diff --git a/web-world/impl.rkt b/web-world/impl.rkt
new file mode 100644
index 0000000..65aeb30
--- /dev/null
+++ b/web-world/impl.rkt
@@ -0,0 +1,8 @@
+#lang s-exp "../lang/js/js.rkt"
+
+(declare-implementation
+ #:racket "racket-impl.rkt"
+ #:javascript ("js-impl.js")
+ #:provided-values (big-bang
+                    initial-view
+                    stop-when))
diff --git a/web-world/main.rkt b/web-world/main.rkt
index 4d0c7c4..3b4e0c5 100644
--- a/web-world/main.rkt
+++ b/web-world/main.rkt
@@ -1 +1,4 @@
 #lang s-exp "../lang/base.rkt"
+
+(require "impl.rkt")
+(provide (all-from-out "impl.rkt"))
\ No newline at end of file
diff --git a/web-world/racket-impl.rkt b/web-world/racket-impl.rkt
new file mode 100644
index 0000000..6d25755
--- /dev/null
+++ b/web-world/racket-impl.rkt
@@ -0,0 +1,12 @@
+#lang racket/base
+
+(provide big-bang initial-view stop-when)
+
+(define (big-bang world . handlers)
+  (error 'big-bang "Please run in JavaScript context."))
+
+(define (initial-view a-view-or-resource)
+  (error 'initial-view "Please run in JavaScript context."))
+
+(define (stop-when a-view-or-resource)
+  (error 'stop-when "Please run in JavaScript context."))
\ No newline at end of file