LINQ in D [Was: Re: Map/Reduce/Filter]

[Robert Fraser]

bearophile Wrote:

> Walter Bright:
> > We could sure use an article like this for D:
> > http://www.25hoursaday.com/weblog/2008/06/16/FunctionalProgrammingInC30HowMapReduceFilterCanRockYourWorld.aspx
> > Anyone game?
> 
> You know that I have spent many months to write a large group of mostly functional-style open source libs for D 1.x (quite more complete and smarter than the stuff in std.algorithm of 2.x, but possibly a bit slower), and on my blog I have discussed many times about this topic, showing usage examples too. So writing another smallish article about such usages seems possible.
> But that article looks mostly about LINQ, that's much better (mostly because it's more integrated and pervasive in the language and systems usable from it, like the DBMS) than anything I can create with D. So maybe a comparison will not show many advantages compared to that LINQ code...
> 
> If someone else has some suggestions I'll willing to listen to them.
> 
> Bye and thank you for the suggestion,
> bearophile

LINQ should actually be possible in D without language integration.
For example, with CTFE/templates this should be possible in D right now:

struct Employee {
    string name;
    int id;
}
Employee[] employees;

//...

auto rows = mixin(query("SELECT name, id FROM employees WHERE id > 5"));
foreach(row; rows)
    writefln("%d - %s", row.id, row.name);