8 ms·

What does the &: do in Ruby?

• raganwald 19y ago
  Actually, it's &(:+) not &:(+). The & takes its argument and converts from a Proc to a block. :+ is a symbol that implements the method #to_proc to give you a block that sums its receiver and its argument.
  • kommissar 19y ago
    Oh, cool. I knew the colon meant a Ruby symbol, but I did not know that you could use & to convert a Proc to block.
• Darmani 19y ago
  Tokens beginning with a colon are literal Ruby symbols. Prepending an ampersand before the last argument of a method call means that argument should be converted into a Proc and sent as a callback block to that method.