assign your ImmutableList to a var and you have to declare the
generic. I was just pointing out that this is language design issue,
not static typing. And of course the issues also go into library
design.
Ya, the blah.join().sort() was a typo, should be blah.sort().join("
"). You get the point. I was just putting a quick example out
there.
As far as the << this code would have been more compelling:
blah << "another" << "one"
of course there is no reason it couldn't be
blah.add("another").add("one")
Seems like you read the code, but not the text.
as I said in my post: "IMO many of the perceived advantages of
dynamic typing have nothing to
do with dynamic typing - it's a result of language design."
I also said:
"I think having an option for dynamic typing is hugely powerful. I
would just prefer that it's not my ONLY option. Most of the time
static typing is great and makes me more productive."
On Apr 25, 6:27 am, Reinier Zwitserloot <[email protected]> wrote:
> Whatever are you on about, Phil?
>
> Point-by-point:
>
> 1. blah = ["this", "argh", "d'oh", "world", "hello"]
>
> Two points. (A) Making explicit lists immutable is obviously a good
> idea. 99.9% of them were never meant to grow or shrink and if you hand
> out reference to these lists this invariant is screwed up for
> everybody. So, +1 for immutable lists when explicitly listing its
> contents like this. In java:
>
> List<String> blah = ImmutableList.of("this", "argh", "d'oh", "world",
> "hello");
>
> Note how "List<String>" is in fact inferred; for example, you can do
> this:
>
> ImmutableList.of("this", "argh", "d'oh", "world",
> "hello").get(0).toLowerCase();
>
> No mention of "String" anywhere in that entire snippet and yet it'll
> compile, because String is inferred.
>
> 2. blah << "another"
>
> It's programming, not cartoon swearing. Left shift has zip squat to do
> with adding things to lists, so this kind of code is silly. However,
> in java:
>
> blah.add("another")
>
> which is just as short, so I'm confused as to why you think this "<<"
> malarkey is such an improvement. Note that .add() unfortunately is
> allowed by the compiler but would fail at runtime if we had our
> ImmutableList created in step 1. This is not a failing of static
> typing systems. On the contrary, it's a failure of java and the google
> collections API (understandable, they wanted to be compatible with the
> java.util. interfaces) to not use the static typing system provided
> properly. A proper design here would have:
>
> public interface List {} // contains only get(), size(), contains(),
> and other non-mutating methods.
> public interface ImmutableList extends List {} // Doesn't add anything
> but highlights that immutability is guaranteed
> public interface MutableList extends List {} // Adds clear, set,
> remove, add, etc.
>
> If this design had been carried through, the compiler would have
> stopped you from trying to add to it. One way or another. Way 1:
>
> MutableList<String> list = ImmutableList.of("1", "2", "3"); //FAIL -
> the 'of' method doesn't return a MutableList.
>
> Way 2:
>
> List<String> or ImmutableList<String> list = ...;
> list.add("foo"); // FAIL - Lists and ImmutableLists do not support the
> add method.
>
> So, static typing wins the day.
>
> 3. blah.join("").sort()
>
> I'm assuming this is a typo. You're sorting a string, which is
> impossible. Perhaps you meant blah.sort().join("")? In that case, in
> java:
>
> Joiner.on("").join(Collections.sort(blah))
>
> I fully agree that 'Collections.sort(blah)' instead of blah.sort() is
> an ugly wart, but this is mostly a failure of java not supporting
> traits nor extension methods. It could have been added and it almost
> was, for java 7. Joiner's API shows that there's some advantages in
> using a separate hierarchy; it has a few more options than python's
> join.
>
> NB: These examples require the google collections API.
>
> On Apr 24, 4:03 pm, "[email protected]" <[email protected]>
> wrote:
>
>
>
>
>
> > First, please don't call a dynamically typed language "weakly typed".
> > All the languages we are talking about here: python, ruby, groovy,
> > perl are STRONGLY typed. They are just dynamically typed, not
> > statically typed. http://en.wikipedia.org/wiki/Dynamic_type
>
> > IMO many of the perceived advantages of dynamic typing have nothing to
> > do with dynamic typing - it's a result of language design.
>
> > There is no reason this code can't be statically typed:
>
> > blah = ["this", "argh", "do'h", "world", "hello"]
> > blah << "another"
> > blah.join(" ").sort()
> > println(blah)
>
> > >> another argh do'h hello this world
>
> > It's obviously an array of string, which can be inferred.
> > The java equivalent would suck in comparison.
>
> > I am watching Charles Nutter's work on Duby, which is a statically
> > typed Ruby on the JVM. Really cool stuff IMO.
> > http://github.com/headius/duby
> > &http://blog.headius.com
> > It's statically typed, but he is adding in optional dynamic typing.
>
> > I think having an option for dynamic typing is hugely powerful. I
> > would just prefer that it's not my ONLY option. Most of the time
> > static typing is great and makes me more productive. However, there
> > are cases in which dynamic typing is very handy:
>
> > In Ruby's Active Record -
> > user = User.findByName("phil")
> > println "user = #{user.name} : #{user.location}"
>
> > >> user = phil : denver, co
>
> > this does a query "select * from user where name = 'phil'"
> > so "findByName" is a dynamic method and the user model creates/methods
> > based on the result set (user.id, user.name). Powerful stuff!
>
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