Get Proc of current block?

[Intransition]

Is there any way to get a hold of the current block? I've been playing
around with recursive enumerations and it occurs to me that the most
flexible technique would simply be to reuse the currently running
block.

For example, where `this` would be the current block:

h = {:a=>1, :b=>{:c=>3}}

h.map{ |k,v| Hash===v ? [k.to_s, v.map(&this)] : [k.to_s,v.to_s] }

#=> {"a"=>"1", "b"=>{"c"=>"3"}}

 

[Michael Fellinger]

Is there any way to get a hold of the current block? I've been playing
around with recursive enumerations and it occurs to me that the most
flexible technique would simply be to reuse the currently running
block.

For example, where `this` would be the current block:

=C2=A0h =3D {:a=3D>1, :b=3D>{:c=3D>3}}

=C2=A0h.map{ |k,v| Hash=3D=3D=3Dv ? [k.to_s, v.map(&this)] : [k.to_s,v.to= _s] }

=C2=A0#=3D> {"a"=3D>"1", "b"=3D>{"c"=3D>"3"}}

That's called the Y-combinator, something i wish could be added to
core, but would be afraid of the many nay-sayers who are already
confused by the current number of ways of creating blocks

def y(*args, &block)
y =3D lambda{|*args| block.(*args, &y) }
end

p y{|n, acc, &b|
n < 2 ? acc : b.(n-1, n * acc)
}.(5, 1)



--=20
Michael Fellinger
CTO, The Rubyists, LLC

 

[John Barnette]

Is there any way to get a hold of the current block? I've been playing
around with recursive enumerations and it occurs to me that the most
flexible technique would simply be to reuse the currently running
block.

Limited, and pure evil:

lambda { |x| p x +=3D 1; redo }[0]

Infinitely increments. `redo` lets you restart the current block, but =
you must manipulate the original args instead of passing 'em. Don't do =
this.


~ j.

 

[Intransition]

That's called the Y-combinator, something i wish could be added to
core, but would be afraid of the many nay-sayers who are already
confused by the current number of ways of creating blocks

def y(*args, &block)
=A0 y =3D lambda{|*args| block.(*args, &y) }
end

p y{|n, acc, &b|
=A0 n < 2 ? acc : b.(n-1, n * acc)

}.(5, 1)

Helpful. Thanks. I am considering adding to Facets, but it would have
to be called #Y b/c YAML defines #y.