On 2010-12-18 22:50, retard wrote:
Sat, 18 Dec 2010 19:09:24 +0100, Jacob Carlborg wrote:
As Nick writes here the Scala/C#-style syntax is one suggestion. There
are also several other syntaxes available, one just have to look at
other languages to get ideas. Here's a list of the syntax used by a
couple of different language, some languages are list more than once
because they support more than one syntax. I've listed the languages in
order from, what I think, the least verbose to the most verbose
lambda/delegate syntax (the number in front of the languages is the
level of verbose, if two languages are at the same level I think they
are equally verbose).
1 D: foo(writeln(3)); // lazy argument
That's not really equivalent to lambdas. It would be unfair to not
mention Scala which also supports lazy arguments.
It depends on how you see it. It passes in a piece of code that can be
executed in "foo". And when you see if like this I think the Scala
syntax I mention below is the basically the same. (BTW, I mentioned it
was lazy argument and not a delegate).
1 Scala: foo(_ * _)
This isn't the same. _ * _ is equivalent to (a, b) => a * b
I know that, but as far as I know I cannot do the same with D's lazy
arguments.
1 Scala: foo(x => x * x)
2 C#: foo(x => x * x);
3 Scala: foo((x) => x * x)
foo(x => x * x) also works in this case
4 Python: foo(lambda x: x * x)
5 Ruby: foo { |bar| x * x }
Maybe you meant
foo { |x| x * x }
5 Ruby: foo do |x| x * x end
6 D: foo((int x) { return x * x; });
7 C++1x: foo([](int x){ return x * x; });
7 Apple's (Objective)-C(++)
block extension: foo(^(int x){ return x * x; });
8 JavaScript:
foo(function(x){ return x * x })
9 PHP: foo(function ($x) use($fooBar) {
return $x * $x; }); // "use" is used for explicitly telling what
variables should be available when the scope is gone.
Note that I have not listed any functional languages here because I've
never used one.
For example:
Lambda calculus: λx.x*x
Haskell: \x -> x * x
As you can see, most of the verbosity comes from the fact that lambdas in
D and C++ contain statements, not a single expression. It's like if-then-
else vs ternary ?: -- In languages like Scala these are the same built-in
feature.
Yeah.
--
/Jacob Carlborg
