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digitalmars.D - Idiomatic D

reply "NoUseForAName" <no spam.com> writes:
I want to implement a small program in D for a personal 
comparison of various programming languages. Given that I am 
already quite familiar with C/C++ (from K&R C to C++11) I could 
probably start write working D code right away by just looking up 
a few basic syntax/standard library things.

However, I would like to write idiomatic D code, not "C++ in D". 
Is there any guide for this? If not, I would like to say that I 
think having one would be very useful.

Assuming a lack of an extensive guide could someone please just 
give me the cliff notes on how to D properly?
Jan 10 2014
next sibling parent Paulo Pinto <pjmlp progtools.org> writes:
Am 10.01.2014 23:52, schrieb NoUseForAName:

 I want to implement a small program in D for a personal comparison of
 various programming languages. Given that I am already quite familiar
 with C/C++ (from K&R C to C++11) I could probably start write working D
 code right away by just looking up a few basic syntax/standard library
 things.

 However, I would like to write idiomatic D code, not "C++ in D". Is
 there any guide for this? If not, I would like to say that I think
 having one would be very useful.

 Assuming a lack of an extensive guide could someone please just give me
 the cliff notes on how to D properly?


A good starting point would be bearophile's work on  Rosetta Code

http://rosettacode.org/wiki/Category:D

--
Paulo
Jan 10 2014
prev sibling next sibling parent "qznc" <qznc web.de> writes:
On Friday, 10 January 2014 at 22:52:36 UTC, NoUseForAName wrote:

 I want to implement a small program in D for a personal 
 comparison of various programming languages. Given that I am 
 already quite familiar with C/C++ (from K&R C to C++11) I could 
 probably start write working D code right away by just looking 
 up a few basic syntax/standard library things.

 However, I would like to write idiomatic D code, not "C++ in 
 D". Is there any guide for this? If not, I would like to say 
 that I think having one would be very useful.

 Assuming a lack of an extensive guide could someone please just 
 give me the cliff notes on how to D properly?


Here is some:
http://qznc.github.io/d-tut/idiomatic.html

It is certainly not complete, though.
Jan 10 2014
prev sibling next sibling parent =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 01/10/2014 02:52 PM, NoUseForAName wrote:


 I would like to write idiomatic D code, not "C++ in D".


I like this style:

   http://wiki.dlang.org/Component_programming_with_ranges

Ali
Jan 10 2014
prev sibling next sibling parent "Brad Anderson" <eco gnuk.net> writes:
On Friday, 10 January 2014 at 22:52:36 UTC, NoUseForAName wrote:

 I want to implement a small program in D for a personal 
 comparison of various programming languages. Given that I am 
 already quite familiar with C/C++ (from K&R C to C++11) I could 
 probably start write working D code right away by just looking 
 up a few basic syntax/standard library things.

 However, I would like to write idiomatic D code, not "C++ in 
 D". Is there any guide for this? If not, I would like to say 
 that I think having one would be very useful.

 Assuming a lack of an extensive guide could someone please just 
 give me the cliff notes on how to D properly?


The first thing that comes to made is learn ranges and slices.

Ranges: http://ddili.org/ders/d.en/ranges.html
Slices: http://dlang.org/d-array-article.html

UFCS (pseudo-member) chains particularly with std.algorithm and 
std.range are becoming something of a strong idiom in D. 
Contrived example:

     void main()
     {
         import std.algorithm, std.uni;
         	
         auto result =  "one two three four five"
                       .splitter()
                       .map!toUpper
                       .filter!(a => a.canFind("E"));
         assert(result.equal(["ONE", "THREE", "FIVE"]));
    }

Users of D generally focus more on compile time polymorphism 
rather than runtime where possible. Nick Sabalausky wrote a 
rather good article about this: 
http://www.semitwist.com/articles/EfficientAndFlexible/MultiplePages/Page1/
Jan 10 2014
prev sibling next sibling parent reply "Kelet" <kelethunter gmail.com> writes:
On Friday, 10 January 2014 at 22:52:36 UTC, NoUseForAName wrote:

 I want to implement a small program in D for a personal 
 comparison of various programming languages. Given that I am 
 already quite familiar with C/C++ (from K&R C to C++11) I could 
 probably start write working D code right away by just looking 
 up a few basic syntax/standard library things.

 However, I would like to write idiomatic D code, not "C++ in 
 D". Is there any guide for this? If not, I would like to say 
 that I think having one would be very useful.

 Assuming a lack of an extensive guide could someone please just 
 give me the cliff notes on how to D properly?


I'm pretty new to D myself, but I always strive to write 
reasonably idiomatic code. So here's more or less what I've 
picked up:

- Use type inference (auto) when possible
- Use variable, function, and parameter qualifiers[1]
- Use compile time function execution[2]
- Constrain templates as much as possible
- foreach or higher-order functions are preferred over for/while 
loops[3]
- Do not overuse OOP[4]
- Use uniform function call syntax when it makes sense to chain 
calls or increase readability
- Know `alias this` and operator overloads
- Put unit tests under each function if you choose to make them
- Use Ddoc-style documentation
- Many of the examples on Rosetta Code are well-written 
http://rosettacode.org/wiki/Category:D I think bearophile did 
many of them.

[1]:
Some Qualifiers to note -
Function:
   - auto: infer return type
   - ref: returns a reference, not a value
   - inout: Deduce immutability (mutable, const, immutability) by 
parameters
   - pure: does not modify or use global state or impure functions
   - nothrow: No possibility to throw an exception
   -  safe: No operation may corrupt memory
   -  trusted – consider function safe, even if it cannot be 
verified so
   -  system – default, all  safe and  trusted functions are also 
 system
Variable:
   - const: this reference to the variable is unchangeable
     - const is nice in function parameters because it can accept 
mutable, const,
       and immutable parameters
   - immutable: all references to the variable are unchangeable
   - shared: requires that variable is sharable between threads
Parameter/Argument:
   - scope: no reference to variable can be leaked outside of 
function
   - in: equivalent to const scope
   - out: like ref, but gives default value, can be used for 
multiple returns
   - inout: see function qualifier definition
   - lazy: calculate only on usage (can duplicate calculations)

Mostly, I find myself trying to use `pure  safe nothrow` in 
functions, `immutable` in variables, and `in` in parameters as 
much as possible without modifying semantics too much.

[2]: See last example here 
http://en.wikipedia.org/wiki/Compile_time_function_execution

[3]:
for(int i = 0; i < 20; i++) =>
foreach(immutable i = 0; 0..20) OR
Use some higher-order function from std.algorithm or whatnot 
instead

[4]:
D is not Java. Modules can have their own constructors and 
private variables and such.

Regards,
Kelet
Jan 10 2014
next sibling parent "Kelet" <kelethunter gmail.com> writes:
On Friday, 10 January 2014 at 23:16:10 UTC, Kelet wrote:

 foreach(immutable i = 0; 0..20) OR


Oops, meant
foreach(immutable i; 0..20)
Jan 10 2014
prev sibling parent "qznc" <qznc web.de> writes:
On Friday, 10 January 2014 at 23:16:10 UTC, Kelet wrote:

 - Many of the examples on Rosetta Code are well-written 
 http://rosettacode.org/wiki/Category:D I think bearophile did 
 many of them.


Contributing to Rosetta Code is a great way to learn idiomatic 
code. Write one of the missing programs [0] and tell bearophile 
about it. He will most certainly tell you how to make it more 
idiomatic and improve it. ;)

[0] http://rosettacode.org/wiki/Reports:Tasks_not_implemented_in_D
Jan 10 2014
prev sibling next sibling parent "deadalnix" <deadalnix gmail.com> writes:
On Friday, 10 January 2014 at 22:52:36 UTC, NoUseForAName wrote:

 I want to implement a small program in D for a personal 
 comparison of various programming languages. Given that I am 
 already quite familiar with C/C++ (from K&R C to C++11) I could 
 probably start write working D code right away by just looking 
 up a few basic syntax/standard library things.

 However, I would like to write idiomatic D code, not "C++ in 
 D". Is there any guide for this? If not, I would like to say 
 that I think having one would be very useful.

 Assuming a lack of an extensive guide could someone please just 
 give me the cliff notes on how to D properly?


Idiomatic D is when you hit compiler errors :D

/sarcastic
Jan 10 2014
prev sibling parent "NoUseForAName" <no spam.com> writes:
On Friday, 10 January 2014 at 22:52:36 UTC, NoUseForAName wrote:

 [snip]


Wow, that is a lot of information to process. Thanks everyone!
Jan 10 2014