import std;
struct sumrange(E){
	//void* me;
	//TypeInfo meta;
	E delegate() front_;
	E front()=>front_();
	void delegate() popFront_;
	void popFront()=>popFront_();
	bool delegate() empty_;
	bool empty()=>empty_();
	void opAssign(T)(ref T t){
		//me=cast(void*)&t;
		static assert(is(typeof(t.front())==E));
		front_=cast(E delegate())&t.front;
		popFront_=cast(void delegate())&t.popFront;
		empty_=cast(bool delegate())&t.empty;
	}
}

unittest{
	sumrange!int foo;
	auto bar=iota(int(10));
	foo=bar;
	foreach(i;foo){
		i.writeln;
	}
	auto bar2=[1,2,3].map!(a=>a);
	foo=bar2;
	foreach(i;foo){
		i.writeln;
	}
	auto bar3=only(1);
	foo=bar3;
	foreach(i;foo){
		i.writeln;
	}
	//foo=iota(10.0);//Error: static assert:  `is(double == int)` is false
}

Using sumtype or choice to get ranges to actually work in dense metaprogramming is very very hard; this looks like it will just work. Id ship it. Maybe aim for SumRange!(ForwardRange!int), SumRange!(BidirectionalAssignable!float) to match upstream style guide

On Wednesday, 24 September 2025 at 00:12:40 UTC, monkyyy wrote:

Please make that a DUB package.

On Wednesday, 24 September 2025 at 02:15:40 UTC, Kapendev wrote:

Only fake anime watchers dub

On Wednesday, 24 September 2025 at 00:12:40 UTC, monkyyy wrote:

import std;
struct sumrange(E){
	//void* me;
	//TypeInfo meta;
	E delegate() front_;
	E front()=>front_();
	void delegate() popFront_;
	void popFront()=>popFront_();
	bool delegate() empty_;
	bool empty()=>empty_();
	void opAssign(T)(ref T t){
		//me=cast(void*)&t;
		static assert(is(typeof(t.front())==E));
		front_=cast(E delegate())&t.front;
		popFront_=cast(void delegate())&t.popFront;
		empty_=cast(bool delegate())&t.empty;
	}
}

unittest{
	sumrange!int foo;
	auto bar=iota(int(10));
	foo=bar;
	foreach(i;foo){
		i.writeln;
	}
	auto bar2=[1,2,3].map!(a=>a);
	foo=bar2;
	foreach(i;foo){
		i.writeln;
	}
	auto bar3=only(1);
	foo=bar3;
	foreach(i;foo){
		i.writeln;
	}
	//foo=iota(10.0);//Error: static assert:  `is(double == int)` is false
}

std.range.interfaces already does this:

import std.range.interfaces;
import std.range;
import std.algorithm;
import std.stdio;

void main()
{
    InputRange!int foo;

    auto bar1 = iota(10);
    foo = bar1.inputRangeObject;
    foreach (i; foo)
        writeln(i);

    auto bar2 = [1, 2, 3].map!(a => a);
    foo = bar2.inputRangeObject;
    foreach (i; foo)
        writeln(i);

    auto bar3 = only(1);
    foo = bar3.inputRangeObject;
    foreach (i; foo)
        writeln(i);
}