Improve syntax for primitive coercions in External Core

Add new syntax in External Core for primitive coercions (trans,
sym, etc.) rather than wiring their names into the ext-core
parser.

diff --git a/compiler/coreSyn/ExternalCore.lhs b/compiler/coreSyn/ExternalCore.lhs
index a326a54..d8eaa3c 100644 (file)
--- a/compiler/coreSyn/ExternalCore.lhs
+++ b/compiler/coreSyn/ExternalCore.lhs
@@ -56,6 +56,16 @@ data Ty
   | 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.
+  | TransCoercion Ty Ty
+  | SymCoercion Ty
+  | UnsafeCoercion Ty Ty
+  | InstCoercion Ty Ty
+  | LeftCoercion Ty
+  | RightCoercion Ty
 
 data Kind 
   = Klifted

diff --git a/compiler/coreSyn/MkExternalCore.lhs b/compiler/coreSyn/MkExternalCore.lhs
index 99ea425..861f501 100644 (file)
--- a/compiler/coreSyn/MkExternalCore.lhs
+++ b/compiler/coreSyn/MkExternalCore.lhs
@@ -225,8 +225,8 @@ make_ty' (TyVarTy tv)        = C.Tvar (make_var_id (tyVarName tv))
 make_ty' (AppTy t1 t2)                  = C.Tapp (make_ty t1) (make_ty t2)
 make_ty' (FunTy t1 t2)                  = make_ty (TyConApp funTyCon [t1,t2])
 make_ty' (ForAllTy tv t)        = C.Tforall (make_tbind tv) (make_ty t)
-make_ty' (TyConApp tc ts)       = foldl C.Tapp (C.Tcon (qtc tc)) 
-                                        (map make_ty ts)
+make_ty' (TyConApp tc ts)       = make_tyConApp tc ts
+
 -- Newtypes are treated just like any other type constructor; not expanded
 -- Reason: predTypeRep does substitution and, while substitution deals
 --        correctly with name capture, it's only correct if you see the uniques!
@@ -241,6 +241,25 @@ make_ty' (TyConApp tc ts)   = foldl C.Tapp (C.Tcon (qtc tc))
 
 make_ty' (PredTy p)    = make_ty (predTypeRep p)
 
+make_tyConApp :: TyCon -> [Type] -> C.Ty
+make_tyConApp tc [t1, t2] | tc == transCoercionTyCon =
+  C.TransCoercion (make_ty t1) (make_ty t2)
+make_tyConApp tc [t]      | tc == symCoercionTyCon =
+  C.SymCoercion (make_ty t)
+make_tyConApp tc [t1, t2] | tc == unsafeCoercionTyCon =
+  C.UnsafeCoercion (make_ty t1) (make_ty t2)
+make_tyConApp tc [t]      | tc == leftCoercionTyCon =
+  C.LeftCoercion (make_ty t)
+make_tyConApp tc [t]      | tc == rightCoercionTyCon =
+  C.RightCoercion (make_ty t)
+make_tyConApp tc [t1, t2] | tc == instCoercionTyCon =
+  C.InstCoercion (make_ty t1) (make_ty t2)
+-- this fails silently if we have an application
+-- of a wired-in coercion tycon to the wrong number of args.
+-- Not great...
+make_tyConApp tc ts =
+  foldl C.Tapp (C.Tcon (qtc tc)) 
+           (map make_ty ts)
 
 
 make_kind :: Kind -> C.Kind

diff --git a/compiler/coreSyn/PprExternalCore.lhs b/compiler/coreSyn/PprExternalCore.lhs
index c34f7b8..25394e2 100644 (file)
--- a/compiler/coreSyn/PprExternalCore.lhs
+++ b/compiler/coreSyn/PprExternalCore.lhs
@@ -5,13 +5,12 @@
 \begin{code}
 module PprExternalCore () where
 
-import ExternalCore
 import Encoding
+import ExternalCore
 
 import Pretty
 import Char
 
-
 instance Show Module where
   showsPrec _ m = shows (pmodule m)
 
@@ -103,6 +102,18 @@ pbty t = paty t
 
 pty (Tapp(Tapp(Tcon tc) t1) t2) | tc == tcArrow = fsep [pbty t1, text "->",pty t2]
 pty (Tforall tb t) = text "%forall" <+> pforall [tb] t
+pty (TransCoercion t1 t2) =
+  sep [text "%trans", paty t1, paty t2]
+pty (SymCoercion t) =
+  sep [text "%sym", paty t]
+pty (UnsafeCoercion t1 t2) =
+  sep [text "%unsafe", paty t1, paty t2]
+pty (LeftCoercion t) =
+  sep [text "%left", paty t]
+pty (RightCoercion t) =
+  sep [text "%right", paty t]
+pty (InstCoercion t1 t2) =
+  sep [text "%inst", paty t1, paty t2]
 pty t = pbty t
 
 pappty :: Ty -> [Ty] -> Doc

diff --git a/utils/ext-core/ParsecParser.hs b/utils/ext-core/ParsecParser.hs
index 9acb138..ab0d284 100644 (file)
--- a/utils/ext-core/ParsecParser.hs
+++ b/utils/ext-core/ParsecParser.hs
@@ -222,13 +222,12 @@ coreTcon =
 data CoercionTy = TransC | InstC | SymC | UnsafeC | LeftC | RightC
 
 symCo, transCo, unsafeCo, instCo, leftCo, rightCo :: Parser CoercionTy
--- Would be better not to wire these in quite this way. Sigh
-symCo    = string "ghczmprim:GHCziPrim.sym"      >> return SymC
-transCo  = string "ghczmprim:GHCziPrim.trans"    >> return TransC 
-unsafeCo = string "ghczmprim:GHCziPrim.CoUnsafe" >> return UnsafeC
-leftCo   = string "ghczmprim:GHCziPrim.left"     >> return LeftC
-rightCo  = string "ghczmprim:GHCziPrim.right"    >> return RightC
-instCo   = string "ghczmprim:GHCziPrim.inst"    >> return InstC
+symCo    = string "%sym"    >> return SymC
+transCo  = string "%trans"  >> return TransC
+unsafeCo = string "%unsafe" >> return UnsafeC
+leftCo   = string "%left"   >> return LeftC
+rightCo  = string "%right"  >> return RightC
+instCo   = string "%inst"   >> return InstC
 
 coreForallTy :: Parser Ty
 coreForallTy = do