Discussion on groupBy

[Laeeth Isharc via Digitalmars-d]

On Saturday, 10 January 2015 at 20:19:14 UTC, Andrei Alexandrescu 
wrote:
> groupBy is an important primitive for relational algebra 
> queries on data. Soon to follow are operators such as 
> aggregate() which is a sort of reduce() but operating on ranges 
> of ranges. With those in tow, a query such as
>
> SELECT COUNT(*), SUM(x) FROM data GROUP BY userid
>
> can be expressed as:
>
> data
>   .groupBy!((a, b) => a.userid == b.userid)
>   .aggregate(count, (a, b) => a.x + b.x);
>
> We're working the kinks out groupBy now. Those interested 
> please follow at https://issues.dlang.org/show_bug.cgi?id=13936.

That's great to hear.

One factor slowing D adoption might be the difference between 
being given a complete solution (finished Ikea furniture item) 
and being handed some raw metal blocks and being told to use the 
milling machine yourself.  The amount of work involves to make 
the minimal useful solution is actually quite small, but on the 
one hand the larger part of the benefit accrues to others (which 
holds some people back), and on the other ability follows a power 
law, and there are many more script kiddies than Adam Ruppe types 
in the world.

So small frictions have cumulatively large consequences.

I think the std.algorithm stuff will come in as very handy as 
building blocks for an implementation of Pandas like 
functionality in D.  Since it seems that parsing data - both 
stuctured and unstructured - is in a bull market, this ought to 
be interesting.