Re: Schwartzian Transform
Adam Turoff wrote:
This message is not an RFC, nor is it an intent to add a feature
to Perl or specify a syntax for that feature[*].
Yay.
We're all for making easy things easy, but the complexities of
"map {} sort {} map {} @list" has always been befuddling to newbies,
especially when reading the code left-to-right.
So you think
@s =
map { $_-[0] }
sort { $a-[1] = $b-[1] }
map { [ $_, /num:(\d+)/ ] }
@t;
would be more clearly written as
@s = schwartzian(
{
second_map = sub { $_-[0] },
the_sort= sub { $a-[1] = $b-[1] },
first_map = sub { [ $_, /num:(\d+)/ ] },
},
@t );
???
I guess that would allow reordering the functions:
@s = schwartzian(
{
first_map = sub { [ $_, /num:(\d+)/ ] },
the_sort= sub { $a-[1] = $b-[1] },
second_map = sub { $_-[0] },
},
@t );
Is that really an improvement?
Every programmer understands right-to-left data flow when it's
written with parentheses. Perl novices just need to understand
that
map { } sort { } map { } @
is a mere syntactic rewrite of
map( , sort( , map( , @ ) ) )
--
John Porter
Useless use of time in void context.
Re: Schwartzian Transform
"JP" == John Porter [EMAIL PROTECTED] writes:
JP Is that really an improvement?
JP Every programmer understands right-to-left data flow when it's
JP written with parentheses. Perl novices just need to understand
JP that
JP map { } sort { } map { } @
JP is a mere syntactic rewrite of
JP map( , sort( , map( , @ ) ) )
well, if anyone is so inclined, they can take over my Sort::Records
module which is gathering major dust. it could be a standard module in
perl6 and help out lots of people. its goal was/is to have the code
describe the sort fields in any complex data tree or string. the module
generates the perl code to extract the fields into a GRT makes a sub out
of that. then you can pass that object lists of records and then do a
sort. you can print out the generated code too for cutting and
pasting. the sort object is reusable with other lists of data. input
records can be strings, or any perl [LH]o[LH]. actual sort keys have to
be scalars and they can be extracted via m// or substr or even custom
callback code.
so this eliminates the need to explicitly use map/sort/map and does all
the key extraction and record management. no need to figure out the code
for a schwartz (drop the 'ian') or GR transform.
the basic design and coding was done but not finished. it got code
reviewed and than i shelved it.
any interest? i would help out but i can't drive the project now.
uri
--
Uri Guttman - [EMAIL PROTECTED] -- http://www.sysarch.com
SYStems ARCHitecture, Software Engineering, Perl, Internet, UNIX Consulting
The Perl Books Page --- http://www.sysarch.com/cgi-bin/perl_books
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Re: Schwartzian Transform
On Tue, Mar 20, 2001 at 11:15:51PM -0500, John Porter wrote:
@s = schwartzian(
{
second_map = sub { $_-[0] },
the_sort= sub { $a-[1] = $b-[1] },
first_map = sub { [ $_, /num:(\d+)/ ] },
},
@t );
Hm. I'd rather see:
schwartzian({/num:(\d+)/}, {^_=^_}, @t), and have perl figure out how to
do the forward and backword mappings. Hmm, I don't see why you couldn't
write that right now. (Other then synthatical shugar -- currying and
getting rid of the need for "sub {}"s.)
Indeed,
map $_-[0], sort {$sort($a-[1], $b-[1])} map [$_, $attrib($_)], @list;
does what I intendeded. (Where ex $sort = sub {$_[0] cmp $_[1]}, and
$attrib = sub {lc $_}.) (Of course, this doesn't always use the optimal
form.)
-=- James Mastros
--
The most beautiful thing we can experience is the mysterious. It is the
source of all true art and science. He to whom this emotion is a stranger,
who can no longer pause to wonder and stand wrapt in awe, is as good as dead.
-=- Albert Einstein
AIM: theorbtwo homepage: http://www.rtweb.net/theorb/
