diff --git a/exe/Main.idr b/exe/Main.idr
index f67aaf2..f8b29ae 100644
--- a/exe/Main.idr
+++ b/exe/Main.idr
@@ -58,16 +58,19 @@ newState = pure $ MkState {
 }
 
 private
-data Error
-  = ParseError String Parser.Error
-  | FromParserError FromParser.Error
-  | EraseError Erase.Error
-  | WriteError FilePath FileError
+data Error =
+  ParseError String Parser.Error
+| FromParserError FromParser.Error
+| EraseError Erase.Error
+| WriteError FilePath FileError
+| NoMain
+| MultipleMains (List Id)
 %hide FromParser.Error
 %hide Erase.Error
 %hide Lexer.Error
 %hide Parser.Error
 
+
 private
 loadError : Loc -> FilePath -> FileError -> Error
 loadError loc file err = FromParserError $ LoadError loc file err
@@ -77,6 +80,10 @@ prettyError : {opts : LayoutOpts} -> Error -> Eff Pretty (Doc opts)
 prettyError (ParseError file e) = prettyParseError file e
 prettyError (FromParserError e) = FromParser.prettyError True e
 prettyError (EraseError      e) = Erase.prettyError True e
+prettyError NoMain              = pure "no #[main] function given"
+prettyError (MultipleMains xs)  =
+  pure $ sep ["multiple #[main] functions given:",
+              separateLoose "," !(traverse prettyId xs)]
 prettyError (WriteError file e) = pure $
   hangSingle 2 (text "couldn't write file \{file}:") (pshow e)
 
@@ -133,9 +140,10 @@ outputStr str =
       rethrow $ mapFst (WriteError f) res
 
 private
-outputDocs : {opts : LayoutOpts} -> List (Doc opts) -> Eff Compile ()
-outputDocs {opts = Opts _} doc =
-  outputStr $ concat $ map (render _) doc
+outputDocs : (opts : Options) ->
+             ({opts : LayoutOpts} -> List (Doc opts)) -> Eff Compile ()
+outputDocs opts doc =
+  outputStr $ concat $ map (render (Opts opts.width)) doc
 
 private
 outputDocStopIf : Phase ->
@@ -144,7 +152,7 @@ outputDocStopIf : Phase ->
 outputDocStopIf p docs = do
   opts <- askAt OPTS
   when (opts.until == Just p) $ Prelude.do
-    lift $ outputDocs (runPretty opts docs) {opts = Opts opts.width}
+    lift $ outputDocs !(askAt OPTS) (runPretty opts docs)
     stopHere
 
 private
@@ -166,10 +174,19 @@ liftErase defs act =
      handleStateIORef !(asksAt STATE suf)]
 
 private
-liftScheme : Eff Scheme a -> Eff CompileStop a
-liftScheme act = runEff act [handleStateIORef !(newIORef empty)]
+liftScheme : Eff Scheme a -> Eff CompileStop (a, List Id)
+liftScheme act = do
+  runEff [|MkPair act (getAt MAIN)|]
+    [handleStateIORef !(newIORef empty),
+     handleStateIORef !(newIORef [])]
 
 
+private
+oneMain : Has (Except Error) fs => List Id -> Eff fs Id
+oneMain []    = throw NoMain
+oneMain [x]   = pure x
+oneMain mains = throw $ MultipleMains mains
+
 private
 processFile : String -> Eff Compile ()
 processFile file = withEarlyStop $ do
@@ -187,11 +204,16 @@ processFile file = withEarlyStop $ do
     traverse (\(x, d) => (x,) <$> eraseDef x d) defList
   outputDocStopIf Erase $
     traverse (uncurry U.prettyDef) erased
-  scheme <- liftScheme $ map catMaybes $
+  (scheme, mains) <- liftScheme $ map catMaybes $
     traverse (uncurry defToScheme) erased
   outputDocStopIf Scheme $
-    (text Scheme.prelude ::) <$> traverse prettySexp scheme
-  die "that's all folks"
+    intersperse empty <$> traverse prettySexp scheme
+  opts <- askAt OPTS
+  main <- oneMain mains
+  lift $ outputDocs opts $ intersperse empty $ runPretty opts $ do
+    res    <- traverse prettySexp scheme
+    runner <- makeRunMain main
+    pure $ text Scheme.prelude :: res ++ [runner]
 
 export
 main : IO ()
diff --git a/lib/Quox/Definition.idr b/lib/Quox/Definition.idr
index 4842c29..1fc19aa 100644
--- a/lib/Quox/Definition.idr
+++ b/lib/Quox/Definition.idr
@@ -26,18 +26,24 @@ namespace DefBody
 public export
 record Definition where
   constructor MkDef
-  qty   : GQty
-  type0 : Term 0 0
-  body0 : DefBody
-  loc_  : Loc
+  qty    : GQty
+  type0  : Term 0 0
+  body0  : DefBody
+  scheme : Maybe String
+  isMain : Bool
+  loc_   : Loc
 
 public export %inline
-mkPostulate : GQty -> (type0 : Term 0 0) -> Loc -> Definition
-mkPostulate qty type0 loc_ = MkDef {qty, type0, body0 = Postulate, loc_}
+mkPostulate : GQty -> (type0 : Term 0 0) -> Maybe String -> Bool -> Loc ->
+              Definition
+mkPostulate qty type0 scheme isMain loc_ =
+  MkDef {qty, type0, body0 = Postulate, scheme, isMain, loc_}
 
 public export %inline
-mkDef : GQty -> (type0, term0 : Term 0 0) -> Loc -> Definition
-mkDef qty type0 term0 loc_ = MkDef {qty, type0, body0 = Concrete term0, loc_}
+mkDef : GQty -> (type0, term0 : Term 0 0) -> Maybe String -> Bool -> Loc ->
+        Definition
+mkDef qty type0 term0 scheme isMain loc_ =
+  MkDef {qty, type0, body0 = Concrete term0, scheme, isMain, loc_}
 
 export Located Definition where def.loc = def.loc_
 export Relocatable Definition where setLoc loc = {loc_ := loc}
@@ -108,10 +114,10 @@ lookupElim0 = lookupElim
 
 export
 prettyDef : {opts : LayoutOpts} -> Name -> Definition -> Eff Pretty (Doc opts)
-prettyDef name (MkDef qty type _ _) = withPrec Outer $ do
-  qty   <- prettyQty qty.qty
+prettyDef name def = withPrec Outer $ do
+  qty   <- prettyQty def.qty.qty
   dot   <- dotD
   name  <- prettyFree name
   colon <- colonD
-  type  <- prettyTerm [<] [<] type
+  type  <- prettyTerm [<] [<] def.type
   hangDSingle (hsep [hcat [qty, dot, name], colon]) type
diff --git a/lib/Quox/Parser/FromParser.idr b/lib/Quox/Parser/FromParser.idr
index 84eaed9..e2f2444 100644
--- a/lib/Quox/Parser/FromParser.idr
+++ b/lib/Quox/Parser/FromParser.idr
@@ -323,35 +323,39 @@ liftTC tc = runEff tc $ with Union.(::)
    \g => send g]
 
 private
-addDef : Has DefsState fs => Name -> GQty -> Term 0 0 -> Term 0 0 -> Loc ->
-         Eff fs NDefinition
-addDef name gqty type term loc = do
-  let def = mkDef gqty type term loc
+addDef : Has DefsState fs => Name -> Definition -> Eff fs NDefinition
+addDef name def = do
   modifyAt DEFS $ insert name def
   pure (name, def)
 
 
 export covering
-fromPDef : PDefinition -> Eff FromParserPure NDefinition
-fromPDef (MkPDef qty pname ptype pterm defLoc) = do
+fromPDef : PDefinition -> Maybe String -> Bool ->
+           Eff FromParserPure NDefinition
+fromPDef (MkPDef qty pname pbody defLoc) scheme isMain = do
   name <- fromPBaseNameNS pname
   when !(getsAt DEFS $ isJust . lookup name) $ do
     throw $ AlreadyExists defLoc name
   gqty <- globalPQty qty.val qty.loc
   let sqty = globalToSubj gqty
-  type <- traverse fromPTerm ptype
-  term <- fromPTerm pterm
-  case type of
-    Just type => do
-      ignore $ liftTC $ do
-        checkTypeC empty type Nothing
-        checkC empty sqty term type
-      addDef name gqty type term defLoc
-    Nothing => do
-      let E elim = term
-        | _ => throw $ AnnotationNeeded term.loc empty term
-      res <- liftTC $ inferC empty sqty elim
-      addDef name gqty res.type term defLoc
+  case pbody of
+    PConcrete ptype pterm => do
+      type <- traverse fromPTerm ptype
+      term <- fromPTerm pterm
+      case type of
+        Just type => do
+          ignore $ liftTC $ do
+            checkTypeC empty type Nothing
+            checkC empty sqty term type
+          addDef name $ mkDef gqty type term scheme isMain defLoc
+        Nothing => do
+          let E elim = term
+            | _ => throw $ AnnotationNeeded term.loc empty term
+          res <- liftTC $ inferC empty sqty elim
+          addDef name $ mkDef gqty res.type term scheme isMain defLoc
+    PPostulate ptype => do
+      type <- fromPTerm ptype
+      addDef name $ mkPostulate gqty type scheme isMain defLoc
 
 
 public export
@@ -359,31 +363,50 @@ data HasFail = NoFail | AnyFail | FailWith String
 
 export
 hasFail : List PDeclMod -> HasFail
-hasFail []                  = NoFail
-hasFail (PFail str _ :: _)  = maybe AnyFail FailWith str
+hasFail []               = NoFail
+hasFail (PFail str :: _) = maybe AnyFail FailWith str
+hasFail (_ :: rest)      = hasFail rest
+
+export
+getScheme : List PDeclMod -> Maybe String
+getScheme []                        = Nothing
+getScheme (PCompileScheme str :: _) = Just str
+getScheme (_ :: rest)               = getScheme rest
+
+export
+isMain : List PDeclMod -> Bool
+isMain []           = False
+isMain (PMain :: _) = True
+isMain (_ :: rest)  = isMain rest
 
 export covering
 fromPDecl : PDecl -> Eff FromParserPure (List NDefinition)
 
 export covering
-fromPDeclBody : PDeclBody -> Eff FromParserPure (List NDefinition)
-fromPDeclBody (PDef def) = singleton <$> fromPDef def
-fromPDeclBody (PNs  ns)  =
+fromPDeclBody : PDeclBody -> Maybe String -> Bool -> Loc ->
+                Eff FromParserPure (List NDefinition)
+fromPDeclBody (PDef def) scheme isMain loc =
+  singleton <$> fromPDef def scheme isMain
+fromPDeclBody (PNs  ns)  scheme isMain loc = do
+  when (isJust scheme) $ throw $ SchemeOnNamespace loc ns.name
+  when isMain $ throw $ MainOnNamespace loc ns.name
   localAt NS (<+> ns.name) $ concat <$> traverse fromPDecl ns.decls
 
 export covering
-expectFail : PDeclBody -> Eff FromParserPure Error
-expectFail body =
-  case fromParserPure !(getAt GEN) !(getAt DEFS) $ fromPDeclBody body of
+expectFail : PDeclBody -> Loc -> Eff FromParserPure Error
+expectFail body loc =
+  let res = fromParserPure !(getAt GEN) !(getAt DEFS) $
+            fromPDeclBody body Nothing False loc in
+  case res of
     Left  err => pure err
     Right _   => throw $ ExpectedFail body.loc
 
 
 fromPDecl (MkPDecl mods decl loc) = case hasFail mods of
-  NoFail       => fromPDeclBody decl
-  AnyFail      => expectFail decl $> []
+  NoFail       => fromPDeclBody decl (getScheme mods) (isMain mods) loc
+  AnyFail      => expectFail decl loc $> []
   FailWith str => do
-    err <- expectFail decl
+    err <- expectFail decl loc
     let msg = runPretty $ prettyError False err {opts = Opts 10_000} -- w/e
     if str `isInfixOf` renderInfinite msg
        then pure []
diff --git a/lib/Quox/Parser/FromParser/Error.idr b/lib/Quox/Parser/FromParser/Error.idr
index eee70b5..f1afbff 100644
--- a/lib/Quox/Parser/FromParser/Error.idr
+++ b/lib/Quox/Parser/FromParser/Error.idr
@@ -35,6 +35,8 @@ data Error =
   | AlreadyExists Loc Name
   | LoadError Loc FilePath FileError
   | ExpectedFail Loc
+  | SchemeOnNamespace Loc Mods
+  | MainOnNamespace Loc Mods
   | WrongFail String Error Loc
   | WrapParseError String ParseError
 
@@ -123,12 +125,22 @@ parameters {opts : LayoutOpts} (showContext : Bool)
           text $ show err]
 
   prettyError (ExpectedFail loc) = pure $
-    sep [!(prettyLoc loc), "expected error"]
+    vsep [!(prettyLoc loc), "expected error"]
+
+  prettyError (SchemeOnNamespace loc ns) = pure $
+    vsep [!(prettyLoc loc),
+          hsep ["namespace", !(hl Free $ text $ joinBy "." $ toList ns),
+                "cannot have #[compile-scheme] attached"]]
+
+  prettyError (MainOnNamespace loc ns) = pure $
+    vsep [!(prettyLoc loc),
+          hsep ["namespace", !(hl Free $ text $ joinBy "." $ toList ns),
+                "cannot have #[main] attached"]]
 
   prettyError (WrongFail str err loc) = pure $
-    sep [!(prettyLoc loc),
-         "wrong error, expected to match", !(hl Tag $ text "\"\{str}\""),
-         "but got", !(prettyError err)]
+    vsep [!(prettyLoc loc),
+          "wrong error, expected to match", !(hl Tag $ text "\"\{str}\""),
+          "but got", !(prettyError err)]
 
   prettyError (WrapParseError file err) =
     prettyParseError file err
diff --git a/lib/Quox/Parser/Lexer.idr b/lib/Quox/Parser/Lexer.idr
index 3780809..3db9736 100644
--- a/lib/Quox/Parser/Lexer.idr
+++ b/lib/Quox/Parser/Lexer.idr
@@ -227,6 +227,9 @@ reserved =
    Word1 "def",
    Word1 "def0",
    Word "defω" `Or` Word "def#",
+   Word1 "postulate",
+   Word1 "postulate0",
+   Word "postulateω" `Or` Word "postulate#",
    Sym1 "=",
    Word1 "load",
    Word1 "namespace"]
diff --git a/lib/Quox/Parser/Parser.idr b/lib/Quox/Parser/Parser.idr
index a5ed716..fb16aaf 100644
--- a/lib/Quox/Parser/Parser.idr
+++ b/lib/Quox/Parser/Parser.idr
@@ -587,32 +587,60 @@ pragma : Grammar True a -> Grammar True a
 pragma p = resC "#[" *> p <* mustWork (resC "]")
 
 export
-declMod : FileName -> Grammar True PDeclMod
-declMod fname = withLoc fname $ pragma $
-  exactName "fail" *> [|PFail $ optional strLit|]
+declMod : Grammar True PDeclMod
+declMod = pragma $
+      exactName "fail" *> [|PFail $ optional strLit|]
+  <|> exactName "compile-scheme" *> [|PCompileScheme strLit|]
+  <|> exactName "main" $> PMain
+  <|> do other <- qname
+         fatalError "unknown declaration flag \{show other}" {c = False}
 
 export
 decl : FileName -> Grammar True PDecl
 
-||| `def` alone means `defω`
+||| `def` alone means `defω`; same for `postulate`
 export
-defIntro : FileName -> Grammar True PQty
-defIntro fname =
-      withLoc fname (PQ Zero <$ resC "def0")
-  <|> withLoc fname (PQ Any  <$ resC "defω")
-  <|> do pos <- bounds $ resC "def"
+defIntro' : (bare, zero, omega : String) ->
+            (0 _ : IsReserved bare) =>
+            (0 _ : IsReserved zero) =>
+            (0 _ : IsReserved omega) =>
+            FileName -> Grammar True PQty
+defIntro' bare zero omega fname =
+      withLoc fname (PQ Zero <$ resC zero)
+  <|> withLoc fname (PQ Any  <$ resC omega)
+  <|> do pos <- bounds $ resC bare
          let any = PQ Any $ makeLoc fname pos.bounds
          option any $ qty fname <* needRes "."
 
 export
-definition : FileName -> Grammar True PDefinition
-definition fname = withLoc fname $ do
+defIntro : FileName -> Grammar True PQty
+defIntro = defIntro' "def" "def0" "defω"
+
+export
+postulateIntro : FileName -> Grammar True PQty
+postulateIntro = defIntro' "postulate" "postulate0" "postulateω"
+
+export
+postulate : FileName -> Grammar True PDefinition
+postulate fname = withLoc fname $ Core.do
+  qty  <- postulateIntro fname
+  name <- baseName
+  type <- resC ":" *> mustWork (term fname)
+  pure $ MkPDef qty name $ PPostulate type
+
+export
+concrete : FileName -> Grammar True PDefinition
+concrete fname = withLoc fname $ do
   qty  <- defIntro fname
   name <- baseName
   type <- optional $ resC ":" *> mustWork (term fname)
   term <- needRes "=" *> mustWork (term fname)
   optRes ";"
-  pure $ MkPDef qty name type term
+  pure $ MkPDef qty name $ PConcrete type term
+
+export
+definition : FileName -> Grammar True PDefinition
+definition fname = try (postulate fname) <|> concrete fname
 
 export
 namespace_ : FileName -> Grammar True PNamespace
@@ -629,7 +657,7 @@ export
 declBody : FileName -> Grammar True PDeclBody
 declBody fname = [|PDef $ definition fname|] <|> [|PNs $ namespace_ fname|]
 
-decl fname = withLoc fname [|MkPDecl (many $ declMod fname) (declBody fname)|]
+decl fname = withLoc fname [|MkPDecl (many declMod) (declBody fname)|]
 
 export
 load : FileName -> Grammar True PTopLevel
diff --git a/lib/Quox/Parser/Syntax.idr b/lib/Quox/Parser/Syntax.idr
index 8edf657..55cfc6a 100644
--- a/lib/Quox/Parser/Syntax.idr
+++ b/lib/Quox/Parser/Syntax.idr
@@ -141,13 +141,18 @@ Located PCaseBody where
   (CaseBox  _ _ loc).loc = loc
 
 
+public export
+data PBody = PConcrete (Maybe PTerm) PTerm | PPostulate PTerm
+%name PBody body
+%runElab derive "PBody" [Eq, Ord, Show, PrettyVal]
+
+
 public export
 record PDefinition where
   constructor MkPDef
   qty  : PQty
   name : PBaseName
-  type : Maybe PTerm
-  term : PTerm
+  body : PBody
   loc_ : Loc
 %name PDefinition def
 %runElab derive "PDefinition" [Eq, Ord, Show, PrettyVal]
@@ -156,7 +161,9 @@ export Located PDefinition where def.loc = def.loc_
 
 public export
 data PDeclMod =
-    PFail (Maybe String) Loc
+    PFail (Maybe String)
+  | PCompileScheme String
+  | PMain
 %name PDeclMod mod
 %runElab derive "PDeclMod" [Eq, Ord, Show, PrettyVal]
 
diff --git a/lib/Quox/Untyped/Erase.idr b/lib/Quox/Untyped/Erase.idr
index ce775f7..4161ecf 100644
--- a/lib/Quox/Untyped/Erase.idr
+++ b/lib/Quox/Untyped/Erase.idr
@@ -46,6 +46,7 @@ data Error =
 | WrapTypeError   TypeError
 | Postulate       Loc Name
 | WhileErasing    Name Q.Definition Error
+| MainIsErased    Loc Name
 %name Error err
 
 private %inline
@@ -58,6 +59,7 @@ Located Error where
   (WrapTypeError err).loc    = err.loc
   (Postulate loc _).loc      = loc
   (WhileErasing _ def e).loc = e.loc `or` def.loc
+  (MainIsErased loc _).loc   = loc
 
 
 parameters {opts : LayoutOpts} (showContext : Bool)
@@ -71,9 +73,11 @@ parameters {opts : LayoutOpts} (showContext : Bool)
     prettyErrorNoLoc showContext err
   prettyErrorNoLoc (Postulate _ x) =
     pure $ sep [!(prettyFree x), "is a postulate with no definition"]
-  prettyErrorNoLoc (WhileErasing name def err) = pure $
-    vsep [hsep ["while erasing the definition", !(prettyFree name)],
+  prettyErrorNoLoc (WhileErasing x def err) = pure $
+    vsep [hsep ["while erasing the definition", !(prettyFree x)],
           !(prettyErrorNoLoc err)]
+  prettyErrorNoLoc (MainIsErased _ x) =
+    pure $ hsep [!(prettyFree x), "is marked #[main] but is erased"]
 
   export
   prettyError : Error -> Eff Pretty (Doc opts)
@@ -485,10 +489,16 @@ trimLets (Erased loc) = Erased loc
 
 export covering
 eraseDef : Name -> Q.Definition -> Eff Erase U.Definition
-eraseDef name def@(MkDef qty type body loc) =
+eraseDef name def@(MkDef qty type body scheme isMain loc) =
   wrapErr (WhileErasing name def) $
   case isErased qty.qty of
-    Erased => pure ErasedDef
-    Kept   => case body of
-      Postulate     => throw $ Postulate loc name
-      Concrete body => KeptDef . trimLets <$> eraseTerm empty type body
+    Erased => do
+      when isMain $ throw $ MainIsErased loc name
+      pure ErasedDef
+    Kept   =>
+      case scheme of
+        Just str => pure $ SchemeDef isMain str
+        Nothing  => case body of
+          Postulate     => throw $ Postulate loc name
+          Concrete body => KeptDef isMain . trimLets <$>
+                           eraseTerm empty type body
diff --git a/lib/Quox/Untyped/Scheme.idr b/lib/Quox/Untyped/Scheme.idr
index b68edc3..db69712 100644
--- a/lib/Quox/Untyped/Scheme.idr
+++ b/lib/Quox/Untyped/Scheme.idr
@@ -7,10 +7,11 @@ import Quox.Pretty
 
 import Quox.EffExtra
 import Quox.CharExtra
+import Data.DPair
+import Data.List1
 import Data.String
 import Data.SortedSet
 import Data.Vect
-import Data.List1
 import Derive.Prelude
 
 %default total
@@ -19,165 +20,6 @@ import Derive.Prelude
 %hide TT.Name
 
 
-public export
-data Id = I String Nat
-%runElab derive "Id" [Eq, Ord]
-
-public export
-Scheme : List (Type -> Type)
-Scheme = [State (SortedSet Id)]
-
-
-public export
-data Sexp =
-  V Id
-| L (List Sexp)
-| Q Sexp
-| N Nat
-| Lambda (List Id) Sexp
-| Let (List (Id, Sexp)) Sexp
-| Case Sexp (List1 (List Sexp, Sexp))
-| Define Id Sexp
-
-export
-FromString Sexp where fromString s = V $ I s 0
-
-
-private
-makeIdBase : Mods -> String -> String
-makeIdBase mods str = joinBy "." $ toList $ mods :< str
-
-export
-makeId : Name -> Id
-makeId (MakeName mods (UN str))   = I (makeIdBase mods str) 0
-makeId (MakeName mods (MN str k)) = I (makeIdBase mods str) (S k)
-makeId (MakeName mods Unused)     = I (makeIdBase mods "_") 0
-
-export
-makeIdB : BindName -> Id
-makeIdB (BN name _) = makeId $ MakeName [<] name
-
-private
-bump : Id -> Id
-bump (I x i) = I x (S i)
-
-export covering
-getFresh : SortedSet Id -> Id -> Id
-getFresh used x =
-  if contains x used then getFresh used (bump x) else x
-
-export covering
-freshIn : Id -> (Id -> Eff Scheme a) -> Eff Scheme a
-freshIn x k =
-  let x = getFresh !get x in
-  local (insert x) $ k x
-
-export covering
-freshInB : BindName -> (Id -> Eff Scheme a) -> Eff Scheme a
-freshInB x = freshIn (makeIdB x)
-
-export covering
-freshInBN : Vect n BindName -> (Vect n Id -> Eff Scheme a) ->
-            Eff Scheme a
-freshInBN xs act = do
-  let (xs', used') = go (map makeIdB xs) !get
-  local_ used' $ act xs'
-where
-  go : forall n. Vect n Id -> SortedSet Id -> (Vect n Id, SortedSet Id)
-  go []        used = ([], used)
-  go (x :: xs) used =
-    let x          = getFresh used x
-        (xs, used) = go xs (insert x used)
-    in
-    (x :: xs, used)
-
-export covering
-toScheme : Context' Id n -> Term n -> Eff Scheme Sexp
-toScheme xs (F x loc) = pure $ V $ makeId x
-
-toScheme xs (B i loc) = pure $ V $ xs !!! i
-
-toScheme xs (Lam x body loc) =
-  freshInB x $ \x =>
-  pure $ Lambda [x] !(toScheme (xs :< x) body)
-
-toScheme xs (App fun arg loc) =
-  pure $ L [!(toScheme xs fun), !(toScheme xs arg)]
-
-toScheme xs (Pair fst snd loc) =
-  pure $ L ["cons", !(toScheme xs fst), !(toScheme xs snd)]
-
-toScheme xs (Fst pair loc) =
-  pure $ L ["car", !(toScheme xs pair)]
-
-toScheme xs (Snd pair loc) =
-  pure $ L ["cdr", !(toScheme xs pair)]
-
-toScheme xs (Tag tag loc) =
-  pure $ Q $ fromString tag
-
-toScheme xs (CaseEnum tag cases loc) =
-  Case <$> toScheme xs tag
-       <*> for cases (\(t, rhs) => ([fromString t],) <$> toScheme xs rhs)
-
-toScheme xs (Absurd loc) =
-  pure $ Q "absurd"
-
-toScheme xs (Zero loc) =
-  pure $ N 0
-
-toScheme xs (Succ nat loc) =
-  case !(toScheme xs nat) of
-    N n => pure $ N n
-    s   => pure $ L ["1+", s]
-
-toScheme xs (CaseNat nat zer (NSRec p ih suc) loc) =
-  freshInBN [p, ih] $ \[p, ih] =>
-  pure $
-    L ["case-nat-rec",
-       Lambda []      !(toScheme xs zer),
-       Lambda [p, ih] !(toScheme (xs :< p :< ih) suc),
-       !(toScheme xs nat)]
-
-toScheme xs (CaseNat nat zer (NSNonrec p suc) loc) =
-  freshInB p $ \p =>
-  pure $
-    L ["case-nat-nonrec",
-       Lambda []  !(toScheme xs zer),
-       Lambda [p] !(toScheme (xs :< p) suc),
-       !(toScheme xs nat)]
-
-toScheme xs (Let x rhs body loc) =
-  freshInB x $ \x =>
-  pure $ Let [(x, !(toScheme xs rhs))] !(toScheme (xs :< x) body)
-
-toScheme xs (Erased loc) =
-  pure $ Q "erased"
-
-
-export
-prelude : String
-prelude = """
-(define (case-nat-rec z s n)
-  (if (= n 0)
-    (z)
-    (let* [(p (1- n))
-           (ih (case-nat-rec z s p))]
-      (s p ih))))
-
-(define (case-nat-nonrec z s n)
-  (if (= n 0) (z) (s (1- n))))
-
-"""
-
-export covering
-defToScheme : Name -> Definition -> Eff Scheme (Maybe Sexp)
-defToScheme x ErasedDef     = pure Nothing
-defToScheme x (KeptDef def) = do
-  let x = makeId x
-  modify $ insert x
-  pure $ Just $ Define x !(toScheme [<] def)
-
 
 export
 isSchemeInitial : Char -> Bool
@@ -222,55 +64,306 @@ where
   doEsc '\'' = "^"
   doEsc c    = singleton c
 
+
+public export
+data Id = I String Nat
+%runElab derive "Id" [Eq, Ord]
+
+private
 prettyId' : {opts : LayoutOpts} -> Id -> Doc opts
 prettyId' (I str 0) = text $ escId str
 prettyId' (I str k) = text $ escId "\{str}:\{show k}"
 
+export
 prettyId : {opts : LayoutOpts} -> Id -> Eff Pretty (Doc opts)
 prettyId x = hl TVar $ prettyId' x
 
+
+public export
+data StateTag = AVOID | MAIN
+
+public export
+Scheme : List (Type -> Type)
+Scheme = [StateL AVOID (SortedSet Id), StateL MAIN (List Id)]
+  -- names to avoid, and functions with #[main] (should only be one)
+
+
+public export
+data Sexp =
+  V Id
+| L (List Sexp)
+| Q Sexp
+| N Nat
+| Lambda (List Id) Sexp
+| LambdaC (List Id) Sexp -- curried lambda
+| Let Id Sexp Sexp
+| Case Sexp (List1 (List Sexp, Sexp))
+| Define Id Sexp
+| Literal String
+
+export
+FromString Sexp where fromString s = V $ I s 0
+
+
+private
+makeIdBase : Mods -> String -> String
+makeIdBase mods str = joinBy "." $ toList $ mods :< str
+
+export
+makeId : Name -> Id
+makeId (MakeName mods (UN str))   = I (makeIdBase mods str) 0
+makeId (MakeName mods (MN str k)) = I (makeIdBase mods str) 0
+makeId (MakeName mods Unused)     = I (makeIdBase mods "_") 0
+
+export
+makeIdB : BindName -> Id
+makeIdB (BN name _) = makeId $ MakeName [<] name
+
+private
+bump : Id -> Id
+bump (I x i) = I x (S i)
+
+export covering
+getFresh : SortedSet Id -> Id -> Id
+getFresh used x =
+  if contains x used then getFresh used (bump x) else x
+
+export covering
+freshIn : Id -> (Id -> Eff Scheme a) -> Eff Scheme a
+freshIn x k =
+  let x = getFresh !(getAt AVOID) x in
+  localAt AVOID (insert x) $ k x
+
+export covering
+freshInB : BindName -> (Id -> Eff Scheme a) -> Eff Scheme a
+freshInB x = freshIn (makeIdB x)
+
+export covering
+freshInBT : Telescope' BindName m n ->
+            (Telescope' Id m n -> Eff Scheme a) ->
+            Eff Scheme a
+freshInBT xs act = do
+  let (xs', used') = go (map makeIdB xs) !(getAt AVOID)
+  localAt_ AVOID used' $ act xs'
+where
+  go : forall n. Telescope' Id m n ->
+       SortedSet Id -> (Telescope' Id m n, SortedSet Id)
+  go [<]       used = ([<], used)
+  go (xs :< x) used =
+    let x          = getFresh used x
+        (xs, used) = go xs (insert x used)
+    in
+    (xs :< x, used)
+
+export covering
+freshInBC : Context' BindName n -> (Context' Id n -> Eff Scheme a) ->
+            Eff Scheme a
+freshInBC = freshInBT
+
+export covering
+toScheme : Context' Id n -> Term n -> Eff Scheme Sexp
+toScheme xs (F x loc) = pure $ V $ makeId x
+
+toScheme xs (B i loc) = pure $ V $ xs !!! i
+
+toScheme xs (Lam x body loc) =
+  let Evidence n' (ys, body) = splitLam [< x] body in
+  freshInBT ys $ \ys => do
+    pure $ LambdaC (toList' ys) !(toScheme (xs . ys) body)
+
+toScheme xs (App fun arg loc) = do
+  let (fun, args) = splitApp fun
+  fun  <- toScheme xs fun
+  args <- traverse (toScheme xs) args
+  arg  <- toScheme xs arg
+  pure $ if null args
+            then L [fun, arg]
+            else L $ "%" :: fun :: toList (args :< arg)
+
+toScheme xs (Pair fst snd loc) =
+  pure $ L ["cons", !(toScheme xs fst), !(toScheme xs snd)]
+
+toScheme xs (Fst pair loc) =
+  pure $ L ["car", !(toScheme xs pair)]
+
+toScheme xs (Snd pair loc) =
+  pure $ L ["cdr", !(toScheme xs pair)]
+
+toScheme xs (Tag tag loc) =
+  pure $ Q $ fromString tag
+
+toScheme xs (CaseEnum tag cases loc) =
+  Case <$> toScheme xs tag
+       <*> for cases (\(t, rhs) => ([fromString t],) <$> toScheme xs rhs)
+
+toScheme xs (Absurd loc) =
+  pure $ Q "absurd"
+
+toScheme xs (Zero loc) =
+  pure $ N 0
+
+toScheme xs (Succ nat loc) =
+  case !(toScheme xs nat) of
+    N n => pure $ N $ S n
+    s   => pure $ L ["+", s, N 1]
+
+toScheme xs (CaseNat nat zer (NSRec p ih suc) loc) =
+  freshInBC [< p, ih] $ \[< p, ih] =>
+  pure $
+    L ["case-nat-rec",
+       Lambda []      !(toScheme xs zer),
+       Lambda [p, ih] !(toScheme (xs :< p :< ih) suc),
+       !(toScheme xs nat)]
+
+toScheme xs (CaseNat nat zer (NSNonrec p suc) loc) =
+  freshInB p $ \p =>
+  pure $
+    L ["case-nat-nonrec",
+       Lambda []  !(toScheme xs zer),
+       Lambda [p] !(toScheme (xs :< p) suc),
+       !(toScheme xs nat)]
+
+toScheme xs (Let x rhs body loc) =
+  freshInB x $ \x =>
+  pure $ Let x !(toScheme xs rhs) !(toScheme (xs :< x) body)
+
+toScheme xs (Erased loc) =
+  pure $ Q "erased"
+
+
+export
+prelude : String
+prelude = """
+#!r6rs
+
+; curried lambda
+(define-syntax lambda%
+  (syntax-rules ()
+    [(_ (x0 x1 ...) body ...)
+     (lambda (x0) (lambda% (x1 ...) body ...))]
+    [(_ () body ...)
+     (begin body ...)]))
+
+; curried application
+(define-syntax %
+  (syntax-rules ()
+    [(_ e0 e1 e2 ...)
+     (% (e0 e1) e2 ...)]
+    [(_ e) e]))
+
+; curried function definition
+(define-syntax define%
+  (syntax-rules ()
+    [(_ (f x ...) body ...)
+     (define f (lambda% (x ...) body ...))]
+    [(_ x body ...)
+     (define x body ...)]))
+
+(define-syntax builtin-io
+  (syntax-rules ()
+    [(_ body ...)
+     (lambda (s)
+       (let [(res (begin body ...))]
+         (cons res s)))]))
+
+(define (case-nat-rec z s n)
+  (let go [(acc (z)) (i 0)]
+    (if (= i n) acc (go (s i acc) (+ i 1)))))
+
+(define (case-nat-nonrec z s n)
+  (if (= n 0) (z) (s (- n 1))))
+
+(define (run-main f) (f 'io-state) (void))
+;;;;;;
+"""
+
+export covering
+defToScheme : Name -> Definition -> Eff Scheme (Maybe Sexp)
+defToScheme x ErasedDef = pure Nothing
+defToScheme x (KeptDef isMain def) = do
+  let x = makeId x
+  when isMain $ modifyAt MAIN (x ::)
+  modifyAt AVOID $ insert x
+  pure $ Just $ Define x !(toScheme [<] def)
+defToScheme x (SchemeDef isMain str) = do
+  let x = makeId x
+  when isMain $ modifyAt MAIN (x ::)
+  modifyAt AVOID $ insert x
+  pure $ Just $ Define x $ Literal str
+
 orIndent : {opts : LayoutOpts} -> Doc opts -> Doc opts -> Doc opts
 orIndent a b =
   parens $ ifMultiline (a <++> b) (a `vappend` indent 2 b)
 
 export covering
 prettySexp : {opts : LayoutOpts} -> Sexp -> Eff Pretty (Doc opts)
+
+private covering
+prettyLambda : {opts : LayoutOpts} ->
+               String -> List Id -> Sexp -> Eff Pretty (Doc opts)
+prettyLambda lam xs e =
+  pure $ orIndent
+    (hsep [!(hl Syntax $ text lam), !(prettySexp $ L $ map V xs)])
+    !(prettySexp e)
+
+private covering
+prettyBind : {opts : LayoutOpts} -> (Id, Sexp) -> Eff Pretty (Doc opts)
+prettyBind (x, e) = parens $ sep [!(prettyId x), !(prettySexp e)]
+
+private covering
+prettyLet : {opts : LayoutOpts} ->
+            SnocList (Id, Sexp) -> Sexp -> Eff Pretty (Doc opts)
+prettyLet ps (Let x rhs body) = prettyLet (ps :< (x, rhs)) body
+prettyLet ps e =
+  pure $ orIndent
+    (hsep [!(hl Syntax "let*"),
+           !(bracks . sep . toList =<< traverse prettyBind ps)])
+    !(prettySexp e)
+
+private covering
+prettyDefine : {opts : LayoutOpts} ->
+               String -> Either Id (List Id) -> Sexp -> Eff Pretty (Doc opts)
+prettyDefine def xs body =
+  parens $ vappend
+    (hsep [!(hl Syntax $ text def),
+           !(either prettyId (prettySexp . L . map V) xs)])
+    (indent 2 !(prettySexp body))
+
 prettySexp (V x) = prettyId x
 prettySexp (L []) = hl Delim "()"
 prettySexp (L (x :: xs)) = do
   d  <- prettySexp x
-  ds <- Prelude.traverse prettySexp xs
-  parens $ ifMultiline (hsep $ d :: ds) (vsep $ d :: map (indent 2) ds)
+  ds <- traverse prettySexp xs
+  parens $ (hsep $ d :: ds) <|> (hsep [d, vsep ds]) <|>
+           (vsep $ d :: map (indent 2) ds)
 prettySexp (Q (V x)) = hl Tag $ "'" <+> prettyId' x
 prettySexp (Q x) = pure $ hcat [!(hl Tag "'"), !(prettySexp x)]
 prettySexp (N n) = hl Tag $ pshow n
-prettySexp (Lambda xs e) =
-  pure $ orIndent
-    (hsep [!(hl Syntax "lambda"), !(prettySexp $ L $ map V xs)])
-    !(prettySexp e)
-prettySexp (Let ps e) =
-  pure $ orIndent
-    (hsep [!(hl Syntax "let"), !(bracks . sep =<< traverse prettyBind ps)])
-    !(prettySexp e)
-where
-  prettyBind : (Id, Sexp) -> Eff Pretty (Doc opts)
-  prettyBind (x, e) = pure $ sep [!(prettyId x), !(prettySexp e)]
+prettySexp (Lambda xs e) = prettyLambda "lambda" xs e
+prettySexp (LambdaC xs e) = prettyLambda "lambda%" xs e
+prettySexp (Let x rhs e) = prettyLet [< (x, rhs)] e
 prettySexp (Case h as) = do
   header' <- prettySexp h
   case_   <- caseD
   let header = ifMultiline (case_ <++> header')
                            (case_ `vappend` indent 2 header')
-  bodys <- traverse prettyCase $ toList as
+  arms <- traverse prettyCase $ toList as
   pure $ ifMultiline
-    (parens $ header <++> hsep bodys)
-    (parens $ header `vappend` indent 2 (vsep bodys))
+    (parens $ header <++> hsep arms)
+    (parens $ vsep $ header :: map (indent 2) arms)
 where
   prettyCase : (List Sexp, Sexp) -> Eff Pretty (Doc opts)
   prettyCase (ps, e) = bracks $
     ifMultiline
       (hsep [!(parens . hsep =<< traverse prettySexp ps), !(prettySexp e)])
       (vsep [!(parens .  sep =<< traverse prettySexp ps), !(prettySexp e)])
-prettySexp (Define x e) =
-  pure $ orIndent
-    (hsep [!(hl Syntax "define"), !(prettyId x)])
-    !(prettySexp e)
+prettySexp (Define x e) = case e of
+  LambdaC xs e => prettyDefine "define%" (Right $ x :: xs) e
+  Lambda  xs e => prettyDefine "define"  (Right $ x :: xs) e
+  _            => prettyDefine "define"  (Left x)          e
+prettySexp (Literal sexp) =
+  pure $ text sexp
+
+export covering
+makeRunMain : {opts : LayoutOpts} -> Id -> Eff Pretty (Doc opts)
+makeRunMain x = prettySexp $ L ["run-main", V x]
diff --git a/lib/Quox/Untyped/Syntax.idr b/lib/Quox/Untyped/Syntax.idr
index a9b6955..2c4b1e0 100644
--- a/lib/Quox/Untyped/Syntax.idr
+++ b/lib/Quox/Untyped/Syntax.idr
@@ -82,7 +82,11 @@ Located (Term n) where
 
 
 public export
-data Definition = ErasedDef | KeptDef (Term 0)
+data Definition =
+  ErasedDef
+| KeptDef   Bool (Term 0)
+| SchemeDef Bool String
+  -- bools are presence of #[main] flag
 
 public export
 0 Definitions : Type
@@ -94,27 +98,33 @@ letD, inD : {opts : LayoutOpts} -> Eff Pretty (Doc opts)
 letD = hl Syntax "let"
 inD  = hl Syntax "in"
 
-export
+export covering
 prettyTerm : {opts : LayoutOpts} -> BContext n ->
              Term n -> Eff Pretty (Doc opts)
 
-export
+export covering
 prettyArg : {opts : LayoutOpts} -> BContext n -> Term n -> Eff Pretty (Doc opts)
 prettyArg xs arg = withPrec Arg $ prettyTerm xs arg
 
-export
-prettyApp' : {opts : LayoutOpts} -> BContext n -> Doc opts ->
-             Term n -> Eff Pretty (Doc opts)
-prettyApp' xs fun arg =
-  parensIfM App =<< do
-    arg <- prettyArg xs arg
-    pure $ sep [fun, arg]
+export covering
+prettyAppHead : {opts : LayoutOpts} -> BContext n ->
+                Term n -> Eff Pretty (Doc opts)
+prettyAppHead xs fun = parensIfM App =<< prettyTerm xs fun
 
 export
+prettyApp' : {opts : LayoutOpts} ->
+             Doc opts -> SnocList (Doc opts) -> Eff Pretty (Doc opts)
+prettyApp' fun args = do
+  d <- askAt INDENT
+  let args = toList args
+  pure $ hsep (fun :: args)
+     <|> hsep [fun, vsep args]
+     <|> vsep (fun :: map (indent d) args)
+
+export covering
 prettyApp : {opts : LayoutOpts} -> BContext n ->
-            Term n -> Term n -> Eff Pretty (Doc opts)
-prettyApp xs fun arg =
-  prettyApp' xs !(withPrec App $ prettyTerm xs fun) arg
+            Doc opts -> SnocList (Term n) -> Eff Pretty (Doc opts)
+prettyApp xs fun args = prettyApp' fun =<< traverse (prettyTerm xs) args
 
 public export
 record PrettyCaseArm a n where
@@ -124,7 +134,7 @@ record PrettyCaseArm a n where
   vars : Vect len BindName
   rhs : Term (len + n)
 
-export
+export covering
 prettyCase : {opts : LayoutOpts} -> BContext n ->
              (a -> Eff Pretty (Doc opts)) ->
              Term n -> List (PrettyCaseArm a n) ->
@@ -145,19 +155,24 @@ private
 sucPat : {opts : LayoutOpts} -> BindName -> Eff Pretty (Doc opts)
 sucPat x = pure $ !succD <++> !(prettyTBind x)
 
-private
+export
+splitApp : Term b -> (Term b, SnocList (Term b))
+splitApp (App f x _) = mapSnd (:< x) $ splitApp f
+splitApp f           = (f, [<])
+
+export
 splitLam : Telescope' BindName a b -> Term b ->
            Exists $ \c => (Telescope' BindName a c, Term c)
 splitLam ys (Lam x body _) = splitLam (ys :< x) body
 splitLam ys t              = Evidence _ (ys, t)
 
-private
+export
 splitLet : Telescope (\i => (BindName, Term i)) a b -> Term b ->
            Exists $ \c => (Telescope (\i => (BindName, Term i)) a c, Term c)
 splitLet ys (Let x rhs body _) = splitLet (ys :< (x, rhs)) body
 splitLet ys t                  = Evidence _ (ys, t)
 
-private
+private covering
 prettyLets : {opts : LayoutOpts} ->
              BContext a -> Telescope (\i => (BindName, Term i)) a b ->
              Eff Pretty (SnocList (Doc opts))
@@ -168,7 +183,7 @@ prettyLets xs lets = sequence $ snd $ go lets where
   go (lets :< (x, rhs)) =
     let (ys, docs) = go lets
         doc = hsep <$> sequence
-              [letD, prettyTBind x, cstD, assert_total prettyTerm ys rhs, inD]
+              [letD, prettyTBind x, cstD, prettyTerm ys rhs, inD]
     in
     (ys :< x, docs :< doc)
 
@@ -180,51 +195,71 @@ sucCaseArm (NSRec x ih s) = pure $
 sucCaseArm (NSNonrec x s) = pure $
   MkPrettyCaseArm !(sucPat x) [x] s
 
+private covering
+prettyNat : {opts : LayoutOpts} ->
+            BContext n -> Term n -> Eff Pretty (Either Nat (Doc opts))
+prettyNat xs (Zero _) = pure $ Left 0
+prettyNat xs (Succ n _) =
+  case !(withPrec Arg $ prettyNat xs n) of
+    Left n    => pure $ Left $ S n
+    Right doc => map Right $ parensIfM App $ sep [!succD, doc]
+prettyNat xs s = map Right $ prettyTerm xs s
+
 prettyTerm _  (F x _) = prettyFree x
 prettyTerm xs (B i _) = prettyTBind $ xs !!! i
 prettyTerm xs (Lam x body _) =
   parensIfM Outer =<< do
     let Evidence n' (ys, body) = splitLam [< x] body
     vars <- hsep . toList' <$> traverse prettyTBind ys
-    body <- withPrec Outer $ assert_total prettyTerm (xs . ys) body
+    body <- withPrec Outer $ prettyTerm (xs . ys) body
     hangDSingle (hsep [!lamD, vars, !darrowD]) body
-prettyTerm xs (App fun arg _) = prettyApp xs fun arg
+prettyTerm xs (App fun arg _) =
+  let (fun, args) = splitApp fun in
+  prettyApp xs !(prettyAppHead xs fun) (args :< arg)
 prettyTerm xs (Pair fst snd _) =
   parens =<< separateTight !commaD <$>
     sequence {t = List} [prettyTerm xs fst, prettyTerm xs snd]
-prettyTerm xs (Fst pair _) = prettyApp' xs !fstD pair
-prettyTerm xs (Snd pair _) = prettyApp' xs !sndD pair
+prettyTerm xs (Fst pair _) = prettyApp xs !fstD [< pair]
+prettyTerm xs (Snd pair _) = prettyApp xs !sndD [< pair]
 prettyTerm xs (Tag tag _) = prettyTag tag
 prettyTerm xs (CaseEnum tag cases _) =
-  assert_total
   prettyCase xs prettyTag tag $
     map (\(t, rhs) => MkPrettyCaseArm t [] rhs) $ toList cases
 prettyTerm xs (Absurd _) = hl Syntax "absurd"
-prettyTerm xs (Zero _) = zeroD
-prettyTerm xs (Succ nat _) = prettyApp' xs !succD nat
+prettyTerm xs (Zero _) = hl Tag "0"
+prettyTerm xs (Succ nat _) =
+  case !(prettyNat xs nat) of
+    Left  n   => hl Tag $ pshow $ S n
+    Right doc => prettyApp' !succD [< doc]
 prettyTerm xs (CaseNat nat zer suc _) =
-  assert_total
   prettyCase xs pure nat [MkPrettyCaseArm !zeroD [] zer, !(sucCaseArm suc)]
 prettyTerm xs (Let x rhs body _) =
   parensIfM Outer =<< do
     let Evidence n' (lets, body) = splitLet [< (x, rhs)] body
     heads <- prettyLets xs lets
-    body  <- withPrec Outer $ assert_total prettyTerm (xs . map fst lets) body
+    body  <- withPrec Outer $ prettyTerm (xs . map fst lets) body
     let lines = toList $ heads :< body
     pure $ ifMultiline (hsep lines) (vsep lines)
 prettyTerm _ (Erased _) =
   hl Syntax =<< ifUnicode "⌷" "[]"
 
-export
+export covering
 prettyDef : {opts : LayoutOpts} -> Name ->
             Definition -> Eff Pretty (Doc opts)
 prettyDef name ErasedDef =
   pure $ hsep [!(prettyFree name), !cstD, !(prettyTerm [<] $ Erased noLoc)]
-prettyDef name (KeptDef rhs) = do
-  name <- prettyFree name
+prettyDef name (KeptDef isMain rhs) = do
+  name <- prettyFree name {opts}
   eq   <- cstD
   rhs  <- prettyTerm [<] rhs
-  hangDSingle (name <++> eq) rhs
+  let header = if isMain then text "#[main]" <++> name else name
+  hangDSingle (header <++> eq) rhs
+prettyDef name (SchemeDef isMain str) = do
+  name <- prettyFree name {opts}
+  eq   <- cstD
+  let rhs = text $ "scheme:" ++ str
+  let header = if isMain then text "#[main]" <++> name else name
+  hangDSingle (header <++> eq) rhs
 
 
 public export
diff --git a/tests/Tests/Equal.idr b/tests/Tests/Equal.idr
index 19568f4..3b0f212 100644
--- a/tests/Tests/Equal.idr
+++ b/tests/Tests/Equal.idr
@@ -2,7 +2,7 @@ module Tests.Equal
 
 import Quox.Equal
 import Quox.Typechecker
-import Quox.ST
+import Control.Monad.ST
 import public TypingImpls
 import TAP
 import Quox.EffExtra
diff --git a/tests/Tests/Parser.idr b/tests/Tests/Parser.idr
index 47b9cab..3884ff6 100644
--- a/tests/Tests/Parser.idr
+++ b/tests/Tests/Parser.idr
@@ -403,36 +403,53 @@ tests = "parser" :- [
   "definitions" :- [
     parseMatch definition "defω x : {a} × {b} = ('a, 'b);"
       `(MkPDef (PQ Any _) "x"
-        (Just (Sig (Unused _) (Enum ["a"] _) (Enum ["b"] _) _))
-        (Pair (Tag "a" _) (Tag "b" _) _) _),
+        (PConcrete
+          (Just (Sig (Unused _) (Enum ["a"] _) (Enum ["b"] _) _))
+          (Pair (Tag "a" _) (Tag "b" _) _)) _),
     parseMatch definition "def# x : {a} ** {b} = ('a, 'b)"
       `(MkPDef (PQ Any _) "x"
-        (Just (Sig (Unused _) (Enum ["a"] _) (Enum ["b"] _) _))
-        (Pair (Tag "a" _) (Tag "b" _) _) _),
+        (PConcrete
+          (Just (Sig (Unused _) (Enum ["a"] _) (Enum ["b"] _) _))
+          (Pair (Tag "a" _) (Tag "b" _) _)) _),
     parseMatch definition "def ω.x : {a} × {b} = ('a, 'b)"
       `(MkPDef (PQ Any _) "x"
-        (Just (Sig (Unused _) (Enum ["a"] _) (Enum ["b"] _) _))
-        (Pair (Tag "a" _) (Tag "b" _) _) _),
+        (PConcrete
+          (Just (Sig (Unused _) (Enum ["a"] _) (Enum ["b"] _) _))
+          (Pair (Tag "a" _) (Tag "b" _) _)) _),
     parseMatch definition "def x : {a} × {b} = ('a, 'b)"
       `(MkPDef (PQ Any _) "x"
-        (Just (Sig (Unused _) (Enum ["a"] _) (Enum ["b"] _) _))
-        (Pair (Tag "a" _) (Tag "b" _) _) _),
+        (PConcrete
+          (Just (Sig (Unused _) (Enum ["a"] _) (Enum ["b"] _) _))
+          (Pair (Tag "a" _) (Tag "b" _) _)) _),
     parseMatch definition "def0 A : ★⁰ = {a, b, c}"
-      `(MkPDef (PQ Zero _) "A" (Just $ TYPE 0 _)
-          (Enum ["a", "b", "c"] _) _)
+      `(MkPDef (PQ Zero _) "A"
+          (PConcrete (Just $ TYPE 0 _) (Enum ["a", "b", "c"] _)) _),
+    parseMatch definition "postulate yeah : ℕ"
+      `(MkPDef (PQ Any _) "yeah" (PPostulate (Nat _)) _),
+    parseMatch definition "postulateω yeah : ℕ"
+      `(MkPDef (PQ Any _) "yeah" (PPostulate (Nat _)) _),
+    parseMatch definition "postulate0 FileHandle : ★"
+      `(MkPDef (PQ Zero _) "FileHandle" (PPostulate (TYPE 0 _)) _),
+    parseFails definition "postulate not-a-postulate : ℕ = 69",
+    parseFails definition "postulate not-a-postulate = 69",
+    parseFails definition "def not-a-def : ℕ"
   ],
 
   "top level" :- [
     parseMatch input "def0 A : ★⁰ = {}; def0 B : ★¹ = A;"
       `([PD $ MkPDecl []
-          (PDef $ MkPDef (PQ Zero _) "A" (Just $ TYPE 0 _) (Enum [] _) _) _,
+          (PDef $ MkPDef (PQ Zero _) "A"
+            (PConcrete (Just $ TYPE 0 _) (Enum [] _)) _) _,
          PD $ MkPDecl []
-          (PDef $ MkPDef (PQ Zero _) "B" (Just $ TYPE 1 _) (V "A" {}) _) _]),
+          (PDef $ MkPDef (PQ Zero _) "B"
+            (PConcrete (Just $ TYPE 1 _) (V "A" {})) _) _]),
     parseMatch input "def0 A : ★⁰ = {} def0 B : ★¹ = A" $
       `([PD $ MkPDecl []
-          (PDef $ MkPDef (PQ Zero _) "A" (Just $ TYPE 0 _) (Enum [] _) _) _,
+          (PDef $ MkPDef (PQ Zero _) "A"
+            (PConcrete (Just $ TYPE 0 _) (Enum [] _)) _) _,
          PD $ MkPDecl []
-          (PDef $ MkPDef (PQ Zero _) "B" (Just $ TYPE 1 _) (V "A" {}) _) _]),
+          (PDef $ MkPDef (PQ Zero _) "B"
+            (PConcrete (Just $ TYPE 1 _) (V "A" {})) _) _]),
     note "empty input",
     parsesAs input "" [],
     parseFails input ";;;;;;;;;;;;;;;;;;;;;;;;;;",
@@ -449,21 +466,23 @@ tests = "parser" :- [
       `([PD (MkPDecl []
           (PNs $ MkPNamespace [< "a"]
             [MkPDecl []
-              (PDef $ MkPDef (PQ Any _) "x" Nothing
-                (Ann (Tag "t" _) (Enum ["t"] _) _) _) _] _) _)]),
-    parseMatch input "namespace a {def x = 't ∷ {t}} def y = a.x"
+              (PDef $ MkPDef (PQ Any _) "x"
+                (PConcrete Nothing
+                           (Ann (Tag "t" _) (Enum ["t"] _) _)) _) _] _) _)]),
+    parseMatch input "namespace a {def x : {t} = 't} def y = a.x"
       `([PD (MkPDecl []
           (PNs $ MkPNamespace [< "a"]
             [MkPDecl []
-              (PDef $ MkPDef (PQ Any _) "x" Nothing
-                             (Ann (Tag "t" _) (Enum ["t"] _) _) _) _] _) _),
+              (PDef $ MkPDef (PQ Any _) "x"
+                (PConcrete (Just (Enum ["t"] _))
+                           (Tag "t" _)) _) _] _) _),
          PD (MkPDecl []
-          (PDef $ MkPDef (PQ Any _) "y" Nothing
-                         (V (MakePName [< "a"] "x") Nothing _) _) _)]),
+          (PDef $ MkPDef (PQ Any _) "y"
+            (PConcrete Nothing (V (MakePName [< "a"] "x") Nothing _)) _) _)]),
     parseMatch input #" load "a.quox"; def b = a.b "#
       `([PLoad "a.quox" _,
          PD (MkPDecl []
-           (PDef $ MkPDef (PQ Any _) "b" Nothing
-                          (V (MakePName [< "a"] "b") Nothing _) _) _)])
+           (PDef $ MkPDef (PQ Any _) "b"
+              (PConcrete Nothing (V (MakePName [< "a"] "b") Nothing _)) _) _)])
   ]
 ]
diff --git a/tests/Tests/Reduce.idr b/tests/Tests/Reduce.idr
index b63d498..a27c6f0 100644
--- a/tests/Tests/Reduce.idr
+++ b/tests/Tests/Reduce.idr
@@ -14,8 +14,8 @@ import Control.Eff
 
 runWhnf : Eff Whnf a -> Either Error a
 runWhnf act = runSTErr $ do
-  runEff act [handleStateSTRef !(liftST $ newSTRef 0),
-              handleExcept (\e => stLeft e)]
+  runEff act [handleExcept (\e => stLeft e),
+              handleStateSTRef !(liftST $ newSTRef 0)]
 
 parameters {0 isRedex : RedexTest tm} {auto _ : CanWhnf tm isRedex} {d, n : Nat}
            {auto _ : (Eq (tm d n), Show (tm d n))}
@@ -32,7 +32,7 @@ parameters {0 isRedex : RedexTest tm} {auto _ : CanWhnf tm isRedex} {d, n : Nat}
   testNoStep label ctx e = testWhnf label ctx e e
 
 private
-ctx : Context (\n => (BindName, Term 0 n)) n -> WhnfContext 0 n
+ctx : {n : Nat} -> Context (\n => (BindName, Term 0 n)) n -> WhnfContext 0 n
 ctx xs = let (ns, ts) = unzip xs in MkWhnfContext [<] ns ts
 
 
diff --git a/tests/Tests/Typechecker.idr b/tests/Tests/Typechecker.idr
index 7e44ecd..8a85815 100644
--- a/tests/Tests/Typechecker.idr
+++ b/tests/Tests/Typechecker.idr
@@ -2,7 +2,7 @@ module Tests.Typechecker
 
 import Quox.Syntax
 import Quox.Typechecker as Lib
-import Quox.ST
+import Control.Monad.ST
 import public TypingImpls
 import TAP
 import Quox.EffExtra