cvs commit: hugs98/src builtin.c

[Alastair Reid]

reid        2001/04/01 21:24:13 PDT

  Modified files:
    src                  builtin.c 
  Log:
  This is a bogus commit because I just accidentally committed all files
  instead of just machdep.c (and I can't remember the cvs magic to undo
  it).
  
  So here's what all those committed files did:
  
  interns.c:
  The old file interns.c (which is usually ifdef'd out) provides access
  to a bunch of Hugs internals.  This provided a primitive:
  
     catchException2 :: a -> Either Cell a
  
  where Cell is an error object.  The only change here is a fix to the
  implementation.  It couldn't possibly work the way it was - which
  leaves me wondering what happened to it.
  
  builtin.c:
  Put a (fixed) copy of catchException2 here and added throwException
  
    data HugsException
    primitive primCatchException :: a -> Either HugsException a
    primitive primThrowException :: HugsException -> a
  
  Note that using these directly would break referential transparency.
  To fix that, one or the other (doesn't matter) ought to be in the IO
  monad.  But there's difficult interactions with the thread
  implementation (that's what the fuss is about after all!) so we
  provide the unsafe versions here and wrap them up before exporting
  them.
  
  Incidentally, notice that these names (which have to be exported from
  the Prelude and so pollute the user's namespace) either include the
  word "hugs" or starts with the word "prim".
  
  printer.c:
  Added a primop for printing Hugs exception objects
  
    primitive primShowException  :: HugsException -> String
  
  It originally had type:
  
    primitive primShowException  :: HugsException -> ShowS
  
  but printDBadRedex ignores its second argument when printing error
  objects.
  
  Revision  Changes    Path
  1.12      +3 -3      hugs98/src/builtin.c