Re: Thought experiment: what would you remove from Lua

On Wed, Aug 1, 2018 at 4:50 PM, Coda Highland <chighland@gmail.com> wrote:

On Wed, Aug 1, 2018 at 4:01 PM, Andrew Starks <andrew@starksfam.org> wrote:
>
>
> On Wed, Aug 1, 2018 at 1:25 PM, Coda Highland <chighland@gmail.com> wrote:
>
>> Well, given that coroutines CAN be implemented in terms of other
>> language features, you could implement them at a higher level -- some
>> sort of automated source transformation at parse time so that the
>> VM/JIT/whatever doesn't have to worry about it. The _javascript_
>> community has done this for quite a while now in order to work around
>> lack of browser-side support, and while the generated code is really
>> hard to read it's definitely just mechanical.
>>
>> /s/ Adam
>>
>
> I think that meta-programming is a useful boarder. Whenever you're adding
> language features into the language that you're programming, you're
> meta-programming. _javascript_s lack of a concurrency framework requires
> immense amounts of meta-programming and complexity.
>
> Lua has this too, but mostly for extending existing mechanisms in particular
> directions: cqueues, object libraries and ad hoc type systems.
>
> I think that wherever there is meta programming, it's good to ask why and
> evaluate whether it's not needed or should be part of the language.
>
> --
> Andrew Starks

By that definition, working on the interpreter itself is
metaprogramming. And while that's technically true -- and other things
like building a source-to-source transpilation tool are also
metaprogramming -- that makes the distinction much less useful for
figuring out what should or shouldn't be part of a language. Because
at some point, SOMEONE has to do some metaprogramming, or else you're
never going to be able to use the language in the first place.

Likewise, it's really not fair to judge a feature by which compiler
pass it's implemented in. That's just an implementation detail and the
design of the language shouldn't have to be concerned about it.

Conversely, a different perspective: If it requires metaprogramming
hackery to be able to do something, isn't that a sign that it's
something that SHOULD be considered for addition to the language, so
that you don't have to do the hacky thing?

/s/ Adam

I can't help but think we're saying exactly the same thing. Meta programming isn't bad. It does happen and it just is. Another way to look at it is attempted growth or mutations to the language. The ones that stick and have wide use are either sufficient as libraries or big red flags that demark potential areas for change that might result in more simplicity.

Type is a great example. Lua has a little type but not a lot. It's tempting to want to extend type in the core language, but then you realize that testing takes care of a lot of the reasons why you want to check for object type. And so a type library does not come to be a required library to download in order to "really use Lua". Often you might find yourself looking in a `._class` field or something. But people do this and while there may be benifits to providing such features or enforcing limitations in the language, those decisions cut off possibilities. And that's pretty much what designing a language must come down to.

Andrew Starks
612 840 2939
andrew@starksfam.org