diff --git a/TODO.md b/TODO.md
index 5c29851..534dd0c 100644
--- a/TODO.md
+++ b/TODO.md
@@ -24,6 +24,7 @@ Syntax -> Parser.Impl ?
   - It would be nice if IO looked like imperative JS, but that might be a bit of a stretch.
 
 - [ ] LSP and/or more editor support
+  - [ ] would be nice to have "add missing cases" and "case split"
   - [ ] Probably need ranges for FC
   - [ ] leave an interactive process running
   - [ ] collect metadata or run through the serialization data
diff --git a/src/Lib/Compile.newt b/src/Lib/Compile.newt
index 452b080..1f3085d 100644
--- a/src/Lib/Compile.newt
+++ b/src/Lib/Compile.newt
@@ -36,6 +36,7 @@ data JSExp : U where
   Apply : JSExp -> List JSExp -> JSExp
   Var : String -> JSExp
   JLam : List String -> JSStmt Return -> JSExp
+  JPrimOp : String → JSExp → JSExp → JSExp
   JUndefined : JSExp
   Index : JSExp -> JSExp -> JSExp
   Dot : JSExp -> String -> JSExp
@@ -134,6 +135,7 @@ termToJS env (CFun nms t) f =
   let (nms', env') = freshNames nms env
   in f $ JLam nms' (termToJS env' t JReturn)
 termToJS env (CRef nm) f = f $ Var (show nm)
+termToJS env (CPrimOp op t u) f = termToJS env t $ \ t => termToJS env u $ \ u => f $ JPrimOp op t u
 termToJS env (CMeta k) f = f $ LitString "META \{show k}"
 termToJS env (CLit lit) f = f (litToJS lit)
 -- if it's a var, just use the original
@@ -258,6 +260,7 @@ expToDoc (JLam nms body) = text "(" <+> commaSep (map jsIdent nms) <+> text ") =
 expToDoc JUndefined = text "null"
 expToDoc (Index obj ix) = expToDoc obj ++ text "(" ++ expToDoc ix ++ text " :: Nil)"
 expToDoc (Dot obj nm) = expToDoc obj ++ text "." ++ jsIdent nm
+expToDoc (JPrimOp op t u) = text "(" ++ expToDoc t <+> text op <+> expToDoc u ++ text ")"
 
 caseBody : ∀ e. JSStmt e -> Doc
 caseBody stmt@(JReturn x) = nest 2 (line ++ stmtToDoc stmt)
@@ -357,6 +360,7 @@ sortedNames defs qn = go Nil Nil qn
     getNames acc (CMeta _) = acc
     getNames acc (CBnd _) = acc
     getNames acc CErased = acc
+    getNames acc (CPrimOp op t u) = getNames (getNames acc t) u
 
     go : List QName → List QName → QName → List QName
     go loop acc qn =
diff --git a/src/Lib/CompileExp.newt b/src/Lib/CompileExp.newt
index f4bf75c..d79de36 100644
--- a/src/Lib/CompileExp.newt
+++ b/src/Lib/CompileExp.newt
@@ -42,6 +42,9 @@ data CExp : U where
   CConstr : Name -> List CExp -> CExp
   -- Raw javascript for `pfunc`
   CRaw : String -> List QName -> CExp
+  -- Need this for magic Nat
+  -- TODO - use for primitives too
+  CPrimOp : String → CExp → CExp -> CExp
 
 -- I'm counting Lam in the term for arity.  This matches what I need in
 -- code gen.
diff --git a/src/Lib/TCO.newt b/src/Lib/TCO.newt
index a591892..dc61dba 100644
--- a/src/Lib/TCO.newt
+++ b/src/Lib/TCO.newt
@@ -39,6 +39,7 @@ tailNames CErased = Nil
 tailNames (CLit _) = Nil
 tailNames (CMeta _) = Nil
 tailNames (CRaw _ _) = Nil
+tailNames (CPrimOp _ _ _) = Nil
 
 -- rewrite tail calls to return an object
 rewriteTailCalls : List QName → CExp → CExp