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I get the feeling this guy likes Lua. Lua combines arrays and dicts into "tables", which are usually indexed from 1 but can be indexed by any type as a dict. He

I get the feeling this guy likes Lua. Lua combines arrays and dicts into "tables", which are usually indexed from 1 but can be indexed by any type as a dict. He never mentions Lua, though. Multidimensional arrays are a blind spot for modern language designers. Not arrays of arrays, as this author points out. FORTRAN had multidimensional arrays, but C didn't. Go and Rust don't have them. Part of the trouble is slices. Once you have slices, people want slicing in multidimensional arrays along any axis, which complicates the basic array representation. Discussions in this area dissolved into bikeshedding and nothing got done for Go and Rust.

zahlman 1y ago
> Lua combines arrays and dicts into "tables", which are usually indexed from 1 but can be indexed by any type as a dict. I think it's more accurate to just call them hash tables ("dicts") that happen to support some very limited array-like functionality. "Appending" still looks like key insertion if you don't use a named method (https://stackoverflow.com/questions/27434142 https://stackoverflow.com/questions/27434142); `ipairs` misses those non-integer keys but also misses non-contiguous keys, or even a zero key (https://stackoverflow.com/questions/55108794 https://stackoverflow.com/questions/55108794); the `#` operator is not well defined once you add those non-contiguous keys (https://stackoverflow.com/questions/2705793 https://stackoverflow.com/questions/2705793) (so you can't actually cleanly override the choice to "start from 1"); slicing etc. aren't provided as operators (https://stackoverflow.com/questions/24821045 https://stackoverflow.com/questions/24821045); etc.
layer8 1y ago
C and C++ do have multidimensional arrays [0], in the sense that they are arrays of arrays where the inner arrays all have the same fixed size, encoded into the multidimensional array type. Likewise in Go and Rust. This is different from, say, Java, where if you have an array of arrays, the inner arrays can all have different sizes, and there is no array type that could express that they shouldn’t. Being able to express slices across arbitrary dimensions natively is another matter. [0] https://en.cppreference.com/w/cpp/language/array.html#Multidimensional_arrays https://en.cppreference.com/w/cpp/language/array.html#Multid...
marcosdumay 1y ago
> Go and Rust The trade-offs are way too severe for people to agree to any implementation in a low level language like Rust or one that wants to be low level like Go. We could get them in something like Python.

zahlman 1y ago

> Lua combines arrays and dicts into "tables", which are usually indexed from 1 but can be indexed by any type as a dict. I think it's more accurate to just call them hash tables ("dicts") that happen to support some very limited array-like functionality. "Appending" still looks like key insertion if you don't use a named method (https://stackoverflow.com/questions/27434142 https://stackoverflow.com/questions/27434142); `ipairs` misses those non-integer keys but also misses non-contiguous keys, or even a zero key (https://stackoverflow.com/questions/55108794 https://stackoverflow.com/questions/55108794); the `#` operator is not well defined once you add those non-contiguous keys (https://stackoverflow.com/questions/2705793 https://stackoverflow.com/questions/2705793) (so you can't actually cleanly override the choice to "start from 1"); slicing etc. aren't provided as operators (https://stackoverflow.com/questions/24821045 https://stackoverflow.com/questions/24821045); etc.

layer8 1y ago

C and C++ do have multidimensional arrays [0], in the sense that they are arrays of arrays where the inner arrays all have the same fixed size, encoded into the multidimensional array type. Likewise in Go and Rust. This is different from, say, Java, where if you have an array of arrays, the inner arrays can all have different sizes, and there is no array type that could express that they shouldn’t. Being able to express slices across arbitrary dimensions natively is another matter. [0] https://en.cppreference.com/w/cpp/language/array.html#Multidimensional_arrays https://en.cppreference.com/w/cpp/language/array.html#Multid...

marcosdumay 1y ago

> Go and Rust The trade-offs are way too severe for people to agree to any implementation in a low level language like Rust or one that wants to be low level like Go. We could get them in something like Python.