diff --git a/Cargo.toml b/Cargo.toml
index dc89349..5ef3ccd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,12 +23,16 @@ optional = true
 path = "bigint"
 
 [dependencies.num-complex]
-optional = false
+optional = true
 path = "complex"
 
 [dependencies.num-integer]
 path = "./integer"
 
+[dependencies.num-iter]
+optional = false
+path = "iter"
+
 [dependencies.num-rational]
 optional = true
 path = "rational"
@@ -55,6 +59,6 @@ version = "0.3.8"
 
 [features]
 bigint = ["num-bigint"]
-complex = []
-default = ["bigint", "complex", "rand", "rational", "rustc-serialize"]
+complex = ["num-complex"]
 rational = ["num-rational"]
+default = ["bigint", "complex", "rand", "rational", "rustc-serialize"]
diff --git a/iter/Cargo.toml b/iter/Cargo.toml
new file mode 100644
index 0000000..0c69411
--- /dev/null
+++ b/iter/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+authors = ["Łukasz Jan Niemier <lukasz@niemier.pl>"]
+name = "num-iter"
+version = "0.1.0"
+
+[dependencies]
+
+[dependencies.num-integer]
+optional = false
+path = "../integer"
+
+[dependencies.num-traits]
+optional = false
+path = "../traits"
diff --git a/iter/src/lib.rs b/iter/src/lib.rs
new file mode 100644
index 0000000..8f567d7
--- /dev/null
+++ b/iter/src/lib.rs
@@ -0,0 +1,376 @@
+// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! External iterators for generic mathematics
+
+extern crate num_traits as traits;
+extern crate num_integer as integer;
+
+use integer::Integer;
+use traits::{Zero, One, CheckedAdd, ToPrimitive};
+use std::ops::{Add, Sub};
+
+/// An iterator over the range [start, stop)
+#[derive(Clone)]
+pub struct Range<A> {
+    state: A,
+    stop: A,
+    one: A
+}
+
+/// Returns an iterator over the given range [start, stop) (that is, starting
+/// at start (inclusive), and ending at stop (exclusive)).
+///
+/// # Example
+///
+/// ```rust
+/// use num::iter;
+///
+/// let array = [0, 1, 2, 3, 4];
+///
+/// for i in iter::range(0, 5) {
+///     println!("{}", i);
+///     assert_eq!(i,  array[i]);
+/// }
+/// ```
+#[inline]
+pub fn range<A>(start: A, stop: A) -> Range<A>
+    where A: Add<A, Output = A> + PartialOrd + Clone + One
+{
+    Range{state: start, stop: stop, one: One::one()}
+}
+
+// FIXME: rust-lang/rust#10414: Unfortunate type bound
+impl<A> Iterator for Range<A>
+    where A: Add<A, Output = A> + PartialOrd + Clone + ToPrimitive
+{
+    type Item = A;
+
+    #[inline]
+    fn next(&mut self) -> Option<A> {
+        if self.state < self.stop {
+            let result = self.state.clone();
+            self.state = self.state.clone() + self.one.clone();
+            Some(result)
+        } else {
+            None
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        // This first checks if the elements are representable as i64. If they aren't, try u64 (to
+        // handle cases like range(huge, huger)). We don't use usize/int because the difference of
+        // the i64/u64 might lie within their range.
+        let bound = match self.state.to_i64() {
+            Some(a) => {
+                let sz = self.stop.to_i64().map(|b| b.checked_sub(a));
+                match sz {
+                    Some(Some(bound)) => bound.to_usize(),
+                    _ => None,
+                }
+            },
+            None => match self.state.to_u64() {
+                Some(a) => {
+                    let sz = self.stop.to_u64().map(|b| b.checked_sub(a));
+                    match sz {
+                        Some(Some(bound)) => bound.to_usize(),
+                        _ => None
+                    }
+                },
+                None => None
+            }
+        };
+
+        match bound {
+            Some(b) => (b, Some(b)),
+            // Standard fallback for unbounded/unrepresentable bounds
+            None => (0, None)
+        }
+    }
+}
+
+/// `Integer` is required to ensure the range will be the same regardless of
+/// the direction it is consumed.
+impl<A> DoubleEndedIterator for Range<A>
+    where A: Integer + Clone + ToPrimitive
+{
+    #[inline]
+    fn next_back(&mut self) -> Option<A> {
+        if self.stop > self.state {
+            self.stop = self.stop.clone() - self.one.clone();
+            Some(self.stop.clone())
+        } else {
+            None
+        }
+    }
+}
+
+/// An iterator over the range [start, stop]
+#[derive(Clone)]
+pub struct RangeInclusive<A> {
+    range: Range<A>,
+    done: bool,
+}
+
+/// Return an iterator over the range [start, stop]
+#[inline]
+pub fn range_inclusive<A>(start: A, stop: A) -> RangeInclusive<A>
+    where A: Add<A, Output = A> + PartialOrd + Clone + One
+{
+    RangeInclusive{range: range(start, stop), done: false}
+}
+
+impl<A> Iterator for RangeInclusive<A>
+    where A: Add<A, Output = A> + PartialOrd + Clone + ToPrimitive
+{
+    type Item = A;
+
+    #[inline]
+    fn next(&mut self) -> Option<A> {
+        match self.range.next() {
+            Some(x) => Some(x),
+            None => {
+                if !self.done && self.range.state == self.range.stop {
+                    self.done = true;
+                    Some(self.range.stop.clone())
+                } else {
+                    None
+                }
+            }
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let (lo, hi) = self.range.size_hint();
+        if self.done {
+            (lo, hi)
+        } else {
+            let lo = lo.saturating_add(1);
+            let hi = match hi {
+                Some(x) => x.checked_add(1),
+                None => None
+            };
+            (lo, hi)
+        }
+    }
+}
+
+impl<A> DoubleEndedIterator for RangeInclusive<A>
+    where A: Sub<A, Output = A> + Integer + Clone + ToPrimitive
+{
+    #[inline]
+    fn next_back(&mut self) -> Option<A> {
+        if self.range.stop > self.range.state {
+            let result = self.range.stop.clone();
+            self.range.stop = self.range.stop.clone() - self.range.one.clone();
+            Some(result)
+        } else if !self.done && self.range.state == self.range.stop {
+            self.done = true;
+            Some(self.range.stop.clone())
+        } else {
+            None
+        }
+    }
+}
+
+/// An iterator over the range [start, stop) by `step`. It handles overflow by stopping.
+#[derive(Clone)]
+pub struct RangeStep<A> {
+    state: A,
+    stop: A,
+    step: A,
+    rev: bool,
+}
+
+/// Return an iterator over the range [start, stop) by `step`. It handles overflow by stopping.
+#[inline]
+pub fn range_step<A>(start: A, stop: A, step: A) -> RangeStep<A>
+    where A: CheckedAdd + PartialOrd + Clone + Zero
+{
+    let rev = step < Zero::zero();
+    RangeStep{state: start, stop: stop, step: step, rev: rev}
+}
+
+impl<A> Iterator for RangeStep<A>
+    where A: CheckedAdd + PartialOrd + Clone
+{
+    type Item = A;
+
+    #[inline]
+    fn next(&mut self) -> Option<A> {
+        if (self.rev && self.state > self.stop) || (!self.rev && self.state < self.stop) {
+            let result = self.state.clone();
+            match self.state.checked_add(&self.step) {
+                Some(x) => self.state = x,
+                None => self.state = self.stop.clone()
+            }
+            Some(result)
+        } else {
+            None
+        }
+    }
+}
+
+/// An iterator over the range [start, stop] by `step`. It handles overflow by stopping.
+#[derive(Clone)]
+pub struct RangeStepInclusive<A> {
+    state: A,
+    stop: A,
+    step: A,
+    rev: bool,
+    done: bool,
+}
+
+/// Return an iterator over the range [start, stop] by `step`. It handles overflow by stopping.
+#[inline]
+pub fn range_step_inclusive<A>(start: A, stop: A, step: A) -> RangeStepInclusive<A>
+    where A: CheckedAdd + PartialOrd + Clone + Zero
+{
+    let rev = step < Zero::zero();
+    RangeStepInclusive{state: start, stop: stop, step: step, rev: rev, done: false}
+}
+
+impl<A> Iterator for RangeStepInclusive<A>
+    where A: CheckedAdd + PartialOrd + Clone + PartialEq
+{
+    type Item = A;
+
+    #[inline]
+    fn next(&mut self) -> Option<A> {
+        if !self.done && ((self.rev && self.state >= self.stop) ||
+                          (!self.rev && self.state <= self.stop)) {
+            let result = self.state.clone();
+            match self.state.checked_add(&self.step) {
+                Some(x) => self.state = x,
+                None => self.done = true
+            }
+            Some(result)
+        } else {
+            None
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::usize;
+    use std::ops::{Add, Mul};
+    use std::cmp::Ordering;
+    use {One, ToPrimitive};
+
+    #[test]
+    fn test_range() {
+        /// A mock type to check Range when ToPrimitive returns None
+        struct Foo;
+
+        impl ToPrimitive for Foo {
+            fn to_i64(&self) -> Option<i64> { None }
+            fn to_u64(&self) -> Option<u64> { None }
+        }
+
+        impl Add<Foo> for Foo {
+            type Output = Foo;
+
+            fn add(self, _: Foo) -> Foo {
+                Foo
+            }
+        }
+
+        impl PartialEq for Foo {
+            fn eq(&self, _: &Foo) -> bool {
+                true
+            }
+        }
+
+        impl PartialOrd for Foo {
+            fn partial_cmp(&self, _: &Foo) -> Option<Ordering> {
+                None
+            }
+        }
+
+        impl Clone for Foo {
+            fn clone(&self) -> Foo {
+                Foo
+            }
+        }
+
+        impl Mul<Foo> for Foo {
+            type Output = Foo;
+
+            fn mul(self, _: Foo) -> Foo {
+                Foo
+            }
+        }
+
+        impl One for Foo {
+            fn one() -> Foo {
+                Foo
+            }
+        }
+
+        assert!(super::range(0, 5).collect::<Vec<isize>>() == vec![0, 1, 2, 3, 4]);
+        assert!(super::range(-10, -1).collect::<Vec<isize>>() ==
+                vec![-10, -9, -8, -7, -6, -5, -4, -3, -2]);
+        assert!(super::range(0, 5).rev().collect::<Vec<isize>>() == vec![4, 3, 2, 1, 0]);
+        assert_eq!(super::range(200, -5).count(), 0);
+        assert_eq!(super::range(200, -5).rev().count(), 0);
+        assert_eq!(super::range(200, 200).count(), 0);
+        assert_eq!(super::range(200, 200).rev().count(), 0);
+
+        assert_eq!(super::range(0, 100).size_hint(), (100, Some(100)));
+        // this test is only meaningful when sizeof usize < sizeof u64
+        assert_eq!(super::range(usize::MAX - 1, usize::MAX).size_hint(), (1, Some(1)));
+        assert_eq!(super::range(-10, -1).size_hint(), (9, Some(9)));
+    }
+
+    #[test]
+    fn test_range_inclusive() {
+        assert!(super::range_inclusive(0, 5).collect::<Vec<isize>>() ==
+                vec![0, 1, 2, 3, 4, 5]);
+        assert!(super::range_inclusive(0, 5).rev().collect::<Vec<isize>>() ==
+                vec![5, 4, 3, 2, 1, 0]);
+        assert_eq!(super::range_inclusive(200, -5).count(), 0);
+        assert_eq!(super::range_inclusive(200, -5).rev().count(), 0);
+        assert!(super::range_inclusive(200, 200).collect::<Vec<isize>>() == vec![200]);
+        assert!(super::range_inclusive(200, 200).rev().collect::<Vec<isize>>() == vec![200]);
+    }
+
+    #[test]
+    fn test_range_step() {
+        assert!(super::range_step(0, 20, 5).collect::<Vec<isize>>() ==
+                vec![0, 5, 10, 15]);
+        assert!(super::range_step(20, 0, -5).collect::<Vec<isize>>() ==
+                vec![20, 15, 10, 5]);
+        assert!(super::range_step(20, 0, -6).collect::<Vec<isize>>() ==
+                vec![20, 14, 8, 2]);
+        assert!(super::range_step(200u8, 255, 50).collect::<Vec<u8>>() ==
+                vec![200u8, 250]);
+        assert!(super::range_step(200, -5, 1).collect::<Vec<isize>>() == vec![]);
+        assert!(super::range_step(200, 200, 1).collect::<Vec<isize>>() == vec![]);
+    }
+
+    #[test]
+    fn test_range_step_inclusive() {
+        assert!(super::range_step_inclusive(0, 20, 5).collect::<Vec<isize>>() ==
+                vec![0, 5, 10, 15, 20]);
+        assert!(super::range_step_inclusive(20, 0, -5).collect::<Vec<isize>>() ==
+                vec![20, 15, 10, 5, 0]);
+        assert!(super::range_step_inclusive(20, 0, -6).collect::<Vec<isize>>() ==
+                vec![20, 14, 8, 2]);
+        assert!(super::range_step_inclusive(200u8, 255, 50).collect::<Vec<u8>>() ==
+                vec![200u8, 250]);
+        assert!(super::range_step_inclusive(200, -5, 1).collect::<Vec<isize>>() ==
+                vec![]);
+        assert!(super::range_step_inclusive(200, 200, 1).collect::<Vec<isize>>() ==
+                vec![200]);
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 36723ee..4ba0ead 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -57,14 +57,15 @@
        html_root_url = "http://rust-num.github.io/num/",
        html_playground_url = "http://play.rust-lang.org/")]
 
-extern crate num_traits;
-extern crate num_integer;
-#[cfg(feature = "complex")]
-extern crate num_complex;
+pub extern crate num_traits;
+pub extern crate num_integer;
+pub extern crate num_iter;
+#[cfg(feature = "num-complex")]
+pub extern crate num_complex;
 #[cfg(feature = "num-bigint")]
-extern crate num_bigint;
+pub extern crate num_bigint;
 #[cfg(feature = "num-rational")]
-extern crate num_rational;
+pub extern crate num_rational;
 
 #[cfg(feature = "rustc-serialize")]
 extern crate rustc_serialize;
@@ -84,7 +85,7 @@ pub use bigint::{BigInt, BigUint};
 pub use rational::Rational;
 #[cfg(all(feature = "num-rational", feature="num-bigint"))]
 pub use rational::BigRational;
-#[cfg(feature = "complex")]
+#[cfg(feature = "num-complex")]
 pub use complex::Complex;
 pub use integer::Integer;
 pub use iter::{range, range_inclusive, range_step, range_step_inclusive};
@@ -99,8 +100,8 @@ use std::ops::{Mul};
 #[cfg(feature = "num-bigint")]
 pub use num_bigint as bigint;
 pub use num_complex as complex;
-pub use num_integer as integers;
-pub mod iter;
+pub use num_integer as integer;
+pub use num_iter as iter;
 pub use num_traits as traits;
 #[cfg(feature = "num-rational")]
 pub use num_rational as rational;
diff --git a/traits/src/lib.rs b/traits/src/lib.rs
index c0dce24..869b92f 100644
--- a/traits/src/lib.rs
+++ b/traits/src/lib.rs
@@ -21,13 +21,13 @@ pub use sign::{Signed, Unsigned};
 pub use int::PrimInt;
 pub use cast::*;
 
-mod identities;
-mod sign;
-mod ops;
-mod bounds;
-mod float;
-mod int;
-mod cast;
+pub mod identities;
+pub mod sign;
+pub mod ops;
+pub mod bounds;
+pub mod float;
+pub mod int;
+pub mod cast;
 
 /// The base trait for numeric types
 pub trait Num: PartialEq + Zero + One