better eval and test for eval,quote

src/stl/decl.rs

@@ -26,17 +26,31 @@ pub fn quote_callback(ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, String> {
     if ast.len() > 1 {
         Err("do not quote more than one thing at a time".to_string())
     } else {
-        Ok(Ctr::Seg(ast.clone()))
+        Ok(*ast.car.clone())
     }
 }
 
-pub const EVAL_DOCSTRING: &str = "takes an unevaluated argument and evaluates it.";
+pub const EVAL_DOCSTRING: &str = "takes an unevaluated argument and evaluates it.
+Specifically, does one pass of the tree simplification algorithm.
+If you have a variable referencing another variable you will get the
+referenced variable.";
 
 pub fn eval_callback(ast: &Seg, syms: &mut SymTable) -> Result<Ctr, String> {
     if ast.len() > 1 {
-        Err("do not quote more than one thing at a time".to_string())
+        Err("do not eval more than one thing at a time".to_string())
     } else {
-        Ok(*eval(ast, syms)?.clone())
+        match *ast.car {
+            Ctr::Seg(ref s) => Ok(*eval(s, syms)?.clone()),
+            Ctr::Symbol(ref sym) => {
+                let intermediate = syms.call_symbol(sym, &Seg::new(), true)?;
+                if let Ctr::Seg(ref s) = *intermediate {
+                    Ok(*eval(s, syms)?.clone())
+                } else {
+                    Ok(*intermediate)
+                }
+            },
+            _ => Ok(*ast.car.clone())
+        }
     }
 }