Ah, that was it; variable declarations are expressions but their value
isn't what you might think. I knew there was some reason for not
trying to use them as one.
Your extends example doesn't make any sense to me. It's the same in
java:
interface X {
int property();
}
class Y implements X {
public int property() {
return 32;
}
}
I gave you a useful definition of 'higher level'. I don't really see
how saying "But I think scala IS higher level" without either defining
what you mean or giving examples that fit my particular definition is
a good idea, given that we just got into a 200+ post mess due to
confusion about the term "complexity".
On Sep 17, 5:50 pm, Kevin Wright <[email protected]> wrote:
> On 17 September 2010 16:18, Reinier Zwitserloot <[email protected]> wrote:
>
> > Correction: In java, as in scala, all expressions "return" a value
> > (not really the right term, that. Expressions *have* a value is closer
> > to the mark). It's just that in scala more things are expressions.
> > Like "if": Expression in scala, statement in java. Not ALL things in
> > scala are expressions. Variable declarations aren't, for example.
>
> Hot from the Scala REPL:
>
> scala> val x = { val y = 32 }
> x: Unit = ()
>
> So even variable assignments evaluate to a value.
>
> > In any java library that isn't completely worthless, the code is
> > "getField()". If you get annoyed at writing out the accessor, use
> > lombok. Claiming that as a benefit to scala seems like you're grasping
> > for reasons.
>
> It's a major benefit:
>
> trait X {
> def property : Int
>
> }
>
> class Y extends X {
> val property = 32
>
> }
>
> When I use `property` from an object of type X, it really doesn't matter if
> it's implemented via a field of if it's computed.
> That freedom from having to know (or care) is a simplification to me.
>
>
>
>
>
> > A useful definition for "higher level" is that it makes invisible /
> > automated whatever's trivial detail. This is a double-edged knife,
> > though: Whether or not a detail is trivial depends on the problem. For
> > example, C conveniently abstracts away the concept of stack, but in
> > the process of doing so, removes the ability to store stacks. The JVM
> > abstracts away memory management, but in the process of doing so
> > introduces non-determinism due to gc runs.
>
> > However, with that definition scala isn't much higher than java. There
> > aren't many things that you can no longer do in scala but which you
> > can do in java, and on the flipside, there aren't many things that are
> > orders of magnitude simpler in scala than java because something has
> > been abstracted away. Scala is more a sideways step: It's operating at
> > the same general level of abstraction as java, but with a different
> > syntax, which includes more emphasis on function objects (something
> > java CAN do, but not with particularly nice syntax), as well as a less
> > rigid syntax structure, and a general more functional outlook.
>
> Function objects are just a tiny part of it, not only does Scala have
> functions that are objects, but also any arbitrary object can be made into a
> function.
> On top of this there's pattern matching, implicits (which allow for type
> classes), higher-kinded types and by-name params.
> Closures alone don't make a language higher level than Java, but Scala
> really isn't about just closures...
>
> Just compare the implementation of a heterogenous list in both
> languages:http://apocalisp.wordpress.com/2008/10/23/heterogeneous-lists-and-the...http://apocalisp.wordpress.com/2010/07/06/type-level-programming-in-s...
>
>
>
> > On Sep 17, 3:28 pm, Kevin Wright <[email protected]> wrote:
> > > I'm recently taking the position that it's impossible to state which of
> > two
> > > languages is "simpler", the term is just too heavily overloaded.
>
> > > Just pick your definition and it's trivial to show that assembly is
> > simpler
> > > than LISP, or vice-versa, but you've still achieved nothing. If we use
> > the
> > > term "higher-level" instead of "simpler", then this difficulty
> > evaporates.
>
> > > Personally I feel that Scala is simpler than Java, but that statement
> > means
> > > nothing without also explaining the particular definition of the term
> > that
> > > matters to me. In this case, it's two features of that language that
> > really
> > > stand out, and show Scala to be the higher-level language..
>
> > > 1. It has constructs that closely match the way I think about problems.
> > > When I have to mangle the design in my head so that it matches the
> > features
> > > of the target language, I perceive that as an unneccessary complication
> > in
> > > the design+implementation process.
> > > 2. Scala has a smaller general-purpose syntax that I can use accross a
> > wide
> > > range of problems, instead of a larger number special-case constructs.
> > For
> > > example:
>
> > > - Java has the ?: operator, but Scala has the much more general idea that
> > > all expressions return a value.
>
> > > - Java has a switch statement over numbers, enums and (soon) Strings,
> > wheras
> > > Scala has pattern matching that isn't limited to any type.
>
> > > - Java has primitives, and operators are limited to only working with
> > > primitives. Everything in Scala is an object, and operators are just
> > > methods.
>
> > > - Java has special behaviour for concatenating an object or primitive to
> > a
> > > string, Scala can do this with implicit conversions - a feature that's
> > > useful in many more situations.
>
> > > - To fetch a value from an object in Java, I must first know if it's a
> > fixed
> > > value or if it'll be calculated, and so use field or getField() as
> > > appropriate, Scala doesn't force this distinction and so it's enough to
> > know
> > > I'm fetching a value, the underlying logic could even be changed in the
> > > future without breaking my code.
>
> > > The ability to work with general concepts and not have to chose exactly
> > > which special feature I need in a given situation... I see that as
> > > simplifying the task of programming.
> > > I could say more, but it's probably just "simpler" to point here:
> >http://stackoverflow.com/questions/727078/whats-so-great-about-scala/...
>
> > > On 17 September 2010 11:30, Reinier Zwitserloot <[email protected]>
> > wrote:
>
> > > > That just sounds like equating "simple" to "less verbose".
>
> > > > For example, with optional () for args-less method calls, you get a
> > > > number of things which one might deem "simpler":
>
> > > > - Less characters to type and read
> > > > - The ability to not have to care about whether the doClick member is
> > > > a method or a field
>
> > > > On the other hand, you also get a few things which are decidedly more
> > > > complicated:
>
> > > > - A stylistic choice about whether or not you add the (). Having to
> > > > make an irrelevant choice of any sort clearly seems like a lack of
> > > > simplicity to me.
> > > > - The INability to tell if doClick is a field or a method. In certain
> > > > circumstances it matters, and having to look it up is more complicated
> > > > than being able to tell at a casual glance.
>
> > > > These are clearly conflicting requirements. Forcing you to care
> > > > whether doClick is a field or a method is needless complexity....
> > > > unless it isn't, in which case not being able to tell is needless
> > > > complexity. Offering the programmer the choice doesn't help, because
> > > > the choice in it self is needless complexity, and by existing we still
> > > > can't tell, given "foo.doClick", if doClick is a field or a method.
> > > > We'd have to rely on a programmer following the local style guidelines
> > > > (if, say, these state that non-fields ought to be called with parens),
> > > > which you can' even unit test. Now we're introducing needless
> > > > complexity there.
>
> > > > Oh, how complicated.
>
> > > > There's also the issue of moving complexity around to the problem
> > > > domain. My usual retort to those complaining about the complexity of
> > > > generics is simply this: Co- and Contravariance is _inherently_
> > > > complicated. When you have a problem where generics is required or
> > > > seems quite useful, then the problem has this complexity, inherently.
> > > > You can choose not to use generics, but then the complexity is just
> > > > hidden away in javadocs and a bunch of casts. You can tweak generics a
> > > > bit, declaration-site generics probably being the most drastic, but a
> > > > truly "simple" generics will never be, because co/contravariance isn't
> > > > simple.
>
> > > > So, did java become more complex when 1.5 was introduced? Yes. Does
> > > > this mean java 1.5 is worse than 1.4? No - in fact, it's better.
>
> > > > So, in certain ways, a more complex language is actually a good thing.
>
> > > > Hence my conclusion that all this talk about "complexity" is not going
> > > > to convince anybody one way or another, because its very very easy for
> > > > anyone reading the word "complexity" and imagine whatever situation is
> > > > least likely to convince them.
>
> > > > So, to try and mitigate this, here's where I believe scala has added
> > > > needless complexity:
>
> > > > Stylistic choice is EVERYWHERE. This is what, as I said, *I* mean by
> > > > DSLish features (yet another vague term that can mean just about
> > > > anything). Should I put () after an args-less method call? There's a
> > > > stylistic choice there. dots to dereference? Another stylistic choice.
> > > > Use operator overloading, or not, and if I do, left-associative or
> > > > right-associative? There's also boatloads of semantic choice in scala.
> > > > If I need to iterate over a map and, say, produce a list containing
> > > > the concatenation of each key and associated value, in java there's
> > > > really only two obvious ways to do it. Both involve looping, and the
> > > > only difference is whether I iterator over entrySet() or keySet(). In
> > > > scala, there's _way_ more choices. I can do a java-style loop, or I
> > > > can use an each construct that fills the list, or I can turn the keys
> > > > and the values into two sets, and then zip them up, functional style,
> > > > or I could use a comprehension of some sort.
>
> > > > Why is this bad:
>
> > > > Well, obviously a language can't eliminate _all_ stylistic choice. At
> > > > the very least you have to pick a name for your methods, and naming is
> > > > clearly up to you, the API author. But, scala goes _way_ too far in my
> > > > opinion. While it seems like a nice idea, give an API designer, and an
> > > > API user, the ability to write in whatever feels most natural (i.e.
> > > > readable, easy to maintain), that's great! Except when it isn't: By
> > > > introducing all these stylistic choices, you're forcing the API user
> > > > to pick at every stage. Sometimes,
>
> ...
>
> read more »
--
You received this message because you are subscribed to the Google Groups "The
Java Posse" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/javaposse?hl=en.
