diff --git a/src/tests/vec.rs b/src/tests/vec.rs
index d7d99b39..740cd0c2 100644
--- a/src/tests/vec.rs
+++ b/src/tests/vec.rs
@@ -80,10 +80,14 @@ macro_rules! test_basis_impl(
         do 10000.times {
             do Basis::canonical_basis::<$t> |e1| {
                 do Basis::canonical_basis::<$t> |e2| {
-                    assert!(e1 == e2 || e1.dot(&e2).approx_eq(&Zero::zero()))
+                    assert!(e1 == e2 || e1.dot(&e2).approx_eq(&Zero::zero()));
+
+                    true
                 }
 
                 assert!(e1.norm().approx_eq(&One::one()));
+
+                true
             }
         }
     );
@@ -102,8 +106,12 @@ macro_rules! test_subspace_basis_impl(
                 assert!(e1.norm().approx_eq(&One::one()));
                 // check vectors form an ortogonal basis
                 do v1.orthonormal_subspace_basis() |e2| {
-                    assert!(e1 == e2 || e1.dot(&e2).approx_eq(&Zero::zero()))
+                    assert!(e1 == e2 || e1.dot(&e2).approx_eq(&Zero::zero()));
+
+                    true
                 }
+
+                true
             }
         }
     );
diff --git a/src/traits/basis.rs b/src/traits/basis.rs
index fe60d99c..aec2c6d6 100644
--- a/src/traits/basis.rs
+++ b/src/traits/basis.rs
@@ -1,17 +1,20 @@
+// FIXME: return an iterator instead
 /// Traits of objecs which can form a basis.
 pub trait Basis {
     /// Iterate through the canonical basis of the space in which this object lives.
-    fn canonical_basis(&fn(Self));
+    fn canonical_basis(&fn(Self) -> bool);
 
     /// Iterate through a basis of the subspace orthogonal to `self`.
-    fn orthonormal_subspace_basis(&self, &fn(Self));
+    fn orthonormal_subspace_basis(&self, &fn(Self) -> bool);
 
     /// Creates the canonical basis of the space in which this object lives.
     fn canonical_basis_list() -> ~[Self] {
         let mut res = ~[];
 
         do Basis::canonical_basis::<Self> |elem| {
-            res.push(elem)
+            res.push(elem);
+
+            true
         }
 
         res
@@ -22,7 +25,9 @@ pub trait Basis {
         let mut res = ~[];
 
         do self.orthonormal_subspace_basis |elem| {
-            res.push(elem)
+            res.push(elem);
+
+            true
         }
 
         res
diff --git a/src/vec0_spec.rs b/src/vec0_spec.rs
index 5bbcb887..b7917fd2 100644
--- a/src/vec0_spec.rs
+++ b/src/vec0_spec.rs
@@ -72,10 +72,10 @@ impl<N> Dim for vec::Vec0<N> {
 
 impl<N: Clone + DivisionRing + Algebraic + ApproxEq<N>> Basis for vec::Vec0<N> {
     #[inline(always)]
-    fn canonical_basis(_: &fn(vec::Vec0<N>)) { }
+    fn canonical_basis(_: &fn(vec::Vec0<N>) -> bool) { }
 
     #[inline(always)]
-    fn orthonormal_subspace_basis(&self, _: &fn(vec::Vec0<N>)) { }
+    fn orthonormal_subspace_basis(&self, _: &fn(vec::Vec0<N>) -> bool) { }
 }
 
 impl<N: Clone + Add<N,N>> Add<vec::Vec0<N>, vec::Vec0<N>> for vec::Vec0<N> {
diff --git a/src/vec_macros.rs b/src/vec_macros.rs
index d978da6c..be956974 100644
--- a/src/vec_macros.rs
+++ b/src/vec_macros.rs
@@ -185,18 +185,18 @@ macro_rules! basis_impl(
     ($t: ident, $dim: expr) => (
         impl<N: Clone + DivisionRing + Algebraic + ApproxEq<N>> Basis for $t<N> {
             #[inline]
-            fn canonical_basis(f: &fn($t<N>)) {
+            fn canonical_basis(f: &fn($t<N>) -> bool) {
                 for i in range(0u, $dim) {
                     let mut basis_element : $t<N> = Zero::zero();
 
                     basis_element.set(i, One::one());
 
-                    f(basis_element);
+                    if !f(basis_element) { return }
                 }
             }
 
             #[inline]
-            fn orthonormal_subspace_basis(&self, f: &fn($t<N>)) {
+            fn orthonormal_subspace_basis(&self, f: &fn($t<N>) -> bool) {
                 // compute the basis of the orthogonal subspace using Gram-Schmidt
                 // orthogonalization algorithm
                 let mut basis: ~[$t<N>] = ~[];
@@ -221,7 +221,7 @@ macro_rules! basis_impl(
                     if !elt.sqnorm().approx_eq(&Zero::zero()) {
                         let new_element = elt.normalized();
 
-                        f(new_element.clone());
+                        if !f(new_element.clone()) { return };
 
                         basis.push(new_element);
                     }
diff --git a/src/vec_spec.rs b/src/vec_spec.rs
index 3859fe92..176aa8b6 100644
--- a/src/vec_spec.rs
+++ b/src/vec_spec.rs
@@ -26,38 +26,38 @@ impl<N: Mul<N, N> + Sub<N, N>> Cross<Vec3<N>> for Vec3<N> {
 
 impl<N: One> Basis for Vec1<N> {
     #[inline(always)]
-    fn canonical_basis(f: &fn(Vec1<N>)) {
-        f(Vec1::new(One::one()))
+    fn canonical_basis(f: &fn(Vec1<N>) -> bool) {
+        f(Vec1::new(One::one()));
     }
 
     #[inline(always)]
-    fn orthonormal_subspace_basis(&self, _: &fn(Vec1<N>)) { }
+    fn orthonormal_subspace_basis(&self, _: &fn(Vec1<N>) -> bool ) { }
 }
 
 impl<N: Clone + One + Zero + Neg<N>> Basis for Vec2<N> {
-    #[inline]
-    fn canonical_basis(f: &fn(Vec2<N>)) {
-        f(Vec2::new(One::one(), Zero::zero()));
+    #[inline(always)]
+    fn canonical_basis(f: &fn(Vec2<N>) -> bool) {
+        if !f(Vec2::new(One::one(), Zero::zero())) { return };
         f(Vec2::new(Zero::zero(), One::one()));
     }
 
     #[inline]
-    fn orthonormal_subspace_basis(&self, f: &fn(Vec2<N>)) {
-        f(Vec2::new(-self.y, self.x.clone()))
+    fn orthonormal_subspace_basis(&self, f: &fn(Vec2<N>) -> bool) {
+        f(Vec2::new(-self.y, self.x.clone()));
     }
 }
 
 impl<N: Clone + DivisionRing + Ord + Algebraic + Signed>
 Basis for Vec3<N> {
     #[inline(always)]
-    fn canonical_basis(f: &fn(Vec3<N>)) {
-        f(Vec3::new(One::one(), Zero::zero(), Zero::zero()));
-        f(Vec3::new(Zero::zero(), One::one(), Zero::zero()));
+    fn canonical_basis(f: &fn(Vec3<N>) -> bool) {
+        if !f(Vec3::new(One::one(), Zero::zero(), Zero::zero())) { return };
+        if !f(Vec3::new(Zero::zero(), One::one(), Zero::zero())) { return };
         f(Vec3::new(Zero::zero(), Zero::zero(), One::one()));
     }
 
     #[inline(always)]
-    fn orthonormal_subspace_basis(&self, f: &fn(Vec3<N>)) {
+    fn orthonormal_subspace_basis(&self, f: &fn(Vec3<N>) -> bool) {
         let a = 
             if self.x.clone().abs() > self.y.clone().abs() {
                 Vec3::new(self.z.clone(), Zero::zero(), -self.x).normalized()
@@ -66,7 +66,7 @@ Basis for Vec3<N> {
                 Vec3::new(Zero::zero(), -self.z, self.y.clone()).normalized()
             };
 
-        f(a.cross(self));
+        if !f(a.cross(self)) { return };
         f(a);
     }
 }