[PRD/FLD] aggregates

I sent this message at the end of the last f2f, but it doesn't seem to have been
delivered. Only today I got a reply that it was rejected by the server.
Anyway, here it goes again:

    Since we did not have time to discuss the aggregates, let's start it by
    email.  Basically, an aggregate is a term that includes a comprehension.
    In addition, there is a need to be able to GROUP BY, as in databases.  (I
    do not know if this latter thing is needed for PRD.)

    So, the syntax I was thinking about is:

	aggfun{Var [ GroupvarList ] | CondFormula}

    The symbols {,},[,],| here are the actual symbols, not metasymbols.
    Var is the comprehension variable, i.e., {Var | CondFormula}.
    GroupvarList is the list of vars to group by. The entire piece
    "[ GroupvarList ]" is optional.

    Note that I need the above general form for FLD. For PRD we might need
    something less general. We just need to make sure that the
    syntaxes are compatible.


	    --michael

Received on Friday, 10 October 2008 23:42:11 UTC