deepakkumarnd · September 22, 2022 13:58 · Sep 22, 2022
diff --git a/ImmutableList.ts b/ImmutableList.ts
@@ -0,0 +1,41 @@
+abstract class ImmutableList<T> {
+    abstract add(elem: T): ImmutableList<T>
+    abstract forEach(fn: (x: T) => void): void
+}
+
+class Cons<T> implements ImmutableList<T> {
+    readonly el: T
+    readonly next: ImmutableList<T>
+
+    constructor(elem: T, list: ImmutableList<T> = Nil) {
+        this.el = elem
+        this.next = list
+    }
+
+    add(elem: T): ImmutableList<T> {
+        return new Cons(elem, this)
+    }
+
+    forEach(fn: (x: T) => void): void {
+        fn(this.el)
+        this.next.forEach(fn)
+    }
+}
+
+class EmptyList extends ImmutableList<never> {
+    add(elem: never): ImmutableList<never> {
+        return this
+    }
+
+    forEach(fn: (x: never) => void): void {}
+}
+
+const Nil = new EmptyList()
+
+let list: ImmutableList<number> = new Cons(1)
+
+list = list.add(2)
+list = list.add(3)
+
+list.forEach(console.log)
+