https://github.com/filepang/proc_bind

proc_bind.rb

class CurriedProc < Proc
  attr_accessor :arity
  def parameters
    (1..arity).map { |i| [:opt, "_#{i}".to_sym] }
  end
end

class Proc
  def bind(pos, value)
    raise ArgumentError.new("wrong position of argument (#{pos} for #{arity})") unless (1..arity).include?(pos)
    ret = CurriedProc.new { |*args| call *args.insert(pos-1, value) }
    ret.arity = arity - 1
    ret
  end
end