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[ghc-hetmet.git] / compiler / prelude / TysPrim.lhs

diff --git a/compiler/prelude/TysPrim.lhs b/compiler/prelude/TysPrim.lhs
index 4e1576f..a6f9b47 100644 (file)
--- a/compiler/prelude/TysPrim.lhs
+++ b/compiler/prelude/TysPrim.lhs
@@ -57,6 +57,7 @@ import OccName                ( mkTcOcc )
 import OccName         ( mkTyVarOccFS, mkTcOccFS )
 import TyCon           ( TyCon, mkPrimTyCon, mkLiftedPrimTyCon, mkAnyTyCon )
 import Type
+import Coercion
 import SrcLoc
 import Unique          ( mkAlphaTyVarUnique )
 import PrelNames
@@ -232,8 +233,14 @@ Note [Uniques of Any]
 Although Any(*->*), say, doesn't have a binding site, it still needs
 to have a Unique.  Unlike tuples (which are also an infinite family)
 there is no convenient way to index them, so we use the Unique from
-their OccName instead.  That should be unique!  (But in principle we
-must take care: it does not include the module/package.)
+their OccName instead.  That should be unique, 
+
+  - both wrt each other, because their strings differ
+
+  - and wrt any other Name, because Names get uniques with 
+    various 'char' tags, but the OccName of Any will 
+    get a Unique built with mkTcOccUnique, which has a particular 'char' 
+    tag; see Unique.mkTcOccUnique!
 
 Note [Strangely-kinded void TyCons]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~