diff --git a/src/cell.rs b/src/cell.rs
index 366a884..cb7d4b0 100644
--- a/src/cell.rs
+++ b/src/cell.rs
@@ -62,7 +62,7 @@ pub struct Cell {
 }
 
 impl Ctr {
-    pub fn to_type(&mut self) -> Type {
+    pub fn to_type(&self) -> Type {
         match self {
             Ctr::Symbol(_s) => Type::Symbol,
             Ctr::String(_s) => Type::String,
@@ -76,7 +76,7 @@ impl Ctr {
 }
 
 impl Type {
-    pub fn to_str(self) -> String {
+    pub fn to_str(&self) -> String {
         let ret: &str;
         match self {
             Type::Symbol => ret = "symbol",
@@ -168,9 +168,9 @@ impl Cell {
      * short circuits on the first false returned.
      * also returns false on a non standard form list
      */
-    pub fn circuit<F: FnOnce(Ctr)-> bool>(&self, func: F) -> bool{
-        if func(self.car) {
-            match self.cdr {
+    pub fn circuit<F: FnMut(&Ctr)-> bool>(&self, func: &mut F) -> bool{
+        if func(&self.car) {
+            match &self.cdr {
                 Ctr::None => true,
                 Ctr::Cell(c) => c.circuit(func),
                 _ => false
@@ -211,24 +211,23 @@ impl Cell {
      * returns length of chain
      */
     pub fn len(&self) -> i128 {
-        match self.cdr {
+        match &self.cdr {
             Ctr::Cell(c) => c.len() + 1,
             _ => 1
         }
     }
 
     /* iterates through a list.
-     * returns a COPY of the cell at the cooresponding index
-     * WARNING: DESTRUCTIVE?
+     * returns a CLONE of the cell at the cooresponding index
      */
     pub fn index(&self, idx: usize) -> Ctr {
         if idx > 0 {
-            match self.cdr {
+            match &self.cdr {
                 Ctr::None => Ctr::None,
                 Ctr::Cell(c) => c.index(idx-1),
                 _ => {
                     if idx == 1 {
-                        self.cdr
+                        self.cdr.clone()
                     } else {
                         Ctr::None
                     }
@@ -238,7 +237,7 @@ impl Cell {
             match self.car {
                 Ctr::None => Ctr::None,
                 _ => {
-                    self.cdr
+                    self.cdr.clone()
                 }
             }
         }
diff --git a/src/eval.rs b/src/eval.rs
index 3fc355a..17a05b3 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -25,9 +25,9 @@ use crate::vars::VTable;
  * representing the simplest possible form of the input
  */
 pub fn eval(
-    _ast: Box<Cell>,
-    _vars: Box<VTable>,
-    _funcs: Box<FTable>,
+    _ast: &Box<Cell>,
+    _vars: &Box<VTable>,
+    _funcs: &Box<FTable>,
     _sym_loose: bool
 ) -> Result<Box<Cell>, String> {
     Err("Unimplemented".to_string())
diff --git a/src/func.rs b/src/func.rs
index 698e34a..4d54c70 100644
--- a/src/func.rs
+++ b/src/func.rs
@@ -25,7 +25,7 @@ use crate::eval::eval;
 pub type FTable = HashMap<String, Box<Function>>;
 
 // Standardized function signature for stdlib functions
-pub type InternalOperation = fn(Box<Cell>, Box<VTable>, Box<FTable>) -> Box<Cell>;
+pub type InternalOperation = fn(&Box<Cell>, &mut Box<VTable>, &mut Box<FTable>) -> Box<Cell>;
 pub struct ExternalOperation {
     // Un-evaluated abstract syntax tree
     // TODO: Intermediate evaluation to simplify branches with no argument in them
@@ -46,7 +46,7 @@ pub enum Operation {
 
 /* Function Args
  * If Lazy, is an integer denoting number of args
- * If Strict, is a list of Ctrs (with no wrapped values) denoting arg type.
+ * If Strict, is a list of type tags denoting argument type.
  */
 pub enum Args {
     // signed: -1 denotes infinite args
@@ -73,14 +73,15 @@ impl Function {
      */
     pub fn call(
         &self,
-        args: Box<Cell>,
-        vars: Box<VTable>,
-        funcs: Box<FTable>
+        args: &Box<Cell>,
+        vars: &mut Box<VTable>,
+        funcs: &mut Box<FTable>
     ) -> Result<Box<Cell>, String> {
-        let mut n_args = args;
+        let n_args: &Box<Cell>;
+        let outer_owner: Box<Cell>;
         if !self.eval_lazy {
             match eval(args, vars, funcs, self.loose_syms) {
-                Ok(box_cell) => n_args = box_cell,
+                Ok(box_cell) => outer_owner = box_cell,
                 Err(s) => return Err(
                     format!(
                         "error evaluating args to {}: {}",
@@ -89,21 +90,24 @@ impl Function {
                     )
                 )
             }
+            n_args = &outer_owner;
+        } else {
+            n_args = args;
         }
 
-        match self.args {
+        match &self.args {
             Args::Lazy(num) => {
-                if num < 0 {
+                if *num < 0 {
                 }
 
-                if !(num == (n_args.len() - 1)) {
+                if !(*num == (n_args.len() - 1)) {
                     return Err(format!("expected {} args in call to {}", num, self.name))
                 }
             },
 
             Args::Strict(arg_types) => {
-                let idx: usize = 0;
-                let mut passes = args.circuit(|c: Ctr| {
+                let mut idx: usize = 0;
+                let passes = n_args.circuit(&mut |c: &Ctr| {
                     if idx >= arg_types.len() {
                         return false;
                     }
@@ -147,28 +151,28 @@ impl Function {
             }
         }
 
-        match self.function {
-            Operation::Internal(f) => Ok((f)(n_args, vars, funcs)),
+        match &self.function {
+            Operation::Internal(f) => Ok((f)(&n_args, vars, funcs)),
             Operation::External(f) => {
                 // copy var table and add args
-                let temp = vars.clone();
+                let mut temp = vars.clone();
                 for n in 0..f.arg_syms.len() {
                     temp.insert(
-                        f.arg_syms[n],
+                        f.arg_syms[n].clone(),
                         Box::new(n_args.index(n))
                     );
                 }
-                eval(f.ast, temp, funcs, self.loose_syms)
+                eval(&f.ast, &temp, funcs, self.loose_syms)
             }
         }
     }
 }
 
 pub fn declare(
-    ft: Box<FTable>,
+    ft: &mut Box<FTable>,
     f: Box<Function>
 ) -> Option<String> {
-    if let Operation::External(fun) = f.function {
+    if let Operation::External(fun) = &f.function {
         if let Args::Lazy(i) = f.args {
             if fun.arg_syms.len() != i.try_into().unwrap() {
                 return Some(
@@ -184,17 +188,6 @@ pub fn declare(
         }
     }
 
-    ft.insert(f.name, f);
+    ft.insert(f.name.clone(), f);
     None
 }
-
-pub fn get(
-    ft: Box<FTable>,
-    identifier: String
-) -> Option<Box<Function>> {
-    if let Some(f) = ft.get(&identifier) {
-        Some(*f)
-    } else {
-        None
-    }
-}
diff --git a/src/lib.rs b/src/lib.rs
index 5ca14df..e0a4022 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -23,8 +23,10 @@ mod vars;
 
 pub mod ast {
     pub use crate::cell::{Cell, Ctr, cons, cell_as_string};
-    pub use crate::lex::{lex};
-    pub use crate::func::{Function, Operation, FTable};
+    pub use crate::lex::lex;
+    pub use crate::func::{Function, Operation, FTable, Args,
+                          InternalOperation, ExternalOperation,
+                          declare};
     pub use crate::vars::VTable;
-    pub use crate::eval::{eval};
+    pub use crate::eval::eval;
 }
diff --git a/src/vars.rs b/src/vars.rs
index 24c8f87..3799123 100644
--- a/src/vars.rs
+++ b/src/vars.rs
@@ -21,14 +21,12 @@ use crate::cell::{Ctr};
 
 /* Mapping between a string token and a tree of Cells
  * The string token can be found in any Ctr::Symbol value
- *
- * Considerations: should I use a structure of cells for this?
- * Current thoughts: if this was a language without proper data types, yes.
+ * it is expected that the trees stored are already evaluated
  */
 pub type VTable = HashMap<String, Box<Ctr>>;
 
 pub fn define(
-    vt: Box<VTable>,
+    vt: &mut Box<VTable>,
     identifier: String,
     var_tree: Box<Ctr>
 ) {
@@ -36,14 +34,3 @@ pub fn define(
         drop(boxed_cell);
     }
 }
-
-pub fn get(
-    vt: Box<VTable>,
-    identifier: String
-) -> Option<Box<Ctr>> {
-    if let Some(c) = vt.get(&identifier) {
-        Some(*c)
-    } else {
-        None
-    }
-}