From: "Florian Groß" <florgro@...>
Date: 2005-08-07T02:53:06+09:00
Subject: Re: new block notation (was: Re: ruby-dev summary 26468-26661)

Yukihiro Matsumoto wrote:

> |Why not go with  lambda(arg-list) { body }  or  fun(arg-list) { body } 
> |or  def(arg-list) { body }  then? I think that the syntax would point 
> |out that this is more than a method that turns a block into an object 
> |and I think that it would be a simple solution.
> 
> Introducing a new reserved word possibly break existing code.  Besides
> that, there's no good candidate for a new keyword: lambda is too
> awkward, def is not sufficient since we don't define anything here,
> and I expect the name fun is used everywhere as local variable names.

Should be okay as long as it isn't used as a method name. The 1.9 () on 
local variables change was undone after all, right?

Having fun as a method name sounds bad. Same as having method1, method2 
etc.. It could have been used as an accessor, though, but I think 
self.fun would be save to do as well.

I'm not sure I agree with lambda being too awkward. It would be awkward 
if we didn't also have blocks.

And JavaScript uses function and C# delegate both of which are more 
awkward than lambda.

Of course there is also Perl's sub.

def might not totally fit (it doesn't bind anything to a name), but it 
might still be the best choice if no new semi-keywords should be 
introduced. There's also undef, of course, but that is a more evil 
choice. :)

> "->" might appear weird at first.  But it doesn't break any code.
> Pure addition to the current syntax.  And it's short enough to
> encourage functional programming.  The last one is my optimistic
> estimation.  There's an opposite possibility that it would be used
> only to obfuscate code.

I know that Huffman encoding is better, but I think it does not take 
into account that human beings are better at remembering words than 
symbols. OTOH symbols usually stick out more visually, but I don't think 
I consider that a good thing in the case of lambdas.

(->(a, b) { a + b }).call
{1: ->(a, b) { puts "Hello World" }}
foo(bar: ->(a, b) { a * b }, qux: ->(str) { str.reverse })
funs = [->(a, b) { a - b }, ->(a, b) { a + b}]
funs = [
   ->(a, b) { a - b },
   ->(a, b) { a + b }
]
def adder(a)
   return ->(b) { a + b }
end
adder = ->(a) do
   ->(b) { a + b }
end
search_fun = ->(x: 0, y: 0, width: @width, height: @height, type:
   Types.All, limit: @objects.size, skip: 0, destructive: false,
   &block) do
   block ||= ->(object) { true }
   found = []
   pos = 0

   @objects.reject! do |object|
     if object.x.between?(x, x + width) and
       object.y.between?(y, y + height) and
       type & object.type != 0 and
       block.call(object)
     then
       pos += 1
       if pos >= skip and pos < limit + skip
         found << object

         destructive
       end
     end
   end

   found
end



fun(a, b) { a + b }.call
{1: fun(a, b) { puts "Hello World" }}
foo(bar: fun(a, b) { a * b }, qux: fun(str) { str.reverse })
funs = [fun(a, b) { a - b }, fun(a, b) { a + b }]
funs = [
   fun(a, b) { a - b },
   fun(a, b) { a + b }
]
def adder(a)
   return fun(b) { a + b }
end
adder = fun(a) do
   fun(b) { a + b }
end
search_fun = fun(x: 0, y: 0, width: @width, height: @height, type:
   Types.All, limit: @objects.size, skip: 0, destructive: false,
   &block) do
   block ||= fun(object) { true }
   found = []
   pos = 0

   @objects.reject! do |object|
     if object.x.between?(x, x + width) and
       object.y.between?(y, y + height) and
       type & object.type != 0 and
       block.call(object)
     then
       pos += 1
       break if pos >= limit + skip
       if pos >= skip then
         found << object

         destructive
       end
     end
   end

   found
end