Ruby

just idea.

class Symbol def ~@ self.to_proc end end case 0 when ~:zero? p :zero end 

What about allowing syntax like this:

->&Proc.new{|y| y.zero?} #=> Should be equivalent to ->{|x| x.zero?} ->&:zero? #=> Should be equivalent to ->{|x| x.zero?} (Symbol#to_proc applies implicitly) 

This would be a parallel to

[*["foo"]] #=> ["foo"] [*{foo: "bar"}] #=> [[:foo, "bar"]] (Symbol#to_a applies implicitly) 

under the understanding that what [] is to * (converse operation) is what -> is to &.

Then, we would be able to do:

case 0 when ->&:zero? p :zero end 

Yukihiro Matsumoto wrote:

The original idea includes dispatch based on type (Symbol), which is not a good idea in general.

I'm not sure I understand. I think the original idea would work for other types too; the syntax would just be a shortcut for a call to to_proc.

For example, I'd expect the following to work too:

x = Object.new def x.to_proc -> { true } end case 42 when &x puts "Always true" end