Re: COBOL compiler

From: Ron Johnson (ron.l.johnson_at_cox.net)
Date: 08/30/03

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    To: Debian-User <debian-user@lists.debian.org>
Date: Sat, 30 Aug 2003 00:00:11 -0500

    On Fri, 2003-08-29 at 19:37, Colin Watson wrote:
    > On Fri, Aug 29, 2003 at 05:46:01PM -0500, Ron Johnson wrote:
    > > On Fri, 2003-08-29 at 16:28, Bijan Soleymani wrote:
    > > > Well then you do it differently:
    > > > open(INPUT,"records.txt");
    > > > LOOP: while($record = <INPUT>)
    > > > {
    > > > if(!input_filter($record))
    > > > {
    > > > next LOOP;
    > > > }
    > > > else
    > > > {
    > > > #code to process record
    > > > }
    > > > }
    > > > close(INPUT);
    > > >
    > > > Where input_filter() is the winnowing function you define.
    > >
    > > That's good, but where's the sort function? Also, what if each
    > > record-to-be-sorted doesn't come directly from records.txt? Maybe,
    > > for each record read from records.txt, you must also query some
    > > other file(s), or a database, or must do some other algorithmic
    > > calculation.
    >
    > RTFM: 'perldoc -f sort'. None of this is terribly hard in Perl at all; I
    > don't see the point of making people write pseudocode to prove the
    > point.

    Maybe it's because I don't know enough about Perl, but that looks
    like it's only for in-memory lists.

    > > The COBOL SORT verb has 3 sections:
    > > INPUT - Records (from whatever input) are RELEASEd to the SORT buffers.
    > > Any winnowing or transformations can happen here.
    > > SORT - You can figure that part out.
    > > OUTPUT - Records are RETURNed from the actual sort and can be pro-
    > > cessed (transformed, summarized, etc).
    >
    > Sounds like the 'map sort map' idiom in Perl that's often used for
    > complex cases. (It's also a common optimization to factor out expensive
    > transformations in the sort comparator.)

    After reading 'perldoc -f map', that also looks like it only works
    on in-memory lists. 

    -- 
-----------------------------------------------------------------
Ron Johnson, Jr. ron.l.johnson@cox.net
Jefferson, LA USA
When Swedes start committing terrorism, I'll become suspicious 
of Scandanavians.
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