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[ghc-hetmet.git] / compiler / types / TypeRep.lhs

diff --git a/compiler/types/TypeRep.lhs b/compiler/types/TypeRep.lhs
index 544b822..b0b5c63 100644 (file)
--- a/compiler/types/TypeRep.lhs
+++ b/compiler/types/TypeRep.lhs
@@ -192,8 +192,11 @@ data Type
        TyVar
        Type    
 
-  | PredTy             -- A high level source type 
-       PredType        -- ...can be expanded to a representation type...
+  | PredTy             -- The type of evidence for a type predictate
+       PredType        -- Can be expanded to a representation type.
+       -- NB: A PredTy (EqPred _ _) can appear only as the kind
+       --     of a coercion variable; never as the argument or result
+       --     of a FunTy (unlike ClassP, IParam)
 
   | NoteTy             -- A type with a note attached
        TyNote