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.
