diff --git a/.github/workflows/integration.yml b/.github/workflows/integration.yml
index 5f3814e63..aeaa3992e 100644
--- a/.github/workflows/integration.yml
+++ b/.github/workflows/integration.yml
@@ -62,4 +62,4 @@ jobs:
         env:
           RAYON_NUM_THREADS: 8
           RUST_LOG: debug
-        run: cargo run --release --package ceno_zkvm --example fibonacci_elf --target ${{ matrix.target }} -- 
\ No newline at end of file
+        run: cargo run --release --package ceno_zkvm --example fibonacci_elf --target ${{ matrix.target }}
diff --git a/ceno_emul/src/vm_state.rs b/ceno_emul/src/vm_state.rs
index c3c06c11c..d1ef6d2e3 100644
--- a/ceno_emul/src/vm_state.rs
+++ b/ceno_emul/src/vm_state.rs
@@ -1,4 +1,4 @@
-use std::collections::HashMap;
+use std::{collections::HashMap, ops::Not};
 
 use super::rv32im::EmuContext;
 use crate::{
@@ -79,13 +79,7 @@ impl VMState {
 
     pub fn iter_until_halt(&mut self) -> impl Iterator<Item = Result<StepRecord>> + '_ {
         let emu = Emulator::new();
-        from_fn(move || {
-            if self.halted() {
-                None
-            } else {
-                Some(self.step(&emu))
-            }
-        })
+        from_fn(move || self.halted().not().then(|| self.step(&emu)))
     }
 
     fn step(&mut self, emu: &Emulator) -> Result<StepRecord> {
diff --git a/ceno_zkvm/examples/fibonacci_elf.rs b/ceno_zkvm/examples/fibonacci_elf.rs
index 168a4b36e..a7c4ac127 100644
--- a/ceno_zkvm/examples/fibonacci_elf.rs
+++ b/ceno_zkvm/examples/fibonacci_elf.rs
@@ -19,7 +19,7 @@ use itertools::{Itertools, MinMaxResult, chain, enumerate};
 use mpcs::{Basefold, BasefoldRSParams, PolynomialCommitmentScheme};
 use std::{
     collections::{HashMap, HashSet},
-    panic,
+    panic::{self, PanicHookInfo},
     time::Instant,
 };
 use tracing_flame::FlameLayer;
@@ -35,6 +35,27 @@ struct Args {
     max_steps: Option<usize>,
 }
 
+/// Temporarily override the panic hook
+///
+/// We restore the original hook after we are done.
+fn with_panic_hook<F, R>(hook: Box<dyn Fn(&PanicHookInfo<'_>) + Sync + Send + 'static>, f: F) -> R
+where
+    F: FnOnce() -> R,
+{
+    // Save the current panic hook
+    let original_hook = panic::take_hook();
+
+    // Set the new panic hook
+    panic::set_hook(hook);
+
+    let result = f();
+
+    // Restore the original panic hook
+    panic::set_hook(original_hook);
+
+    result
+}
+
 fn main() {
     let args = Args::parse();
 
@@ -125,7 +146,7 @@ fn main() {
 
     let pk = zkvm_cs
         .clone()
-        .key_gen::<Pcs>(pp.clone(), vp.clone(), zkvm_fixed_traces.clone())
+        .key_gen::<Pcs>(pp, vp, zkvm_fixed_traces.clone())
         .expect("keygen failed");
     let vk = pk.get_vk();
 
@@ -153,14 +174,14 @@ fn main() {
             record.insn().codes().kind == EANY
                 && record.rs1().unwrap().value == CENO_PLATFORM.ecall_halt()
         })
-        .and_then(|halt_record| halt_record.rs2())
+        .and_then(StepRecord::rs2)
         .map(|rs2| rs2.value);
 
     let final_access = vm.tracer().final_accesses();
     let end_cycle: u32 = vm.tracer().cycle().try_into().unwrap();
 
     let pi = PublicValues::new(
-        exit_code.unwrap_or(0),
+        exit_code.unwrap_or_default(),
         vm.program().entry,
         Tracer::SUBCYCLES_PER_INSN as u32,
         vm.get_pc().into(),
@@ -188,7 +209,7 @@ fn main() {
                 MemFinalRecord {
                     addr: rec.addr,
                     value: vm.peek_register(index),
-                    cycle: *final_access.get(&vma).unwrap_or(&0),
+                    cycle: final_access.get(&vma).copied().unwrap_or_default(),
                 }
             } else {
                 // The table is padded beyond the number of registers.
@@ -209,7 +230,7 @@ fn main() {
             MemFinalRecord {
                 addr: rec.addr,
                 value: vm.peek_memory(vma),
-                cycle: *final_access.get(&vma).unwrap_or(&0),
+                cycle: final_access.get(&vma).copied().unwrap_or_default(),
             }
         })
         .collect_vec();
@@ -218,7 +239,12 @@ fn main() {
     // Find the final public IO cycles.
     let io_final = io_init
         .iter()
-        .map(|rec| *final_access.get(&rec.addr.into()).unwrap_or(&0))
+        .map(|rec| {
+            final_access
+                .get(&rec.addr.into())
+                .copied()
+                .unwrap_or_default()
+        })
         .collect_vec();
 
     // assign table circuits
@@ -269,18 +295,16 @@ fn main() {
     }
 
     let transcript = Transcript::new(b"riscv");
-    // change public input maliciously should cause verifier to reject proof
+    // Maliciously changing the public input should cause the verifier to reject the proof.
     zkvm_proof.raw_pi[0] = vec![<GoldilocksExt2 as ff_ext::ExtensionField>::BaseField::ONE];
     zkvm_proof.raw_pi[1] = vec![<GoldilocksExt2 as ff_ext::ExtensionField>::BaseField::ONE];
 
-    // capture panic message, if have
-    let default_hook = panic::take_hook();
-    panic::set_hook(Box::new(|_info| {
-        // by default it will print msg to stdout/stderr
-        // we override it to avoid print msg since we will capture the msg by our own
-    }));
-    let result = panic::catch_unwind(|| verifier.verify_proof(zkvm_proof, transcript));
-    panic::set_hook(default_hook);
+    // capture panic message, if any
+    // by default it will print msg to stdout/stderr
+    // we override it to avoid print msg since we will capture the msg by ourselves
+    let result = with_panic_hook(Box::new(|_info| ()), || {
+        panic::catch_unwind(|| verifier.verify_proof(zkvm_proof, transcript))
+    });
     match result {
         Ok(res) => {
             res.expect_err("verify proof should return with error");
@@ -322,11 +346,11 @@ fn debug_memory_ranges(vm: &VMState, mem_final: &[MemFinalRecord]) {
 
     tracing::debug!(
         "Memory range (accessed): {:?}",
-        format_segments(vm.platform(), accessed_addrs.iter().copied())
+        format_segments(vm.platform(), &accessed_addrs)
     );
     tracing::debug!(
         "Memory range (handled):  {:?}",
-        format_segments(vm.platform(), handled_addrs.iter().copied())
+        format_segments(vm.platform(), &handled_addrs)
     );
 
     for addr in &accessed_addrs {
@@ -334,11 +358,12 @@ fn debug_memory_ranges(vm: &VMState, mem_final: &[MemFinalRecord]) {
     }
 }
 
-fn format_segments(
+fn format_segments<'a>(
     platform: &Platform,
-    addrs: impl Iterator<Item = ByteAddr>,
-) -> HashMap<String, MinMaxResult<ByteAddr>> {
+    addrs: impl IntoIterator<Item = &'a ByteAddr>,
+) -> HashMap<String, MinMaxResult<&'a ByteAddr>> {
     addrs
+        .into_iter()
         .into_grouping_map_by(|addr| format_segment(platform, addr.0))
         .minmax()
 }
diff --git a/ceno_zkvm/src/instructions/riscv/rv32im/mmu.rs b/ceno_zkvm/src/instructions/riscv/rv32im/mmu.rs
index 8c9b35524..64722bd25 100644
--- a/ceno_zkvm/src/instructions/riscv/rv32im/mmu.rs
+++ b/ceno_zkvm/src/instructions/riscv/rv32im/mmu.rs
@@ -46,11 +46,7 @@ impl<E: ExtensionField> MmuConfig<E> {
         io_addrs: &[Addr],
     ) {
         assert!(
-            chain(
-                static_mem_init.iter().map(|record| record.addr),
-                io_addrs.iter().copied(),
-            )
-            .all_unique(),
+            chain(static_mem_init.iter().map(|record| &record.addr), io_addrs,).all_unique(),
             "memory addresses must be unique"
         );
 
@@ -142,14 +138,9 @@ impl MemPadder {
         new_len: usize,
         records: Vec<MemInitRecord>,
     ) -> Vec<MemInitRecord> {
-        if records.is_empty() {
-            self.padded(new_len, records)
-        } else {
-            self.padded(new_len, records)
-                .into_iter()
-                .sorted_by_key(|record| record.addr)
-                .collect()
-        }
+        let mut padded = self.padded(new_len, records);
+        padded.sort_by_key(|record| record.addr);
+        padded
     }
 
     /// Pad `records` to `new_len` using unused addresses.
diff --git a/ceno_zkvm/src/scheme.rs b/ceno_zkvm/src/scheme.rs
index 3143f2287..57e9200c6 100644
--- a/ceno_zkvm/src/scheme.rs
+++ b/ceno_zkvm/src/scheme.rs
@@ -1,5 +1,4 @@
 use ff_ext::ExtensionField;
-use itertools::Itertools;
 use mpcs::PolynomialCommitmentScheme;
 use serde::{Deserialize, Serialize};
 use std::{collections::BTreeMap, fmt::Debug};
@@ -133,15 +132,15 @@ impl<E: ExtensionField, PCS: PolynomialCommitmentScheme<E>> ZKVMProof<E, PCS> {
             .iter()
             .map(|pv| {
                 if pv.len() == 1 {
-                    // this is constant poly, and always evaluate to same constant value
+                    // this is constant poly, and always evaluates to same constant value
                     E::from(pv[0])
                 } else {
-                    // set 0 as placeholder. will be evaluate lazily
+                    // set 0 as placeholder. will be evaluated lazily
                     // Or the vector is empty, i.e. the constant 0 polynomial.
                     E::ZERO
                 }
             })
-            .collect_vec();
+            .collect();
         Self {
             raw_pi,
             pi_evals,
diff --git a/ceno_zkvm/src/scheme/prover.rs b/ceno_zkvm/src/scheme/prover.rs
index 30d8d9a6d..9729be88c 100644
--- a/ceno_zkvm/src/scheme/prover.rs
+++ b/ceno_zkvm/src/scheme/prover.rs
@@ -1241,7 +1241,7 @@ impl TowerProver {
                         virtual_polys.add_mle_list(vec![&eq, &q1, &q2], *alpha_denominator);
                     }
                 }
-                tracing::debug!("generated tower proof at round {}/{}", round, max_round_index);
+                tracing::debug!("generated tower proof at round {round}/{max_round_index}");
 
                 let wrap_batch_span = entered_span!("wrap_batch");
                 // NOTE: at the time of adding this span, visualizing it with the flamegraph layer
diff --git a/ceno_zkvm/src/scheme/verifier.rs b/ceno_zkvm/src/scheme/verifier.rs
index bdce2bd09..d7e8cfd6c 100644
--- a/ceno_zkvm/src/scheme/verifier.rs
+++ b/ceno_zkvm/src/scheme/verifier.rs
@@ -60,12 +60,12 @@ impl<E: ExtensionField, PCS: PolynomialCommitmentScheme<E>> ZKVMVerifier<E, PCS>
         transcript: Transcript<E>,
         does_halt: bool,
     ) -> Result<bool, ZKVMError> {
-        // require ecall/halt proof to exist, depending whether we expect a halt.
+        // require ecall/halt proof to exist, depending on whether we expect a halt.
         let num_instances = vm_proof
             .opcode_proofs
             .get(&HaltInstruction::<E>::name())
             .map(|(_, p)| p.num_instances)
-            .unwrap_or(0);
+            .unwrap_or_default();
         if num_instances != (does_halt as usize) {
             return Err(ZKVMError::VerifyError(format!(
                 "ecall/halt num_instances={}, expected={}",
@@ -117,12 +117,12 @@ impl<E: ExtensionField, PCS: PolynomialCommitmentScheme<E>> ZKVMVerifier<E, PCS>
             }
         }
 
-        for (name, (_, proof)) in vm_proof.opcode_proofs.iter() {
+        for (name, (_, proof)) in &vm_proof.opcode_proofs {
             tracing::debug!("read {}'s commit", name);
             PCS::write_commitment(&proof.wits_commit, &mut transcript)
                 .map_err(ZKVMError::PCSError)?;
         }
-        for (name, (_, proof)) in vm_proof.table_proofs.iter() {
+        for (name, (_, proof)) in &vm_proof.table_proofs {
             tracing::debug!("read {}'s commit", name);
             PCS::write_commitment(&proof.wits_commit, &mut transcript)
                 .map_err(ZKVMError::PCSError)?;