Remove unnecessary mutability

src/prolog/machine/compile.rs

@@ -143,7 +143,7 @@ pub fn compile_term(wam: &mut Machine, packet: TopLevelPacket) -> EvalSession
     match packet {
         TopLevelPacket::Query(terms, queue) =>
             match compile_query(terms, queue, wam.machine_flags()) {
-                Ok((mut code, vars)) => wam.submit_query(code, vars),
+                Ok((code, vars)) => wam.submit_query(code, vars),
                 Err(e) => EvalSession::from(e)
             },
         TopLevelPacket::Decl(TopLevel::Declaration(decl), _) => {

src/prolog/machine/machine_state.rs

@@ -691,7 +691,7 @@ pub(crate) trait CallPolicy: Any {
                 return_from_clause!(machine_st.last_call, machine_st)
             },
             &BuiltInClauseType::PartialString => {
-                let mut s = machine_st.try_string_list(temp_v!(1))?;
+                let s = machine_st.try_string_list(temp_v!(1))?;
                 let a2 = machine_st[temp_v!(2)].clone();
 
                 s.set_expandable(true);
@@ -719,7 +719,7 @@ pub(crate) trait CallPolicy: Any {
                 machine_st.check_keysort_errors()?;
 
                 let stub = MachineError::functor_stub(clause_name!("keysort"), 2);
-                let mut list = machine_st.try_from_list(temp_v!(1), stub)?;
+                let list = machine_st.try_from_list(temp_v!(1), stub)?;
                 let mut key_pairs = Vec::new();
 
                 for val in list {

src/prolog/machine/mod.rs

@@ -430,7 +430,7 @@ impl Machine {
             EvalSession::InitialQuerySuccess(alloc_locs) =>
                 loop {
                     let bindings = {
-                        let mut output = PrinterOutputter::new();
+                        let output = PrinterOutputter::new();
                         self.toplevel_heap_view(output).result()
                     };
 

src/prolog/machine/modules.rs

@@ -142,7 +142,7 @@ pub trait SubModuleUser
 
         if let Some(code_data) = submodule.code_dir.get(&(name.clone(), arity)) {
             let name = name.with_table(submodule.atom_tbl.clone());
-            let mut atom_tbl = self.atom_tbl();
+            let atom_tbl = self.atom_tbl();
 
             atom_tbl.borrow_mut().insert(name.to_rc());
 

src/prolog/machine/system_calls.rs

@@ -1079,7 +1079,7 @@ impl MachineState {
                 self.truncate_if_no_lifted_heap_diff(|_| Addr::Con(Constant::EmptyList)),
             &SystemClauseType::GetAttributedVariableList => {
                 let attr_var = self.store(self.deref(self[temp_v!(1)].clone()));
-                let mut attr_var_list = match attr_var {
+                let attr_var_list = match attr_var {
                     Addr::AttrVar(h) => h + 1,
                     attr_var @ Addr::HeapCell(_) | attr_var @ Addr::StackCell(..) => {
                         // create an AttrVar in the heap.
@@ -1322,7 +1322,7 @@ impl MachineState {
                 };
             },
             &SystemClauseType::RedoAttrVarBindings => {
-                let mut bindings = mem::replace(&mut self.attr_var_init.bindings, vec![]);
+                let bindings = mem::replace(&mut self.attr_var_init.bindings, vec![]);
 
                 for (h, addr) in bindings {
                     self.heap[h] = HeapCellValue::Addr(addr);
@@ -1707,7 +1707,7 @@ impl MachineState {
                         return Err(err)
                 }
 
-                let mut output  = printer.print(addr);
+                let output  = printer.print(addr);
                 print!("{}", output.result());
                 stdout().flush().unwrap();
             }

src/prolog/machine/toplevel.rs

@@ -372,7 +372,7 @@ fn flatten_hook(mut term: Term) -> Term {
                     _ => None
                 };
 
-                if let Some(mut inner_term) = inner_term {
+                if let Some(inner_term) = inner_term {
                     mem::swap(&mut terms[0], &mut Box::new(inner_term));
                 }
             },