diff --git a/djx/src/main/ts/observable.ts b/djx/src/main/ts/observable.ts
--- a/djx/src/main/ts/observable.ts
+++ b/djx/src/main/ts/observable.ts
@@ -88,6 +88,8 @@ export interface Observable<T> extends S
     scan<A>(accumulator: (acc: A, value: T) => A, initial: A): Observable<A>;
 
     cat(...seq: Subscribable<T>[]): Observable<T>;
+
+    pipe<U>(f: (source: Observable<T>) => Producer<U>): Observable<U>;
 }
 
 const noop = () => { };
@@ -169,7 +171,9 @@ const _observe = <T>(producer: Producer<
         cleanup = producer({ next, complete, ...rest }) ?? noop;
 
         return () => cleanup();
-    })
+    }),
+
+    pipe: <U>(f: (source: Observable<T>) => Producer<U>) => observe(f(_observe(producer)))
 });
 
 export interface OrderUpdate<T> {
diff --git a/djx/src/test/ts/observable-tests.ts b/djx/src/test/ts/observable-tests.ts
--- a/djx/src/test/ts/observable-tests.ts
+++ b/djx/src/test/ts/observable-tests.ts
@@ -35,7 +35,7 @@ subj1
         maps++;
         return v * 2;
     })
-    .map (v => {
+    .map(v => {
         t.comment(`map2: ${v * 2}`);
         maps++;
         return v * 2;
@@ -50,3 +50,33 @@ subj1
 t.equal(consumer2.value, 8, "Should map");
 t.equal(maps, 3, "The map chain should not be executed after completion");
 t.ok(consumer2.completed, "The completion signal should pass through");
+
+const subj2 = observe<number>(({ next, complete }) => {
+    [1, 2, 3, 4, 5].forEach(next);
+    complete();
+}).pipe<string>(self => ({ next, complete, error }) => {
+    t.comment("subj2: subscribe");
+    const h = self.subscribe({
+        next: val => {
+            if (val % 2 === 0)
+                next("odd");
+            else
+                next("even");
+        },
+        complete,
+        error
+    });
+    return () =>{
+        t.comment("subj2: unsubscribe");
+        h.unsubscribe();
+    };
+});
+
+subj2.subscribe({
+    next: val => t.comment("subj2: ", val),
+    complete: () => t.comment("subj2: complete")
+});
+subj2.subscribe({
+    next: val => t.comment("subj2: ", val),
+    complete: () => t.comment("subj2: complete")
+});
\ No newline at end of file
diff --git a/playground/package-lock.json b/playground/package-lock.json
--- a/playground/package-lock.json
+++ b/playground/package-lock.json
@@ -30,7 +30,6 @@
         },
         "../djx/build/npm/package": {
             "name": "@implab/djx",
-            "version": "1.4.4",
             "dev": true,
             "license": "BSD-2-Clause",
             "peerDependencies": {