I don't suppose there is a digital.D.beginner forum?

I've been staring at this definition for about an hour and I still can't decode it.

int[string][double[int[]]] a;  //
...
auto b = to!(short[wstring][string[double[]]])(a);  // this doesn't help either


int[string} a  // would be an Associate Array of integers with a string key?

int[]  // would be a dynamic array of integers,i believe?

But put the int[] inside of double[] and put that inside of [] and put that after the associative array, and my head can't stop for spinning.


If there is a better site or forum, please tell me and I won't waste people's time here. I did buy Andrei Alexandrescu's book and have it pretty well dog-eared. But i must be a pretty mediocre programmer.

On Tuesday, 2 April 2013 at 16:24:46 UTC, WhatMeWorry wrote:
>
> I don't suppose there is a digital.D.beginner forum?
>

There is D.learn. Scroll down in the webinterface :-)

> I've been staring at this definition for about an hour and I still can't decode it.
>
> int[string][double[int[]]] a;  //
Read it left to right :-)

Let's rewrite the type with placeholders U,V.
int[string][double[int[]]] --> int[U][V]

int[U][V] is an AA mapping keys of type V to values int[U], which is itself an AA that maps U's to int's.

Now, what is U and V? U is string that was easy. V is double[int[]]. That again is an AA, mapping from int[] to double.


> int[string} a  // would be an Associate Array of integers with a string key?

Nope, thats in syntax error.

> int[]  // would be a dynamic array of integers,i believe?
>
Correct.

On Tuesday, 2 April 2013 at 16:24:46 UTC, WhatMeWorry wrote:
>
> I don't suppose there is a digital.D.beginner forum?
>
> I've been staring at this definition for about an hour and I still can't decode it.
>
> int[string][double[int[]]] a;  //
> ...
> auto b = to!(short[wstring][string[double[]]])(a);  // this doesn't help either
>
>
> int[string} a  // would be an Associate Array of integers with a string key?
>
> int[]  // would be a dynamic array of integers,i believe?
>
> But put the int[] inside of double[] and put that inside of [] and put that after the associative array, and my head can't stop for spinning.
>
>
> If there is a better site or forum, please tell me and I won't waste people's time here. I did buy Andrei Alexandrescu's book and have it pretty well dog-eared. But i must be a pretty mediocre programmer.

I'm confused, did you find that definition somewhere or did you write it yourself?

int[string][double[int[]]]

Let's split it up:
alias double[int[]] T;

T is an associative array with key type int[] and value type double

So we now have
int[string][T]
Which is an associative array with key type T and value type int[string] (itself an associative array)

I hope that makes more sense.

On Tuesday, 2 April 2013 at 16:51:45 UTC, Tobias Pankrath wrote:
> On Tuesday, 2 April 2013 at 16:24:46 UTC, WhatMeWorry wrote:
>>
>> I don't suppose there is a digital.D.beginner forum?
>>
>
> There is D.learn. Scroll down in the webinterface :-)

This is in D.learn already.

>> int[string} a  // would be an Associate Array of integers with a string key?
>
> Nope, thats in syntax error.

Just a } vs ]  typo (just to avoid confusion)

On 04/02/2013 09:24 AM, WhatMeWorry wrote:>
> I don't suppose there is a digital.D.beginner forum?
>
> I've been staring at this definition for about an hour and I still can't
> decode it.
>
> int[string][double[int[]]] a;  //

alias usually makes the syntax cleaner but that is still pretty crazy. :)

void main()
{
    int[string][double[int[]]] a;

    alias Numbers = int[];
    alias NumbersToDoubleDict = double[Numbers];
    alias StringToIntDict = int[string];
    alias CrazyDict = StringToIntDict[NumbersToDoubleDict];

    CrazyDict b;

    static assert(is(typeof(a) == typeof(b)));
}

Ali

On Tuesday, 2 April 2013 at 16:52:17 UTC, John Colvin wrote:

int[string][double[int[]]] a;

>
> I'm confused, did you find that definition somewhere or did you write it yourself?
>

I found the above in an example in std.conv; Thank you, but I can assure you my brain is not powerful enough to come up with such a construct.