diff --git a/playground/samples/Prelude.newt b/playground/samples/Prelude.newt
index da29d0a..9ac4446 100644
--- a/playground/samples/Prelude.newt
+++ b/playground/samples/Prelude.newt
@@ -37,23 +37,23 @@ fromMaybe a Nothing = a
 fromMaybe _ (Just a) = a
 
 data Either : U -> U -> U where
-  Left : {a b : U} -> a -> Either a b
-  Right : {a b : U} -> b -> Either a b
+  Left : {0 a b : U} -> a -> Either a b
+  Right : {0 a b : U} -> b -> Either a b
 
 infixr 7 _::_
 data List : U -> U where
-  Nil : {A} → List A
-  _::_ : {A} → A → List A → List A
+  Nil : ∀ A. List A
+  _::_ : ∀ A. A → List A → List A
 
 
 infixl 7 _:<_
 data SnocList : U → U where
-  Lin : {A} → SnocList A
-  _:<_ : {A} → SnocList A → A → SnocList A
+  Lin : ∀ A. SnocList A
+  _:<_ : ∀ A. SnocList A → A → SnocList A
 
 -- 'chips'
 infixr 6 _<>>_
-_<>>_ : {a} → SnocList a → List a → List a
+_<>>_ : ∀ a. SnocList a → List a → List a
 Lin <>> ys = ys
 (xs :< x) <>> ys = xs <>> x :: ys
 
@@ -67,7 +67,7 @@ f $ a = f a
 infixr 8 _×_
 infixr 2 _,_
 data _×_ : U → U → U where
-  _,_ : {A B} → A → B → A × B
+  _,_ : ∀ A B. A → B → A × B
 
 infixl 6 _<_
 class Ord a where
@@ -81,14 +81,14 @@ instance Ord Nat where
 -- Monad
 
 class Monad (m : U → U) where
-  bind : {a b} → m a → (a → m b) → m b
-  pure : {a} → a → m a
+  bind : {0 a b} → m a → (a → m b) → m b
+  pure : {0 a} → a → m a
 
 infixl 1 _>>=_ _>>_
-_>>=_ : {m} {{Monad m}} {a b} -> (m a) -> (a -> m b) -> m b
+_>>=_ : {0 m} {{Monad m}} {0 a b} -> (m a) -> (a -> m b) -> m b
 ma >>= amb = bind ma amb
 
-_>>_ :  {m} {{Monad m}} {a b} -> m a -> m b -> m b
+_>>_ :  {0 m} {{Monad m}} {0 a b} -> m a -> m b -> m b
 ma >> mb = mb
 
 -- Equality
@@ -108,10 +108,10 @@ sym Refl = Refl
 -- Functor
 
 class Functor (m : U → U) where
-  map : {a b} → (a → b) → m a → m b
+  map : {0 a b} → (a → b) → m a → m b
 
 infixr 4 _<$>_
-_<$>_ : {f} {{Functor f}} {a b} → (a → b) → f a → f b
+_<$>_ : {0 f} {{Functor f}} {0 a b} → (a → b) → f a → f b
 f <$> ma = map f ma
 
 instance Functor Maybe where
@@ -130,12 +130,12 @@ instance Functor SnocList where
 infixl 3 _<*>_
 class Applicative (f : U → U) where
   -- appIsFunctor : Functor f
-  return : {a} → a → f a
-  _<*>_ : {a b} -> f (a → b) → f a → f b
+  return : {0 a} → a → f a
+  _<*>_ : {0 a b} -> f (a → b) → f a → f b
 
 infixr 2 _<|>_
 class Alternative (m : U → U) where
-  _<|>_ : {a} → m a → m a → m a
+  _<|>_ : {0 a} → m a → m a → m a
 
 instance Alternative Maybe where
   Nothing <|> x = x
@@ -266,9 +266,9 @@ instance Monad IO where
     MkIORes a w => mab a w
   pure a = \ w => MkIORes a w
 
-pfunc putStrLn : String -> IO Unit := `(s) => (w) => {
+pfunc putStrLn uses (MkIORes MkUnit) : String -> IO Unit := `(s) => (w) => {
   console.log(s)
-  return MkIORes(Unit,MkUnit,w)
+  return MkIORes(undefined,MkUnit,w)
 }`
 
 pfunc showInt : Int -> String := `(i) => String(i)`
@@ -285,8 +285,7 @@ instance Show Int where
 pfunc ord : Char -> Int := `(c) => c.charCodeAt(0)`
 
 infix 6 _<=_
-pfunc _<=_ : Int -> Int -> Bool := `(x,y) => (x <= y) ? True : False`
-
+pfunc _<=_ uses (True False) : Int -> Int -> Bool := `(x,y) => (x <= y) ? True : False`
 
 pfunc unpack : String -> List Char
   := `(s) => {
@@ -309,7 +308,7 @@ _∘_ : {A B C : U} -> (B -> C) -> (A -> B) -> A -> C
 pfunc addInt : Int → Int → Int := `(x,y) => x + y`
 pfunc mulInt : Int → Int → Int := `(x,y) => x * y`
 pfunc subInt : Int → Int → Int := `(x,y) => x - y`
-pfunc ltInt : Int → Int → Bool := `(x,y) => x < y ? True : False`
+pfunc ltInt uses (True False) : Int → Int → Bool := `(x,y) => x < y ? True : False`
 
 instance Mul Int where
   x * y = mulInt x y
diff --git a/playground/samples/Tour.newt b/playground/samples/Tour.newt
index 3c5977a..b0195e3 100644
--- a/playground/samples/Tour.newt
+++ b/playground/samples/Tour.newt
@@ -209,3 +209,33 @@ prod xs ys = do
   x <- xs
   y <- ys
   pure (x, y)
+
+-- The playground is compiling to javascript and will give an error if
+-- main isn't implemented, so I'll crib the definition of IO from
+-- Prelude:
+
+data Unit : U where
+  MkUnit : Unit
+
+ptype World
+
+data IORes : U -> U where
+  MkIORes : ∀ a. a -> World -> IORes a
+
+IO : U -> U
+IO a = World -> IORes a
+
+instance Monad IO where
+  bind ma mab = \ w => case ma w of
+    MkIORes a w => mab a w
+  pure a = \ w => MkIORes a w
+
+-- Here we declare `uses` to let the dead code elimination know we're poking
+-- at MKIORes and MkUnit behind the compiler's back.
+pfunc putStrLn uses (MkIORes MkUnit) : String -> IO Unit := `(s) => (w) => {
+  console.log(s)
+  return MkIORes(undefined,MkUnit,w)
+}`
+
+main : IO Unit
+main = putStrLn "hello, world"
diff --git a/src/Lib/Compile.idr b/src/Lib/Compile.idr
index 621c6f9..2a9dc46 100644
--- a/src/Lib/Compile.idr
+++ b/src/Lib/Compile.idr
@@ -308,7 +308,12 @@ process (done,docs) nm = do
 
 export
 compile : M (List Doc)
--- compile = do
---   top <- get
---   traverse entryToDoc top.defs
-compile = reverse . snd <$> process ([],[]) "main"
+compile = do
+  top <- get
+  case lookup "main" top of
+    Just _ => reverse . snd <$> process ([],[]) "main"
+    -- If there is no main, compile everything for the benefit of the playground
+    Nothing => do
+      top <- get
+      traverse entryToDoc top.defs
+
diff --git a/src/Lib/CompileExp.idr b/src/Lib/CompileExp.idr
index 833dfa6..0626482 100644
--- a/src/Lib/CompileExp.idr
+++ b/src/Lib/CompileExp.idr
@@ -110,20 +110,8 @@ compileTerm (Meta _ k) = pure $ CRef "meta$\{show k}" -- FIXME
 compileTerm (Lam _ nm t) = pure $ CLam nm !(compileTerm t)
 compileTerm tm@(App _ _ _) with (funArgs tm)
   _ | (Meta _ k, args) = do
-        -- FIXME get arity or zonk?
-        -- let's see if this happens after zonking
-        error (getFC tm) "Lambda in CompileExp"
-        -- Maybe we should be storing the Term without the lambdas...
-        -- we don't have a lot here, but JS has an "environment" with names and
-        -- we can assume fully applied.
-        -- meta <- lookupMeta k
-        -- args' <- traverse compileTerm args
-        -- -- apply (CRef "Meta\{show k}") args' [<] 0
-        -- arity <- case meta of
-        --         -- maybe throw
-        --         (Unsolved x j ctx _ _ _) => pure 0 -- FIXME # of Bound in ctx.bds
-        --         (Solved _ j tm) => pure $ lamArity !(quote 0 tm)
-        -- apply (CRef "Meta\{show k}") args' [<] arity
+        -- this will be undefined, should only happen for use metas
+        pure $ CApp (CRef "Meta\{show k}") []
   _ | (t@(Ref fc nm _), args) = do
         args' <- traverse compileTerm args
         arity <- arityForName fc nm
@@ -160,4 +148,3 @@ compileFun tm = go tm [<]
     go tm args = pure $ CFun (args <>> []) !(compileTerm tm)
 
 
-