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/eval.rs

@@ -0,0 +1,34 @@
+/* relish: versatile lisp shell
+ * Copyright (C) 2021 Aidan Hahn
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+use std::boxed::Box;
+use crate::cell::{Cell};
+use crate::func::FTable;
+use crate::vars::VTable;
+
+/* iterates over a syntax tree
+ * returns a NEW LIST of values
+ * representing the simplest possible form of the input
+ */
+pub fn eval(
+    _ast: Box<Cell>,
+    _vars: Box<VTable>,
+    _funcs: Box<FTable>,
+    _sym_loose: bool
+) -> Result<Box<Cell>, String> {
+    Err("Unimplemented".to_string())
+}