Wrote a blog post about CTFE and D

[Danny Arends]

On Thursday, 30 August 2012 at 17:40:16 UTC, Philippe Sigaud 
wrote:
> On Thu, Aug 30, 2012 at 7:10 PM, Danny Arends 
> <Danny.Arends at gmail.com> wrote:
>
>>>> I wrote a blog post about the stuff I've been doing last 
>>>> weekend using
>>>> CTFE.
>>>> All comments are welcome, you can find the blog post at:
>>>>
>>>> http://www.dannyarends.nl/index.cgi?viewDetailed=00029
>
> Nice article, Danny!
>
> A few remarks:
>
> degToRad!(float,int) 45
>
> First, it seems like you missed a parenthesis pair?
>

Indeed, fixed

> The compiler will be able to determine V in degToRad, you can 
> call it like this:
>
> degToRad!(float)(45)
>
> Following bearophile's use of isFloatingPoint, you can use a 
> default
> value, if that's what you need most of the time:
>
> import std.traits;
> pure U degToRad(U = float, V)(in V deg) if (isFloatingPoint!U 
> && isIntegral!V)
> { return (deg * PI) / 180.0; }
>

Interesting, I knew about defaults but I tend to forget about 
them, when I can use them...

> Then, to call it:
>
> degToRad(45) => automatically expand to detToRad!(float,int)(45)
>
> And the same type deduction for cordic gives you
>
> cordic( degToRad(45) );
>
> instead of
>
> cordic!(float)(degToRad!(float,int) 45);
>
> In gen_trigonometric, I think the float call should be a T:
>
> result ~= cordic!T(degToRad!(float,int)(i), iter);
>

Indeed, fixed !

> =>
>
> result ~= cordic( degToRad!(T)(i), iter);
>
> And, since you know the result's size in advance, you might 
> want to
> generate it at once:
>
> T[2][] result = new (T[2][])(iter);
> foreach(i; 0 .. 360)
>     result[i] = cordic(degToRad!(T)(i), iter);
> return result;
>
> (no need for braces for a one-expression foreach)
>

Again valid point. Though the compile time benefits will be minor 
with all the memory CTFE is gobbling up anyway.

> Or even, using map:
>
> import std.algorithm, std.array;
>
> return map!( i => cordic(degToRag!(T)(i), iter) )(result).array;

I like the map syntax, that's prob. because I've got an R 
background
where we have lapply (1D) and apply (2D)

Still I don't seem to get used to the => syntax...

Thanks for the feedback,

Gr,
Danny

If I get round to it I'll also update the code to use default 
return types.
Though I like being explicit with types, if you got them flaunt 
them...