Refactor: Analyze node purity and recursion

The Analyzer has been refactored to decorate `TypedNode`s with their
purity and recursion status. This involves creating a new `AnalyzedNode`
type and a `NodeMetrics` struct to hold this information. The `Analyzer`
now returns an `AnalyzedNode` instead of a separate `Analysis` struct.
This change lays the groundwork for future optimizations and analysis
passes.

src/ast/compiler/tco.rs

@@ -1,16 +1,15 @@
-use crate::ast::compiler::bound_nodes::{BoundKind, TypedNode};
+use crate::ast::compiler::bound_nodes::{AnalyzedNode, BoundKind};
 use crate::ast::nodes::Node;
 use crate::ast::types::StaticType;
 use std::rc::Rc;
-
 use std::fmt::Debug;
 
 #[derive(Clone)]
 pub struct RuntimeMetadata {
     pub ty: StaticType,
     pub is_tail: bool,
-    /// The original, high-level typed node. Perfect for Debuggers and Optimizers.
-    pub original: Rc<TypedNode>,
+    /// The analyzed node, containing metrics and a link to the original TypedNode.
+    pub original: Rc<AnalyzedNode>,
 }
 
 impl Debug for RuntimeMetadata {
@@ -22,18 +21,18 @@ impl Debug for RuntimeMetadata {
     }
 }
 
-/// The ExecNode is the AST used by the VM. It carries TCO flags and links to source.
+/// The ExecNode is the AST used by the VM. It carries TCO flags and links to metrics.
 pub type ExecNode = Node<BoundKind<RuntimeMetadata>, RuntimeMetadata>;
 
 pub struct TCO;
 
 impl TCO {
-    /// Lowers a TypedNode (Compiler-AST) to an ExecNode (VM-AST) and marks tail positions.
-    pub fn optimize(node: TypedNode) -> ExecNode {
+    /// Lowers an AnalyzedNode to an ExecNode and marks tail positions.
+    pub fn optimize(node: AnalyzedNode) -> ExecNode {
         Self::transform(Rc::new(node), true)
     }
 
-    fn transform(node_rc: Rc<TypedNode>, is_tail_position: bool) -> ExecNode {
+    fn transform(node_rc: Rc<AnalyzedNode>, is_tail_position: bool) -> ExecNode {
         let node = &*node_rc;
         let new_kind = match &node.kind {
             BoundKind::Call { callee, args } => BoundKind::Call {
@@ -158,7 +157,7 @@ impl TCO {
             identity: node.identity.clone(),
             kind: new_kind,
             ty: RuntimeMetadata {
-                ty: node.ty.clone(),
+                ty: node.ty.original.ty.clone(),
                 is_tail: is_tail_position,
                 original: node_rc,
             },