Ruby

Enumerator#with yields each element along with the arguments

class Enumerator def with(*options) return to_enum(:with, *options) unless defined? yield each do |entry| yield entry, *options end end end 

Suppose we have a proc that accepts more than 1 argument.

format = proc do |value, *option| value.to_s(*option) end 

Normally to apply the argument we enclosed it in a block, like so:

(10..15).map { |n| format.(n, 16) } # => ["a", "b", "c", "d", "e", "f"] 

I found Enumerator#with_object method awkward to use.

(10..15).each.with_object(16).map(&format) # => ["a", "b", "c", "d", "e", "f"] 

Tried simplifying this code further, but Enumerator#with_object ignores the given block and just returns the argument.

(10..15).map.with_object(16, &format) # => 16 

Compare to how concise this line using Enumerator#with

(10..15).map.with(16, &format) # => ["a", "b", "c", "d", "e", "f"]