in progress commit

- added vars to lib
- fixed adders and getters to both vtable and ftable
- made function operations a dual type (enum)
- prototyped calling of stored external ASTs with
arguments (additional operation type
- stub for eval
- added index function to Cell

src/vars.rs

@@ -17,7 +17,7 @@
 
 use std::boxed::Box;
 use std::collections::HashMap;
-use crate::cell::{Ctr, Cell};
+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
@@ -25,23 +25,25 @@ use crate::cell::{Ctr, Cell};
  * Considerations: should I use a structure of cells for this?
  * Current thoughts: if this was a language without proper data types, yes.
  */
-pub type VTable = HashMap<String, Cell>;
+pub type VTable = HashMap<String, Box<Ctr>>;
 
-impl VTable {
-    pub fn define(
-        &mut self,
-        identifier: String,
-        var_tree: Box<Cell>
-    ) {
-        if let Some(boxed_cell) = self.insert(identifier, var_tree) {
-            drop(boxed_cell);
-        }
-    }
-
-    pub fn get(
-        &self,
-        identifier: String
-    ) -> Option<Box<Cell>> {
-        self.get(identifier)
+pub fn define(
+    vt: Box<VTable>,
+    identifier: String,
+    var_tree: Box<Ctr>
+) {
+    if let Some(boxed_cell) = vt.insert(identifier, var_tree) {
+        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
     }
 }