diff --git a/lp/stable-stringify.js b/lp/stable-stringify.js
new file mode 100644
index 00000000..c1f1b302
--- /dev/null
+++ b/lp/stable-stringify.js
@@ -0,0 +1,75 @@
+function stableStringify(obj, opts)
+{
+    if (!opts)
+        opts = {};
+    if (typeof opts === 'function')
+        opts = { cmp: opts };
+    let space = opts.space || '';
+    if (typeof space === 'number')
+        space = Array(space+1).join(' ');
+    const cycles = (typeof opts.cycles === 'boolean') ? opts.cycles : false;
+    const cmp = opts.cmp && (function (f)
+    {
+        return function (node)
+        {
+            return function (a, b)
+            {
+                let aobj = { key: a, value: node[a] };
+                let bobj = { key: b, value: node[b] };
+                return f(aobj, bobj);
+            };
+        };
+    })(opts.cmp);
+    const seen = new Map();
+    return (function stringify (parent, key, node, level)
+    {
+        const indent = space ? ('\n' + new Array(level + 1).join(space)) : '';
+        const colonSeparator = space ? ': ' : ':';
+        if (node === undefined)
+        {
+            return;
+        }
+        if (typeof node !== 'object' || node === null)
+        {
+            return JSON.stringify(node);
+        }
+        if (node instanceof Array)
+        {
+            const out = [];
+            for (let i = 0; i < node.length; i++)
+            {
+                const item = stringify(node, i, node[i], level+1) || JSON.stringify(null);
+                out.push(indent + space + item);
+            }
+            return '[' + out.join(',') + indent + ']';
+        }
+        else
+        {
+            if (seen.has(node))
+            {
+                if (cycles)
+                    return JSON.stringify('__cycle__');
+                throw new TypeError('Converting circular structure to JSON');
+            }
+            else
+                seen.set(node, true);
+            const keys = Object.keys(node).sort(cmp && cmp(node));
+            const out = [];
+            for (let i = 0; i < keys.length; i++)
+            {
+                const key = keys[i];
+                const value = stringify(node, key, node[key], level+1);
+                if (!value)
+                    continue;
+                const keyValue = JSON.stringify(key)
+                    + colonSeparator
+                    + value;
+                out.push(indent + space + keyValue);
+            }
+            seen.delete(node);
+            return '{' + out.join(',') + indent + '}';
+        }
+    })({ '': obj }, '', obj, 0);
+}
+
+module.exports = stableStringify;