diff --git a/benches/end2end.rs b/benches/end2end.rs
index 7d7821c857..23ed65d05c 100644
--- a/benches/end2end.rs
+++ b/benches/end2end.rs
@@ -303,7 +303,7 @@ fn prove_benchmark(c: &mut Criterion) {
 
         b.iter(|| {
             let result = prover
-                .prove(&pp, &frames, &mut store, lang_pallas_rc.clone())
+                .prove(&pp, &frames, &store, lang_pallas_rc.clone())
                 .unwrap();
             black_box(result);
         })
@@ -350,7 +350,7 @@ fn prove_compressed_benchmark(c: &mut Criterion) {
 
         b.iter(|| {
             let (proof, _, _, _) = prover
-                .prove(&pp, &frames, &mut store, lang_pallas_rc.clone())
+                .prove(&pp, &frames, &store, lang_pallas_rc.clone())
                 .unwrap();
 
             let compressed_result = proof.compress(&pp).unwrap();
@@ -394,7 +394,7 @@ fn verify_benchmark(c: &mut Criterion) {
                 .get_evaluation_frames(ptr, empty_sym_env(&store), &mut store, limit, &lang_pallas)
                 .unwrap();
             let (proof, z0, zi, num_steps) = prover
-                .prove(&pp, &frames, &mut store, lang_pallas_rc.clone())
+                .prove(&pp, &frames, &store, lang_pallas_rc.clone())
                 .unwrap();
 
             b.iter_batched(
@@ -446,7 +446,7 @@ fn verify_compressed_benchmark(c: &mut Criterion) {
                 .get_evaluation_frames(ptr, empty_sym_env(&store), &mut store, limit, &lang_pallas)
                 .unwrap();
             let (proof, z0, zi, num_steps) = prover
-                .prove(&pp, &frames, &mut store, lang_pallas_rc.clone())
+                .prove(&pp, &frames, &store, lang_pallas_rc.clone())
                 .unwrap();
 
             let compressed_proof = proof.compress(&pp).unwrap();
diff --git a/benches/fibonacci.rs b/benches/fibonacci.rs
index 060180b759..85b2dbc088 100644
--- a/benches/fibonacci.rs
+++ b/benches/fibonacci.rs
@@ -104,7 +104,7 @@ fn fibo_prove<M: measurement::Measurement>(
             b.iter_batched(
                 || (frames, lang_rc.clone()),
                 |(frames, lang_rc)| {
-                    let result = prover.prove(&pp, frames, &mut store, lang_rc);
+                    let result = prover.prove(&pp, frames, &store, lang_rc);
                     let _ = black_box(result);
                 },
                 BatchSize::LargeInput,
diff --git a/clutch/src/lib.rs b/clutch/src/lib.rs
index e1a1329b2d..37b5a31e9a 100644
--- a/clutch/src/lib.rs
+++ b/clutch/src/lib.rs
@@ -510,14 +510,14 @@ impl ClutchState<F, Coproc<F>> {
         println!();
         Ok(None)
     }
-    fn proof_claim(&self, store: &mut Store<F>, rest: Ptr<F>) -> Result<Option<Ptr<F>>> {
+    fn proof_claim(&self, store: &Store<F>, rest: Ptr<F>) -> Result<Option<Ptr<F>>> {
         let proof = self.get_proof(store, rest)?;
 
         println!("{0:#?}", proof.claim);
         Ok(None)
     }
 
-    fn get_proof(&self, store: &mut Store<F>, rest: Ptr<F>) -> Result<Proof<'_, F>> {
+    fn get_proof(&self, store: &Store<F>, rest: Ptr<F>) -> Result<Proof<'_, F>> {
         let (proof_cid, _rest1) = store.car_cdr(&rest)?;
         let zptr_string = store
             .fetch_string(&proof_cid)
@@ -579,7 +579,7 @@ impl ClutchState<F, Coproc<F>> {
             bail!("verification of new proof failed");
         }
     }
-    fn verify(&mut self, store: &mut Store<F>, rest: Ptr<F>) -> Result<Option<Ptr<F>>> {
+    fn verify(&mut self, store: &Store<F>, rest: Ptr<F>) -> Result<Option<Ptr<F>>> {
         let (proof_cid, _) = store.car_cdr(&rest)?;
 
         let zptr_string = store
diff --git a/fcomm/src/lib.rs b/fcomm/src/lib.rs
index e61cf8d973..9b568c90ce 100644
--- a/fcomm/src/lib.rs
+++ b/fcomm/src/lib.rs
@@ -405,7 +405,7 @@ impl ReductionCount {
 
 impl Evaluation {
     fn new<F: LurkField>(
-        s: &mut Store<F>,
+        s: &Store<F>,
         input: IO<F>,
         output: IO<F>,
         iterations: Option<usize>, // This might be padded, so is not quite 'iterations' in the sense of number of actual reduction steps required
@@ -491,7 +491,7 @@ impl<F: LurkField + Serialize + DeserializeOwned> PtrEvaluation<F> {
 }
 
 impl<F: LurkField + Serialize + DeserializeOwned> Commitment<F> {
-    pub fn from_comm(s: &mut Store<F>, ptr: &Ptr<F>) -> Result<Self, Error> {
+    pub fn from_comm(s: &Store<F>, ptr: &Ptr<F>) -> Result<Self, Error> {
         assert_eq!(ExprTag::Comm, ptr.tag);
 
         let digest = *s
@@ -589,7 +589,7 @@ impl<F: LurkField + Serialize + DeserializeOwned> LurkPtr<F> {
         }
     }
 
-    pub fn from_ptr(s: &mut Store<F>, ptr: &Ptr<F>) -> Self {
+    pub fn from_ptr(s: &Store<F>, ptr: &Ptr<F>) -> Self {
         let (z_store, z_ptr) = ZStore::new_with_expr(s, ptr);
         let z_ptr = z_ptr.unwrap();
         Self::ZStorePtr(ZStorePtr { z_store, z_ptr })
@@ -599,7 +599,7 @@ impl<F: LurkField + Serialize + DeserializeOwned> LurkPtr<F> {
 impl LurkCont {
     pub fn cont_ptr<F: LurkField + Serialize + DeserializeOwned>(
         &self,
-        s: &mut Store<F>,
+        s: &Store<F>,
     ) -> ContPtr<F> {
         match self {
             Self::Outermost => s.get_cont_outermost(),
diff --git a/src/circuit/gadgets/hashes.rs b/src/circuit/gadgets/hashes.rs
index 6d3bdeb8b1..ebb638974f 100644
--- a/src/circuit/gadgets/hashes.rs
+++ b/src/circuit/gadgets/hashes.rs
@@ -173,7 +173,7 @@ impl<'a, F: LurkField> HashConst<'a, F> {
     #[allow(dead_code)]
     fn cache_hash_witness<CS: ConstraintSystem<F>>(
         &self,
-        cs: &mut CS,
+        cs: &CS,
         preimage: Vec<F>,
         hash_circuit_witness_cache: &mut HashCircuitWitnessCache<F>,
     ) {
@@ -364,7 +364,7 @@ impl<'a, F: LurkField> AllocatedContWitness<'a, F> {
     // Currently unused, but not necessarily useless.
     #[allow(dead_code)]
     fn make_hash_cache<CS: ConstraintSystem<F>>(
-        cs: &mut CS,
+        cs: &CS,
         names_and_ptrs: &[(ContName, (Option<ContPtr<F>>, Option<Vec<F>>))],
         hash_constants: HashConst<'_, F>,
     ) -> Option<HashCircuitWitnessCache<F>> {
diff --git a/src/cli/repl.rs b/src/cli/repl.rs
index da20b286f6..71571c73d6 100644
--- a/src/cli/repl.rs
+++ b/src/cli/repl.rs
@@ -237,7 +237,7 @@ impl Repl<F> {
 
                         info!("Proving");
                         let (proof, public_inputs, public_outputs, num_steps) =
-                            prover.prove(&pp, frames, &mut self.store, self.lang.clone())?;
+                            prover.prove(&pp, frames, &self.store, self.lang.clone())?;
                         info!("Compressing proof");
                         let proof = proof.compress(&pp)?;
                         assert_eq!(self.rc * num_steps, pad(n_frames, self.rc));
diff --git a/src/field.rs b/src/field.rs
index 0640583e01..f9f26a7bab 100644
--- a/src/field.rs
+++ b/src/field.rs
@@ -309,7 +309,7 @@ impl<F: LurkField> Hash for FWrap<F> {
 
 impl<F: LurkField> PartialOrd for FWrap<F> {
     fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
-        (self.0.to_repr().as_ref()).partial_cmp(other.0.to_repr().as_ref())
+        Some(self.cmp(other))
     }
 }
 
diff --git a/src/hash_witness.rs b/src/hash_witness.rs
index 191953839a..65e705ecf3 100644
--- a/src/hash_witness.rs
+++ b/src/hash_witness.rs
@@ -296,28 +296,6 @@ impl<F: LurkField> ConsStub<F> {
         }
     }
 
-    pub fn car_cdr_mut(
-        &mut self,
-        s: &mut Store<F>,
-        cons: &Ptr<F>,
-    ) -> Result<(Ptr<F>, Ptr<F>), store::Error> {
-        match self {
-            Self::Dummy => {
-                let (car, cdr) = Cons::get_car_cdr_mut(s, cons)?;
-
-                *self = Self::Value(Cons {
-                    car,
-                    cdr,
-                    cons: *cons,
-                });
-
-                Ok((car, cdr))
-            }
-            Self::Blank => unreachable!("Blank ConsStub should be used only in blank circuits."),
-            Self::Value(h) => Ok(h.car_cdr(cons)),
-        }
-    }
-
     pub fn cons(&mut self, store: &mut Store<F>, car: Ptr<F>, cdr: Ptr<F>) -> Ptr<F> {
         match self {
             Self::Dummy => {
@@ -572,10 +550,10 @@ impl<F: LurkField> ConsWitness<F> {
     pub fn car_cdr_mut_named(
         &mut self,
         name: ConsName,
-        store: &mut Store<F>,
+        store: &Store<F>,
         cons: &Ptr<F>,
     ) -> Result<(Ptr<F>, Ptr<F>), store::Error> {
-        self.get_assigned_slot(name).car_cdr_mut(store, cons)
+        self.get_assigned_slot(name).car_cdr(store, cons)
     }
 
     pub fn extend_named(
@@ -610,17 +588,13 @@ impl<F: LurkField> Cons<F> {
     fn get_car_cdr(s: &Store<F>, cons: &Ptr<F>) -> Result<(Ptr<F>, Ptr<F>), store::Error> {
         s.car_cdr(cons)
     }
-
-    fn get_car_cdr_mut(s: &mut Store<F>, cons: &Ptr<F>) -> Result<(Ptr<F>, Ptr<F>), store::Error> {
-        s.car_cdr(cons)
-    }
 }
 
 impl<F: LurkField> ContWitness<F> {
     pub fn fetch_named_cont(
         &mut self,
         name: ContName,
-        store: &mut Store<F>,
+        store: &Store<F>,
         cont: &ContPtr<F>,
     ) -> Option<Continuation<F>> {
         self.get_assigned_slot(name).fetch_cont(store, cont)
@@ -638,11 +612,7 @@ impl<F: LurkField> ContWitness<F> {
 }
 
 impl<F: LurkField> ContStub<F> {
-    pub fn fetch_cont(
-        &mut self,
-        store: &mut Store<F>,
-        cont: &ContPtr<F>,
-    ) -> Option<Continuation<F>> {
+    pub fn fetch_cont(&mut self, store: &Store<F>, cont: &ContPtr<F>) -> Option<Continuation<F>> {
         match self {
             Self::Dummy => {
                 let continuation = store.fetch_cont(cont)?;
diff --git a/src/proof/nova.rs b/src/proof/nova.rs
index 4008836397..6aa43c6024 100644
--- a/src/proof/nova.rs
+++ b/src/proof/nova.rs
@@ -277,7 +277,7 @@ where
         &'a self,
         pp: &'a PublicParams<'_, F, C>,
         frames: &[Frame<IO<F>, Witness<F>, C>],
-        store: &'a mut Store<F>,
+        store: &'a Store<F>,
         lang: Arc<Lang<F, C>>,
     ) -> Result<(Proof<'_, F, C>, Vec<F>, Vec<F>, usize), ProofError> {
         let z0 = frames[0].input.to_vector(store)?;
diff --git a/src/public_parameters/mem_cache.rs b/src/public_parameters/mem_cache.rs
index 1b2a0de7d7..3c93794dff 100644
--- a/src/public_parameters/mem_cache.rs
+++ b/src/public_parameters/mem_cache.rs
@@ -126,7 +126,7 @@ impl PublicParamMemCache {
         // retrieve the per-Coproc public param table
         let entry = mem_cache.entry::<PublicParamMap<F, C>>();
         // deduce the map and populate it if needed
-        let param_entry = entry.or_insert_with(HashMap::new);
+        let param_entry = entry.or_default();
         match param_entry.entry((rc, abomonated)) {
             Entry::Occupied(o) => Ok(o.into_mut()),
             Entry::Vacant(v) => {
diff --git a/src/repl.rs b/src/repl.rs
index e313bf5f88..95b7b44f9f 100644
--- a/src/repl.rs
+++ b/src/repl.rs
@@ -106,8 +106,6 @@ pub trait ReplTrait<F: LurkField, C: Coprocessor<F>> {
         state: Rc<RefCell<State>>,
         file_path: P,
     ) -> Result<()> {
-        let file_path = file_path;
-
         let input = read_to_string(file_path)?;
         eprintln!(
             "Read from {}: {}",
@@ -324,7 +322,7 @@ pub fn run_repl<P: AsRef<Path>, F: LurkField, T: ReplTrait<F, C>, C: Coprocessor
 }
 
 impl<F: LurkField, C: Coprocessor<F>> ReplState<F, C> {
-    pub fn new(s: &mut Store<F>, limit: usize, command: Option<Command>, lang: Lang<F, C>) -> Self {
+    pub fn new(s: &Store<F>, limit: usize, command: Option<Command>, lang: Lang<F, C>) -> Self {
         Self {
             env: empty_sym_env(s),
             limit,
diff --git a/src/z_data/z_ptr.rs b/src/z_data/z_ptr.rs
index 00856c8eab..fa40144a58 100644
--- a/src/z_data/z_ptr.rs
+++ b/src/z_data/z_ptr.rs
@@ -54,24 +54,23 @@ impl<E: Tag + Display, F: LurkField> Display for ZPtr<E, F> {
 
 impl<E: Tag, F: LurkField> PartialOrd for ZPtr<E, F> {
     fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl<E: Tag, F: LurkField> Ord for ZPtr<E, F> {
+    fn cmp(&self, other: &Self) -> core::cmp::Ordering {
         (
             self.0.to_field_bytes::<F>().as_ref(),
             self.1.to_repr().as_ref(),
         )
-            .partial_cmp(&(
+            .cmp(&(
                 other.0.to_field_bytes::<F>().as_ref(),
                 other.1.to_repr().as_ref(),
             ))
     }
 }
 
-impl<E: Tag, F: LurkField> Ord for ZPtr<E, F> {
-    fn cmp(&self, other: &Self) -> core::cmp::Ordering {
-        self.partial_cmp(other)
-            .expect("ZPtr::cmp: partial_cmp domain invariant violation")
-    }
-}
-
 #[allow(clippy::derived_hash_with_manual_eq)]
 impl<E: Tag, F: LurkField> Hash for ZPtr<E, F> {
     fn hash<H: std::hash::Hasher>(&self, state: &mut H) {