No top level definition for operator symbol

[Ralf Hinze]

A fixity declaration for which no top-level definition is given
provokes an error in Hugs:

ERROR "MergeSort.lhs": No top level definition for operator symbol "\+/"

The report is not that restrictive (I briefly skimmed through the
relevant section) and I can see no reason why this could be required.
IMHO it's okay when the identifier is bound at in inner level (or does
not even occur at all). Do you agree?

Ralf