Finally have things printing to the screen

Nothing fancy yet. This commit adds a bunch of stuff (oops):

* compiling code
* VM with instructions
* remove eval.rs and just eval in the Machine struct itself
* squash most warnings now that we're using stuff here

And probably more. But that's all for now folks

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

src/object.rs

@@ -4,8 +4,13 @@
 #![allow(dead_code)]
 
 use crate::syn::ast::SpExpr;
+use crate::{
+    syn::{span::Span, words::Scope},
+    vm::inst::Inst,
+};
 use std::cell::RefCell;
 use std::collections::{BTreeMap, HashMap};
+use std::fmt::{self, Display};
 use std::rc::{Rc, Weak};
 
 pub type Str = String;
@@ -13,22 +18,106 @@ pub type Int = i64;
 pub type Float = f64;
 pub type VTable = HashMap<String, Value>;
 
+// /////////////////////////////////////////////////////////////////////////////
+// Quote
+// /////////////////////////////////////////////////////////////////////////////
+
+/// A handle to a quote pointing to an element in a `QuoteTable`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Quote(usize);
+
+impl Quote {
+    pub fn index(&self) -> usize {
+        self.0
+    }
+}
+
+/// A table of compiled quotes, their expression trees, and their spans.
+#[derive(Debug, Clone, Default)]
+pub struct QuoteTable {
+    table: Vec<(Span, Scope, Vec<SpExpr>, Vec<Inst>)>,
+}
+
+impl QuoteTable {
+    pub fn new() -> Self {
+        Default::default()
+    }
+
+    pub fn insert(
+        &mut self,
+        span: Span,
+        scope: Scope,
+        quote: Vec<SpExpr>,
+        compiled: Vec<Inst>,
+    ) -> Quote {
+        let next = Quote(self.table.len());
+        self.table.push((span, scope, quote, compiled));
+        next
+    }
+
+    pub fn get(&self, quote: Quote) -> &(Span, Scope, Vec<SpExpr>, Vec<Inst>) {
+        &self.table[quote.0]
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////////
+// Value
+// /////////////////////////////////////////////////////////////////////////////
+
 #[derive(Debug, Clone)]
 pub enum Value {
     Array(Vec<Value>),
     Float(Float),
     Int(Int),
     Str(Str),
-    Quote(Vec<SpExpr>),
+    Quote(Quote),
     ObjPtr(ObjPtr),
 }
 
+impl Value {
+    pub fn name(&self) -> &str {
+        use Value::*;
+        match self {
+            Array(_) => "array",
+            Float(_) => "float",
+            Int(_) => "int",
+            Str(_) => "str",
+            Quote(_) => "quote",
+            ObjPtr(_) => "object",
+        }
+    }
+}
+
+impl Display for Value {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        use Value::*;
+        match self {
+            Array(_) => write!(fmt, "[array]"),
+            Float(f) => write!(fmt, "{}", f),
+            Int(i) => write!(fmt, "{}", i),
+            Str(s) => write!(fmt, "{}", s),
+            Quote(q) => write!(fmt, "[quoted value #{}]", q.index()),
+            ObjPtr(o) => write!(fmt, "[object #{}]", o.slot()),
+        }
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////////
+// Obj
+// /////////////////////////////////////////////////////////////////////////////
+
 #[derive(Debug, Clone)]
 pub struct ObjPtr {
     arena: Weak<RefCell<Arena>>,
     slot: usize,
 }
 
+impl ObjPtr {
+    pub fn slot(&self) -> usize {
+        self.slot
+    }
+}
+
 #[derive(Debug, Default)]
 pub struct Obj {
     vtable: VTable,
@@ -48,6 +137,10 @@ impl Obj {
     }
 }
 
+// /////////////////////////////////////////////////////////////////////////////
+// Arena
+// /////////////////////////////////////////////////////////////////////////////
+
 #[derive(Debug)]
 pub struct Arena {
     slots: Vec<SlotRange>,
@@ -170,6 +263,10 @@ impl Arena {
     }
 }
 
+// /////////////////////////////////////////////////////////////////////////////
+// Slots
+// /////////////////////////////////////////////////////////////////////////////
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum SlotRange {
     /// A list of slots that are in a range, exclusive.