On 06/02/2020 20:06, Andrea Faulds wrote:
Haskell has a nice approach (probably some other languages have this
too) where it has typeclasses that contain related operators, which
means that e.g. if you want to overload +, your type needs to support
Num which also contains -, *, abs, the sign function, and conversion
from integers.
[...]
Also, Haskell also lets you just define arbitrary operators, which may
even look the same as the built-in ones if you really want to, so
maybe it's a bad comparison point :p
It's interesting that in this sense, Haskell supports *both* of the
"philosophies" of overloading that I mentioned in my last message. [1]
I guess they're intended for different "levels" of programming in a sense:
- From what I've heard Haskell tries to make as little distinction
between "built-in" and "user-defined" as possible, so like Postgres, the
actual "normal" definitions of the operators need to be defined by some
low-level language feature.
- On the other hand, that low-level feature is used to build a standard
higher-level language, and that high-level language treats types as more
important than symbols.
In general, I think PHP is quite a high-level language, and doesn't tend
to let you re-define core concepts to build new versions of the
language, so the type-based approach to operator overloading feels more
in keeping to me.
If we had other low-level features - hygienic macros, meta-programming,
meta-classes, that kind of thing - then defining new meanings for
individual operator symbols would make more sense.
[1] https://news-web.php.net/php.internals/108347 - not showing on
https://externals.io for some reason
Regards,
--
Rowan Tommins (né Collins)
[IMSoP]
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