lambda recursion

[Ali Çehreli]

On 11/27/20 9:01 AM, ddcovery wrote:
> On Friday, 27 November 2020 at 16:40:43 UTC, ddcovery wrote:
>> ...
>> * Can the lambda be transformed to a template (using T instead "int") 
>> but avoiding function/return syntax?
>>
>> This is an example using function
>>
>>   template qs(T){
>>     T[] qs( T[] items ){
>>       return items.length==0
>>         ? items
>>         : chain(
>>           qs(items[1..$].filter!(i=> i<items[0] ).array),
>>           items[0..1],
>>           qs(items[1..$].filter!(i=> i >= items[0]).array)
>>         ).array;
>>     }
>> }
> 
> I mean... transform this into a lambda expression:
> 
>      T[] qs(T)( T[] items ){
>        return items.length==0
>          ? items
>          : chain(
>            qs(items[1..$].filter!(i=> i<items[0] ).array),
>            items[0..1],
>            qs(items[1..$].filter!(i=> i >= items[0]).array)
>          ).array;
>      }
> 

This has been done with the Y-combinator, where the lambda refers to 
itself as 'self':

 
https://github.com/gecko0307/atrium/blob/master/dlib/functional/combinators.d

There has been been other discussions on it on these forums.

Ali