Remove RuntimeSpanError and just incorporate it into RuntimeError; add Span information to compiled instructions

* RuntimeSpanError was an extraneous solution to adding spans to the
  errors; so instead this behavior has been delegated to the
  RuntimeError itself.
* Usage of Inst has mostly been replaced with SpInst so if an error is
  encountered, we can spit out where it happened in the source code
  (hopefully with a stack trace).

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/object.rs

@@ -5,7 +5,7 @@
 
 use crate::syn::ast::SpStmt;
 use crate::vm::{error::Result, machine::Machine};
-use crate::{scope::Scope, syn::span::Span, vm::inst::Inst};
+use crate::{scope::Scope, syn::span::Span, vm::inst::SpInst};
 use std::cell::RefCell;
 use std::collections::{BTreeMap, HashMap};
 use std::fmt::{self, Debug, Display};
@@ -33,7 +33,7 @@ impl Quote {
 /// A table of compiled quotes, their expression trees, and their spans.
 #[derive(Debug, Clone, Default)]
 pub struct QuoteTable {
-    table: Vec<(Span, Scope, Vec<SpStmt>, Rc<Vec<Inst>>)>,
+    table: Vec<(Span, Scope, Vec<SpStmt>, Rc<Vec<SpInst>>)>,
 }
 
 impl QuoteTable {
@@ -46,14 +46,14 @@ impl QuoteTable {
         span: Span,
         scope: Scope,
         quote: Vec<SpStmt>,
-        compiled: Rc<Vec<Inst>>,
+        compiled: Rc<Vec<SpInst>>,
     ) -> Quote {
         let next = Quote(self.table.len());
         self.table.push((span, scope, quote, compiled));
         next
     }
 
-    pub fn get(&self, quote: Quote) -> &(Span, Scope, Vec<SpStmt>, Rc<Vec<Inst>>) {
+    pub fn get(&self, quote: Quote) -> &(Span, Scope, Vec<SpStmt>, Rc<Vec<SpInst>>) {
         &self.table[quote.0]
     }
 }
@@ -136,15 +136,21 @@ pub enum BuiltinExit {
 }
 
 #[derive(Clone)]
-pub struct BuiltinFn(Rc<BuiltinFnPtr>);
+pub struct BuiltinFn {
+    name: Rc<String>,
+    fun: Rc<BuiltinFnPtr>,
+}
 
 impl BuiltinFn {
-    pub fn new(fun: Rc<BuiltinFnPtr>) -> Self {
-        BuiltinFn(fun)
+    pub fn new(name: String, fun: Rc<BuiltinFnPtr>) -> Self {
+        BuiltinFn {
+            name: Rc::new(name),
+            fun,
+        }
     }
 
     pub fn call(&self, machine: &mut Machine, reentry: usize) -> Result<BuiltinExit> {
-        (self.0)(machine, reentry)
+        (self.fun)(machine, reentry)
     }
 }
 
@@ -156,7 +162,7 @@ impl Debug for BuiltinFn {
         write!(
             fmt,
             "builtin function at {:#x}",
-            (&self.0 as *const _ as usize)
+            (&self.fun as *const _ as usize)
         )
     }
 }