diff --git a/index.ts b/index.ts
index e69de29..0e3a946 100644
--- a/index.ts
+++ b/index.ts
@@ -0,0 +1 @@
+export * from './lazy/index.js'
diff --git a/lazy/index.ts b/lazy/index.ts
new file mode 100644
index 0000000..7f47604
--- /dev/null
+++ b/lazy/index.ts
@@ -0,0 +1,17 @@
+/**
+ * A lazy function for typescript projects.
+ */
+export const lazy = <T>(create: () => T) => {
+  let instance: T | undefined = undefined
+  return (): T => instance ??= create()
+}
+
+/*
+ * Example:
+ *   const config = lazy(
+ *     () => fs.readFileSync('config.json').then(f => cfgSchema.parse(f))
+ *   )
+ *
+ *   config().PROP_1
+ *   config().PROP_2 // config file is read and parsed only once
+ */
diff --git a/lazy/lazy.test.ts b/lazy/lazy.test.ts
new file mode 100644
index 0000000..ff42dd3
--- /dev/null
+++ b/lazy/lazy.test.ts
@@ -0,0 +1,45 @@
+import { expect, test } from 'vitest'
+import { lazy } from './index.js'
+
+test('lazy remembers the value of its function', () => {
+  const lazyValue = lazy(() => 1)
+
+  expect(lazyValue()).toBe(1)
+})
+
+test('lazy executes its function only once', () => {
+  let countExecutions = 0
+
+  const lazyValue = lazy(() => {
+    countExecutions++
+    return 1
+  })
+
+  lazyValue()
+  lazyValue()
+
+  expect(countExecutions).toBe(1)
+})
+
+test('lazy does propagate exceptions on first use', () => {
+  const lazyValue = lazy(() => {
+    throw new Error()
+  })
+
+  expect(lazyValue).toThrowError()
+})
+
+test('lazy retries on exceptions', () => {
+  let countExecutions = 0
+
+  const lazyValue = lazy(() => {
+    if (countExecutions === 0) {
+      countExecutions++
+      throw new Error()
+    }
+    return 1
+  })
+
+  expect(lazyValue).toThrowError()
+  expect(lazyValue()).toBe(1)
+})