diff --git a/timely/src/dataflow/operators/enterleave.rs b/timely/src/dataflow/operators/core/enterleave.rs
similarity index 87%
rename from timely/src/dataflow/operators/enterleave.rs
rename to timely/src/dataflow/operators/core/enterleave.rs
index 97ada7ae2..23da0e201 100644
--- a/timely/src/dataflow/operators/enterleave.rs
+++ b/timely/src/dataflow/operators/core/enterleave.rs
@@ -25,16 +25,14 @@ use crate::logging::{TimelyLogger, MessagesEvent};
 use crate::progress::Timestamp;
 use crate::progress::timestamp::Refines;
 use crate::progress::{Source, Target};
-use crate::order::Product;
 use crate::{Container, Data};
 use crate::communication::Push;
 use crate::dataflow::channels::pushers::{Counter, Tee};
 use crate::dataflow::channels::{Bundle, Message};
 
 use crate::worker::AsWorker;
-use crate::dataflow::{StreamCore, Scope, Stream};
-use crate::dataflow::scopes::{Child, ScopeParent};
-use crate::dataflow::operators::delay::Delay;
+use crate::dataflow::{StreamCore, Scope};
+use crate::dataflow::scopes::Child;
 
 /// Extension trait to move a `Stream` into a child of its current `Scope`.
 pub trait Enter<G: Scope, T: Timestamp+Refines<G::Timestamp>, C: Container> {
@@ -55,34 +53,6 @@ pub trait Enter<G: Scope, T: Timestamp+Refines<G::Timestamp>, C: Container> {
     fn enter<'a>(&self, _: &Child<'a, G, T>) -> StreamCore<Child<'a, G, T>, C>;
 }
 
-use crate::dataflow::scopes::child::Iterative;
-
-/// Extension trait to move a `Stream` into a child of its current `Scope` setting the timestamp for each element.
-pub trait EnterAt<G: Scope, T: Timestamp, D: Data> {
-    /// Moves the `Stream` argument into a child of its current `Scope` setting the timestamp for each element by `initial`.
-    ///
-    /// # Examples
-    /// ```
-    /// use timely::dataflow::scopes::Scope;
-    /// use timely::dataflow::operators::{EnterAt, Leave, ToStream};
-    ///
-    /// timely::example(|outer| {
-    ///     let stream = (0..9u64).to_stream(outer);
-    ///     let output = outer.iterative(|inner| {
-    ///         stream.enter_at(inner, |x| *x).leave()
-    ///     });
-    /// });
-    /// ```
-    fn enter_at<'a, F:FnMut(&D)->T+'static>(&self, scope: &Iterative<'a, G, T>, initial: F) -> Stream<Iterative<'a, G, T>, D> ;
-}
-
-impl<G: Scope, T: Timestamp, D: Data, E: Enter<G, Product<<G as ScopeParent>::Timestamp, T>, Vec<D>>> EnterAt<G, T, D> for E {
-    fn enter_at<'a, F:FnMut(&D)->T+'static>(&self, scope: &Iterative<'a, G, T>, mut initial: F) ->
-        Stream<Iterative<'a, G, T>, D> {
-            self.enter(scope).delay(move |datum, time| Product::new(time.clone().to_outer(), initial(datum)))
-    }
-}
-
 impl<G: Scope, T: Timestamp+Refines<G::Timestamp>, C: Data+Container> Enter<G, T, C> for StreamCore<G, C> {
     fn enter<'a>(&self, scope: &Child<'a, G, T>) -> StreamCore<Child<'a, G, T>, C> {
 
diff --git a/timely/src/dataflow/operators/core/mod.rs b/timely/src/dataflow/operators/core/mod.rs
index 758eb5231..d81a5c625 100644
--- a/timely/src/dataflow/operators/core/mod.rs
+++ b/timely/src/dataflow/operators/core/mod.rs
@@ -2,6 +2,7 @@
 //! are independent of specific container types.
 
 pub mod concat;
+pub mod enterleave;
 pub mod exchange;
 pub mod feedback;
 pub mod inspect;
@@ -10,6 +11,7 @@ pub mod rc;
 pub mod reclock;
 
 pub use concat::{Concat, Concatenate};
+pub use enterleave::{Enter, Leave};
 pub use exchange::Exchange;
 pub use feedback::{Feedback, LoopVariable, ConnectLoop};
 pub use inspect::{Inspect, InspectCore};
diff --git a/timely/src/dataflow/operators/mod.rs b/timely/src/dataflow/operators/mod.rs
index 29f62299b..458566ddc 100644
--- a/timely/src/dataflow/operators/mod.rs
+++ b/timely/src/dataflow/operators/mod.rs
@@ -8,7 +8,6 @@
 //! operators whose behavior can be supplied using closures accepting input and output handles.
 //! Most of the operators in this module are defined using these two general operators.
 
-pub use self::enterleave::{Enter, EnterAt, Leave};
 pub use self::input::Input;
 pub use self::unordered_input::{UnorderedInput, UnorderedInputCore};
 pub use self::partition::Partition;
@@ -32,7 +31,7 @@ pub use self::count::Accumulate;
 
 pub mod core;
 
-pub mod enterleave;
+pub use self::core::enterleave::{self, Enter, Leave};
 pub mod input;
 pub mod flow_controlled;
 pub mod unordered_input;