【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 
Block 与Proc的区别：
Block是代码块，Proc是对象；
参数列表中最多只能有一个Block， 但是可以有多个Proc或Lambda;
Block可以看成是Proc的一个类实例.
Proc 与Lambda 区别：
Proc和Lambda都是Proc对象；
Lambda检查参数个数，当传递的参数超过一个时，会报错，而Proc不检查，当传递参数多于一个时，只传递第一个参数，忽略掉其他参数;
Proc和Lambda中return关键字的行为是不同的.
# Block Examples
[1,2,3].each { |x| puts x*2 } # block is in between the curly braces
[1,2,3].each do |x| puts x*2 # block is everything between the do and end end
# Proc Examples
p = Proc.new { |x| puts x*2 } [1,2,3].each(&p) # The '&' tells ruby to turn the proc into a block
proc = Proc.new { puts "Hello World" }
proc.call # The body of the Proc object gets executed when called
# Lambda Examples
lam = lambda { |x| puts x*2 }
[1,2,3].each(&lam)
lam = lambda { puts "Hello World" }
lam.call
# 参数传递
lam = lambda { |x| puts x } # creates a lambda that takes 1 argument
lam.call(2) # prints out 2 lam.call # ArgumentError: wrong number of arguments (0 for 1)
lam.call(1,2,3) # ArgumentError: wrong number of arguments (3 for 1)
proc = Proc.new { |x| puts x } # creates a proc that takes 1 argument
proc.call(2) # prints out 2
proc.call # returns nil
proc.call(1,2,3) # prints out 1 and forgets about the extra arguments
# Return行为
# lambda中return跳出lambda，仍然执行lambda外部代码
def lambda_test
lam = lambda { return }
lam.call puts "Hello world"
end
lambda_test # calling lambda_test prints 'Hello World'
def proc_test
#proc中return直接跳出函数
proc = Proc.new { return }
proc.call
puts "Hello world"
end
proc_test # calling proc_test prints nothing
来源：oschina
链接：https://my.oschina.net/u/811744/blog/152802