On Sunday, 23 May 2021 at 08:35:31 UTC, Tony wrote:
Why is metaprogramming added features better than the same
features added in the language? One is standard between
entities, the other is not.
Some points:
- Some features aren't general enough to be added as builtin but
make sense to have them in libraries
- library features could be extended and modified arbitrarily
which isn't possible with builtin features
- if better library features are found they can simply be removed
from the library while probably breaking the library, it doesn't
break the language which is much of a bigger problem
- most problems with builtin features is that they overwrite
grammar for a certain scope a.k.a syntactic sugar leading to
learn new rules/a new language (see C++) while a general
framework would reuse the same grammar again and again providing
uniformity
- most builtin features are added incrementally to a language in
order to be predictable/implementable, unfortunately this leads
often to fragmentation because later with enough practical
experience you see another approach to solve the problem, making
this approach available may overlap with the feature you already
added, i.e. it solves to some extent the same problems but with
other tradeoffs making it hard to choose the right approach.
There are also disadvantages, among them the locality/globaility
problem: Implementing features via macros may need context
information and other existing features need to be informed of
the new feature in order to handle it correctly which would
require many hooks which can't be solved solely with macros. We
would require massive compiler reflection support for this.
Further, it is unclear how it would behave at boundaries where
hooks would collide with each other.
