Does D support nested Templates aka Higher Kinded Polymorphism?

sighoya sighoya at gmail.com
Tue Oct 3 12:58:47 UTC 2017


On Tuesday, 3 October 2017 at 12:09:04 UTC, rikki cattermole 
wrote:
> On 03/10/2017 1:05 PM, sighoya wrote:
>> Especially, I mean something like
>> 
>> T<S> foo(S,T)(T<S> i)
>> {
>>      ...
>> }
>
> struct Foo(T) {
> 	T value;	
> }
>
> T!S foo(S, alias T)(T!S v) { return v; }
>
>
> void main() {
> 	import std.stdio;	
> 	writeln(foo!(int, Foo)(Foo!int(1)));
> }

Cool, but it seems that only a nesting of two is allowed, right?
This one gives an error:

T!S!R bar(alias T,alias S,R)(T!S!R v) {return v;}
Error: multiple ! arguments are not allowed




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