D Recurrences

[Ben Grabham]

On 09/06/11 16:19, Ben Grabham wrote:
> Hey,
>
> Shouldn't both these programs output the fibonnacci numbers? Only the
> first one does.
>
> import std.range;
> import std.stdio;
> int main() {
> auto a = recurrence!("a[n-1] + a[n-2]")(0,1);
> int i = 0;
> foreach(int n; a) {
> if(i++ > 20) break;
> writefln("%d", n);
> }
> return 0;
> }
>
>
>
> import std.range;
> import std.stdio;
> int main() {
> auto a = recurrence!("a[n-1] + (n < 2 ? 0 : a[n-2])")(1);
> int i = 0;
> foreach(int n; a) {
> if(i++ > 20) break;
> writefln("%d", n);
> }
> return 0;
> }

Also, is there a takeWhile function?
I can't find one in the documents...