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Do so many languages conflate arrays and hashes? I know of PHP and JavaScript. PHP was not designed at all so no point discussing it. JavaScript was initially

• deleted 15y ago
  [deleted]
• mikeryan 15y ago
  I'm not sure if I'd characterize Javascript's handling of arrays and hashes as conflated. The two are treated differently. To take an example from the post, Javascript Objects (hashes/Associative arrays) do not have a splice function. To answer your question I don't know of many languages which conflate the two. I know a lot of languages which offer similar methods, to create parity between arrays and hashes (since they are similar enough data structures) but not many which treat them the same.
  • __david__ 15y ago
    > I'm not sure if I'd characterize Javascript's handling of arrays and hashes as conflated. Insomuch as [] and {} produce arrays and object, yes, you are correct. But those objects are strikingly similar and the functions in each prototype work on the other. To the outside observer, only the length bit works differently. I can do: a = new Array(); a["b"] = 1; for (x in a) { /* x will be "b" here*/ } a.length /* 0 */ and d = {0:"a",1:"b",2:"c",3:"d",length:4} Array.prototype.slice.call(d, 1,3) /* returns ["b", "c"] */ That's conflated a little bit.
• m0th87 15y ago
  JavaScript does not do this. It doesn't even have hashes in the traditional sense (all keys are stringified in prototypical objects).
• kylemaxwell 15y ago
  That's a good question, because hashes (especially the deliciously-named "multi-dimensional associative arrays") figure so prominently in most of the stuff I do. I'd like to think Python or maybe Ruby does this well.
• mnutt 15y ago
  Javascript doesn't really conflate arrays and hashes in the way PHP does. It uses the same bracket syntax for both, but you either instantiate an array or a hash. I don't think that allowing you to iterate over a hash as if it were an array is all that unforgivable, though it's often not the right thing to do and you can't expect the values in any particular order.
  • jleader 15y ago
    Perl has 3 ways to iterate over a hash: "keys", "values", and "each". The first two do what you'd think; "each" in array context iterates over key/value pairs. All three return their results in an "apparently random" order. You can also use "for" to iterate over a hash, same as you would over an array, but in that case the hash is converted to a list of alternating keys and values, which isn't as useful. [edited to correct a typo]
    • akronim 15y ago
      The results are random in order, but consistent between calls, so it's not all bad
      • ratsbane 15y ago
        I had to look this up because I was thinking otherwise, but now I believe you are correct - it is just inconsistent between runs: http://perldoc.perl.org/functions/each.html http://perldoc.perl.org/functions/each.html says "Hash entries are returned in an apparently random order. The actual random order is subject to change in future versions of Perl, but it is guaranteed to be in the same order as either the keys or values function would produce on the same (unmodified) hash. Since Perl 5.8.2 the ordering can be different even between different runs of Perl for security reasons (see Algorithmic Complexity Attacks in perlsec)."
  • epochwolf 15y ago
    > I don't think that allowing you to iterate over a hash as if it were an array is all that unforgivable Ruby allows this. Both arrays and hashes provide an each method and include the Enumerable module.
• masklinn 15y ago
  Javascript does not conflate arrays and hashes. Technically Javascript does not have hashes at all, and you use bare objects instead, the confusion between objects and Array comes from PHP reprobates. Lua is an other language with no arrays, and where hashes are used in stead. Additional entrants in the category are ~~Tcl~~ (got corrected, Tcl's associative arrays are called "arrays" but it has a separate "list" type for indexed sequences) and Awk.
  • jbellis 15y ago
    Tcl doesn't really fall into this category -- Tcl's hashes are called arrays, but for sequential structures you would use a list instead.
    • masklinn 15y ago
      Oh crap, the terminology got me confused, I thought they were used the same. Fixing now.
  • sjs 15y ago
    Ok don't include JavaScript. So there is only PHP that does this? I'm just trying to find out where the article is coming from. I didn't think this was a common theme amongst languages.
• IsaacL 15y ago
  Ruby 1.9 hashes preserve insertion order, so you could use them as arrays. Not sure why you'd want to, Ruby still has separate arrays.
  • lambda_cube 15y ago
    The point of preserving insertion order is not to be able to treat hashes as arrays. It's to get deterministic and repeatable iteration order between different runs. Java has LinkedHashMap and LinkedHashSet if you care about iteration order and HashMap and HashSet if you don't. With the repeatability it's easier to write automatic tests. I worked at a company making a compiler in Java and we got different binaries when compiling without changing the source code. After we changed to LinkedHashMap and LinkedHashSet that problem was gone. That's an example where we wanted the deterministic aspect of the Linked versions. Another way to get the same behavior in Java is to use TreeMap and TreeSet, but that only works if the things you put in are comparable, and you get different time complexities as well.