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Array model: Difference between revisions
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Based array model
(→"Array languages" without arrays: I don't think the "see also" is really related? It's almost entirely true array languages.) |
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Flat array theory is often called "grounded" in contrast to "floating" nested array theory. | Flat array theory is often called "grounded" in contrast to "floating" nested array theory. | ||
== Based array theory == | |||
Based array theory discards the principle that all data should be stored in arrays, instead defining basic types such as characters and numbers independently of arrays and arrays as a collection type—possibly one of many—that can contain any data. This model does not have any widely accepted name, with the term "based system" introduced in an [[APL Quote Quad]] paper in 1981.<ref>Randall Mercer. [https://dl.acm.org/doi/abs/10.1145/586656.586663 "A based system for general arrays"]. [[APL Quote Quad]] Volume 12, Issue 2. 1981-12.</ref> However, as it is the natural model when arrays are added to an existing programming system, it is common in array libraries such as [[NumPy]], [[wikipedia:ILNumerics|ILNumerics]], and [[wikipedia:Haskell (programming language)|Haskell]]'s [https://hackage.haskell.org/package/repa Repa], as well as the language [[Julia]]. It is used by the APL-family language [[BQN]]. | |||
=== Mutable based arrays === | |||
In many languages with this array style, such as NumPy and Julia, the arrays are [[wikipedia:Immutable Object|mutable]], meaning that copies of an array can be made, so that one copy reflects changes made to any copy. In contrast, APL operations that appear to modify an array, like [[indexed assignment]], will only change the particular copy of the array used, and can be said to create a new array rather than change an existing one: there is no special connection between the old and modified array. Mutable arrays make it possible for an array to contain itself, by replacing one element of an existing array with the whole array. This means that more values are possible than in an immutable based array language, and that some properties of immutable arrays, such as a finite [[depth]], do not hold. | |||
== Other features of the array model == | == Other features of the array model == | ||