It is possible to define and use first-class functions in
Ruby. They are defined using a familiar lambda notation (see below).
You can pass as many functions as you want to a function. Note that to
call the function, you use call method, just like for a
block. Syntactically, however, blocks are different from lambdas and
allow you to write more natural code where blocks are used as a "loop"
body. You cannot do it with a lambda.
###### may be used to write a traverse-like function in #################
###### Nested Array to write all other methods as calls to traverse #####
# creating a function that you can pass to another function
add_two = lambda {|x| x + 2}
p add_two.call(5)
repeat = lambda {|y, z| y.call(y.call(z))}
# functions can now be passed around
# cannot do it with blocks :-(
def call_two_functions(f1, f2)
return f2.call(f1, 5)
end
p call_two_functions(add_two, repeat)