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Re: StringBuilder Difficulties

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On 04/07/2011 3:45 PM, Robert Klemme wrote:
> On 04.07.2011 16:52, Gene Wirchenko wrote:
>> It is horribly verbose. Java: COBOL++?
>
> In part it's the price you pay for static typing

Wrong. Lots of strongly statically typed languages don't have nearly the 
verbosity, including Haskell and the ML family of languages. Generally 
what they have is very smart type inference capabilities in the 
compilers, so you have to specify types quite rarely, e.g. specifying 
the precision a literal number should be considered to have, and 
specifying argument types to functions. In-function declarations and 
sometimes return types are inferred by data flow analysis. A Java 
equivalent would be if you could do

public foobar (int a, String b) {
     x = a + b.length();
     y = 1.3*x;
     return y.toString();
}

and this would work, with the compiler first resolving .length() to 
String's method and seeing that this returns int, seeing then that a 
b.length() adds two ints so is of type int, and inferring x is an int; 
then y is a double times an int so y is a double; then resolving 
.toString(); to Double's method (post-autoboxing of y) and inferring 
that foobar's return type is String.

pubic wontwork (int a, String ) {
     x = a + b
}

blows up, meanwhile, because int + String is not defined anywhere.

In this case, x and y lack *manifest* typing but have compile-time types 
more specific than Object.

The thing is, javac already does some type inference, and indeed decides 
which .length() method is being called in line 1 and the type of the 
expression a + b.length() in exactly the way described above. It just 
won't go on to infer x's type if it's not specified. (Partly, also, the 
absence of a type before x would make declaring and initializing a local 
not look different from assigning to it. A nice rule would be that

mutable x = ...

declares and initializes a mutable local and

x = ...

declares and initializes an immutable local if no mutable x is within 
scope, and assigns to the innermost in-scope mutable x otherwise. This 
would favor less use of mutation and type inference would take much of 
the pain out of any proposed syntax for lambdas in Java, making Java 
more supportive of using a functional style in areas where that's 
appropriate and avoiding some of the mutation "side-effect spaghetti 
code" that's all too common these days.

The semantics above would be that if x isn't explicitly declared 
"mutable", it acts like in current Java when it's declared "final". 
Definite assignment rules would still apply, more-or-less unchanged, 
with "mutable x;" being allowed as "int x;" is now and

if foo
     x = baz;
else
     quux.frobnicate();
return x + 3;

being a definite assignment violation if no local x existed above "if 
foo" in that method body, a violation of finalness if a final x existed 
above "if foo" in the same block, and OK if a mutable x existed above 
"if foo" in the same scope and was definitely assigned to even if the 
else clause executed (say because it was "mutable x = 0;" at the point 
of declaration). An immutable x in a block enclosing the block but not 
in the same block as the if would create a conundrum: depending on the 
if branch taken there seem to be two different xs that the return could 
mean. I'd say though that the x = baz; creates a local x in the directly 
enclosing block that exists, but is not definitely assigned, at the 
return statement. As for

x = foo;
mutable x = bar;

in the same block: illegal. But in nested blocks, inner shadows outer as 
always.

Let me know if you find any obvious problem with the above ideas 
(besides the high improbability that Oracle will ever implement them).

> Tools are good enough these days to offload
> you from most of the hand typing via completion.

A proof of concept that javac could do more of the type-inference heavy 
lifting itself.

> If you look for a language on the JVM with less overhead maybe Scala is
> for you. Some people do find it too compact though.

Another functional language with type inference.

Define "too compact", given that it doesn't go to line-noisy extremes 
like perl.

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Thread

StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-06-28 17:54 -0700
  Re: StringBuilder Difficulties Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-28 21:29 -0400
    Re: StringBuilder Difficulties Lew <noone@lewscanon.com> - 2011-06-29 00:48 -0400
      Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-06-29 12:19 -0700
    Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-06-29 12:11 -0700
      Re: StringBuilder Difficulties Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-29 22:06 -0400
  Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-29 20:17 +0000
    Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-06-29 18:55 -0700
      Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-30 20:30 +0000
        Re: StringBuilder Difficulties Patricia Shanahan <pats@acm.org> - 2011-06-30 14:17 -0700
          Re: StringBuilder Difficulties Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-30 21:36 -0400
            Re: StringBuilder Difficulties "John B. Matthews" <nospam@nospam.invalid> - 2011-07-01 01:41 -0400
        Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-06-30 14:26 -0700
          Re: StringBuilder Difficulties Steve Sobol <sjsobol@JustThe.net> - 2011-06-30 17:33 -0700
          Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-01 20:47 +0000
            Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-01 17:29 -0700
              Re: StringBuilder Difficulties rossum <rossum48@coldmail.com> - 2011-07-02 11:36 +0100
              Re: StringBuilder Difficulties Robert Klemme <shortcutter@googlemail.com> - 2011-07-02 12:58 +0200
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-04 07:52 -0700
                Re: StringBuilder Difficulties Robert Klemme <shortcutter@googlemail.com> - 2011-07-04 21:45 +0200
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-05 02:06 -0400
                Re: StringBuilder Difficulties markspace <-@.> - 2011-07-05 09:32 -0700
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-05 14:13 -0400
                Re: StringBuilder Difficulties markspace <-@.> - 2011-07-05 12:51 -0700
                Re: StringBuilder Difficulties Silvio <silvio@moc.com> - 2011-07-05 23:16 +0200
                Re: StringBuilder Difficulties markspace <-@.> - 2011-07-05 15:08 -0700
                Re: StringBuilder Difficulties Silvio <silvio@moc.com> - 2011-07-06 09:41 +0200
                Re: StringBuilder Difficulties "eye" <eye@mocka.com> - 2011-07-06 09:55 +0000
                Re: StringBuilder Difficulties thoolen <thoolen@tholenbot.thorium> - 2011-07-06 05:37 -0400
                Re: StringBuilder Difficulties "thoolen" <thoolen@tholenbot.thorium> - 2011-07-06 08:43 -0400
                Re: StringBuilder Difficulties thoolen <thoolen@tholenbot.thorium> - 2011-07-06 22:30 -0400
                Re: StringBuilder Difficulties "Stefan Robacki" <noemail@noemail.foobar> - 2011-07-06 00:04 -0400
                Re: StringBuilder Difficulties thoolen <thoolen@tholenbot.thorium> - 2011-07-06 05:45 -0400
                Re: StringBuilder Difficulties thoolen <thoolen@tholenbot.thorium> - 2011-07-06 08:26 -0400
                Re: StringBuilder Difficulties thoolen <thoolen@tholenbot.thorium> - 2011-07-06 22:36 -0400
                Re: StringBuilder Difficulties "tholen@antispam.ham" <tholen@ifa.hawaii.edu> - 2011-07-06 06:09 -0700
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 22:40 -0400
                Re: StringBuilder Difficulties John Doe <jdoe@usenetlove.invalid> - 2011-07-14 06:50 +0000
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-14 02:58 -0400
                Re: StringBuilder Difficulties Jane Doe <jdoe@love.in.d.jungle.invalid> - 2011-07-14 10:20 -0400
                Re: StringBuilder Difficulties thoolen <tholen01@gmail.com> - 2011-07-14 07:33 -0700
                Re: StringBuilder Difficulties Stanimir Stamenkov <s7an10@netscape.net> - 2011-07-05 23:44 +0300
                Re: StringBuilder Difficulties markspace <-@.> - 2011-07-05 14:08 -0700
              Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-02 18:33 +0000
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-02 16:56 -0400
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-03 01:34 +0000
                Re: StringBuilder Difficulties Patricia Shanahan <pats@acm.org> - 2011-07-02 19:55 -0700
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-04 03:32 +0000
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-04 08:04 -0700
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-05 19:12 +0000
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-05 14:06 -0700
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-05 21:16 +0000
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-05 17:29 -0700
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-06 16:59 +0000
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 19:52 -0400
                Re: StringBuilder Difficulties Patricia Shanahan <pats@acm.org> - 2011-07-06 16:58 -0700
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 19:52 -0400
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 21:54 -0400
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 22:18 -0400
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 22:41 -0400
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-08 17:45 +0000
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 05:48 -0400
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-06 16:59 +0000
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-06 10:56 -0700
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-08 17:44 +0000
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-08 11:51 -0700
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-10 19:08 +0000
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-11 07:54 -0700
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-11 22:37 +0000
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-11 15:52 -0700
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 08:25 -0400
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 19:41 -0400
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 19:58 -0400
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 21:57 -0400
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 22:17 -0400
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 22:44 -0400
                Re: StringBuilder Difficulties Steve Erwin <trollHunter@Usenet.4.usenetizens.org.invalid> - 2011-07-07 12:51 +1000
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-06 23:02 -0400
                Re: StringBuilder Difficulties John Doe <jdoe@usenetlove.invalid> - 2011-07-14 06:32 +0000
                Re: StringBuilder Difficulties supercalifragilisticexpialadiamaticonormalizeringelimatisticantations <supercalifragilisticexpialadiamaticonormalizeringelimatisticantations@averylongandannoyingdomainname.com> - 2011-07-14 02:57 -0400
                Re: StringBuilder Difficulties Jane Doe <jdoe@love.in.d.jungle.invalid> - 2011-07-14 10:07 -0400
                Re: StringBuilder Difficulties thoolen <tholen01@gmail.com> - 2011-07-14 07:24 -0700
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-04 07:58 -0700
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-05 19:09 +0000
                Re: StringBuilder Difficulties KitKat <kitkat_11697@gmail.example.com> - 2011-07-05 15:15 -0400
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-05 20:03 +0000
                Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-07-05 14:11 -0700
                Re: StringBuilder Difficulties blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-06 16:55 +0000
      Re: StringBuilder Difficulties lewbloch <lewbloch@gmail.com> - 2011-07-03 00:08 -0700
        Re: StringBuilder Difficulties Robert Klemme <shortcutter@googlemail.com> - 2011-07-03 12:35 +0200
          Re: StringBuilder Difficulties lewbloch <lewbloch@gmail.com> - 2011-07-04 04:07 -0700
  Re: StringBuilder Difficulties Patricia Shanahan <pats@acm.org> - 2011-06-29 14:38 -0700
    Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-06-29 15:00 -0700
      Re: StringBuilder Difficulties Patricia Shanahan <pats@acm.org> - 2011-06-29 15:52 -0700
        Re: StringBuilder Difficulties Gene Wirchenko <genew@ocis.net> - 2011-06-29 18:58 -0700
          Re: StringBuilder Difficulties Patricia Shanahan <pats@acm.org> - 2011-06-29 19:26 -0700
          Re: StringBuilder Difficulties lewbloch <lewbloch@gmail.com> - 2011-07-03 00:11 -0700
  Re: StringBuilder Difficulties Roedy Green <see_website@mindprod.com.invalid> - 2011-06-29 18:32 -0700

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