPrinter.{PrettyPrinter, YamlPrintable, YamlPrinter}
 import std.collection.ArrayList
 import std.deriving.Derive
 
@@ -22,7 +22,7 @@ public struct NodeId <: Hashable {
     }
 }
 
-public abstract class Node <: Hashable & Equatable<Node> {
+public abstract class Node <: Hashable & Equatable<Node> & YamlPrintable {
     private var id_: NodeId
 
     public Node(id: NodeId) {
@@ -36,6 +36,20 @@ public abstract class Node <: Hashable & Equatable<Node> {
      */
     public func prettyPrint(printer: PrettyPrinter): Unit
 
+    public func yamlPrint(printer: YamlPrinter): Unit
+
+    public func prettyPrint(): String {
+        let printer: PrettyPrinter = PrettyPrinter()
+        prettyPrint(printer)
+        return printer.toString()
+    }
+
+    public func yamlPrint(): String {
+        let printer: YamlPrinter = YamlPrinter()
+        yamlPrint(printer)
+        return printer.toString()
+    }
+
     public mut prop id: NodeId {
         get() {
             id_
@@ -74,6 +88,11 @@ public class Argument <: Node {
         expr.prettyPrint(printer)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "Argument")
+        printer.printObject("expr", expr)
+    }
+
     public mut prop expr: Node {
         get() {
             expr_
@@ -106,6 +125,11 @@ public class Program <: Node {
         )
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "Program")
+        printer.printList("decls", decls)
+    }
+
     public mut prop decls: ArrayList<Decl> {
         get() {
             decls_
@@ -143,6 +167,11 @@ public class Body <: Node {
         printer.append("\n}")
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "Body")
+        printer.printList("decls", decls)
+    }
+
     public override func traverse<R>(v: Visitor<R>): R {
         v.visit(this)
     }
diff --git a/src/visitor/Reference.cj b/src/visitor/Reference.cj
index 33a5d1b..0c99bc8 100644
--- a/src/visitor/Reference.cj
+++ b/src/visitor/Reference.cj
@@ -1,6 +1,6 @@
 package cjcj.visitor
 
-import cjcj.prettyPrinter.PrettyPrinter
+import cjcj.prettyPrinter.{PrettyPrinter, YamlPrinter}
 import cjcj.scanner.Token
 import std.collection.*
 
@@ -21,6 +21,10 @@ public open class Reference <: Expr & Equatable<Reference> & ToString {
         printer.append(identifier.value)
     }
 
+    public open override func yamlPrint(_: YamlPrinter): Unit {
+        throw UnsupportedException("Unimplemented method")
+    }
+
     public open override func traverse<R>(_: Visitor<R>): R {
         throw UnsupportedException("Unimplemented method")
     }
diff --git a/src/visitor/TypeNodes.cj b/src/visitor/TypeNodes.cj
index 2aed85f..3de62b1 100644
--- a/src/visitor/TypeNodes.cj
+++ b/src/visitor/TypeNodes.cj
@@ -1,6 +1,6 @@
 package cjcj.visitor
 
-import cjcj.prettyPrinter.PrettyPrinter
+import cjcj.prettyPrinter.{PrettyPrinter, YamlPrinter}
 import cjcj.scanner.*
 
 /*
@@ -32,6 +32,11 @@ public open class TypeNode <: Node {
     public open override func prettyPrint(_: PrettyPrinter): Unit {
     }
 
+    public open override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("typeParameterName", typeParameterName)
+        printer.print("typeName", typeName)
+    }
+
     public mut prop typeParameterName: Token {
         get() {
             typeParameterName_
@@ -73,6 +78,12 @@ public class PrimitiveType <: TypeNode {
         printer.append(typeName.value)
     }
 
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "PrimitiveType")
+        super.yamlPrint(printer)
+        printer.print("primitive", true)
+    }
+
     private func isPrimitive(typeName: Token): Bool {
         TokenKindHelper.CHAR_LANG_TYPES.iterator().any({t => t == typeName.kind})
     }
@@ -91,4 +102,10 @@ public class RefType <: TypeNode {
         super.prettyPrint(printer)
         printer.append(typeName.value)
     }
+
+    public override func yamlPrint(printer: YamlPrinter): Unit {
+        printer.print("type", "RefType")
+        super.yamlPrint(printer)
+        printer.print("primitive", false)
+    }
 }