From c9da4fcf2613fe3175ae8013847c6f8ea2794f35 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
Date: Thu, 9 Dec 2021 18:47:43 +0100
Subject: [PATCH] Stack utilities

---
 packages/core/src/runtime/stack.ts | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/packages/core/src/runtime/stack.ts b/packages/core/src/runtime/stack.ts
index de4e50c..059c340 100644
--- a/packages/core/src/runtime/stack.ts
+++ b/packages/core/src/runtime/stack.ts
@@ -41,3 +41,21 @@ export function dropNonEmpty<T>(s: NonEmptyStack<T>, n: number): NonEmptyStack<T
     }
     return s;
 }
+
+export function depth<T>(s: Stack<T>): number {
+    let count = 0;
+    while (s !== null) {
+        count++;
+        s = s.rest;
+    }
+    return count;
+}
+
+export function toArray<T>(s: Stack<T>): T[] {
+    const result = [];
+    while (s !== null) {
+        result.push(s.item);
+        s = s.rest;
+    }
+    return result;
+}