diff --git a/halo2_gadgets/src/poseidon.rs b/halo2_gadgets/src/poseidon.rs
index ffd745ad6d..bfd78f3dee 100644
--- a/halo2_gadgets/src/poseidon.rs
+++ b/halo2_gadgets/src/poseidon.rs
@@ -157,7 +157,7 @@ impl<
                     .unwrap(),
             ),
             state,
-            _marker: PhantomData::default(),
+            _marker: PhantomData,
         })
     }
 
@@ -204,7 +204,7 @@ impl<
             chip: self.chip,
             mode,
             state: self.state,
-            _marker: PhantomData::default(),
+            _marker: PhantomData,
         })
     }
 }
diff --git a/halo2_gadgets/src/poseidon/pow5.rs b/halo2_gadgets/src/poseidon/pow5.rs
index 0fb37994e5..51c1f059ca 100644
--- a/halo2_gadgets/src/poseidon/pow5.rs
+++ b/halo2_gadgets/src/poseidon/pow5.rs
@@ -240,30 +240,25 @@ impl<F: Field, S: Spec<F, WIDTH, RATE>, const WIDTH: usize, const RATE: usize>
                 // Load the initial state into this region.
                 let state = Pow5State::load(&mut region, config, initial_state)?;
 
-                let state = (0..config.half_full_rounds).fold(Ok(state), |res, r| {
-                    res.and_then(|state| state.full_round(&mut region, config, r, r))
+                let state = (0..config.half_full_rounds)
+                    .try_fold(state, |res, r| res.full_round(&mut region, config, r, r))?;
+
+                let state = (0..config.half_partial_rounds).try_fold(state, |res, r| {
+                    res.partial_round(
+                        &mut region,
+                        config,
+                        config.half_full_rounds + 2 * r,
+                        config.half_full_rounds + r,
+                    )
                 })?;
 
-                let state = (0..config.half_partial_rounds).fold(Ok(state), |res, r| {
-                    res.and_then(|state| {
-                        state.partial_round(
-                            &mut region,
-                            config,
-                            config.half_full_rounds + 2 * r,
-                            config.half_full_rounds + r,
-                        )
-                    })
-                })?;
-
-                let state = (0..config.half_full_rounds).fold(Ok(state), |res, r| {
-                    res.and_then(|state| {
-                        state.full_round(
-                            &mut region,
-                            config,
-                            config.half_full_rounds + 2 * config.half_partial_rounds + r,
-                            config.half_full_rounds + config.half_partial_rounds + r,
-                        )
-                    })
+                let state = (0..config.half_full_rounds).try_fold(state, |res, r| {
+                    res.full_round(
+                        &mut region,
+                        config,
+                        config.half_full_rounds + 2 * config.half_partial_rounds + r,
+                        config.half_full_rounds + config.half_partial_rounds + r,
+                    )
                 })?;
 
                 Ok(state.0)
diff --git a/halo2_gadgets/src/poseidon/primitives.rs b/halo2_gadgets/src/poseidon/primitives.rs
index 06f199f118..c456c87f54 100644
--- a/halo2_gadgets/src/poseidon/primitives.rs
+++ b/halo2_gadgets/src/poseidon/primitives.rs
@@ -220,7 +220,7 @@ impl<F: Field, S: Spec<F, T, RATE>, const T: usize, const RATE: usize>
             state,
             mds_matrix,
             round_constants,
-            _marker: PhantomData::default(),
+            _marker: PhantomData,
         }
     }
 
@@ -257,7 +257,7 @@ impl<F: Field, S: Spec<F, T, RATE>, const T: usize, const RATE: usize>
             state: self.state,
             mds_matrix: self.mds_matrix,
             round_constants: self.round_constants,
-            _marker: PhantomData::default(),
+            _marker: PhantomData,
         }
     }
 }
@@ -364,7 +364,7 @@ impl<F: Field, S: Spec<F, T, RATE>, D: Domain<F, RATE>, const T: usize, const RA
     pub fn init() -> Self {
         Hash {
             sponge: Sponge::new(D::initial_capacity_element()),
-            _domain: PhantomData::default(),
+            _domain: PhantomData,
         }
     }
 }
diff --git a/halo2_gadgets/src/poseidon/primitives/grain.rs b/halo2_gadgets/src/poseidon/primitives/grain.rs
index 99711f97f3..1a780d5899 100644
--- a/halo2_gadgets/src/poseidon/primitives/grain.rs
+++ b/halo2_gadgets/src/poseidon/primitives/grain.rs
@@ -70,7 +70,7 @@ impl<F: PrimeField> Grain<F> {
         let mut grain = Grain {
             state,
             next_bit: STATE,
-            _field: PhantomData::default(),
+            _field: PhantomData,
         };
 
         // Discard the first 160 bits.
diff --git a/halo2_gadgets/src/poseidon/primitives/p128pow5t3.rs b/halo2_gadgets/src/poseidon/primitives/p128pow5t3.rs
index e31ce04263..fdd4b22959 100644
--- a/halo2_gadgets/src/poseidon/primitives/p128pow5t3.rs
+++ b/halo2_gadgets/src/poseidon/primitives/p128pow5t3.rs
@@ -84,7 +84,7 @@ mod tests {
 
     impl<F: Field, const SECURE_MDS: usize> P128Pow5T3Gen<F, SECURE_MDS> {
         pub fn new() -> Self {
-            P128Pow5T3Gen(PhantomData::default())
+            P128Pow5T3Gen(PhantomData)
         }
     }
 
diff --git a/halo2_gadgets/src/sha256/table16/compression/compression_util.rs b/halo2_gadgets/src/sha256/table16/compression/compression_util.rs
index 324fe8f695..99706023df 100644
--- a/halo2_gadgets/src/sha256/table16/compression/compression_util.rs
+++ b/halo2_gadgets/src/sha256/table16/compression/compression_util.rs
@@ -111,7 +111,7 @@ pub fn get_round_row(round_idx: RoundIdx) -> usize {
         RoundIdx::Init => 0,
         RoundIdx::Main(MainRoundIdx(idx)) => {
             assert!(idx < 64);
-            (idx as usize) * SUBREGION_MAIN_WORD
+            idx * SUBREGION_MAIN_WORD
         }
     }
 }
@@ -783,7 +783,7 @@ impl CompressionConfig {
                 || "h_prime_carry",
                 a_9,
                 row + 1,
-                || h_prime_carry.map(|value| pallas::Base::from(value as u64)),
+                || h_prime_carry.map(pallas::Base::from),
             )?;
 
             let h_prime: Value<[bool; 32]> = h_prime.map(|w| i2lebsp(w.into()));
diff --git a/halo2_gadgets/src/sha256/table16/message_schedule/schedule_util.rs b/halo2_gadgets/src/sha256/table16/message_schedule/schedule_util.rs
index 79a9fa2621..42ed58a835 100644
--- a/halo2_gadgets/src/sha256/table16/message_schedule/schedule_util.rs
+++ b/halo2_gadgets/src/sha256/table16/message_schedule/schedule_util.rs
@@ -40,20 +40,17 @@ pub fn get_word_row(word_idx: usize) -> usize {
     if word_idx == 0 {
         0
     } else if (1..=13).contains(&word_idx) {
-        SUBREGION_0_ROWS + SUBREGION_1_WORD * (word_idx - 1) as usize
+        SUBREGION_0_ROWS + SUBREGION_1_WORD * (word_idx - 1)
     } else if (14..=48).contains(&word_idx) {
         SUBREGION_0_ROWS + SUBREGION_1_ROWS + SUBREGION_2_WORD * (word_idx - 14) + 1
     } else if (49..=61).contains(&word_idx) {
-        SUBREGION_0_ROWS
-            + SUBREGION_1_ROWS
-            + SUBREGION_2_ROWS
-            + SUBREGION_3_WORD * (word_idx - 49) as usize
+        SUBREGION_0_ROWS + SUBREGION_1_ROWS + SUBREGION_2_ROWS + SUBREGION_3_WORD * (word_idx - 49)
     } else {
         SUBREGION_0_ROWS
             + SUBREGION_1_ROWS
             + SUBREGION_2_ROWS
             + SUBREGION_3_ROWS
-            + DECOMPOSE_0_ROWS * (word_idx - 62) as usize
+            + DECOMPOSE_0_ROWS * (word_idx - 62)
     }
 }
 
diff --git a/halo2_gadgets/src/sha256/table16/message_schedule/subregion2.rs b/halo2_gadgets/src/sha256/table16/message_schedule/subregion2.rs
index 43e96c934f..9733b46039 100644
--- a/halo2_gadgets/src/sha256/table16/message_schedule/subregion2.rs
+++ b/halo2_gadgets/src/sha256/table16/message_schedule/subregion2.rs
@@ -261,7 +261,7 @@ impl MessageScheduleConfig {
                 || format!("carry_{}", new_word_idx),
                 a_9,
                 get_word_row(new_word_idx - 16) + 1,
-                || carry.map(|carry| pallas::Base::from(carry as u64)),
+                || carry.map(pallas::Base::from),
             )?;
             let (word, halves) = self.assign_word_and_halves(region, word, new_word_idx)?;
             w.push(MessageWord(word));
diff --git a/halo2_gadgets/src/sha256/table16/message_schedule/subregion3.rs b/halo2_gadgets/src/sha256/table16/message_schedule/subregion3.rs
index b23046e42e..aebe1945d9 100644
--- a/halo2_gadgets/src/sha256/table16/message_schedule/subregion3.rs
+++ b/halo2_gadgets/src/sha256/table16/message_schedule/subregion3.rs
@@ -177,7 +177,7 @@ impl MessageScheduleConfig {
                 || format!("carry_{}", new_word_idx),
                 a_9,
                 get_word_row(new_word_idx - 16) + 1,
-                || carry.map(|carry| pallas::Base::from(carry as u64)),
+                || carry.map(pallas::Base::from),
             )?;
             let (word, halves) = self.assign_word_and_halves(region, word, new_word_idx)?;
             w.push(MessageWord(word));
diff --git a/halo2_gadgets/src/sha256/table16/util.rs b/halo2_gadgets/src/sha256/table16/util.rs
index 6a790d3797..d3da5317ca 100644
--- a/halo2_gadgets/src/sha256/table16/util.rs
+++ b/halo2_gadgets/src/sha256/table16/util.rs
@@ -110,7 +110,7 @@ pub fn sum_with_carry(words: Vec<(Value<u16>, Value<u16>)>) -> (Value<u32>, Valu
         sum_lo.zip(sum_hi).map(|(lo, hi)| lo + (1 << 16) * hi)
     };
 
-    let carry = sum.map(|sum| (sum >> 32) as u64);
+    let carry = sum.map(|sum| (sum >> 32));
     let sum = sum.map(|sum| sum as u32);
 
     (sum, carry)
diff --git a/halo2_gadgets/src/sinsemilla.rs b/halo2_gadgets/src/sinsemilla.rs
index 48b929cbeb..4a20ce4830 100644
--- a/halo2_gadgets/src/sinsemilla.rs
+++ b/halo2_gadgets/src/sinsemilla.rs
@@ -197,7 +197,7 @@ where
         // Each message piece must have at most `floor(C::Base::CAPACITY / K)` words.
         // This ensures that the all-ones bitstring is canonical in the field.
         let piece_max_num_words = C::Base::CAPACITY as usize / K;
-        assert!(num_words <= piece_max_num_words as usize);
+        assert!(num_words <= piece_max_num_words);
 
         // Closure to parse a bitstring (little-endian) into a base field element.
         let to_base_field = |bits: &[Value<bool>]| -> Value<C::Base> {
@@ -496,6 +496,7 @@ pub(crate) mod tests {
 
     #[derive(Debug, Clone, Eq, PartialEq)]
     pub(crate) struct TestHashDomain;
+    #[allow(non_snake_case)]
     impl HashDomains<pallas::Affine> for TestHashDomain {
         fn Q(&self) -> pallas::Affine {
             *Q
@@ -654,11 +655,7 @@ pub(crate) mod tests {
                         |(l, (left, right))| {
                             let merkle_crh = sinsemilla::HashDomain::from_Q((*Q).into());
                             let point = merkle_crh
-                                .hash_to_point(
-                                    l.into_iter()
-                                        .chain(left.into_iter())
-                                        .chain(right.into_iter()),
-                                )
+                                .hash_to_point(l.into_iter().chain(left).chain(right))
                                 .unwrap();
                             point.to_affine()
                         },
diff --git a/halo2_gadgets/src/utilities.rs b/halo2_gadgets/src/utilities.rs
index 887ee92475..50d939b055 100644
--- a/halo2_gadgets/src/utilities.rs
+++ b/halo2_gadgets/src/utilities.rs
@@ -99,7 +99,7 @@ impl<F: PrimeFieldBits> RangeConstrained<F, Value<F>> {
         Self {
             inner: value.map(|value| bitrange_subset(value, bitrange)),
             num_bits,
-            _phantom: PhantomData::default(),
+            _phantom: PhantomData,
         }
     }
 }
@@ -114,7 +114,7 @@ impl<F: Field> RangeConstrained<F, AssignedCell<F, F>> {
         Self {
             inner: cell,
             num_bits,
-            _phantom: PhantomData::default(),
+            _phantom: PhantomData,
         }
     }
 
@@ -123,7 +123,7 @@ impl<F: Field> RangeConstrained<F, AssignedCell<F, F>> {
         RangeConstrained {
             inner: self.inner.value().copied(),
             num_bits: self.num_bits,
-            _phantom: PhantomData::default(),
+            _phantom: PhantomData,
         }
     }
 }
@@ -405,7 +405,6 @@ mod tests {
             }
             assert_eq!(field_elem, sum);
         };
-
         decompose(pallas::Base::random(rng), &[0..255]);
         decompose(pallas::Base::random(rng), &[0..1, 1..255]);
         decompose(pallas::Base::random(rng), &[0..254, 254..255]);
diff --git a/halo2_gadgets/src/utilities/lookup_range_check.rs b/halo2_gadgets/src/utilities/lookup_range_check.rs
index 22a8bf2bf2..7312206970 100644
--- a/halo2_gadgets/src/utilities/lookup_range_check.rs
+++ b/halo2_gadgets/src/utilities/lookup_range_check.rs
@@ -49,7 +49,7 @@ impl<F: PrimeFieldBits> RangeConstrained<F, AssignedCell<F, F>> {
             .map(|inner| Self {
                 inner,
                 num_bits,
-                _phantom: PhantomData::default(),
+                _phantom: PhantomData,
             })
     }
 }
diff --git a/halo2_proofs/benches/commit_zk.rs b/halo2_proofs/benches/commit_zk.rs
index bdf5c88a51..a6a33a934b 100644
--- a/halo2_proofs/benches/commit_zk.rs
+++ b/halo2_proofs/benches/commit_zk.rs
@@ -29,7 +29,7 @@ fn rand_poly_serial(mut rng: ChaCha20Rng, domain: usize) -> Vec<Scalar> {
 
 fn rand_poly_par(mut rng: ChaCha20Rng, domain: usize) -> Vec<Scalar> {
     // Sample a random polynomial of degree n - 1
-    let n = 1usize << domain as usize;
+    let n = 1usize << domain;
     let mut random_poly = vec![Scalar::ZERO; n];
 
     let num_threads = current_num_threads();
diff --git a/halo2_proofs/src/dev.rs b/halo2_proofs/src/dev.rs
index a1132c97a0..38c805b085 100644
--- a/halo2_proofs/src/dev.rs
+++ b/halo2_proofs/src/dev.rs
@@ -837,7 +837,7 @@ impl<F: FromUniformBytes<64> + Ord> MockProver<F> {
                 .flat_map(|(gate_index, gate)| {
                     let blinding_rows =
                         (self.n as usize - (self.cs.blinding_factors() + 1))..(self.n as usize);
-                    (gate_row_ids.clone().chain(blinding_rows.into_iter())).flat_map(move |row| {
+                    (gate_row_ids.clone().chain(blinding_rows)).flat_map(move |row| {
                         let row = row as i32 + n;
                         gate.polynomials().iter().enumerate().filter_map(
                             move |(poly_index, poly)| match poly.evaluate_lazy(
@@ -2028,7 +2028,7 @@ mod tests {
                                     || Value::known(Fp::from(2 * i as u64)),
                                 )
                             })
-                            .fold(Ok(()), |acc, res| acc.and(res))
+                            .try_fold((), |_, res| res)
                     },
                 )?;
 
diff --git a/halo2_proofs/src/dev/cost.rs b/halo2_proofs/src/dev/cost.rs
index 5dd2842867..1f131a2d40 100644
--- a/halo2_proofs/src/dev/cost.rs
+++ b/halo2_proofs/src/dev/cost.rs
@@ -338,7 +338,6 @@ impl<G: PrimeGroup, ConcreteCircuit: Circuit<G::Scalar>> CircuitCost<G, Concrete
             lookups: cs.lookups.len(),
             permutation_cols,
             point_sets: point_sets.len(),
-            _marker: PhantomData::default(),
             max_rows: layout.total_rows,
             max_advice_rows: layout.total_advice_rows,
             max_fixed_rows: layout.total_fixed_rows,
@@ -348,6 +347,7 @@ impl<G: PrimeGroup, ConcreteCircuit: Circuit<G::Scalar>> CircuitCost<G, Concrete
             num_total_columns: cs.num_instance_columns
                 + cs.num_advice_columns
                 + cs.num_fixed_columns,
+            _marker: PhantomData,
         }
     }
 
@@ -381,7 +381,7 @@ impl<G: PrimeGroup, ConcreteCircuit: Circuit<G::Scalar>> CircuitCost<G, Concrete
                 if chunks == 0 { chunks } else { 3 * chunks - 1 },
             ),
 
-            _marker: PhantomData::default(),
+            _marker: PhantomData,
         }
     }
 
@@ -424,7 +424,7 @@ impl<G: PrimeGroup, ConcreteCircuit: Circuit<G::Scalar>> CircuitCost<G, Concrete
             // - xi
             polycomm: ProofContribution::new((1 + 2 * self.k).try_into().unwrap(), 2),
 
-            _marker: PhantomData::default(),
+            _marker: PhantomData,
         }
     }
 }
diff --git a/halo2_proofs/src/plonk/circuit.rs b/halo2_proofs/src/plonk/circuit.rs
index a5736f28ca..8b48f836b2 100644
--- a/halo2_proofs/src/plonk/circuit.rs
+++ b/halo2_proofs/src/plonk/circuit.rs
@@ -1488,7 +1488,7 @@ impl<F: Field, C: Into<Constraint<F>>, Iter: IntoIterator<Item = C>> IntoIterato
 
     fn into_iter(self) -> Self::IntoIter {
         std::iter::repeat(self.selector)
-            .zip(self.constraints.into_iter())
+            .zip(self.constraints)
             .map(apply_selector_to_constraint)
     }
 }
@@ -1967,7 +1967,7 @@ impl<F: Field> ConstraintSystem<F> {
         let (polys, selector_assignment) = compress_selectors::process(
             selectors
                 .into_iter()
-                .zip(degrees.into_iter())
+                .zip(degrees)
                 .enumerate()
                 .map(
                     |(i, (activations, max_degree))| compress_selectors::SelectorDescription {
diff --git a/halo2_proofs/src/poly.rs b/halo2_proofs/src/poly.rs
index 02779d0e79..9cb6b149bc 100644
--- a/halo2_proofs/src/poly.rs
+++ b/halo2_proofs/src/poly.rs
@@ -199,7 +199,7 @@ pub(crate) fn batch_invert_assigned<F: Field>(
 
     assigned
         .iter()
-        .zip(assigned_denominators.into_iter())
+        .zip(assigned_denominators)
         .map(|(poly, inv_denoms)| poly.invert(inv_denoms.into_iter().map(|d| d.unwrap_or(F::ONE))))
         .collect()
 }
@@ -214,7 +214,7 @@ impl<F: Field> Polynomial<Assigned<F>, LagrangeCoeff> {
             values: self
                 .values
                 .iter()
-                .zip(inv_denoms.into_iter())
+                .zip(inv_denoms)
                 .map(|(a, inv_den)| a.numerator() * inv_den)
                 .collect(),
             _marker: self._marker,
diff --git a/halo2_proofs/src/poly/ipa/multiopen/prover.rs b/halo2_proofs/src/poly/ipa/multiopen/prover.rs
index 8998f38723..2ae745d457 100644
--- a/halo2_proofs/src/poly/ipa/multiopen/prover.rs
+++ b/halo2_proofs/src/poly/ipa/multiopen/prover.rs
@@ -107,7 +107,7 @@ impl<'params, C: CurveAffine> Prover<'params, IPACommitmentScheme<C>> for Prover
 
         let x_4: ChallengeX4<_> = transcript.squeeze_challenge_scalar();
 
-        let (p_poly, p_poly_blind) = q_polys.into_iter().zip(q_blinds.into_iter()).fold(
+        let (p_poly, p_poly_blind) = q_polys.into_iter().zip(q_blinds).fold(
             (q_prime_poly, q_prime_blind),
             |(q_prime_poly, q_prime_blind), (poly, blind)| {
                 (
diff --git a/halo2_proofs/tests/plonk_api.rs b/halo2_proofs/tests/plonk_api.rs
index 36df18393e..307dbdfef0 100644
--- a/halo2_proofs/tests/plonk_api.rs
+++ b/halo2_proofs/tests/plonk_api.rs
@@ -514,7 +514,7 @@ fn plonk_api() {
         Scheme::Scalar: Ord + WithSmallOrderMulGroup<3> + FromUniformBytes<64>,
     {
         let (_, instance, _) = common!(Scheme);
-        let pubinputs = vec![instance];
+        let pubinputs = [instance];
 
         let mut transcript = T::init(proof);