diff --git a/format/lib/tools.ts b/format/lib/tools.ts
index 7e59612..5d3e746 100644
--- a/format/lib/tools.ts
+++ b/format/lib/tools.ts
@@ -1,4 +1,4 @@
-import {NodeType} from "../resolver/ast";
+import {NodeType} from "../../syntax/parser/ast";
 import {Bundle} from "../resolver/bundle";
 import {ErrorKind} from "../resolver/error";
 import {Resource} from "../resolver/resource";
diff --git a/format/resolver/bundle.ts b/format/resolver/bundle.ts
index 4079797..ca1048b 100644
--- a/format/resolver/bundle.ts
+++ b/format/resolver/bundle.ts
@@ -1,4 +1,4 @@
-import {NodeType, Pattern} from "./ast";
+import {NodeType, Pattern} from "../../syntax/parser/ast";
 import {ScopeError} from "./error";
 import {Message} from "./message";
 import {Resource} from "./resource";
diff --git a/format/resolver/message.ts b/format/resolver/message.ts
index 5f2de37..2a82e98 100644
--- a/format/resolver/message.ts
+++ b/format/resolver/message.ts
@@ -1,4 +1,4 @@
-import {Pattern} from "./ast";
+import {Pattern} from "../../syntax/parser/ast";
 
 export interface Message {
     readonly id: string;
diff --git a/format/resolver/resource.ts b/format/resolver/resource.ts
index 767cde5..8ea8fd0 100644
--- a/format/resolver/resource.ts
+++ b/format/resolver/resource.ts
@@ -1,5 +1,5 @@
+import {Entry} from "../../syntax/parser/ast";
 import {Resource as ResourceParser} from "../../syntax/parser/grammar";
-import {Entry} from "./ast";
 
 export class Resource {
     public readonly body: Array<Entry>;
diff --git a/format/resolver/scope.ts b/format/resolver/scope.ts
index 5b48b6b..0b7ac91 100644
--- a/format/resolver/scope.ts
+++ b/format/resolver/scope.ts
@@ -1,4 +1,4 @@
-import * as ast from "./ast";
+import * as ast from "../../syntax/parser/ast";
 import {ErrorKind, ScopeError} from "./error";
 import {Message} from "./message";
 import {NoneValue, StringValue, Value} from "./value";
diff --git a/format/resolver/ast.ts b/syntax/parser/ast.d.ts
similarity index 73%
rename from format/resolver/ast.ts
rename to syntax/parser/ast.d.ts
index b7acb07..fb39ef0 100644
--- a/format/resolver/ast.ts
+++ b/syntax/parser/ast.d.ts
@@ -10,22 +10,22 @@ export enum NodeType {
     Resource = "Resource",
 }
 
-export interface SyntaxNode {
+export declare class SyntaxNode {
     readonly type: NodeType;
 }
 
-export interface Identifier extends SyntaxNode {
+export declare class Identifier extends SyntaxNode {
     readonly type: NodeType.Identifer;
     readonly name: string;
 }
 
-export interface StringLiteral extends SyntaxNode {
+export declare class StringLiteral extends SyntaxNode {
     readonly type: NodeType.StringLiteral;
     readonly value: string;
     parse(): {value: string};
 }
 
-export interface MessageReference extends SyntaxNode {
+export declare class MessageReference extends SyntaxNode {
     readonly type: NodeType.MessageReference;
     readonly id: Identifier;
     readonly attribute: Identifier | null;
@@ -35,31 +35,31 @@ export type InlineExpression = StringLiteral | MessageReference;
 
 export type Expression = InlineExpression;
 
-export interface TextElement extends SyntaxNode {
+export declare class TextElement extends SyntaxNode {
     readonly type: NodeType.TextElement;
     readonly value: string;
 }
 
-export interface Placeable extends SyntaxNode {
+export declare class Placeable extends SyntaxNode {
     readonly type: NodeType.Placeable;
     readonly expression: Expression;
 }
 
 export type PatternElement = TextElement | Placeable;
 
-export interface Pattern extends SyntaxNode {
+export declare class Pattern extends SyntaxNode {
     readonly type: NodeType.Pattern;
     readonly elements: Array<PatternElement>;
 }
 
-export interface Message extends SyntaxNode {
+export declare class Message extends SyntaxNode {
     readonly type: NodeType.Message;
     readonly id: Identifier;
     readonly value: Pattern | null;
     readonly attributes: Array<Attribute>;
 }
 
-export interface Attribute extends SyntaxNode {
+export declare class Attribute extends SyntaxNode {
     readonly type: NodeType.Attribute;
     readonly id: Identifier;
     readonly value: Pattern;
@@ -67,7 +67,7 @@ export interface Attribute extends SyntaxNode {
 
 export type Entry = Message;
 
-export interface Resource extends SyntaxNode {
+export declare class Resource extends SyntaxNode {
     readonly type: NodeType.Resource;
     readonly body: Array<Entry>;
 }
diff --git a/syntax/parser/grammar.d.ts b/syntax/parser/grammar.d.ts
index 22ccad7..56a3c14 100644
--- a/syntax/parser/grammar.d.ts
+++ b/syntax/parser/grammar.d.ts
@@ -1,10 +1,10 @@
-import {Resource} from "../../format/resolver/ast";
+import * as ast from "./ast";
 interface Result<T, E> {
     fold(s: (value: T) => T, f: (err: E) => never): T;
 }
 
 interface Parser {
-    run(input: string): Result<Resource, string>;
+    run(input: string): Result<ast.Resource, string>;
 }
 
 export declare let Resource: Parser;