[skocznymroczny]

auto natsBelow1000 = iota(1000);

How do I pass this output to some other function without doing .array()? It's rare that you do all your processing in one method. Should I do this:

void processFurther(T)(T t) if isInputRange!T { } ?

I mean, it would probably work, but I don't like how the conditions are detached from type definitions :S

[EvenThisAcronym]

Yes, or if you don't want to use a template function, for whatever reason, you can wrap the result of iota(1000) into an InputRangeObject (see https://dlang.org/phobos/std_range_interfaces.html#InputRang... for an example).

> I don't like how the conditions are detached from type definitions

I can understand that; it's something that takes a bit of getting used to. See https://dlang.org/concepts.html for an explanation of template constraints and why they were designed this way.