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Array model: Difference between revisions
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→Based array theory: Link to WP instead of APL Wiki for NumPy and Julia
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== Based 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 has also been promoted with the mnemonic "APL+1" by Jacob Brickman<ref>Jacob Brickman. "Behavior of APL primitives in a system with depth-1 scalars (APL+1)". [[APL-Germany]] ''APL-Journal'' 2019 1-2 ([https://apl-germany.de/wp-content/uploads/2020/06/APL_Journal_2019_12.pdf#page=5 pdf]).</ref>, and is used by the APL-family language [[BQN]]. | 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 [[wikipedia:NumPy|NumPy]], [[wikipedia:ILNumerics|ILNumerics]], and [[wikipedia:Haskell (programming language)|Haskell]]'s [https://hackage.haskell.org/package/repa Repa], as well as the language [[wikipedia:Julia (programming language)|Julia]]. It has also been promoted with the mnemonic "APL+1" by Jacob Brickman<ref>Jacob Brickman. "Behavior of APL primitives in a system with depth-1 scalars (APL+1)". [[APL-Germany]] ''APL-Journal'' 2019 1-2 ([https://apl-germany.de/wp-content/uploads/2020/06/APL_Journal_2019_12.pdf#page=5 pdf]).</ref>, and is used by the APL-family language [[BQN]]. | ||
=== Mutable based arrays === | === Mutable based arrays === | ||
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In nested APLs, a simple non-scalar array has depth 1, an array containing only depth 1 arrays has depth 2, and a simple scalar (e.g a number or character) has depth 0. | In nested APLs, a simple non-scalar array has depth 1, an array containing only depth 1 arrays has depth 2, and a simple scalar (e.g a number or character) has depth 0. | ||
Most APLs provide a Depth function < | Most APLs provide a Depth function <syntaxhighlight lang=apl inline>≡</syntaxhighlight> to find an array's depth. For example: | ||
< | <syntaxhighlight lang=apl> | ||
≡('ab' 'cde')('fg' 'hi') | ≡('ab' 'cde')('fg' 'hi') | ||
3 | 3 | ||
</ | </syntaxhighlight> | ||
APLs vary in their definition of depth: for example some may return the depth with a sign to indicate that some level of the array mixes elements of different depths. | APLs vary in their definition of depth: for example some may return the depth with a sign to indicate that some level of the array mixes elements of different depths. | ||