How to instantiate a map with multiple functions

[Karthikeyan via Digitalmars-d-learn]

On Sunday, 27 December 2015 at 00:27:12 UTC, Ali Çehreli wrote:
> On 12/26/2015 11:46 AM, karthikeyan wrote:
>
> > Thanks but the following returns an error for me
> >
> >    import std.algorithm.comparison : equal;
> >    import std.range : chain;
> >    int[] arr1 = [ 1, 2, 3, 4 ];
> >    int[] arr2 = [ 5, 6 ];
> >    auto dd = map!(z => z * z, c => c * c * c)(chain(arr1,
> arr2));
> >    writeln(dd);
> >
> > Error :
> >
> > /usr/include/dmd/phobos/std/meta.d(546): Error: template
> instance
> > F!(__lambda2) cannot use local '__lambda2' as parameter to
> non-global
> > template AppliedReturnType(alias f)
>
> That looks like a bug to me. Please report here:
>
>   https://issues.dlang.org/
>
> You can call tuple() as a workaround:
>
> import std.stdio;
> import std.algorithm;
> import std.range;
> import std.typecons;
>
> void main() {
>     int[] arr1 = [ 1, 2, 3, 4 ];
>     int[] arr2 = [ 5, 6 ];
>     auto dd = map!(z => tuple(z * z, z * z * z))(chain(arr1, 
> arr2));
>     writeln(dd);
> }
>
> Ali

Thanks Ali. I think it's been around like this for a long time. I 
searched issue tracker but no issues of this type. Also if I need 
to map on a array of tuples will that work with the tuple being 
unpacked or do I need to get it as single element and do 
unpacking myself? Sorry on mobile so couldn't check.