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All the Perl that's Practical to Extract and Report

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Static and Dynamic Types: A Definition 5 Comments More | Login | Reply /

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  • Perl's static type system cares more about containers than values. Ponder that for a while, if you really want to confuse the debate.

    • That's actually a point explicitly raised in the article. Dynamic systems focus tracking what kinds of data are used in a system, not on syntactic evaluation of expressions. See the "Problems with Common Definitions" section which begins with this:

      One common saying, quoted often in an attempt to reconcile static and dynamic typing, goes something like this: Statically typed languages assign types to variables, while dynamically typed languages assign types to values. Of course, this doesn't actually defin

      • That's not quite the same. Perl 5's built-in static types are scalar, array, and hash (and Maybe reference, if you pardon the Haskellish pun). You do get compile-time checks on using them appropriately.

        • While those three are what most people are aware of using, Perl 5 has more static types than that. For example typeglobs. Perl 5 also has a parallel static type system in its attribute system.

          That said, the article did not draw the usual simplistic divisions. And made a point of saying that many languages have both static and dynamic systems, but usually one is more fully developed. Meaning that there are classes of problems that can be solved either through a dynamic type system or a static type system

          • Inside interface boundaries, quite likely, but I suspect that the use of static types will be quite common for published APIs at least in certain kinds of domains. At the point where client code might lob parameters at you and you can’t be certain that you’ll be called correctly, you need checks on the values anyway, and it’s much easier to do that by declaring signatures than by hand-rolling validation code (or even writing validation profiles for Params::Validate or whatever). Even so I expect to see few people go whole hog and take a Haskell-level gonzo approach to types – though some will.

            It’ll be immensely interesting to watch how C6AN plays out.

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