diff --git a/hkmc2/jvm/src/test/scala/hkmc2/BbmlDiffMaker.scala b/hkmc2/jvm/src/test/scala/hkmc2/BbmlDiffMaker.scala
index 447f74d71..603147d7d 100644
--- a/hkmc2/jvm/src/test/scala/hkmc2/BbmlDiffMaker.scala
+++ b/hkmc2/jvm/src/test/scala/hkmc2/BbmlDiffMaker.scala
@@ -21,7 +21,7 @@ abstract class BbmlDiffMaker extends JSBackendDiffMaker:
   
   lazy val bbCtx =
     given Elaborator.Ctx = curCtx
-    bbml.BbCtx.init(_ => die, curCtx.allMembers)
+    bbml.BbCtx.init(_ => die)
   
   
   var bbmlTyper: Opt[BBTyper] = None
diff --git a/hkmc2/jvm/src/test/scala/hkmc2/DiffMaker.scala b/hkmc2/jvm/src/test/scala/hkmc2/DiffMaker.scala
index 62c200132..b93eaa461 100644
--- a/hkmc2/jvm/src/test/scala/hkmc2/DiffMaker.scala
+++ b/hkmc2/jvm/src/test/scala/hkmc2/DiffMaker.scala
@@ -98,6 +98,7 @@ abstract class DiffMaker:
   val expectTypeErrors = NullaryCommand("e")
   val expectRuntimeErrors = NullaryCommand("re")
   val expectCodeGenErrors = NullaryCommand("ge")
+  def expectRuntimeOrCodeGenErrors = expectRuntimeErrors.isSet || expectCodeGenErrors.isSet
   val allowRuntimeErrors = NullaryCommand("allowRuntimeErrors")
   val expectWarnings = NullaryCommand("w")
   val showRelativeLineNums = NullaryCommand("showRelativeLineNums")
@@ -174,7 +175,7 @@ abstract class DiffMaker:
             unexpected("runtime error", blockLineNum)
         case Diagnostic.Source.Runtime =>
           runtimeErrors += 1
-          if expectRuntimeErrors.isUnset && !tolerateErrors then
+          if !expectRuntimeOrCodeGenErrors && !tolerateErrors then
             failures += globalStartLineNum
             unexpected("runtime error", blockLineNum)
       case Diagnostic.Kind.Warning =>
diff --git a/hkmc2/jvm/src/test/scala/hkmc2/JSBackendDiffMaker.scala b/hkmc2/jvm/src/test/scala/hkmc2/JSBackendDiffMaker.scala
index a0722cca9..50f2a7324 100644
--- a/hkmc2/jvm/src/test/scala/hkmc2/JSBackendDiffMaker.scala
+++ b/hkmc2/jvm/src/test/scala/hkmc2/JSBackendDiffMaker.scala
@@ -62,7 +62,7 @@ abstract class JSBackendDiffMaker extends MLsDiffMaker:
         output(jsStr)
       def mkQuery(prefix: Str, jsStr: Str) =
         val queryStr = jsStr.replaceAll("\n", " ")
-        val (reply, stderr) = host.query(queryStr, expectRuntimeErrors.isUnset && fixme.isUnset && todo.isUnset)
+        val (reply, stderr) = host.query(queryStr, !expectRuntimeOrCodeGenErrors && fixme.isUnset && todo.isUnset)
         reply match
           case ReplHost.Result(content, stdout) =>
             if silent.isUnset then
diff --git a/hkmc2/shared/src/main/scala/hkmc2/bbml/bbML.scala b/hkmc2/shared/src/main/scala/hkmc2/bbml/bbML.scala
index 070e39baf..ea48cfe3b 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/bbml/bbML.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/bbml/bbML.scala
@@ -61,7 +61,7 @@ object BbCtx:
     ClassLikeType(ctx.getCls("Region").get, Wildcard(sk, sk) :: Nil)
   def refTy(ct: Type, sk: Type)(using ctx: BbCtx): Type =
     ClassLikeType(ctx.getCls("Ref").get, Wildcard(ct, ct) :: Wildcard.out(sk) :: Nil)
-  def init(raise: Raise, predefs: Map[Str, Symbol])(using Elaborator.State, Elaborator.Ctx): BbCtx =
+  def init(raise: Raise)(using Elaborator.State, Elaborator.Ctx): BbCtx =
     new BbCtx(raise, summon, None, 1, HashMap.empty, HashMap.empty, HashMap.empty)
 end BbCtx
 
diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/Lowering.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/Lowering.scala
index f0dbfba52..3a94b8843 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/Lowering.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/Lowering.scala
@@ -58,35 +58,7 @@ class Lowering(using TL, Raise, Elaborator.State):
         args => subTerm(a.value)(r => acc(r :: args))
       )(Nil)
     case st.Ref(sym) =>
-      sym match
-      case sym: BlockMemberSymbol =>
-        // k(subst(Value.Ref(sym.modTree.get.symbol)))
-        k(subst(Value.Ref(sym)))
-      case sym: LocalSymbol =>
-        k(subst(Value.Ref(sym)))
-      case sym: ClassSymbol =>
-        k(subst(Value.Ref(sym)))
-      case sym: ModuleSymbol =>
-        k(subst(Value.Ref(sym)))
-      case sym: TopLevelSymbol =>
-        k(subst(Value.Ref(sym)))
-      /* // * Old logic that auto-lifted `C` ~> `(...) => new C(...)`
-      case sym: ClassSymbol => // TODO rm
-        // k(subst(Value.Ref(sym)))
-        sym.defn match
-        case N => End("error: class has no declaration") // TODO report?
-        case S(clsDefn) =>
-          if clsDefn.kind is syntax.Mod then
-            k(Value.Ref(sym))
-          else
-            val ps = clsDefn.paramsOpt.getOrElse(Nil)
-            val psSyms = ps.map(p => 
-              p.copy(sym = new VarSymbol(p.sym.id, summon[Elaborator.State].nextUid)))
-            k(Value.Lam(psSyms,
-              Return(Instantiate(Value.Ref(sym),
-                psSyms.map(p => Value.Ref(p.sym))), false)))
-      */
-    // * Perhaps this `new` insertion should also be removed...?
+      k(subst(Value.Ref(sym)))
     case st.App(f, arg) =>
       arg match
       case Tup(fs) =>
@@ -104,7 +76,6 @@ class Lowering(using TL, Raise, Elaborator.State):
           rec(as, Nil)
       case _ =>
         TODO("Other argument list forms")
-    
     case st.Blk(Nil, res) => term(res)(k)
     case st.Blk(Lit(Tree.UnitLit(true)) :: stats, res) =>
       subTerm(st.Blk(stats, res))(k)
diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/js/JSBuilder.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/js/JSBuilder.scala
index 96c02c0f7..285d4a666 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/js/JSBuilder.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/js/JSBuilder.scala
@@ -15,6 +15,8 @@ import hkmc2.semantics.InnerSymbol
 import hkmc2.semantics.ParamList
 import hkmc2.codegen.Value.Lam
 import hkmc2.semantics.BlockMemberSymbol
+import hkmc2.semantics.BuiltinSymbol
+import hkmc2.Message.MessageContext
 
 
 // TODO factor some logic for other codegen backends
@@ -43,6 +45,11 @@ class JSBuilder extends CodeBuilder:
     case Argument
     case Operand(prec: Int)
   
+  def err(errMsg: Message)(using Raise, Scope): Document =
+    raise(ErrorReport(errMsg -> N :: Nil,
+      source = Diagnostic.Source.Compilation))
+    doc"(()=>{throw globalThis.Error(${result(Value.Lit(syntax.Tree.StrLit(errMsg.show)))})})()"
+  
   def getVar(l: Local)(using Raise, Scope): Document = l match
     case ts: semantics.TermSymbol =>
       ts.owner match
@@ -63,34 +70,25 @@ class JSBuilder extends CodeBuilder:
   
   def result(r: Result)(using Raise, Scope): Document = r match
     case Value.This(sym) => summon[Scope].findThis_!(sym)
-    case Value.Ref(l) => getVar(l)
     case Value.Lit(Tree.StrLit(value)) => JSBuilder.makeStringLiteral(value)
     case Value.Lit(lit) => lit.idStr
+    case Value.Ref(l: BuiltinSymbol) =>
+      if l.nullary then l.nme
+      else err(msg"Illegal reference to builtin symbol '${l.nme}'")
+    case Value.Ref(l) => getVar(l)
     
-    
-    // * FIXME: this should be done in the Elaborator
-    
-    // case Call(Value.Ref(l: semantics.InnerSymbol), lhs :: rhs :: Nil) if builtinOpsMap contains l.nme =>
-    // case Call(Value.Ref(l), lhs :: rhs :: Nil) if builtinOpsMap contains l.nme =>
-    
-    case Call(Select(Value.Ref(_: TopLevelSymbol), Tree.Ident(nme)), lhs :: rhs :: Nil) if builtinOpsMap contains nme =>
-      val op = builtinOpsMap(nme)
-      val res = doc"${result(lhs)} ${op} ${result(rhs)}"
-      if needsParens(op) then doc"(${res})" else res
-    case Call(Select(Value.Ref(_: TopLevelSymbol), Tree.Ident(nme)), lhs :: Nil) if builtinOpsMap contains nme =>
-      val op = builtinOpsMap(nme)
-      val res = doc"${op} ${result(lhs)}"
-      if needsParens(op) then doc"(${res})" else res
-      
-    case Call(Value.Ref(sym: BlockMemberSymbol), lhs :: rhs :: Nil) if builtinOpsMap contains sym.nme =>
-      val op = builtinOpsMap(sym.nme)
-      val res = doc"${result(lhs)} ${op} ${result(rhs)}"
-      if needsParens(op) then doc"(${res})" else res
-    case Call(Value.Ref(sym: BlockMemberSymbol), lhs :: Nil) if builtinOpsMap contains sym.nme =>
-      val op = builtinOpsMap(sym.nme)
-      val res = doc"${op} ${result(lhs)}"
-      if needsParens(op) then doc"(${res})" else res
-    
+    case Call(Value.Ref(l: BuiltinSymbol), lhs :: rhs :: Nil) =>
+      if l.binary then
+        val res = doc"${result(lhs)} ${l.nme} ${result(rhs)}"
+        if needsParens(l.nme) then doc"(${res})" else res
+      else err(msg"Cannot call non-binary builtin symbol '${l.nme}'")
+    case Call(Value.Ref(l: BuiltinSymbol), rhs :: Nil) =>
+      if l.unary then
+        val res = doc"${l.nme} ${result(rhs)}"
+        if needsParens(l.nme) then doc"(${res})" else res
+      else err(msg"Cannot call non-unary builtin symbol '${l.nme}'")
+    case Call(Value.Ref(l: BuiltinSymbol), args) =>
+      err(msg"Illeal arity for builtin symbol '${l.nme}'")
     
     case Call(fun, args) =>
       val base = fun match
diff --git a/hkmc2/shared/src/main/scala/hkmc2/semantics/Desugarer.scala b/hkmc2/shared/src/main/scala/hkmc2/semantics/Desugarer.scala
index 413df1025..122793508 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/semantics/Desugarer.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/semantics/Desugarer.scala
@@ -202,13 +202,7 @@ class Desugarer(tl: TraceLogger, elaborator: Elaborator)
       post = (res: Split) => s"termSplit: after op >>> $res"
     ):
       // Resolve the operator.
-      val opRef =
-        ctx.get(opName) match
-        case S(sym) => sym.ref(opIdent)
-        case N =>
-          raise(ErrorReport(msg"Name not found: $opName" -> tree.toLoc :: Nil))
-          Term.Error
-      .withLocOf(opIdent)
+      val opRef = term(opIdent)
       // Elaborate and finish the LHS. Nominate the LHS if necessary.
       nominate(ctx, finish(term(lhs)(using ctx))): lhsSymbol =>
         // Compose a function that takes the RHS and finishes the application.
diff --git a/hkmc2/shared/src/main/scala/hkmc2/semantics/Elaborator.scala b/hkmc2/shared/src/main/scala/hkmc2/semantics/Elaborator.scala
index c3d2b314b..bee794c27 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/semantics/Elaborator.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/semantics/Elaborator.scala
@@ -18,6 +18,24 @@ import Keyword.{`let`, `set`}
 
 object Elaborator:
   
+  val builtinOpsMap: Map[Str, BuiltinSymbol] =
+    val binOps: Ls[Str] = Ls(
+      ",",
+      "+", "-", "*", "/", "%",
+      "==", "!=", "<", "<=", ">", ">=",
+      "===",
+      "&&", "||")
+    val isUnary: Str => Bool = Set("-", "+", "!", "~").contains
+    val baseBuiltins = binOps.map: op =>
+        op -> BuiltinSymbol(op, binary = true, unary = isUnary(op), nullary = false)
+      .toMap
+    baseBuiltins
+      + (";" -> baseBuiltins(","))
+      + ("+." -> baseBuiltins("+"))
+      + ("-." -> baseBuiltins("-"))
+      + ("*." -> baseBuiltins("*"))
+  val reservedNames = builtinOpsMap.keySet + "NaN" + "Infinity"
+  
   case class Ctx(outer: Opt[InnerSymbol], parent: Opt[Ctx], env: Map[Str, Ctx.Elem]):
     def +(local: Str -> Symbol): Ctx = copy(outer, env = env + local.mapSecond(Ctx.RefElem(_)))
     def ++(locals: IterableOnce[Str -> Symbol]): Ctx =
@@ -171,8 +189,11 @@ extends Importer:
       ctx.get(name) match
       case S(sym) => sym.ref(id)
       case N =>
-        raise(ErrorReport(msg"Name not found: $name" -> tree.toLoc :: Nil))
-        Term.Error
+        builtinOpsMap.get(name) match
+        case S(bi) => bi.ref(id)
+        case N =>
+          raise(ErrorReport(msg"Name not found: $name" -> tree.toLoc :: Nil))
+          Term.Error
     case TyApp(lhs, targs) =>
       Term.TyApp(term(lhs), targs.map {
         case Modified(Keyword.`in`, inLoc, arg) => Term.WildcardTy(S(term(arg)), N)
diff --git a/hkmc2/shared/src/main/scala/hkmc2/semantics/Symbol.scala b/hkmc2/shared/src/main/scala/hkmc2/semantics/Symbol.scala
index b407d51e7..1b2451b30 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/semantics/Symbol.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/semantics/Symbol.scala
@@ -82,6 +82,10 @@ class VarSymbol(val id: Ident, uid: Int) extends BlockLocalSymbol(id.name, uid)
   val name: Str = id.name
   // override def toString: Str = s"$name@$uid"
 
+class BuiltinSymbol(val nme: Str, val binary: Bool, val unary: Bool, val nullary: Bool) extends Symbol:
+  def toLoc: Option[Loc] = N
+  override def toString: Str = s"builtin:$nme"
+
 
 /** This is the outside-facing symbol associated to a possibly-overloaded
   * definition living in a block – e.g., a module or class. */
diff --git a/hkmc2/shared/src/main/scala/hkmc2/semantics/Term.scala b/hkmc2/shared/src/main/scala/hkmc2/semantics/Term.scala
index 1da3d70dc..967b3d08d 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/semantics/Term.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/semantics/Term.scala
@@ -10,6 +10,7 @@ final case class QuantVar(sym: VarSymbol, ub: Opt[Term], lb: Opt[Term])
 enum Term extends Statement:
   case Error
   case Lit(lit: Literal)
+  case Builtin(id: Tree.Ident, nme: Str)
   case Ref(sym: Symbol)(val tree: Tree.Ident, val refNum: Int)
   case App(lhs: Term, rhs: Term)(val tree: Tree.App, val resSym: FlowSymbol)
   case TyApp(lhs: Term, targs: Ls[Term])
@@ -77,7 +78,7 @@ sealed trait Statement extends AutoLocated:
     case Blk(stats, res) => stats ::: res :: Nil
     case _ => subTerms
   def subTerms: Ls[Term] = this match
-    case Error | _: Lit | _: Ref => Nil
+    case Error | _: Lit | _: Ref | _: Builtin => Nil
     case App(lhs, rhs) => lhs :: rhs :: Nil
     case FunTy(lhs, rhs, eff) => lhs :: rhs :: eff.toList
     case TyApp(pre, tarsg) => pre :: tarsg
diff --git a/hkmc2/shared/src/test/mlscript-compile/Example.mjs b/hkmc2/shared/src/test/mlscript-compile/Example.mjs
index 0cd6e077c..db49bdc05 100644
--- a/hkmc2/shared/src/test/mlscript-compile/Example.mjs
+++ b/hkmc2/shared/src/test/mlscript-compile/Example.mjs
@@ -1,14 +1,11 @@
 import "./Predef.mjs";
-class Int {
-  constructor() {
-    
-  }
-  toString() { return "Int"; }
-};
 const Example$class = class Example {
   constructor() {
     
   }
+  funnySlash(f, arg) {
+    return f(arg)
+  } 
   inc(x) {
     return x + 1
   }
diff --git a/hkmc2/shared/src/test/mlscript-compile/Example.mls b/hkmc2/shared/src/test/mlscript-compile/Example.mls
index c411d88da..bdaa9c9f9 100644
--- a/hkmc2/shared/src/test/mlscript-compile/Example.mls
+++ b/hkmc2/shared/src/test/mlscript-compile/Example.mls
@@ -3,14 +3,11 @@ import "./Predef.mls"
 open Predef
 
 
-class Int
-
-fun (+): (Int, Int) -> Int
-
-
 module Example with ...
 
 
+fun (/) funnySlash(f, arg) = f(arg)
+
 fun inc(x) = x + 1
 
 
diff --git a/hkmc2/shared/src/test/mlscript/bbml/bbBasics.mls b/hkmc2/shared/src/test/mlscript/bbml/bbBasics.mls
index 5ed5d5e69..fae2a4594 100644
--- a/hkmc2/shared/src/test/mlscript/bbml/bbBasics.mls
+++ b/hkmc2/shared/src/test/mlscript/bbml/bbBasics.mls
@@ -207,11 +207,11 @@ class Pair[A, B](fst: A, snd: B)
 
 :fixme
 if 1 < 2 then 1 else 0
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@130),LitPat(BoolLit(true)),Else(Lit(IntLit(1)))),Else(Lit(IntLit(0)))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@112),LitPat(BoolLit(true)),Else(Lit(IntLit(1)))),Else(Lit(IntLit(0)))) (of class hkmc2.semantics.Split$Cons)
 
 :fixme
 if false then 1 else "1"
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@132),LitPat(BoolLit(true)),Else(Lit(IntLit(1)))),Else(Lit(StrLit(1)))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@114),LitPat(BoolLit(true)),Else(Lit(IntLit(1)))),Else(Lit(StrLit(1)))) (of class hkmc2.semantics.Split$Cons)
 
 
 if 1 is Int then 1 else 0
@@ -240,7 +240,7 @@ test("1")
 :fixme
 fun fact(n) =
   if n > 1 then n * fact(n - 1) else 1
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@146),LitPat(BoolLit(true)),Else(App(Sel(Ref(globalThis:import#bbPredef),Ident(*)),Tup(List(Fld(‹›,Ref(n@144),None), Fld(‹›,App(Sel(Ref(globalThis:block#49),Ident(fact)),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@144),None), Fld(‹›,Lit(IntLit(1)),None)))),None)))),None)))))),Else(Lit(IntLit(1)))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@128),LitPat(BoolLit(true)),Else(App(Sel(Ref(globalThis:import#bbPredef),Ident(*)),Tup(List(Fld(‹›,Ref(n@126),None), Fld(‹›,App(Sel(Ref(globalThis:block#49),Ident(fact)),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@126),None), Fld(‹›,Lit(IntLit(1)),None)))),None)))),None)))))),Else(Lit(IntLit(1)))) (of class hkmc2.semantics.Split$Cons)
 
 fact
 //│ Type: ⊥
@@ -253,7 +253,7 @@ fact(1)
 fun fact2 = case
   0 then 1
   n then n * fact2(n - 1)
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@155),LitPat(IntLit(0)),Else(Lit(IntLit(1)))),Let(n@156,Ref(caseScrut@155),Else(App(Sel(Ref(globalThis:import#bbPredef),Ident(*)),Tup(List(Fld(‹›,Ref(n@156),None), Fld(‹›,App(Sel(Ref(globalThis:block#52),Ident(fact2)),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@156),None), Fld(‹›,Lit(IntLit(1)),None)))),None)))),None))))))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@137),LitPat(IntLit(0)),Else(Lit(IntLit(1)))),Let(n@138,Ref(caseScrut@137),Else(App(Sel(Ref(globalThis:import#bbPredef),Ident(*)),Tup(List(Fld(‹›,Ref(n@138),None), Fld(‹›,App(Sel(Ref(globalThis:block#52),Ident(fact2)),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@138),None), Fld(‹›,Lit(IntLit(1)),None)))),None)))),None))))))) (of class hkmc2.semantics.Split$Cons)
 
 fact2
 //│ Type: ⊥
diff --git a/hkmc2/shared/src/test/mlscript/bbml/bbBorrowing.mls b/hkmc2/shared/src/test/mlscript/bbml/bbBorrowing.mls
index 5f143e035..681c3f5af 100644
--- a/hkmc2/shared/src/test/mlscript/bbml/bbBorrowing.mls
+++ b/hkmc2/shared/src/test/mlscript/bbml/bbBorrowing.mls
@@ -61,7 +61,7 @@ letreg of r =>
     123
     if next(it) > 0 then () => 0 else () => clear(b)
   k()
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@120),LitPat(BoolLit(true)),Else(Lam(List(),Lit(IntLit(0))))),Else(Lam(List(),App(Sel(Ref(globalThis:block#5),Ident(clear)),Tup(List(Fld(‹›,Ref(b@109),None))))))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@102),LitPat(BoolLit(true)),Else(Lam(List(),Lit(IntLit(0))))),Else(Lam(List(),App(Sel(Ref(globalThis:block#5),Ident(clear)),Tup(List(Fld(‹›,Ref(b@91),None))))))) (of class hkmc2.semantics.Split$Cons)
 
 :e
 letreg of r =>
diff --git a/hkmc2/shared/src/test/mlscript/bbml/bbCheck.mls b/hkmc2/shared/src/test/mlscript/bbml/bbCheck.mls
index ea3c81e8b..66d782c49 100644
--- a/hkmc2/shared/src/test/mlscript/bbml/bbCheck.mls
+++ b/hkmc2/shared/src/test/mlscript/bbml/bbCheck.mls
@@ -103,7 +103,7 @@ high(x => x + 1)
 
 :fixme
 (if false then x => x else y => y): [A] -> A -> A
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@105),LitPat(BoolLit(true)),Else(Lam(List(Param(‹›,x@106,None)),Ref(x@106)))),Else(Lam(List(Param(‹›,y@104,None)),Ref(y@104)))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref($scrut@87),LitPat(BoolLit(true)),Else(Lam(List(Param(‹›,x@88,None)),Ref(x@88)))),Else(Lam(List(Param(‹›,y@86,None)),Ref(y@86)))) (of class hkmc2.semantics.Split$Cons)
 
 
 fun baz: Int -> (([A] -> A -> A), Int) -> Int
diff --git a/hkmc2/shared/src/test/mlscript/bbml/bbGPCE.mls b/hkmc2/shared/src/test/mlscript/bbml/bbGPCE.mls
index ecc2e039b..05cc5dad3 100644
--- a/hkmc2/shared/src/test/mlscript/bbml/bbGPCE.mls
+++ b/hkmc2/shared/src/test/mlscript/bbml/bbGPCE.mls
@@ -7,7 +7,7 @@ fun power(x) = case
   0 then `1.0
   n then x `*. power(x)(n - 1)
 power
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@51),LitPat(IntLit(0)),Else(Quoted(Lit(DecLit(1.0))))),Let(n@52,Ref(caseScrut@51),Else(Quoted(App(Sel(Ref(globalThis:import#Prelude),Ident(*.)),Tup(List(Fld(‹›,Unquoted(Ref(x@50)),None), Fld(‹›,Unquoted(App(App(Sel(Ref(globalThis:block#0),Ident(power)),Tup(List(Fld(‹›,Ref(x@50),None)))),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@52),None), Fld(‹›,Lit(IntLit(1)),None)))),None))))),None)))))))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@33),LitPat(IntLit(0)),Else(Quoted(Lit(DecLit(1.0))))),Let(n@34,Ref(caseScrut@33),Else(Quoted(App(Ref(builtin:*),Tup(List(Fld(‹›,Unquoted(Ref(x@32)),None), Fld(‹›,Unquoted(App(App(Sel(Ref(globalThis:block#0),Ident(power)),Tup(List(Fld(‹›,Ref(x@32),None)))),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@34),None), Fld(‹›,Lit(IntLit(1)),None)))),None))))),None)))))))) (of class hkmc2.semantics.Split$Cons)
 
 
 fun id: [A] -> A -> A
@@ -53,7 +53,7 @@ fun body(x, y) = case
 fun gib_naive(n) =
   (x, y) `=> body(x, y)(n)
 let gn5 = run(gib_naive(5))
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@97),LitPat(IntLit(0)),Else(Ref(x@95))),Cons(Branch(Ref(caseScrut@97),LitPat(IntLit(1)),Else(Ref(y@96))),Let(n@98,Ref(caseScrut@97),Else(App(App(Sel(Ref(globalThis:block#7),Ident(body)),Tup(List(Fld(‹›,Ref(y@96),None), Fld(‹›,Quoted(App(Sel(Ref(globalThis:import#bbPredef),Ident(+)),Tup(List(Fld(‹›,Unquoted(Ref(x@95)),None), Fld(‹›,Unquoted(Ref(y@96)),None))))),None)))),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@98),None), Fld(‹›,Lit(IntLit(1)),None)))),None)))))))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@79),LitPat(IntLit(0)),Else(Ref(x@77))),Cons(Branch(Ref(caseScrut@79),LitPat(IntLit(1)),Else(Ref(y@78))),Let(n@80,Ref(caseScrut@79),Else(App(App(Sel(Ref(globalThis:block#7),Ident(body)),Tup(List(Fld(‹›,Ref(y@78),None), Fld(‹›,Quoted(App(Sel(Ref(globalThis:import#bbPredef),Ident(+)),Tup(List(Fld(‹›,Unquoted(Ref(x@77)),None), Fld(‹›,Unquoted(Ref(y@78)),None))))),None)))),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@80),None), Fld(‹›,Lit(IntLit(1)),None)))),None)))))))) (of class hkmc2.semantics.Split$Cons)
 
 fun bind(rhs, k) = `let x = rhs `in k(x)
 bind
@@ -66,7 +66,7 @@ fun body(x, y) = case
   0 then x
   1 then y
   n then bind of x `+ y, (z => body(y, z)(n - 1)): [C] -> CodeBase[out Int, out C, out Any] -> CodeBase[out C, out Any]
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@125),LitPat(IntLit(0)),Else(Ref(x@123))),Cons(Branch(Ref(caseScrut@125),LitPat(IntLit(1)),Else(Ref(y@124))),Let(n@126,Ref(caseScrut@125),Else(App(Sel(Ref(globalThis:block#8),Ident(bind)),Tup(List(Fld(‹›,Quoted(App(Sel(Ref(globalThis:import#bbPredef),Ident(+)),Tup(List(Fld(‹›,Unquoted(Ref(x@123)),None), Fld(‹›,Unquoted(Ref(y@124)),None))))),None), Fld(‹›,Lam(List(Param(‹›,z@129,None)),App(App(Sel(Ref(globalThis:block#9),Ident(body)),Tup(List(Fld(‹›,Ref(y@124),None), Fld(‹›,Ref(z@129),None)))),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@126),None), Fld(‹›,Lit(IntLit(1)),None)))),None))))),Some(Forall(List(QuantVar(C@133,None,None)),FunTy(Tup(List(Fld(‹›,TyApp(Sel(Ref(globalThis:import#bbPredef),Ident(CodeBase)),List(WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Int)))), WildcardTy(None,Some(Ref(C@133))), WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Any)))))),None))),TyApp(Sel(Ref(globalThis:import#bbPredef),Ident(CodeBase)),List(WildcardTy(None,Some(Ref(C@133))), WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Any)))))),None))))))))))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@107),LitPat(IntLit(0)),Else(Ref(x@105))),Cons(Branch(Ref(caseScrut@107),LitPat(IntLit(1)),Else(Ref(y@106))),Let(n@108,Ref(caseScrut@107),Else(App(Sel(Ref(globalThis:block#8),Ident(bind)),Tup(List(Fld(‹›,Quoted(App(Sel(Ref(globalThis:import#bbPredef),Ident(+)),Tup(List(Fld(‹›,Unquoted(Ref(x@105)),None), Fld(‹›,Unquoted(Ref(y@106)),None))))),None), Fld(‹›,Lam(List(Param(‹›,z@111,None)),App(App(Sel(Ref(globalThis:block#9),Ident(body)),Tup(List(Fld(‹›,Ref(y@106),None), Fld(‹›,Ref(z@111),None)))),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@108),None), Fld(‹›,Lit(IntLit(1)),None)))),None))))),Some(Forall(List(QuantVar(C@115,None,None)),FunTy(Tup(List(Fld(‹›,TyApp(Sel(Ref(globalThis:import#bbPredef),Ident(CodeBase)),List(WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Int)))), WildcardTy(None,Some(Ref(C@115))), WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Any)))))),None))),TyApp(Sel(Ref(globalThis:import#bbPredef),Ident(CodeBase)),List(WildcardTy(None,Some(Ref(C@115))), WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Any)))))),None))))))))))) (of class hkmc2.semantics.Split$Cons)
 
 fun bind: [G] -> (CodeBase[out Int, out G, out Any], [C] -> CodeBase[out Int, out C, out Any] -> CodeBase[out Int, out C | G, out Any]) -> CodeBase[out Int, out G, out Any]
 fun bind(rhs, k) = `let x = rhs `in k(x)
@@ -81,7 +81,7 @@ fun body(x, y) = case
   1 then y
   n then bind of x `+ y, (z => body(y, z)(n - 1)): [C] -> CodeBase[out Int, out C, out Any] -> CodeBase[out Int, out C, out Any]
 body
-//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@152),LitPat(IntLit(0)),Else(Ref(x@150))),Cons(Branch(Ref(caseScrut@152),LitPat(IntLit(1)),Else(Ref(y@151))),Let(n@153,Ref(caseScrut@152),Else(App(Sel(Ref(globalThis:block#10),Ident(bind)),Tup(List(Fld(‹›,Quoted(App(Sel(Ref(globalThis:import#bbPredef),Ident(+)),Tup(List(Fld(‹›,Unquoted(Ref(x@150)),None), Fld(‹›,Unquoted(Ref(y@151)),None))))),None), Fld(‹›,Lam(List(Param(‹›,z@156,None)),App(App(Sel(Ref(globalThis:block#11),Ident(body)),Tup(List(Fld(‹›,Ref(y@151),None), Fld(‹›,Ref(z@156),None)))),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@153),None), Fld(‹›,Lit(IntLit(1)),None)))),None))))),Some(Forall(List(QuantVar(C@160,None,None)),FunTy(Tup(List(Fld(‹›,TyApp(Sel(Ref(globalThis:import#bbPredef),Ident(CodeBase)),List(WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Int)))), WildcardTy(None,Some(Ref(C@160))), WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Any)))))),None))),TyApp(Sel(Ref(globalThis:import#bbPredef),Ident(CodeBase)),List(WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Int)))), WildcardTy(None,Some(Ref(C@160))), WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Any)))))),None))))))))))) (of class hkmc2.semantics.Split$Cons)
+//│ /!!!\ Uncaught error: scala.MatchError: Cons(Branch(Ref(caseScrut@134),LitPat(IntLit(0)),Else(Ref(x@132))),Cons(Branch(Ref(caseScrut@134),LitPat(IntLit(1)),Else(Ref(y@133))),Let(n@135,Ref(caseScrut@134),Else(App(Sel(Ref(globalThis:block#10),Ident(bind)),Tup(List(Fld(‹›,Quoted(App(Sel(Ref(globalThis:import#bbPredef),Ident(+)),Tup(List(Fld(‹›,Unquoted(Ref(x@132)),None), Fld(‹›,Unquoted(Ref(y@133)),None))))),None), Fld(‹›,Lam(List(Param(‹›,z@138,None)),App(App(Sel(Ref(globalThis:block#11),Ident(body)),Tup(List(Fld(‹›,Ref(y@133),None), Fld(‹›,Ref(z@138),None)))),Tup(List(Fld(‹›,App(Sel(Ref(globalThis:import#bbPredef),Ident(-)),Tup(List(Fld(‹›,Ref(n@135),None), Fld(‹›,Lit(IntLit(1)),None)))),None))))),Some(Forall(List(QuantVar(C@142,None,None)),FunTy(Tup(List(Fld(‹›,TyApp(Sel(Ref(globalThis:import#bbPredef),Ident(CodeBase)),List(WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Int)))), WildcardTy(None,Some(Ref(C@142))), WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Any)))))),None))),TyApp(Sel(Ref(globalThis:import#bbPredef),Ident(CodeBase)),List(WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Int)))), WildcardTy(None,Some(Ref(C@142))), WildcardTy(None,Some(Sel(Ref(globalThis:import#Prelude),Ident(Any)))))),None))))))))))) (of class hkmc2.semantics.Split$Cons)
 
 fun gib(n) = (x, y) `=> body(x, y)(n)
 let g5 = run(gib(5))
diff --git a/hkmc2/shared/src/test/mlscript/bbml/bbRec.mls b/hkmc2/shared/src/test/mlscript/bbml/bbRec.mls
index dad96205c..14ff893ae 100644
--- a/hkmc2/shared/src/test/mlscript/bbml/bbRec.mls
+++ b/hkmc2/shared/src/test/mlscript/bbml/bbRec.mls
@@ -19,7 +19,7 @@ f
 
 :todo
 fun f(x) = f(x.a)
-//│ ╔══[ERROR] Term shape not yet supported by BbML: Sel(Ref(x@57),Ident(a))
+//│ ╔══[ERROR] Term shape not yet supported by BbML: Sel(Ref(x@39),Ident(a))
 //│ ║  l.21: 	fun f(x) = f(x.a)
 //│ ╙──      	             ^
 //│ Type: ⊤
diff --git a/hkmc2/shared/src/test/mlscript/bbml/bbTODOs.mls b/hkmc2/shared/src/test/mlscript/bbml/bbTODOs.mls
index 2081dad30..8f0b8cf32 100644
--- a/hkmc2/shared/src/test/mlscript/bbml/bbTODOs.mls
+++ b/hkmc2/shared/src/test/mlscript/bbml/bbTODOs.mls
@@ -24,6 +24,6 @@ fun id: [A] -> A -> A => x = x
 //│ ╔══[ERROR] Name not found: x
 //│ ║  l.20: 	fun id: [A] -> A -> A => x = x
 //│ ╙──      	                         ^
-//│ /!!!\ Uncaught error: scala.MatchError: Lam(List(Param(‹›,A@55,None)),Error) (of class hkmc2.semantics.Term$Lam)
+//│ /!!!\ Uncaught error: scala.MatchError: Lam(List(Param(‹›,A@37,None)),Error) (of class hkmc2.semantics.Term$Lam)
 
 
diff --git a/hkmc2/shared/src/test/mlscript/codegen/BadNew.mls b/hkmc2/shared/src/test/mlscript/codegen/BadNew.mls
index df803d799..1b592c1c3 100644
--- a/hkmc2/shared/src/test/mlscript/codegen/BadNew.mls
+++ b/hkmc2/shared/src/test/mlscript/codegen/BadNew.mls
@@ -12,11 +12,12 @@ new 2
 //│ ═══[RUNTIME ERROR] TypeError: 2 is not a constructor
 
 :sjs
-:re
+:ge
 new 2 + 2
+//│ ═══[COMPILATION ERROR] Illegal reference to builtin symbol '+'
 //│ JS:
-//│ new this["+"].class(2, 2)
-//│ ═══[RUNTIME ERROR] TypeError: Cannot read properties of undefined (reading 'class')
+//│ new (()=>{throw globalThis.Error("Illegal reference to builtin symbol '+'")})()(2, 2)
+//│ ═══[RUNTIME ERROR] TypeError: (intermediate value) is not a constructor
 
 :re
 new()
@@ -25,14 +26,14 @@ new()
 :pe
 new {}
 //│ ╔══[PARSE ERROR] Expected expression after `new` keyword; found end of block instead
-//│ ║  l.26: 	new {}
+//│ ║  l.27: 	new {}
 //│ ╙──      	    ^^
 
 // FIXME the error...
 :todo
 new { x = 1 }
 //│ ╔══[ERROR] Wrong number of type arguments
-//│ ║  l.33: 	new { x = 1 }
+//│ ║  l.34: 	new { x = 1 }
 //│ ╙──      	      ^
 
 
diff --git a/hkmc2/shared/src/test/mlscript/codegen/BasicTerms.mls b/hkmc2/shared/src/test/mlscript/codegen/BasicTerms.mls
index 05ddcd7f4..00a7a3f25 100644
--- a/hkmc2/shared/src/test/mlscript/codegen/BasicTerms.mls
+++ b/hkmc2/shared/src/test/mlscript/codegen/BasicTerms.mls
@@ -41,7 +41,7 @@ log("Hi")
 //│ Program:
 //│   imports = Nil
 //│   main = Assign:
-//│     lhs = $tmp@36
+//│     lhs = $tmp@18
 //│     rhs = Call:
 //│       fun = Select:
 //│         qual = Ref of globalThis:import#Prelude
diff --git a/hkmc2/shared/src/test/mlscript/codegen/BuiltinOps.mls b/hkmc2/shared/src/test/mlscript/codegen/BuiltinOps.mls
new file mode 100644
index 000000000..ce5ec9e06
--- /dev/null
+++ b/hkmc2/shared/src/test/mlscript/codegen/BuiltinOps.mls
@@ -0,0 +1,31 @@
+:js
+
+
+:sjs
+2 + 2
+//│ JS:
+//│ 2 + 2
+//│ = 4
+
+:sjs
+2 +. 2
+//│ JS:
+//│ 2 + 2
+//│ = 4
+
+:sjs
++2
+//│ JS:
+//│ + 2
+//│ = 2
+
+
+fun (+) lol(a, b) = [a, b]
+
+:sjs
+1 + 2
+//│ JS:
+//│ this.lol(1, 2)
+//│ = [ 1, 2 ]
+
+
diff --git a/hkmc2/shared/src/test/mlscript/codegen/ImportExample.mls b/hkmc2/shared/src/test/mlscript/codegen/ImportExample.mls
index 9400cbca7..38ee66151 100644
--- a/hkmc2/shared/src/test/mlscript/codegen/ImportExample.mls
+++ b/hkmc2/shared/src/test/mlscript/codegen/ImportExample.mls
@@ -8,3 +8,35 @@ Example.inc(123)
 //│ = 124
 
 
+Example.funnySlash(Example.inc, 123)
+//│ = 124
+
+
+let n = 42
+//│ n = 42
+
+:sjs
+n / 2
+//│ JS:
+//│ this.n / 2
+//│ = 21
+
+
+// * Builtin operators can be shadowed/rebound
+
+open Example
+
+:sjs
+inc / 2
+//│ JS:
+//│ Example.funnySlash(Example.inc, 2)
+//│ = 3
+
+:sjs
+:re
+n / 2
+//│ JS:
+//│ Example.funnySlash(this.n, 2)
+//│ ═══[RUNTIME ERROR] TypeError: f is not a function
+
+
diff --git a/hkmc2/shared/src/test/mlscript/codegen/While.mls b/hkmc2/shared/src/test/mlscript/codegen/While.mls
index 5cf1872af..0e00ce400 100644
--- a/hkmc2/shared/src/test/mlscript/codegen/While.mls
+++ b/hkmc2/shared/src/test/mlscript/codegen/While.mls
@@ -158,10 +158,10 @@ if x
   else 42
 //│ Normalized:
 //│ >  if
-//│ >    let $scrut@134 = globalThis:block#7.x#666
-//│ >    $scrut@134 is true and
-//│ >      let $scrut@135 = globalThis:block#7.y#666
-//│ >      $scrut@135 is true then 0
+//│ >    let $scrut@116 = globalThis:block#7.x#666
+//│ >    $scrut@116 is true and
+//│ >      let $scrut@117 = globalThis:block#7.y#666
+//│ >      $scrut@117 is true then 0
 //│ >      else 1
 //│ >    else 42
 //│ = 42
@@ -174,10 +174,10 @@ if x
   else 42
 //│ Normalized:
 //│ >  if
-//│ >    let $scrut@137 = globalThis:block#7.x#666
-//│ >    $scrut@137 is true and
-//│ >      let $scrut@138 = globalThis:block#7.y#666
-//│ >      $scrut@138 is true then 0
+//│ >    let $scrut@119 = globalThis:block#7.x#666
+//│ >    $scrut@119 is true and
+//│ >      let $scrut@120 = globalThis:block#7.y#666
+//│ >      $scrut@120 is true then 0
 //│ >      else 1
 //│ >    else 42
 //│ = 42
diff --git a/hkmc2/shared/src/test/mlscript/decls/Prelude.mls b/hkmc2/shared/src/test/mlscript/decls/Prelude.mls
index 94bd2f803..fc4f816ba 100644
--- a/hkmc2/shared/src/test/mlscript/decls/Prelude.mls
+++ b/hkmc2/shared/src/test/mlscript/decls/Prelude.mls
@@ -19,27 +19,7 @@ declare val process
 declare val fs
 
 
-fun (;): [A] -> ((), A) -> A
-
-fun (+): (Int, Int) -> Int
-fun (-): (Int, Int) -> Int
-fun (*): (Int, Int) -> Int
-fun (/): (Int, Int) -> Num
-fun (<): (Int, Int) -> Bool
-fun (>): (Int, Int) -> Bool
-fun (<=): (Int, Int) -> Bool
-fun (>=): (Int, Int) -> Bool
-fun (&&): (Bool, Bool) -> Bool
-fun (||): (Bool, Bool) -> Bool
-
-fun (+.): (Num, Num) -> Num
-fun (-.): (Num, Num) -> Num
-fun (*.): (Num, Num) -> Num
-fun (/.): (Num, Num) -> Num
-
-// [CY:] poly is not supported here
-fun (==): (Any, Any) -> Bool
-fun (===): (Any, Any) -> Bool
+// TODO: rm
 
 fun log: (Any) -> ()
 
diff --git a/hkmc2/shared/src/test/mlscript/parser/PrefixOps.mls b/hkmc2/shared/src/test/mlscript/parser/PrefixOps.mls
index ec5e1ce96..7c93263dd 100644
--- a/hkmc2/shared/src/test/mlscript/parser/PrefixOps.mls
+++ b/hkmc2/shared/src/test/mlscript/parser/PrefixOps.mls
@@ -24,34 +24,46 @@
 
 :w
 :pe
+:ge
 1
 * 2
 * 3
 //│ ╔══[PARSE ERROR] Expected end of input; found literal instead
-//│ ║  l.28: 	* 2
+//│ ║  l.29: 	* 2
 //│ ╙──      	  ^
 //│ ╔══[WARNING] Pure expression in statement position
-//│ ║  l.27: 	1
+//│ ║  l.28: 	1
 //│ ╙──      	^
+//│ ═══[COMPILATION ERROR] Illegal reference to builtin symbol '*'
+//│ ═══[RUNTIME ERROR] Error: Illegal reference to builtin symbol '*'
 
 
 :sjs
+:ge
 +
+//│ ═══[COMPILATION ERROR] Illegal reference to builtin symbol '+'
 //│ JS:
-//│ this["+"]
+//│ (()=>{throw globalThis.Error("Illegal reference to builtin symbol '+'")})()
+//│ ═══[RUNTIME ERROR] Error: Illegal reference to builtin symbol '+'
 
+:ge
 *
+//│ ═══[COMPILATION ERROR] Illegal reference to builtin symbol '*'
+//│ ═══[RUNTIME ERROR] Error: Illegal reference to builtin symbol '*'
 
 :w
 :pt
+:ge
 1
 *
 //│ Parsed tree:
 //│ IntLit of 1
 //│ Ident of "*"
 //│ ╔══[WARNING] Pure expression in statement position
-//│ ║  l.47: 	1
+//│ ║  l.57: 	1
 //│ ╙──      	^
+//│ ═══[COMPILATION ERROR] Illegal reference to builtin symbol '*'
+//│ ═══[RUNTIME ERROR] Error: Illegal reference to builtin symbol '*'
 
 
 fun (??) foo(x, y) = x + y
@@ -78,7 +90,7 @@ fun (??) foo(x, y) = x + y
 :pe
 ?? 1
 //│ ╔══[PARSE ERROR] Expected end of input; found literal instead
-//│ ║  l.79: 	?? 1
+//│ ║  l.91: 	?? 1
 //│ ╙──      	   ^
 //│ = [Function: foo]
 
@@ -87,10 +99,10 @@ fun (??) foo(x, y) = x + y
 1
 ?? 2
 //│ ╔══[PARSE ERROR] Expected end of input; found literal instead
-//│ ║  l.88: 	?? 2
-//│ ╙──      	   ^
+//│ ║  l.100: 	?? 2
+//│ ╙──       	   ^
 //│ ╔══[WARNING] Pure expression in statement position
-//│ ║  l.87: 	1
+//│ ║  l.99: 	1
 //│ ╙──      	^
 //│ = [Function: foo]
 
diff --git a/hkmc2/shared/src/test/mlscript/ucs/general/CardSuits.mls b/hkmc2/shared/src/test/mlscript/ucs/general/CardSuits.mls
index ddb40738f..afa4ec277 100644
--- a/hkmc2/shared/src/test/mlscript/ucs/general/CardSuits.mls
+++ b/hkmc2/shared/src/test/mlscript/ucs/general/CardSuits.mls
@@ -22,18 +22,18 @@ fun foo(x) = if x is
   else 4
 //│ Desugared:
 //│ >  if
-//│ >    x@40 is Card($param0@41) $param0@41 is Heart then 0
-//│ >    x@40 is Card($param0@41) $param0@41 is Diamond then 1
-//│ >    x@40 is Card($param0@41) $param0@41 is Spade then 2
-//│ >    x@40 is Card($param0@41) $param0@41 is Club then 3
+//│ >    x@22 is Card($param0@23) $param0@23 is Heart then 0
+//│ >    x@22 is Card($param0@23) $param0@23 is Diamond then 1
+//│ >    x@22 is Card($param0@23) $param0@23 is Spade then 2
+//│ >    x@22 is Card($param0@23) $param0@23 is Club then 3
 //│ >    else 4
 //│ Normalized:
 //│ >  if
-//│ >    x@40 is Card($param0@41) and
-//│ >      $param0@41 is Heart then 0
-//│ >      $param0@41 is Diamond then 1
-//│ >      $param0@41 is Spade then 2
-//│ >      $param0@41 is Club then 3
+//│ >    x@22 is Card($param0@23) and
+//│ >      $param0@23 is Heart then 0
+//│ >      $param0@23 is Diamond then 1
+//│ >      $param0@23 is Spade then 2
+//│ >      $param0@23 is Club then 3
 //│ >      else 4
 //│ >    else 4
 
diff --git a/hkmc2/shared/src/test/mlscript/ucs/hygiene/PatVars.mls b/hkmc2/shared/src/test/mlscript/ucs/hygiene/PatVars.mls
index 80a7b931e..542550815 100644
--- a/hkmc2/shared/src/test/mlscript/ucs/hygiene/PatVars.mls
+++ b/hkmc2/shared/src/test/mlscript/ucs/hygiene/PatVars.mls
@@ -7,8 +7,8 @@ if 0 is
   x then 12
 //│ Desugared:
 //│ >  if
-//│ >    let $scrut@29 = 0
-//│ >    let x@30 = $scrut@29#0
+//│ >    let $scrut@11 = 0
+//│ >    let x@12 = $scrut@11#0
 //│ >    else 12
 //│ = 12
 
diff --git a/hkmc2/shared/src/test/mlscript/ucs/normalization/OverlapOfPrimitives.mls b/hkmc2/shared/src/test/mlscript/ucs/normalization/OverlapOfPrimitives.mls
index 7e37adde4..fed495613 100644
--- a/hkmc2/shared/src/test/mlscript/ucs/normalization/OverlapOfPrimitives.mls
+++ b/hkmc2/shared/src/test/mlscript/ucs/normalization/OverlapOfPrimitives.mls
@@ -6,10 +6,10 @@ fun test(x, p) = if x is
   else "qax"
 //│ Desugared:
 //│ >  if
-//│ >    x@29 is Int and
-//│ >      let $scrut@32 = p@30#666(x@29#666)
-//│ >      $scrut@32 is true then "foo"
-//│ >    x@29 is 0 then "bar"
+//│ >    x@11 is Int and
+//│ >      let $scrut@14 = p@12#666(x@11#666)
+//│ >      $scrut@14 is true then "foo"
+//│ >    x@11 is 0 then "bar"
 //│ >    else "qax"
 
 fun test(x, p) = if x is
@@ -18,10 +18,10 @@ fun test(x, p) = if x is
   else "qax"
 //│ Desugared:
 //│ >  if
-//│ >    x@35 is Str and
-//│ >      let $scrut@38 = p@36#666(x@35#666)
-//│ >      $scrut@38 is true then "foo"
-//│ >    x@35 is "lol" then "bar"
+//│ >    x@17 is Str and
+//│ >      let $scrut@20 = p@18#666(x@17#666)
+//│ >      $scrut@20 is true then "foo"
+//│ >    x@17 is "lol" then "bar"
 //│ >    else "qax"
 
 test(0, _ => true)
@@ -34,11 +34,11 @@ fun test(x, p) = if x is
   else "other"
 //│ Desugared:
 //│ >  if
-//│ >    x@44 is Num and
-//│ >      let $scrut@47 = p@45#666(x@44#666)
-//│ >      $scrut@47 is true then "great"
-//│ >    x@44 is 2.71828 then "E"
-//│ >    x@44 is 3.14159 then "PI"
+//│ >    x@26 is Num and
+//│ >      let $scrut@29 = p@27#666(x@26#666)
+//│ >      $scrut@29 is true then "great"
+//│ >    x@26 is 2.71828 then "E"
+//│ >    x@26 is 3.14159 then "PI"
 //│ >    else "other"
 
 fun test(x, p) = if x is
@@ -47,11 +47,11 @@ fun test(x, p) = if x is
   false then "true"
 //│ Desugared:
 //│ >  if
-//│ >    x@50 is Bool and
-//│ >      let $scrut@53 = p@51#666(x@50#666)
-//│ >      $scrut@53 is true then "great"
-//│ >    x@50 is true then "false"
-//│ >    x@50 is false then "true"
+//│ >    x@32 is Bool and
+//│ >      let $scrut@35 = p@33#666(x@32#666)
+//│ >      $scrut@35 is true then "great"
+//│ >    x@32 is true then "false"
+//│ >    x@32 is false then "true"
 
 fun test(x, p) = if x is
   Object and p(x) then "great"
@@ -60,11 +60,11 @@ fun test(x, p) = if x is
   false then "true"
 //│ Desugared:
 //│ >  if
-//│ >    x@56 is Object and
-//│ >      let $scrut@61 = p@57#666(x@56#666)
-//│ >      $scrut@61 is true then "great"
-//│ >    x@56 is Bool and
-//│ >      let $scrut@59 = p@57#666(x@56#666)
-//│ >      $scrut@59 is true then "great, again"
-//│ >    x@56 is true then "false"
-//│ >    x@56 is false then "true"
+//│ >    x@38 is Object and
+//│ >      let $scrut@43 = p@39#666(x@38#666)
+//│ >      $scrut@43 is true then "great"
+//│ >    x@38 is Bool and
+//│ >      let $scrut@41 = p@39#666(x@38#666)
+//│ >      $scrut@41 is true then "great, again"
+//│ >    x@38 is true then "false"
+//│ >    x@38 is false then "true"
diff --git a/hkmc2/shared/src/test/mlscript/ucs/normalization/UnifySubScrutinees.mls b/hkmc2/shared/src/test/mlscript/ucs/normalization/UnifySubScrutinees.mls
index 1cd2537a3..80df3d0ae 100644
--- a/hkmc2/shared/src/test/mlscript/ucs/normalization/UnifySubScrutinees.mls
+++ b/hkmc2/shared/src/test/mlscript/ucs/normalization/UnifySubScrutinees.mls
@@ -16,23 +16,23 @@ fun foo(xs) =
     Nil then 3
 //│ Desugared:
 //│ >  if
-//│ >    xs@38 is Cons($param0@39, $param1@40) and $param0@39 is "abc" and $param1@40 is Cons($param0@41, $param1@42) and $param0@41 is "xyz" and
-//│ >      let xs@44 = $param1@42#1
+//│ >    xs@20 is Cons($param0@21, $param1@22) and $param0@21 is "abc" and $param1@22 is Cons($param0@23, $param1@24) and $param0@23 is "xyz" and
+//│ >      let xs@26 = $param1@24#1
 //│ >      else 0
-//│ >    xs@38 is Cons($param0@39, $param1@40) and $param0@39 is "abc" and $param1@40 is Cons($param0@41, $param1@42) and $param0@41 is "uvw" and
-//│ >      let xs@43 = $param1@42#0
+//│ >    xs@20 is Cons($param0@21, $param1@22) and $param0@21 is "abc" and $param1@22 is Cons($param0@23, $param1@24) and $param0@23 is "uvw" and
+//│ >      let xs@25 = $param1@24#0
 //│ >      else 1
-//│ >    xs@38 is Nil then 3
+//│ >    xs@20 is Nil then 3
 //│ Normalized:
 //│ >  if
-//│ >    xs@38 is Cons($param0@39, $param1@40) and $param0@39 is "abc" and $param1@40 is Cons($param0@41, $param1@42) and
-//│ >      $param0@41 is "xyz" and
-//│ >        let xs@44 = $param1@42#1
+//│ >    xs@20 is Cons($param0@21, $param1@22) and $param0@21 is "abc" and $param1@22 is Cons($param0@23, $param1@24) and
+//│ >      $param0@23 is "xyz" and
+//│ >        let xs@26 = $param1@24#1
 //│ >        else 0
-//│ >      $param0@41 is "uvw" and
-//│ >        let xs@43 = $param1@42#0
+//│ >      $param0@23 is "uvw" and
+//│ >        let xs@25 = $param1@24#0
 //│ >        else 1
-//│ >    xs@38 is Nil then 3
+//│ >    xs@20 is Nil then 3
 
 fun sum(acc, xs) = 
   if xs is
@@ -40,18 +40,18 @@ fun sum(acc, xs) =
     Nil     then acc
 //│ Desugared:
 //│ >  if
-//│ >    xs@48 is Cons($param0@49, $param1@50) and
-//│ >      let x@51 = $param0@49#0
-//│ >      let xs@52 = $param1@50#0
-//│ >      else globalThis:block#3#666.sum‹member:sum›(globalThis:import#Prelude#666.+‹member:+›(acc@47#666, x@51#666), xs@52#666)
-//│ >    xs@48 is Nil then acc@47#666
+//│ >    xs@30 is Cons($param0@31, $param1@32) and
+//│ >      let x@33 = $param0@31#0
+//│ >      let xs@34 = $param1@32#0
+//│ >      else globalThis:block#3#666.sum‹member:sum›(builtin:+#82(acc@29#666, x@33#666), xs@34#666)
+//│ >    xs@30 is Nil then acc@29#666
 //│ Normalized:
 //│ >  if
-//│ >    xs@48 is Cons($param0@49, $param1@50) and
-//│ >      let x@51 = $param0@49#0
-//│ >      let xs@52 = $param1@50#0
-//│ >      else globalThis:block#3#666.sum‹member:sum›(globalThis:import#Prelude#666.+‹member:+›(acc@47#666, x@51#666), xs@52#666)
-//│ >    xs@48 is Nil then acc@47#666
+//│ >    xs@30 is Cons($param0@31, $param1@32) and
+//│ >      let x@33 = $param0@31#0
+//│ >      let xs@34 = $param1@32#0
+//│ >      else globalThis:block#3#666.sum‹member:sum›(builtin:+#82(acc@29#666, x@33#666), xs@34#666)
+//│ >    xs@30 is Nil then acc@29#666
 
 :todo
 // The normalization does not distinguish between bindings and their aliases.
@@ -66,37 +66,37 @@ fun test(xs) =
     None then "nothing"
 //│ Desugared:
 //│ >  if
-//│ >    xs@57 is Some($param0@58) and $param0@58 is Cons($param0@59, $param1@60) and $param0@59 is "add" and $param1@60 is Cons($param0@63, $param1@64) and
-//│ >      let x@70 = $param0@63#1
-//│ >      $param1@64 is Cons($param0@66, $param1@67) and
-//│ >        let y@71 = $param0@66#1
-//│ >        $param1@67 is Nil then globalThis:import#Prelude#666.+‹member:+›(x@70#666, y@71#666)
-//│ >    xs@57 is Some($param0@58) and $param0@58 is Cons($param0@59, $param1@60) and $param0@59 is "mul" and $param1@60 is Cons($param0@63, $param1@64) and
-//│ >      let x@65 = $param0@63#0
-//│ >      $param1@64 is Cons($param0@66, $param1@67) and
-//│ >        let y@68 = $param0@66#0
-//│ >        $param1@67 is Nil then globalThis:import#Prelude#666.*‹member:*›(x@65#666, y@68#666)
-//│ >    xs@57 is Some($param0@58) and $param0@58 is Cons($param0@59, $param1@60) and $param0@59 is "sum" and
-//│ >      let xs@61 = $param1@60#0
-//│ >      else globalThis:block#3#666.sum‹member:sum›(0, xs@61#666)
-//│ >    xs@57 is Some($param0@58) $param0@58 is Nil then "nothing"
-//│ >    xs@57 is None then "nothing"
+//│ >    xs@39 is Some($param0@40) and $param0@40 is Cons($param0@41, $param1@42) and $param0@41 is "add" and $param1@42 is Cons($param0@45, $param1@46) and
+//│ >      let x@52 = $param0@45#1
+//│ >      $param1@46 is Cons($param0@48, $param1@49) and
+//│ >        let y@53 = $param0@48#1
+//│ >        $param1@49 is Nil then builtin:+#83(x@52#666, y@53#666)
+//│ >    xs@39 is Some($param0@40) and $param0@40 is Cons($param0@41, $param1@42) and $param0@41 is "mul" and $param1@42 is Cons($param0@45, $param1@46) and
+//│ >      let x@47 = $param0@45#0
+//│ >      $param1@46 is Cons($param0@48, $param1@49) and
+//│ >        let y@50 = $param0@48#0
+//│ >        $param1@49 is Nil then builtin:*#23(x@47#666, y@50#666)
+//│ >    xs@39 is Some($param0@40) and $param0@40 is Cons($param0@41, $param1@42) and $param0@41 is "sum" and
+//│ >      let xs@43 = $param1@42#0
+//│ >      else globalThis:block#3#666.sum‹member:sum›(0, xs@43#666)
+//│ >    xs@39 is Some($param0@40) $param0@40 is Nil then "nothing"
+//│ >    xs@39 is None then "nothing"
 //│ Normalized:
 //│ >  if
-//│ >    xs@57 is Some($param0@58) and
-//│ >      $param0@58 is Cons($param0@59, $param1@60) and
-//│ >        $param0@59 is "add" and $param1@60 is Cons($param0@63, $param1@64) and
-//│ >          let x@70 = $param0@63#1
-//│ >          $param1@64 is Cons($param0@66, $param1@67) and
-//│ >            let y@71 = $param0@66#1
-//│ >            $param1@67 is Nil then globalThis:import#Prelude#666.+‹member:+›(x@70#666, y@71#666)
-//│ >        $param0@59 is "mul" and $param1@60 is Cons($param0@63, $param1@64) and
-//│ >          let x@65 = $param0@63#0
-//│ >          $param1@64 is Cons($param0@66, $param1@67) and
-//│ >            let y@68 = $param0@66#0
-//│ >            $param1@67 is Nil then globalThis:import#Prelude#666.*‹member:*›(x@65#666, y@68#666)
-//│ >        $param0@59 is "sum" and
-//│ >          let xs@61 = $param1@60#0
-//│ >          else globalThis:block#3#666.sum‹member:sum›(0, xs@61#666)
-//│ >      $param0@58 is Nil then "nothing"
-//│ >    xs@57 is None then "nothing"
+//│ >    xs@39 is Some($param0@40) and
+//│ >      $param0@40 is Cons($param0@41, $param1@42) and
+//│ >        $param0@41 is "add" and $param1@42 is Cons($param0@45, $param1@46) and
+//│ >          let x@52 = $param0@45#1
+//│ >          $param1@46 is Cons($param0@48, $param1@49) and
+//│ >            let y@53 = $param0@48#1
+//│ >            $param1@49 is Nil then builtin:+#83(x@52#666, y@53#666)
+//│ >        $param0@41 is "mul" and $param1@42 is Cons($param0@45, $param1@46) and
+//│ >          let x@47 = $param0@45#0
+//│ >          $param1@46 is Cons($param0@48, $param1@49) and
+//│ >            let y@50 = $param0@48#0
+//│ >            $param1@49 is Nil then builtin:*#23(x@47#666, y@50#666)
+//│ >        $param0@41 is "sum" and
+//│ >          let xs@43 = $param1@42#0
+//│ >          else globalThis:block#3#666.sum‹member:sum›(0, xs@43#666)
+//│ >      $param0@40 is Nil then "nothing"
+//│ >    xs@39 is None then "nothing"
diff --git a/hkmc2/shared/src/test/mlscript/ucs/papers/OperatorSplit.mls b/hkmc2/shared/src/test/mlscript/ucs/papers/OperatorSplit.mls
index e1d7703a6..ba5cb8a47 100644
--- a/hkmc2/shared/src/test/mlscript/ucs/papers/OperatorSplit.mls
+++ b/hkmc2/shared/src/test/mlscript/ucs/papers/OperatorSplit.mls
@@ -78,13 +78,13 @@ fun example(args) =
 //│           params = Ls of 
 //│             Param:
 //│               flags = ()
-//│               sym = args@40
+//│               sym = args@22
 //│               sign = N
 //│       sign = N
 //│       body = S of IfLike:
 //│         kw = keyword 'if'
 //│         desugared = Let:
-//│           sym = $scrut@42
+//│           sym = $scrut@24
 //│           term = App:
 //│             lhs = Sel:
 //│               prefix = Ref of globalThis:block#1
@@ -92,18 +92,16 @@ fun example(args) =
 //│             rhs = Tup of Ls of 
 //│               Fld:
 //│                 flags = ()
-//│                 value = Ref of args@40
+//│                 value = Ref of args@22
 //│                 asc = N
 //│           tail = Let: \
-//│           sym = $scrut@52
+//│           sym = $scrut@34
 //│           term = App:
-//│             lhs = Sel:
-//│               prefix = Ref of globalThis:import#Prelude
-//│               nme = Ident of "<"
+//│             lhs = Ref of builtin:<
 //│             rhs = Tup of Ls of 
 //│               Fld:
 //│                 flags = ()
-//│                 value = Ref of $scrut@42
+//│                 value = Ref of $scrut@24
 //│                 asc = N
 //│               Fld:
 //│                 flags = ()
@@ -111,19 +109,17 @@ fun example(args) =
 //│                 asc = N
 //│           tail = Cons: \
 //│           head = Branch:
-//│             scrutinee = Ref of $scrut@52
+//│             scrutinee = Ref of $scrut@34
 //│             pattern = LitPat of BoolLit of true
 //│             continuation = Else of Lit of StrLit of "invalid"
 //│           tail = Let: \
-//│           sym = $scrut@50
+//│           sym = $scrut@32
 //│           term = App:
-//│             lhs = Sel:
-//│               prefix = Ref of globalThis:import#Prelude
-//│               nme = Ident of "=="
+//│             lhs = Ref of builtin:==
 //│             rhs = Tup of Ls of 
 //│               Fld:
 //│                 flags = ()
-//│                 value = Ref of $scrut@42
+//│                 value = Ref of $scrut@24
 //│                 asc = N
 //│               Fld:
 //│                 flags = ()
@@ -131,11 +127,11 @@ fun example(args) =
 //│                 asc = N
 //│           tail = Cons: \
 //│           head = Branch:
-//│             scrutinee = Ref of $scrut@50
+//│             scrutinee = Ref of $scrut@32
 //│             pattern = LitPat of BoolLit of true
 //│             continuation = Else of Lit of StrLit of "null"
 //│           tail = Let: \
-//│           sym = $scrut@44
+//│           sym = $scrut@26
 //│           term = App:
 //│             lhs = Sel:
 //│               prefix = Ref of globalThis:block#1
@@ -143,7 +139,7 @@ fun example(args) =
 //│             rhs = Tup of Ls of 
 //│               Fld:
 //│                 flags = ()
-//│                 value = Ref of $scrut@42
+//│                 value = Ref of $scrut@24
 //│                 asc = N
 //│               Fld:
 //│                 flags = ()
@@ -152,15 +148,13 @@ fun example(args) =
 //│                   nme = Ident of "abs"
 //│                 asc = N
 //│           tail = Let: \
-//│           sym = $scrut@48
+//│           sym = $scrut@30
 //│           term = App:
-//│             lhs = Sel:
-//│               prefix = Ref of globalThis:import#Prelude
-//│               nme = Ident of ">"
+//│             lhs = Ref of builtin:>
 //│             rhs = Tup of Ls of 
 //│               Fld:
 //│                 flags = ()
-//│                 value = Ref of $scrut@44
+//│                 value = Ref of $scrut@26
 //│                 asc = N
 //│               Fld:
 //│                 flags = ()
@@ -168,19 +162,17 @@ fun example(args) =
 //│                 asc = N
 //│           tail = Cons: \
 //│           head = Branch:
-//│             scrutinee = Ref of $scrut@48
+//│             scrutinee = Ref of $scrut@30
 //│             pattern = LitPat of BoolLit of true
 //│             continuation = Else of Lit of StrLit of "large"
 //│           tail = Let: \
-//│           sym = $scrut@46
+//│           sym = $scrut@28
 //│           term = App:
-//│             lhs = Sel:
-//│               prefix = Ref of globalThis:import#Prelude
-//│               nme = Ident of "<"
+//│             lhs = Ref of builtin:<
 //│             rhs = Tup of Ls of 
 //│               Fld:
 //│                 flags = ()
-//│                 value = Ref of $scrut@44
+//│                 value = Ref of $scrut@26
 //│                 asc = N
 //│               Fld:
 //│                 flags = ()
@@ -188,11 +180,11 @@ fun example(args) =
 //│                 asc = N
 //│           tail = Cons: \
 //│           head = Branch:
-//│             scrutinee = Ref of $scrut@46
+//│             scrutinee = Ref of $scrut@28
 //│             pattern = LitPat of BoolLit of true
 //│             continuation = Else of Lit of StrLit of "small"
 //│           tail = Else of Lit of StrLit of "medium"
-//│       resSym = ‹result of member:example›@53
+//│       resSym = ‹result of member:example›@35
 //│   res = Lit of UnitLit of true
 
 
diff --git a/hkmc2/shared/src/test/mlscript/ucs/patterns/AliasPattern.mls b/hkmc2/shared/src/test/mlscript/ucs/patterns/AliasPattern.mls
index ea080895b..5304c8916 100644
--- a/hkmc2/shared/src/test/mlscript/ucs/patterns/AliasPattern.mls
+++ b/hkmc2/shared/src/test/mlscript/ucs/patterns/AliasPattern.mls
@@ -9,32 +9,32 @@ fun map(f) = case
   None as n then n
 //│ Desugared:
 //│ >  if
-//│ >    caseScrut@33 is Some($param0@35) and
-//│ >      let x@36 = $param0@35#0
-//│ >      else globalThis:import#Option#666.Some‹member:Some›(f@32#666(x@36#666))
-//│ >    caseScrut@33 is None and
-//│ >      let n@34 = caseScrut@33#1
-//│ >      else n@34#666
+//│ >    caseScrut@15 is Some($param0@17) and
+//│ >      let x@18 = $param0@17#0
+//│ >      else globalThis:import#Option#666.Some‹member:Some›(f@14#666(x@18#666))
+//│ >    caseScrut@15 is None and
+//│ >      let n@16 = caseScrut@15#1
+//│ >      else n@16#666
 
 fun map(f) = case
   Some(x as n) then Some of f(n)
   None as n then n
 //│ Desugared:
 //│ >  if
-//│ >    caseScrut@42 is Some($param0@44) and
-//│ >      let x@46 = $param0@44#0
-//│ >      let n@45 = $param0@44#1
-//│ >      else globalThis:import#Option#666.Some‹member:Some›(f@41#666(n@45#666))
-//│ >    caseScrut@42 is None and
-//│ >      let n@43 = caseScrut@42#1
-//│ >      else n@43#666
+//│ >    caseScrut@24 is Some($param0@26) and
+//│ >      let x@28 = $param0@26#0
+//│ >      let n@27 = $param0@26#1
+//│ >      else globalThis:import#Option#666.Some‹member:Some›(f@23#666(n@27#666))
+//│ >    caseScrut@24 is None and
+//│ >      let n@25 = caseScrut@24#1
+//│ >      else n@25#666
 
 fun foo = case
   Some(Some(a as b) as c) as d then [a, b, c, d]
 //│ Desugared:
-//│ >  if caseScrut@51 is Some($param0@53) and $param0@53 is Some($param0@55) and
-//│ >    let a@57 = $param0@55#0
-//│ >    let b@56 = $param0@55#1
-//│ >    let c@54 = $param0@53#1
-//│ >    let d@52 = caseScrut@51#1
-//│ >    else [a@57#666, b@56#666, c@54#666, d@52#666]
+//│ >  if caseScrut@33 is Some($param0@35) and $param0@35 is Some($param0@37) and
+//│ >    let a@39 = $param0@37#0
+//│ >    let b@38 = $param0@37#1
+//│ >    let c@36 = $param0@35#1
+//│ >    let d@34 = caseScrut@33#1
+//│ >    else [a@39#666, b@38#666, c@36#666, d@34#666]
diff --git a/hkmc2/shared/src/test/mlscript/ucs/patterns/NamePattern.mls b/hkmc2/shared/src/test/mlscript/ucs/patterns/NamePattern.mls
index 7e5dd72dd..eb4d80c4e 100644
--- a/hkmc2/shared/src/test/mlscript/ucs/patterns/NamePattern.mls
+++ b/hkmc2/shared/src/test/mlscript/ucs/patterns/NamePattern.mls
@@ -4,6 +4,6 @@ fun id(x) = x
 if id(0) is t then t
 //│ Desugared:
 //│ >  if
-//│ >    let $scrut@33 = member:Predef#666.id‹member:id›(0)
-//│ >    let t@34 = $scrut@33#0
-//│ >    else t@34#666
+//│ >    let $scrut@15 = member:Predef#666.id‹member:id›(0)
+//│ >    let t@16 = $scrut@15#0
+//│ >    else t@16#666
diff --git a/hkmc2/shared/src/test/mlscript/ucs/patterns/Refinement.mls b/hkmc2/shared/src/test/mlscript/ucs/patterns/Refinement.mls
index 70368c898..e8bbfb070 100644
--- a/hkmc2/shared/src/test/mlscript/ucs/patterns/Refinement.mls
+++ b/hkmc2/shared/src/test/mlscript/ucs/patterns/Refinement.mls
@@ -40,7 +40,7 @@ x => if x is
 //│ ║  l.34: 	  refined(None) then x
 //│ ╙──      	  ^^^^^^^
 //│ Normalized:
-//│ >  if x@36 is Some then x@36#666
+//│ >  if x@18 is Some then x@18#666
 
 x => if x is
   refined(None) then x
diff --git a/hkmc2/shared/src/test/mlscript/ucs/syntax/NestedOpSplits.mls b/hkmc2/shared/src/test/mlscript/ucs/syntax/NestedOpSplits.mls
index 65a71dead..953fcb507 100644
--- a/hkmc2/shared/src/test/mlscript/ucs/syntax/NestedOpSplits.mls
+++ b/hkmc2/shared/src/test/mlscript/ucs/syntax/NestedOpSplits.mls
@@ -20,36 +20,32 @@ fun f(x) =
 //│           params = Ls of 
 //│             Param:
 //│               flags = ()
-//│               sym = x@29
+//│               sym = x@11
 //│               sign = N
 //│       sign = N
 //│       body = S of IfLike:
 //│         kw = keyword 'if'
 //│         desugared = Let:
-//│           sym = $scrut@31
+//│           sym = $scrut@13
 //│           term = App:
-//│             lhs = Sel:
-//│               prefix = Ref of globalThis:import#Prelude
-//│               nme = Ident of "=="
+//│             lhs = Ref of builtin:==
 //│             rhs = Tup of Ls of 
 //│               Fld:
 //│                 flags = ()
-//│                 value = Ref of x@29
+//│                 value = Ref of x@11
 //│                 asc = N
 //│               Fld:
 //│                 flags = ()
 //│                 value = Lit of IntLit of 1
 //│                 asc = N
 //│           tail = Let: \
-//│           sym = $scrut@33
+//│           sym = $scrut@15
 //│           term = App:
-//│             lhs = Sel:
-//│               prefix = Ref of globalThis:import#Prelude
-//│               nme = Ident of "+"
+//│             lhs = Ref of builtin:+
 //│             rhs = Tup of Ls of 
 //│               Fld:
 //│                 flags = ()
-//│                 value = Ref of $scrut@31
+//│                 value = Ref of $scrut@13
 //│                 asc = N
 //│               Fld:
 //│                 flags = ()
@@ -57,11 +53,11 @@ fun f(x) =
 //│                 asc = N
 //│           tail = Cons: \
 //│           head = Branch:
-//│             scrutinee = Ref of $scrut@33
+//│             scrutinee = Ref of $scrut@15
 //│             pattern = LitPat of BoolLit of true
 //│             continuation = Else of Lit of IntLit of 0
 //│           tail = Else of Lit of IntLit of 1
-//│       resSym = ‹result of member:f›@34
+//│       resSym = ‹result of member:f›@16
 //│   res = Lit of UnitLit of true