diff --git a/src/ast.ts b/src/ast.ts
index c18ba274..1323f7ec 100644
--- a/src/ast.ts
+++ b/src/ast.ts
@@ -46,3 +46,74 @@ export type Statement<Meta = {}> = Meta & {
 export type Program<Meta = {}> = {
   statements: Statement<Meta>[];
 };
+
+export type Span = [startIdx: number, endIdx: number];
+export type SpanMeta = { span: Span };
+
+function spanContains([start, end]: Span, offset: number) {
+  return start <= offset && end >= offset;
+}
+
+function exprByOffset<T extends SpanMeta>(
+  ast: Expr<T>,
+  offset: number,
+): T | undefined {
+  if (!spanContains(ast.span, offset)) {
+    return;
+  }
+
+  switch (ast.type) {
+    case "constant":
+    case "identifier":
+      return ast;
+    case "application":
+      for (const arg of ast.args) {
+        const t = exprByOffset(arg, offset);
+        if (t !== undefined) {
+          return t;
+        }
+      }
+      return exprByOffset(ast.caller, offset) ?? ast;
+
+    case "let":
+      if (spanContains(ast.binding.span, offset)) {
+        return ast.binding;
+      }
+      return (
+        exprByOffset(ast.value, offset) ?? exprByOffset(ast.body, offset) ?? ast
+      );
+
+    case "fn":
+      for (const param of ast.params) {
+        if (spanContains(param.span, offset)) {
+          return param;
+        }
+      }
+      return exprByOffset(ast.body, offset) ?? ast;
+
+    case "if":
+      return (
+        exprByOffset(ast.condition, offset) ??
+        exprByOffset(ast.then, offset) ??
+        exprByOffset(ast.else, offset) ??
+        ast
+      );
+  }
+}
+
+export function declByOffset<T extends SpanMeta>(
+  program: Program<T>,
+  offset: number,
+): T | undefined {
+  for (const st of program.statements) {
+    if (spanContains(st.binding.span, offset)) {
+      return st.binding;
+    }
+    const e = exprByOffset(st.value, offset);
+    if (e !== undefined) {
+      return e;
+    }
+  }
+
+  return undefined;
+}
diff --git a/src/cli/commands/lsp.ts b/src/cli/commands/lsp.ts
index 50bc2780..7de95bee 100644
--- a/src/cli/commands/lsp.ts
+++ b/src/cli/commands/lsp.ts
@@ -7,83 +7,15 @@ import {
   createConnection,
 } from "vscode-languageserver";
 import { TextDocument } from "vscode-languageserver-textdocument";
-import { Span, SpanMeta, parse } from "../../parser";
+import { parse } from "../../parser";
 import { typeErrorPPrint, typePPrint } from "../../typecheck/pretty-printer";
 import { TypeMeta, typecheck } from "../../typecheck/typecheck";
 import { prelude } from "../../typecheck/prelude";
-import { Expr, Program } from "../../ast";
+import { Program, SpanMeta, declByOffset } from "../../ast";
 
 const documents = new TextDocuments(TextDocument);
 const docs = new Map<string, [TextDocument, Program<SpanMeta & TypeMeta>]>();
 
-function spanContains([start, end]: Span, offset: number) {
-  return start <= offset && end >= offset;
-}
-
-function exprByOffset<T extends SpanMeta>(
-  ast: Expr<T>,
-  offset: number,
-): T | undefined {
-  if (!spanContains(ast.span, offset)) {
-    return;
-  }
-
-  switch (ast.type) {
-    case "constant":
-    case "identifier":
-      return ast;
-    case "application":
-      for (const arg of ast.args) {
-        const t = exprByOffset(arg, offset);
-        if (t !== undefined) {
-          return t;
-        }
-      }
-      return exprByOffset(ast.caller, offset) ?? ast;
-
-    case "let":
-      if (spanContains(ast.binding.span, offset)) {
-        return ast.binding;
-      }
-      return (
-        exprByOffset(ast.value, offset) ?? exprByOffset(ast.body, offset) ?? ast
-      );
-
-    case "fn":
-      for (const param of ast.params) {
-        if (spanContains(param.span, offset)) {
-          return param;
-        }
-      }
-      return exprByOffset(ast.body, offset) ?? ast;
-
-    case "if":
-      return (
-        exprByOffset(ast.condition, offset) ??
-        exprByOffset(ast.then, offset) ??
-        exprByOffset(ast.else, offset) ??
-        ast
-      );
-  }
-}
-
-function declByOffset<T extends SpanMeta>(
-  program: Program<T>,
-  offset: number,
-): T | undefined {
-  for (const st of program.statements) {
-    if (spanContains(st.binding.span, offset)) {
-      return st.binding;
-    }
-    const e = exprByOffset(st.value, offset);
-    if (e !== undefined) {
-      return e;
-    }
-  }
-
-  return undefined;
-}
-
 export function lspCmd() {
   const connection =
     // @ts-ignore
@@ -94,11 +26,6 @@ export function lspCmd() {
       textDocumentSync: TextDocumentSyncKind.Incremental,
       hoverProvider: true,
       documentSymbolProvider: true,
-      // inlayHintProvider: true,
-      // codeLensProvider: {
-      //   resolveProvider: true,
-      // },
-      // documentSymbolProvider: true,
     },
   }));
 
diff --git a/src/cli/commands/typecheck.ts b/src/cli/commands/typecheck.ts
index ae96a21d..0ba1dfbc 100644
--- a/src/cli/commands/typecheck.ts
+++ b/src/cli/commands/typecheck.ts
@@ -1,8 +1,9 @@
 import { readFileSync } from "fs";
-import { Span, unsafeParse } from "../../parser";
+import { unsafeParse } from "../../parser";
 import { typecheck } from "../../typecheck/typecheck";
 import { typeErrorPPrint } from "../../typecheck/pretty-printer";
 import { prelude } from "../../typecheck/prelude";
+import { Span } from "../../ast";
 
 const FgRed = "\x1b[31m";
 const Reset = "\x1b[0m";
diff --git a/src/parser.ts b/src/parser.ts
index 20027eb1..d2577b65 100644
--- a/src/parser.ts
+++ b/src/parser.ts
@@ -1,5 +1,5 @@
 import grammar from "./parser/grammar.ohm-bundle";
-import { ConstLiteral, Program, Expr, Statement } from "./ast";
+import { ConstLiteral, Program, Expr, Statement, Span, SpanMeta } from "./ast";
 import type {
   MatchResult,
   NonterminalNode,
@@ -7,9 +7,6 @@ import type {
   TerminalNode,
 } from "ohm-js";
 
-export type Span = [startIdx: number, endIdx: number];
-export type SpanMeta = { span: Span };
-
 function getSpan({ source }: OhmNode): Span {
   return [source.startIdx, source.endIdx];
 }
diff --git a/src/typecheck/typecheck.ts b/src/typecheck/typecheck.ts
index 7c63d073..0a1fde40 100644
--- a/src/typecheck/typecheck.ts
+++ b/src/typecheck/typecheck.ts
@@ -1,5 +1,4 @@
-import { ConstLiteral, Expr, Program, Statement } from "../ast";
-import { Span, SpanMeta } from "../parser";
+import { ConstLiteral, Expr, Program, Statement, Span, SpanMeta } from "../ast";
 import { TVar, Type, unify, Context, generalize, instantiate } from "./unify";
 
 export type UnifyErrorType = "type-mismatch" | "occurs-check";