Hiding non-existent entities

Simon Marlow simonmar@microsoft.com
Wed, 29 Aug 2001 14:11:07 +0100

The Haskell 98 errata page currently contains this item related to a
hiding clause on an import declaration which refers to a non-existent

  [Aug 2001] Page 66, Section 5.3, Import Declarations,
  numbered item 2. Add "It is not an error to hide an entity
  that is not, in fact, exported by the imported module, although
  compilers are encouraged to flag a warning in this case." (This
  is different from what I proposed by email, which made this case
  an error, but it allow a bit more flexibility as modules change.)

IMO allowing a hiding clause to refer to a non-existent entity is a bit
odd.  Haskell doesn't have any other features like this: it's always an
error to refer to an entity that isn't defined anywhere, even if the
reference is otherwise harmless.  Does anyone else have any opinions on