I’m stuck. I tried wrapping up my thoughts and failed. Now I’ll just leave it as the stub it is.
Thanks, Raul, my first reaction was: Why would anyone talk about them differently? (an ignorant/arrogant reaction) Then I thought Looks like I just bought into everything I read when learning J. … and then I remembered how I am talking about J I usually say something like “In J, there’s a single compound data structure: the arbitrarily dimensioned (rectangular; homogeneous) array” So that’s why for me there hasn’t been any hurdle conceptually for I always thought of an array as something by definition composite (though maybe in edge cases containing less than two elements), a container for other things. This is both about the words “compound” and “structure”. Atoms are by definition not structured (at least when viewed as atoms; there may be structures /inside/ a box). And if we had more than this one compound data structure, all of them would eventually come down to being built from atoms. The problem arises in a language where there is no different structure showing atoms to be the necessary condition of the possibility of structures. And there isn’t even a visible syntax for the most elementary kind of array literal. It looks exactly like the syntax for an atom literal. Even lisp distinguishes visibly between a value and its singleton structure. And whenever you have only this one compound structure, it will be able to represent a list/1-D-array which may contain a single element. And that might look like it’s nothing but an atom. But it isn’t! What about Raul’s “arrays vs array contents” distinction? Atoms are ontology, the matter (and thus may be contents). Arrays are ideas, relationships between atoms. But there’s more to that distinction. At its heart, I think, there is a double meaning: We use the word “array” both for the structure and for the “array of atoms” denoting the data assembled in that structure. This actually holds for any kind of data structure. (The sentence “This array of data is given in form of an array” seems to be nonsensical. Now substitute “bunch” for the first “array”. You couldn’t say “bunch” instead of the second one. This is about grammar.) And an array can never not be an array of (possibly 0) atoms. A user is always dealing with data represented in a structure. So both with an array and its contents. She uses verbs like |. dealing with the structure, and *: dealing with the contents. But both can be called “working on an array”. Confusion galore. Having items entails being a structure. It all comes down to this distinction. Any array has items. Maybe their count is 0. Still, that would be 0 items. An item always either is a singleton (containing an atom) or an array (containing items, and eventually atoms). An atom never has items. It’s data, not structure. I’d tend to describe them simply this way: The items of A are the things (compound or not) A has been built from. It’s just like packing and unpacking, like boxing and unboxing, in multiple layers. You need to open the outermost layer first. A 3 by 4 matrix is not built from numbers, its rows are. And only after its rows all have been built, the matrix could be built /from them/. And a noun? To me, that’s on a completely different language level. It’s not by chance that we use grammar terms for telling verbs and nouns apart. If we actually had different kinds of composite data structure other than arrays, they all would qualify as nouns. The structure is the exact thing the concept “noun” is meant to not care about. Think about it: it doesn’t even care aroubt the structured/ness/ of data (atom or structure). [ It’s rather like the equivalence class of all (data and) data structures if you so will. ] Am 20.01.21 um 03:43 schrieb Raul Miller: > I had not spent enough time in nuvoc to notice this "atom is not an > array" distinction. > > Even now, looking at https://code.jsoftware.com/wiki/Vocabulary/AET#, > this distinction does not really leap out at me. > > Still... it might be useful to have a word for the thing which an > array with no dimensions (or an array whose dimensions are all 1s) > contains. (And, other arrays would also contain atoms, of course, > unless they had a dimension which was zero). > > That said... since all atoms in J are contained in arrays, from a user > perspective, this also seems like a non-issue. (Which, perhaps, is why > that distinction did not leap out at me). > > But, also, the line "An atom is a noun with the rank of zero" seems to > get at the user perspective (where we're talking about arrays rather > than array contents). > > It seems to me that if we explicitly wanted to talk about array > contents as distinct from arrays, we would emphasize that issue and > instead say that atoms cannot have rank, or something like that? [I am > not convinced that this is a good idea. Since it's more about > implementation details than the interface the user works with, nuvoc > probably isn't the place for it?] > > And, *that* said, I think what you're getting at is the clause in the > definition of "array" which says that it has more than zero > dimensions. So... as far as nuvoc's glossary is concerned, we need to > say "noun" if we want to talk about things with zero or more > dimensions. Kind of sneaky, for those of us used to using 'array' for > that purpose. > > But this gets into a bit of a bind with the definition of 'item'. > There, to stick to this usage, you would say, perhaps: "A sub-noun > whose rank is one less than that of the noun". Otherwise, a noun of > rank 1 could not have items. (But my rephrasing also feels awkward.) > > Anyways... something to think about? > > Thanks, > -- ---------------------- mail written using NEO neo-layout.org ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
