diff --git a/docs/inv/rust/inv_raw.txt b/docs/inv/rust/inv_raw.txt
index c9eb936d..e31da99b 100644
--- a/docs/inv/rust/inv_raw.txt
+++ b/docs/inv/rust/inv_raw.txt
@@ -19,3 +19,8 @@ std::ops::Div rust:trait 1 https://doc.rust-lang.org/stable/std/ops/trait.Div.ht
 std::ops::Mul rust:trait 1 https://doc.rust-lang.org/stable/std/ops/trait.Mul.html std::ops::Mul
 std::ops::Rem rust:trait 1 https://doc.rust-lang.org/stable/std/ops/trait.Rem.html std::ops::Rem
 seq_macro::seq rust:macro 1 https://docs.rs/seq-macro/latest/seq_macro/macro.seq.html seq_macro::seq
+std::iter::TakeWhile rust:Struct 1 https://doc.rust-lang.org/beta/std/iter/struct.TakeWhile.html std::iter::TakeWhile
+std::any::TypeId rust:Struct 1 https://doc.rust-lang.org/beta/std/any/struct.TypeId.html std::any::TypeId
+std::sync::Mutex rust:Struct 1 https://doc.rust-lang.org/beta/std/sync/struct.Mutex.html std::sync::Mutex
+std::sync::RwLock rust:Struct 1 https://doc.rust-lang.org/beta/std/sync/struct.RwLock.html std::sync::RwLock
+std::sync::Once rust:Struct 1 https://doc.rust-lang.org/beta/std/sync/struct.Once.html std::sync::Once
diff --git a/docs/src/rust/lib/iter_cache.rst b/docs/src/rust/lib/iter_cache.rst
new file mode 100644
index 00000000..9efdb8c5
--- /dev/null
+++ b/docs/src/rust/lib/iter_cache.rst
@@ -0,0 +1,28 @@
+iter_cache.rs
+=============
+
+View source code :source:`rust/src/include/iter_cache.rs`
+
+Includes
+--------
+
+- :external:rust:struct:`std::any::TypeId`
+- :external:rust:struct:`std::collections::HashMap`
+- :external:rust:trait:`std::sync::Mutex`
+- :external:rust:struct:`std::sync::RwLock`
+- :external:rust:fn:`std::sync::Once`
+
+.. rust:struct:: pub struct iter_cache::CachingIterator<I, T> where I: Iterator<Item = T> + 'static, T: Clone + 'static
+
+    This struct implements a global cache that maps an iterator-iterated pair to a cache of values. It is mostly
+    intended for use with the prime function generator.
+
+  .. rust:fn:: pub fn iter_cache::CachingIterator::new() -> CachingIterator<I, T> where I: Iterator<Item = T> + 'static, T: Clone + 'static
+
+  .. rust:fn:: pub fn iter_cache::CachingIterator::default() -> CachingIterator<I, T> where I: Iterator<Item = T> + 'static, T: Clone + 'static
+
+  .. rust:fn:: pub fn iter_cache::CachingIterator::next() -> Option<T> where T: Clone + 'static
+
+.. literalinclude:: ../../../../rust/src/include/iter_cache.rs
+   :language: rust
+   :linenos:
diff --git a/docs/src/rust/lib/primes.rst b/docs/src/rust/lib/primes.rst
index 2d85dcd2..eb3a0ffe 100644
--- a/docs/src/rust/lib/primes.rst
+++ b/docs/src/rust/lib/primes.rst
@@ -6,12 +6,14 @@ View source code :source:`rust/src/include/primes.rs`
 Includes
 --------
 
+- `iter_cache.rs <./iter_cache.html>`_
 - :external:rust:trait:`num_traits::One`
 - :external:rust:trait:`num_traits::Zero`
 - :external:rust:fn:`num_traits::one`
 - :external:rust:fn:`num_traits::zero`
 - :external:rust:trait:`itertools::Itertools`
 - :external:rust:struct:`std::collections::HashMap`
+- :external:rust:struct:`std::iter::TakeWhile`
 - :external:rust:trait:`std::cmp::Ord`
 - :external:rust:trait:`std::hash::Hash`
 - :external:rust:trait:`std::ops::Add`
@@ -19,11 +21,11 @@ Includes
 - :external:rust:trait:`std::ops::Mul`
 - :external:rust:trait:`std::ops::Rem`
 
-.. rust:fn:: pub fn primes::primes<I>() -> Eratosthenes<I> where I: Hash + One + Zero + Add
+.. rust:fn:: pub fn primes::primes<I>() -> impl Iterator<Item = I>
 
   A convenience method that returns an iterator over the prime numbers.
 
-.. rust:fn:: pub fn primes::primes_until<I>(x: I) -> Eratosthenes<I> where I: Hash + One + Zero + Add
+.. rust:fn:: pub fn primes::primes_until<I>(x: I) -> impl Iterator<Item = I>
 
   A convenience method that returns an iterator over the prime numbers until a given limit.
 
@@ -41,8 +43,6 @@ Includes
 
   .. rust:fn:: pub fn primes::Eratosthenes::default() -> Eratosthenes<I> where I: Hash + One + Zero + Add
 
-  .. rust:fn:: pub fn primes::Eratosthenes::with_limit(limit: I) -> Eratosthenes<I> where I: Hash + One + Zero + Add
-
   .. rust:fn:: pub fn primes::Eratosthenes::next() -> Option<I> where I: Hash + One + Zero + Add + Mul + Ord + Copy
 
 .. rust:fn:: pub fn primes::prime_factors<I>(x: I) -> PrimeFactors<I>
diff --git a/rust/src/include/iter_cache.rs b/rust/src/include/iter_cache.rs
new file mode 100644
index 00000000..5c9f322c
--- /dev/null
+++ b/rust/src/include/iter_cache.rs
@@ -0,0 +1,93 @@
+use std::any::TypeId;
+use std::collections::HashMap;
+use std::sync::{Mutex, RwLock};
+use std::sync::Once;
+
+static INIT: Once = Once::new();
+static mut CACHE_MAP: Option<RwLock<HashMap<(TypeId, TypeId), Mutex<Vec<Box<dyn std::any::Any>>>>>> = None;
+
+pub struct CachingIterator<I, T>
+where
+    I: Iterator<Item = T> + 'static,
+    T: Copy + 'static
+{
+    inner: I,
+    index: usize,
+    inner_index: usize,
+    type_id: (TypeId, TypeId),
+}
+
+impl<I, T> CachingIterator<I, T>
+where
+    I: Iterator<Item = T> + 'static,
+    T: Copy + 'static
+{
+    pub fn new(inner: I) -> Self {
+        // Initialize the global cache map if it hasn't been initialized yet
+        unsafe {
+            INIT.call_once(|| {
+                CACHE_MAP = Some(RwLock::new(HashMap::new()));
+            });
+        }
+        CachingIterator {
+            inner,
+            index: 0,
+            inner_index: 0,
+            type_id: (TypeId::of::<I>(), TypeId::of::<T>())
+        }
+    }
+
+    // Initialize the cache for the given type
+    fn initialize_cache(&self) {
+        unsafe {
+            let mut cache_map = CACHE_MAP.as_ref().unwrap().write().unwrap();
+            cache_map.entry(self.type_id)
+                .or_insert_with(|| Mutex::new(Vec::new()));
+        }
+    }
+}
+
+impl<I, T> Iterator for CachingIterator<I, T>
+where
+    I: Iterator<Item = T> + 'static,
+    T: Copy + 'static
+{
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        // Ensure the cache is initialized
+        self.initialize_cache();
+        
+        // Access the global cache map
+        let cache_map = unsafe { CACHE_MAP.as_ref().unwrap().read().unwrap() };
+
+        let mut cache = cache_map
+            .get(&self.type_id)
+            .expect("Cache for this type should be initialized")
+            .lock()
+            .unwrap();
+        
+        if self.index < cache.len() {
+            // Return the cached result
+            let boxed_item = &cache[self.index];
+            let result = boxed_item.downcast_ref::<T>().unwrap();
+            self.index += 1;
+            Some(result)
+        } else {
+            // Fetch the next result from the inner iterator and cache it
+            while self.inner_index < self.index {
+                self.inner.next();
+                self.inner_index += 1;
+            }
+            match self.inner.next() {
+                Some(value) => {
+                    cache.push(Box::new(value));
+                    self.index += 1;
+                    self.inner_index += 1;
+                    Some(value)
+                }
+                None => None,
+            }
+        }
+    }
+}
diff --git a/rust/src/include/mod.rs b/rust/src/include/mod.rs
index e7cae63a..1d9ca496 100644
--- a/rust/src/include/mod.rs
+++ b/rust/src/include/mod.rs
@@ -1,3 +1,4 @@
+pub mod iter_cache;
 pub mod factors;
 pub mod math;
 pub mod primes;
diff --git a/rust/src/include/primes.rs b/rust/src/include/primes.rs
index 7237607f..4429d806 100644
--- a/rust/src/include/primes.rs
+++ b/rust/src/include/primes.rs
@@ -1,17 +1,19 @@
-use std::collections::HashMap;
 use std::cmp::Ord;
+use std::collections::HashMap;
 use std::hash::Hash;
+use std::iter::TakeWhile;
 use std::ops::{Add,Div,Mul,Rem};
 
 use num_traits::{one,zero,One,Zero};
 
+use crate::include::iter_cache::CachingIterator;
+
 pub struct Eratosthenes<I>
 where I: Hash
 {
     sieve: HashMap<I, Vec<I>>,
     prime: I,
     candidate: I,
-    limit: Option<I>,
 }
 
 impl<I> Default for Eratosthenes<I>
@@ -22,7 +24,6 @@ where I: Hash + One + Zero + Add
             sieve: HashMap::new(),
             prime: zero::<I>(),
             candidate: one::<I>() + one(),
-            limit: None,
         };
     }
 }
@@ -33,13 +34,6 @@ where I: Hash + One + Zero + Add
     pub fn new() -> Eratosthenes<I> {
         return Default::default();
     }
-
-    pub fn with_limit(limit: I) -> Eratosthenes<I> {
-        return Eratosthenes{
-            limit: Some(limit),
-            ..Default::default()
-        };
-    }
 }
 
 impl<I> Iterator for Eratosthenes<I>
@@ -71,24 +65,20 @@ where I: Hash + One + Zero + Add + Mul + Ord + Copy
 
         self.prime = next_prime::<I>(&mut self.sieve, self.candidate);
         self.candidate = self.prime + one();
-
-        if self.limit.is_some() && self.prime > self.limit? {
-            return None;
-        }
         return Some(self.prime);
     }
 }
 
-pub fn primes<I>() -> Eratosthenes<I>
-where I: Hash + One + Zero + Add
+pub fn primes<I>() -> impl Iterator<Item = I>
+where I: Hash + One + Zero + Add + Mul + Ord + Copy
 {
-    return Eratosthenes::new();
+    return CachingIterator::new(Eratosthenes::new());
 }
 
-pub fn primes_until<I>(x: I) -> Eratosthenes<I>
-where I: Hash + One + Zero + Add
+pub fn primes_until<I>(x: I) -> impl Iterator<Item = I>
+where I: Hash + One + Zero + Add + Mul + Ord + Copy
 {
-    return Eratosthenes::with_limit(x);
+    return primes::<I>().take_while(|n| n < x);
 }
 
 pub struct PrimeFactors<I>
@@ -111,7 +101,7 @@ where I: Hash + Zero + One + Add + Ord + Copy + Div<Output=I> + Rem<Output=I>
     type Item = I;
 
     fn next(&mut self) -> Option<Self::Item> {
-        for p in Eratosthenes::new() {
+        for p in primes() {
             if self.number % p == zero() {
                 self.number = self.number / p;
                 return Some(p);