I understand the point of lazy evaluation but I often want to use the lazy algorithm library functions in an eager way. Other than looping through them all which feels rather messy is there a good way of doing this?

Is there a reason not to allow the following to be automatically treated eagerly or is there some kind of cast or conv way of doing it?

	int[] test1 = [1,2,3,4];
	int[] test2 = map!("a + a")(test1); //Eager, not allowed

	auto test3 = map!("a + a")(test1); //Lazy

On Tue, 20 Mar 2012 18:36:46 +0100, ixid <nuaccount@gmail.com> wrote:

> I understand the point of lazy evaluation but I often want to use the lazy algorithm library functions in an eager way. Other than looping through them all which feels rather messy is there a good way of doing this?
>
> Is there a reason not to allow the following to be automatically treated eagerly or is there some kind of cast or conv way of doing it?
>
> 	int[] test1 = [1,2,3,4];
> 	int[] test2 = map!("a + a")(test1); //Eager, not allowed
>
> 	auto test3 = map!("a + a")(test1); //Lazy

std.array includes a method, array(), for doing exactly this:
int[] test2 = array(map!"a+a"(test1)); //eager

simendsjo:

> std.array includes a method, array(), for doing exactly this:
> int[] test2 = array(map!"a+a"(test1)); //eager

With 2.059 you can write that also in a more readable way, because there is less nesting:

int[] test2 = test1.map!q{a + a}().array();

Bye,
bearophile

Thanks, very handy!

On 03/20/2012 10:50 AM, bearophile wrote:
> simendsjo:
>
>> std.array includes a method, array(), for doing exactly this:
>> int[] test2 = array(map!"a+a"(test1)); //eager
>
> With 2.059 you can write that also in a more readable way, because there is less nesting:
>
> int[] test2 = test1.map!q{a + a}().array();

Going off-topic but there is also the new => lambda syntax:

    int[] test2 = test1.map!(a => a + a)(test1).array();

Although, it makes it longer in cases like the one above. :)

By the way, is there a name for "the => syntax"?

>
> Bye,
> bearophile

Ali

On Tue, Mar 20, 2012 at 02:52:05PM -0700, Ali Çehreli wrote: [...]
> By the way, is there a name for "the => syntax"?
[...]

You just named it. :-)


T

-- 
"Real programmers can write assembly code in any language. :-)" -- Larry Wall