X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FcoreSyn%2FExternalCore.lhs;fp=compiler%2FcoreSyn%2FExternalCore.lhs;h=359419ca0654a1f8f3da9479b60ead108cc10e1c;hp=07a1dfbd8ee1b8bcc7f48a41d2be7ba071425d1d;hb=fdf8656855d26105ff36bdd24d41827b05037b91;hpb=a52ff7619e8b7d74a9d933d922eeea49f580bca8

diff --git a/compiler/coreSyn/ExternalCore.lhs b/compiler/coreSyn/ExternalCore.lhs
index 07a1dfb..359419c 100644
--- a/compiler/coreSyn/ExternalCore.lhs
+++ b/compiler/coreSyn/ExternalCore.lhs
@@ -4,7 +4,6 @@
 \begin{code}
 module ExternalCore where
 
-
 data Module 
  = Module Mname [Tdef] [Vdefg]
 
@@ -51,21 +50,21 @@ data Alt
 type Vbind = (Var,Ty)
 type Tbind = (Tvar,Kind)
 
+-- Internally, we represent types and coercions separately; but for
+-- the purposes of external core (at least for now) it's still
+-- convenient to collapse them into a single type.
 data Ty 
   = Tvar Tvar
   | Tcon (Qual Tcon)
   | Tapp Ty Ty
   | Tforall Tbind Ty 
--- We distinguish primitive coercions
--- (represented in GHC by wired-in names), because
--- External Core treats them specially, so we have
--- to print them out with special syntax.
+-- We distinguish primitive coercions because External Core treats
+-- them specially, so we have to print them out with special syntax.
   | TransCoercion Ty Ty
   | SymCoercion Ty
   | UnsafeCoercion Ty Ty
   | InstCoercion Ty Ty
-  | LeftCoercion Ty
-  | RightCoercion Ty
+  | NthCoercion Int Ty
 
 data Kind 
   = Klifted