There should be a way to call a primitive type's function by string.

[caimantilla]

It was mildly frustrating to find out that Callable only works with objects.

My understanding is that adding this functionality to non-Object types would add a lot of overhead, so I'm not asking for it to support those types. I sure don't want to grind performance to a halt just so that I can store a reference to Vector3i.clamped.
However, wouldn't it make sense if maybe there were some wrapper class that does this? Like ArrayCallable, or Vector3Callable, which would store a copy or (preferably) reference of that type and allow calling its functions that way. This could be done in GDScript, but it's... kind of a pain to solve what should be a simple problem. Execution speed would also suffer, since IIRC match statements in GDScript are syntactic sugar and every condition still needs to be checked.

A real-world example of this can be seen here. I was trying to call Array.pop_front in a while loop in my dialogue script, only to find out that every single Array function has to be hard-coded, and pop_front wasn't implemented. So, while not entirely necessary, a native class for this type of case would be incredibly helpful, although a bit of extra maintenance would be required if it can't be auto-generated.

Note 1: Maybe accepting a Variant and being called PrimitiveCallable would be ideal?
Note 2: It also might only make sense to support this for reference types (Array, Dictionary, packed arrays...)

[theraot]

You can already write your own method on your script and make a Callable out of it, or directly use a "lambda", which I believe is a good approach since you want a reference to the value and not a copy. The hassle, of course, would be making one for each method you want, but I think it will do for your situation at hand, as apparently you only need pop_front.

[dalexeev]

This is implemented for future 4.3:

• Core: Allow methods of built-in Variant types to be used as Callables godot#82264
• Core: Add Callable.create static method for Variant callables godot#88948