In Examples 6.43 and 6.72 we suggested that a Ruby proc (a block, passed to a function as an implicit extra argument) was “roughly” equivalent to a lambda expression. As it turns out, Ruby has both...

In Examples 6.43 and 6.72 we suggested that a Ruby proc (a block, passed to a function as an implicit extra argument) was “roughly” equivalent to a lambda expression. As it turns out, Ruby has both procs and lambda expressions, and they’re almost—but not quite—the same. Learn about the details, and the history of their development. In what situations will a proc and a lambda behave differently, and why?