feat: initial parallel type-checker implementation

src/main/wacc/frontend/microWacc.scala

@@ -1,5 +1,7 @@
 package wacc
 
+import cats.data.Chain
+
 object microWacc {
   import wacc.types._
 
@@ -78,12 +80,12 @@ object microWacc {
   }
 
   case class Assign(lhs: LValue, rhs: Expr) extends Stmt
-  case class If(cond: Expr, thenBranch: List[Stmt], elseBranch: List[Stmt]) extends Stmt
-  case class While(cond: Expr, body: List[Stmt]) extends Stmt
+  case class If(cond: Expr, thenBranch: Chain[Stmt], elseBranch: Chain[Stmt]) extends Stmt
+  case class While(cond: Expr, body: Chain[Stmt]) extends Stmt
   case class Call(target: CallTarget, args: List[Expr]) extends Stmt with Expr(target.retTy)
   case class Return(expr: Expr) extends Stmt
 
   // Program
-  case class FuncDecl(name: Ident, params: List[Ident], body: List[Stmt])
-  case class Program(funcs: List[FuncDecl], stmts: List[Stmt])
+  case class FuncDecl(name: Ident, params: List[Ident], body: Chain[Stmt])
+  case class Program(funcs: Chain[FuncDecl], stmts: Chain[Stmt])
 }