View source for Why program in D

<blockquote>
[Many] of D's improvements appear to be small, but the aggregate is large enough that once you write a project<br/>
in D, you'll find it pretty hard to go back to another language. <br/>
-- Walter Bright <br/> <br/>
</blockquote>

<blockquote>
Often, programming teams will resort to a hybrid approach, where they will mix Python and C++, trying to get <br/>
the productivity of Python and the performance of C++. The frequency of this approach indicates that there <br/>
is a large unmet need in the programming language department.<br/>

D intends to fill that need. It combines the ability to do low-level manipulation of the machine with the <br/>
latest technologies in building reliable, maintainable, portable, high-level code. D has moved well ahead of <br/>
any other language in its abilities to support and integrate multiple paradigms like imperative, OOP, and <br/>
generic programming.

-- Walter Bright  <br/>  <br/>
</blockquote>

<blockquote>
Should one choose C over D for maximum performance? <br/>

My answer is an emphatic no, and I bring as evidence the fact that warp is significantly faster than the <br/>
preprocessor in my own older Digital Mars C/C++ compiler tool chain, which was already the fastest on the <br/>
market, and on which I've spared no effort optimizing and tuning over months and years. Modern compiler <br/>
technology working in concert with D language fundamentals (white-box templates, simple object models) takes <br/>
high-level compositions of templated code and optimizes it down to code that is virtually indistinguishable <br/>
from what a C programmer would write for maximum efficiency. <br/>

The neato thing about D is that by separating the code into ranges and algorithms, it becomes easy to keep <br/>
trying different range implementations and different algorithms. I tried all sorts of things. Like breeding <br/>
racehorses, I kept the profile winners and culled the losers, step by step, through the code. That would have <br/>
been a lot more difficult to do in other languages. <br/>

[https://code.facebook.com/posts/476987592402291/under-the-hood-warp-a-fast-c-and-c-preprocessor/ -- Facebook's warp C/C++ preprocessor written by Walter Bright]  <br/>  <br/>
</blockquote>

The detailed [http://dlang.org/overview.html overview] of the language should give you the big picture.

Now if you are looking for reasons to start using D you are probably also looking for reasons not to use it. This was pointed out by Andrei Alexandrescu in [http://www.ddj.com/hpc-high-performance-computing/217801225 The Case for D], "Trying to find quick reasons to avoid [learning a new language] is a survival instinct." And like any language there are reasons not to use D, but you might find that they don't apply to you or that the benefits are greater.

* [[MoreLinks#DBuzz | D Buzz]]
* [[PerfectD | Imperfect C++ and More Perfect D]]
* [http://dlang.org/faq.html FAQ]

<p></p>

== Videos - language ==
W. Bright: [http://channel9.msdn.com/Events/Lang-NEXT/Lang-NEXT-2012/The-D-Programming-Language The D Programming Language] (2012)

A. Alexandrescu: [http://channel9.msdn.com/Events/Lang-NEXT/Lang-NEXT-2012/Three-Unlikely-Successful-Features-of-D Three Unlikely Successful Features of D] (2012)

A. Alexandrescu: [http://www.infoq.com/presentations/Generic-Programming-Galore-Using-D Generic Programming Galore Using D] (2012)

A. Alexandrescu: [http://www.youtube.com/watch?v=RlVpPstLPEc Three Cool Things About D - The Case for the D Programing Language] (2010)

W. Bright: [http://vimeo.com/4333802 Metaprogramming in D] (2009)


== Videos - D users ==

[http://dconf.org/2016/talks/zvibel.html Weka.io: Using D for implementing a large scale primary storage system] (2016)

[http://dconf.org/2016/talks/watson.html Quantum Break: AAA Gaming with Some D Code] (2016)

[http://dconf.org/2014/talks/clugston.html Sociomantic: Real-Time Big Data in D] (2014)

[http://dconf.org/2015/talks/smith.html Large Hedge Fund: Using D in production in finance] (2014)

[http://dconf.org/2014/talks/crapuchettes.html EMSI: economic modelling at scale using D] (2014)

[http://dconf.org/2014/talks/simpkins.html Facebook: Experience Report - Using D at Facebook and Beyond](2014)


Here is a full list of [[Videos | videos]] relating to D.
Here is a list of [http://dlang.org/orgs-using-d.html organisations using D]

== Articles ==
You will find in the main website more than a dozen articles discussing several design decisions for the language and its library. Don't forget to have a look there.
A few examples
* D. Clugston [http://dlang.org/d-floating-point.html Real Close to the Machine: Floating Point in D]
* S. Schweighoffer [http://dlang.org/d-array-article.html D Slices]
* B. Mileswski [http://dlang.org/safed.html Safe D]

Until that journal's untimely demise, Walter Bright regularly wrote enlightening [http://www.drdobbs.com/author/6839 columns in Dr Dobb's]. Many were directly related to D (access is free, but it may require registering if you read more than a couple articles/day).

* [http://www.drdobbs.com/blogs/cpp/232700394 Uniform function call syntax] (2012)
* [http://www.drdobbs.com/blogs/cpp/232601305 Inheriting purity] (2012)
* [http://www.drdobbs.com/blogs/cpp/231902461 Type Qualifiers and Wild Cards] (2011)
* [http://www.drdobbs.com/blogs/cpp/231600610 Member function pointers] (2011)

A. Alexandrescu wrote several equally important articles :
* [http://www.informit.com/articles/article.aspx?p=1621867 Interview part 1] [http://www.informit.com/articles/article.aspx?p=1622265 part 2] [http://www.informit.com/articles/article.aspx?p=1623791 part 3] (2010)
* [http://www.informit.com/articles/article.aspx?p=1609144 Concurrency in the D Programming Language](2010) (from ''The D Programming Language'' book)
* [http://www.informit.com/articles/article.aspx?p=1407357 On iteration] (2009)
* [http://www.ddj.com/hpc-high-performance-computing/217801225 Case For D] (2009)

* N. Sabalausky [https://www.semitwist.com/articles/article/view/combine-coroutines-and-input-ranges-for-dead-simple-d-iteration Combine Coroutines and Input Ranges for Dead-Simple D Iteration]


You can find more articles in the [[Articles | articles section]].

See also the [https://dlang.org/blog/ official D blog] and [http://arsdnet.net/this-week-in-d/ This Week in D], the summary of what is going on in the D community.


== Application Developers ==

Each language has a preferred application domain. D has a high degree of versatility as a language - it does have a sweet spot in high performance desktop and server side applications, but it can nonetheless be used where a scripting language would be the traditional choice: it provides the performance of low-level languages (of the order of C++) with the safety and ease of expression reminiscent of languages like Java and Python.

In fact, nearly everywhere Java is suitable, D could replace it, bringing in more expressive power, better performance and better memory management. Although its [https://code.dlang.org/ current libraries] are nowhere near as extensive as the Java libraries, most fundamental bricks are already here, and D has native interfacing to both C and C++, with library solutions for other languages such as Python,R and Lua.  You may want to have a look at [http://dlang.org/phobos/index.html Phobos] and [https://github.com/D-Programming-Deimos Deimos] libraries, as well as third-party libraries to make your own opinion on that matter. A very nice port of Java's SWT library has been created under the name [https://github.com/d-widget-toolkit/dwt DWT] (with older but more complete documentation available at the [http://www.dsource.org/projects/dwt legacy dsource site]).  There are also [http://gtkd.org/ bindings for GTK], and [https://github.com/buggins/dlangui a cross-platform idiomatic D GUI].


== Embedded Developers ==

Being targeted at 32 bit and 64 bit machines, D is not designed for embedded development on small devices. However, with the advent of Android and iOS smartphones which embed powerful CPUs and large amounts of RAM, D may be suitable for such development. The GCC and LLVM compiler backends being able to target these devices, the community is making progress.

Find out more at StackOverflow:
* [http://stackoverflow.com/questions/1207958/getting-embedded-with-d-the-programming-language Getting Embedded with D (the programming language)]
* [http://stackoverflow.com/questions/1113938/how-would-you-approach-using-d-in-a-embedded-real-time-environment How would you approach using D in a embedded real-time environment?]

== Numerical programmers ==

D provides high precision floating point, NaN, and complex/imaginary numbers. There are also a number of mathematical and scientific libraries in development, e.g. SciD.  Notably the [https://github.com/libmir/mir Mir] and [https://github.com/libmir/mir-glas Mir-GLAS] projects provide an implementation of numerical libraries that offer performance comparable to Intel MKL, and better than Eigen and OpenBLAS without the use of assembler and implemented in a way that makes porting to new platforms very simple.


== Script Fan ==

Since D provides type inference, high-level constructs, and fast compile-time it is a great language for writing scripts. The first line of the file is ignored if it begins with #! ('shebang') and combining this with [https://dlang.org/rdmd.html rdmd] which handles dependency resolution, D becomes a leader in native-code scripting languages.  

<syntaxhighlight lang="D">
   #!/usr/bin/env rdmd

    void main() {
	import std.stdio : writeln;
	writeln("Hello, World!");
    }
</syntaxhighlight>

Scripts with library dependencies can also be written using a shebang with the [https://code.dlang.org/getting_started dub package manager].  The example below uses the [http://vibed.org/tutorials async fiber-based framework vibe.d]

<syntaxhighlight lang="D">
   #!/usr/bin/env rdmd
   /+ dub.sdl:
	name "hello"
        version "~master"
        dependency "vibe-d" version="~master"
    +/
    import vibe.core.log;
    import vibe.mail.smtp;

    void main()
    {
	auto settings = new SMTPClientSettings("smtp.example.com", 25);
	settings.connectionType = SMTPConnectionType.startTLS;
	settings.authType = SMTPAuthType.plain;
	settings.username = "username";
	settings.password = "secret";

	auto mail = new Mail;
	mail.headers["From"] = "<user@isp.com>";
	mail.headers["To"] = "<recipient@domain.com>";
	mail.headers["Subject"] = "Testmail";
	mail.bodyText = "Hello, World!";
	
	logInfo("Sending mail...");
	sendMail(settings, mail);
	logInfo("done.");
    }
</syntaxhighlight>

== Language Lover ==

Walter, Andrei and the D community work to make D a practical language that combines native code efficiency and control with the modeling power, safety, and productivity found in high-level languages and those that stick strictly to a single paradigm. If you enjoy languages D is interesting in the way it combines many paradigms in a C-like syntax, and yet D is also a language [http://dlang.org/orgs-using-d.html used in production at scale] in industry and academe.

== Related ==
* [[Coming_From | Learning D as a second language]]
* [http://dlang.org/spec.html Language Specification]
* [[D__Tutorial/StartingWithD | Setting up an environment to compile programs]]
* [[Development_With_D | Development with D]]
* [http://dlang.org/faq.html FAQ]
* [[Current D Use | Current uses of D]]