diff --git a/Cargo.toml b/Cargo.toml
index c5552775e..1093c7616 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -42,7 +42,7 @@ approx = "0.4"
 
 ndarray = { version = "0.15", features = ["approx"] }
 ndarray-linalg = { version = "0.16", optional = true }
-sprs = { version = "0.11", default-features = false }
+sprs = { version = "=0.11.1", default-features = false }
 
 thiserror = "1.0"
 
diff --git a/algorithms/linfa-ftrl/Cargo.toml b/algorithms/linfa-ftrl/Cargo.toml
index 1b8abbb87..c5a2cacbe 100644
--- a/algorithms/linfa-ftrl/Cargo.toml
+++ b/algorithms/linfa-ftrl/Cargo.toml
@@ -24,7 +24,7 @@ version = "1.0"
 features = ["derive"]
 
 [dependencies]
-ndarray = { version = "0.15.4", features = ["serde"] }
+ndarray = { version = "0.15", features = ["serde"] }
 ndarray-rand = "0.14.0"
 argmin = { version = "0.9.0", default-features = false }
 argmin-math = { version = "0.3", features = ["ndarray_v0_15-nolinalg"] }
diff --git a/algorithms/linfa-kernel/Cargo.toml b/algorithms/linfa-kernel/Cargo.toml
index 4646cea27..266ce1e0e 100644
--- a/algorithms/linfa-kernel/Cargo.toml
+++ b/algorithms/linfa-kernel/Cargo.toml
@@ -26,7 +26,7 @@ features = ["std", "derive"]
 [dependencies]
 ndarray = "0.15"
 num-traits = "0.2"
-sprs = { version="0.11", default-features = false }
+sprs = { version="=0.11.1", default-features = false }
 
 linfa = { version = "0.7.0", path = "../.." }
 linfa-nn = { version = "0.7.0", path = "../linfa-nn" }
diff --git a/algorithms/linfa-preprocessing/Cargo.toml b/algorithms/linfa-preprocessing/Cargo.toml
index 6f9687aa8..25f030b04 100644
--- a/algorithms/linfa-preprocessing/Cargo.toml
+++ b/algorithms/linfa-preprocessing/Cargo.toml
@@ -29,7 +29,7 @@ ndarray-rand = { version = "0.14" }
 unicode-normalization = "0.1.8"
 regex = "1.4.5"
 encoding = "0.2"
-sprs = { version = "0.11.0", default-features = false }
+sprs = { version = "=0.11.1", default-features = false }
 
 serde_regex = { version = "1.1", optional = true }
 
diff --git a/src/correlation.rs b/src/correlation.rs
index e77905813..d157d10b0 100644
--- a/src/correlation.rs
+++ b/src/correlation.rs
@@ -128,7 +128,7 @@ impl<F: Float> PearsonCorrelation<F> {
     ///
     /// * `dataset`: Data for the correlation analysis
     /// * `num_iter`: optionally number of iterations of the p-value test, if none then no p-value
-    /// are calculate
+    ///   are calculated
     ///
     /// # Example
     ///
@@ -153,7 +153,6 @@ impl<F: Float> PearsonCorrelation<F> {
     /// lamotrigine                                                                                                                        +0.47 (0.14)
     /// blood sugar level
     /// ```
-
     pub fn from_dataset<D: Data<Elem = F>, T>(
         dataset: &DatasetBase<ArrayBase<D, Ix2>, T>,
         num_iter: Option<usize>,
diff --git a/src/dataset/impl_dataset.rs b/src/dataset/impl_dataset.rs
index b8148793f..cb1e28a90 100644
--- a/src/dataset/impl_dataset.rs
+++ b/src/dataset/impl_dataset.rs
@@ -208,7 +208,7 @@ where
     ///     println!("{} => {}", x, y);
     /// }
     /// ```
-    pub fn sample_iter(&'a self) -> Iter<'a, '_, F, T::Elem, T::Ix> {
+    pub fn sample_iter(&'a self) -> Iter<'a, 'a, F, T::Elem, T::Ix> {
         Iter::new(self.records.view(), self.targets.as_targets())
     }
 }
@@ -232,7 +232,7 @@ where
     ///
     /// This iterator produces dataset views with only a single feature, while the set of targets remain
     /// complete. It can be useful to compare each feature individual to all targets.
-    pub fn feature_iter(&'a self) -> DatasetIter<'a, '_, ArrayBase<D, Ix2>, T> {
+    pub fn feature_iter(&'a self) -> DatasetIter<'a, 'a, ArrayBase<D, Ix2>, T> {
         DatasetIter::new(self, true)
     }
 
@@ -241,7 +241,7 @@ where
     /// This functions creates an iterator which produces dataset views complete records, but only
     /// a single target each. Useful to train multiple single target models for a multi-target
     /// dataset.
-    pub fn target_iter(&'a self) -> DatasetIter<'a, '_, ArrayBase<D, Ix2>, T> {
+    pub fn target_iter(&'a self) -> DatasetIter<'a, 'a, ArrayBase<D, Ix2>, T> {
         DatasetIter::new(self, false)
     }
 }
@@ -318,7 +318,7 @@ impl<L: Label, T: Labels<Elem = L>, R: Records> Labels for DatasetBase<R, T> {
 }
 
 #[allow(clippy::type_complexity)]
-impl<'a, 'b: 'a, F, L: Label, T, D> DatasetBase<ArrayBase<D, Ix2>, T>
+impl<F, L: Label, T, D> DatasetBase<ArrayBase<D, Ix2>, T>
 where
     D: Data<Elem = F>,
     T: AsSingleTargets<Elem = L> + Labels<Elem = L>,
@@ -680,8 +680,8 @@ where
     /// - `k`: the number of folds to apply to the dataset
     /// - `params`: the desired parameters for the fittable algorithm at hand
     /// - `fit_closure`: a closure of the type `(params, training_data) -> fitted_model`
-    /// that will be used to produce the trained model for each fold. The training data given in input
-    /// won't outlive the closure.
+    ///   that will be used to produce the trained model for each fold. The training data given in
+    ///   input won't outlive the closure.
     ///
     /// ## Returns
     ///
@@ -732,7 +732,7 @@ where
         &'a mut self,
         k: usize,
         fit_closure: C,
-    ) -> impl Iterator<Item = (O, DatasetBase<ArrayView2<F>, ArrayView<E, I>>)> {
+    ) -> impl Iterator<Item = (O, DatasetBase<ArrayView2<'a, F>, ArrayView<'a, E, I>>)> {
         assert!(k > 0);
         assert!(k <= self.nsamples());
         let samples_count = self.nsamples();
@@ -794,9 +794,9 @@ where
     /// - `k`: the number of folds to apply
     /// - `parameters`: a list of models to compare
     /// - `eval`: closure used to evaluate the performance of each trained model. This closure is
-    /// called on the model output and validation targets of each fold and outputs the performance
-    /// score for each target. For single-target dataset the signature is `(Array1, Array1) ->
-    /// Array0`. For multi-target dataset the signature is `(Array2, Array2) -> Array1`.
+    ///   called on the model output and validation targets of each fold and outputs the performance
+    ///   score for each target. For single-target dataset the signature is `(Array1, Array1) ->
+    ///   Array0`. For multi-target dataset the signature is `(Array2, Array2) -> Array1`.
     ///
     /// ### Returns
     ///
diff --git a/src/dataset/mod.rs b/src/dataset/mod.rs
index 544d8243a..ab8f5417d 100644
--- a/src/dataset/mod.rs
+++ b/src/dataset/mod.rs
@@ -161,7 +161,7 @@ impl Deref for Pr {
 /// # Fields
 ///
 /// * `records`: a two-dimensional matrix with dimensionality (nsamples, nfeatures), in case of
-/// kernel methods a quadratic matrix with dimensionality (nsamples, nsamples), which may be sparse
+///   kernel methods a quadratic matrix with dimensionality (nsamples, nsamples), which may be sparse
 /// * `targets`: a two-/one-dimension matrix with dimensionality (nsamples, ntargets)
 /// * `weights`: optional weights for each sample with dimensionality (nsamples)
 /// * `feature_names`: optional descriptive feature names with dimensionality (nfeatures)
@@ -170,7 +170,7 @@ impl Deref for Pr {
 ///
 /// * `R: Records`: generic over feature matrices or kernel matrices
 /// * `T`: generic over any `ndarray` matrix which can be used as targets. The `AsTargets` trait
-/// bound is omitted here to avoid some repetition in implementation `src/dataset/impl_dataset.rs`
+///   bound is omitted here to avoid some repetition in implementation `src/dataset/impl_dataset.rs`
 #[derive(Debug, Clone, PartialEq)]
 pub struct DatasetBase<R, T>
 where
diff --git a/src/metrics_clustering.rs b/src/metrics_clustering.rs
index b49f4c5be..5eab97cb8 100644
--- a/src/metrics_clustering.rs
+++ b/src/metrics_clustering.rs
@@ -63,9 +63,8 @@ impl<F: Float> DistanceCount<F> {
 }
 
 impl<
-        'a,
         F: Float,
-        L: 'a + Label,
+        L: Label,
         D: Data<Elem = F>,
         T: AsSingleTargets<Elem = L> + Labels<Elem = L>,
     > SilhouetteScore<F> for DatasetBase<ArrayBase<D, Ix2>, T>