How do I pass an argument to array.map short cut? [duplicate]

Question

Given the following array a:

a = [1, 2, 3, 4, 5]   

How do I do:

a.map { |num| num + 1 }   

using the short notation:

a.map(&:+ 1)   

or:

a.map(&:+ 2)   

where 1 and 2 are the arguments?

Answer 1

In this case you can do

a.map(&1.method(:+)) 

But only because 1 + x is usually the same as x + 1.

Here is a discussion of this practice in a performance context.