When I first responded to the OP I suspect I was misreading the term "associative array" for "association list" (the particular way the OP was using hash and array reinforced that for me). But I persisted in my point because the more I think about it, I really do think that the term "associative array" is one of the not-so-smart-terms that has developed in our industry and is fundamentally misleading, despite a history that goes back at least as far as AWK.

The term 'associative array' isn't implementation free to everyone, Wikipedia and even some recent text books aside. At the bottom of the Wikipedia discussion page for "associative array" there is a brief back and forth about potential confusion between the two terms "associative list" and "associative array" (the decision was to discourage implementation specific meanings). Consider also, for example, this definition from Mastering Algorithms with C, (Kyle Louden, O'Reilly, 1999) which defines an associative array as:

Associative arrays consist of data arranged so that the nth element of one array corresponds to the nth element of another. p. 142

I agree with you that the term "hash" is also laden with implementation associations, though less so, in my opinion. Although the term hash implies a hash function (as opposed to a balanced tree which uses structure to facilitate retrieval), there are many different hash function implementations, so ultimately even a hash function is more of a concept than a specific implementation. More importantly, it is hard to make assumptions about the physical arrangement of a data structure when the "implementation" is a category of functions.

I don't think the same thing can be said of the word "array". An array is a physical structure that supports both sequenced and random access. Because its indices are integers, it has implications for ordering that are directly contradictory to the intent of the abstract meaning of the term "associative array" used in the AWK documentation or the Wikipedia definition. Both those definitions attempt to generalize the term "array" by focusing on random access (via non-numerical keys) at the expense of sequenced access.

There are, of course, better conceptual terms: "map", "dictionary", or even "association container". If we were talking Java, I would use the term Map (Java's abstract container for this purpose). However, in Perl we are stuck with "hash" and it is the Perl use of the word we need to explain.

Best, beth

In reply to Re^5: Associative array by ELISHEVA
in thread Associative array by gem555

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