Functional programming with Ruby

Question

Ruby has support for functional programming features like code blocks and higher-level functions (see Array#map, inject, & select).

How can I write functional code in Ruby?

Would appreciate examples like implementing a callback.

Look over this http://stackoverflow.com/questions/159797/is-ruby-a-functional-language — Bijendra, Sep 10 '13 at 18:51
Follow this thread: http://stackoverflow.com/questions/3833372/functional-code-examples-in-ruby — vinchinzu, Sep 10 '13 at 18:55
@SergioTulentsev, maybe it is not pure functional, but supports some paradigms of functional programming. — khanmizan, Sep 10 '13 at 19:00
An example like "how to implement callback" isn't much good for this question, because callbacks aren't really the way you do things in pure functional programming. A function called asynchronously can't rely return anything, and do can't do anything useful without side effects. — Ben, Sep 10 '13 at 21:24

score 0 · Answer 1 · answered Sep 10 '13 at 21:16

You could use yield

def method(foo,bar)
    operation=foo+bar
    yield operation
end

then you call it like this:

foo=1
bar=2
method(foo,bar) {|result| puts "the result of the operation using arguments #{foo} and #{bar} is #{result}"}

the code in the block (a block is basically "a chunk of code" paraphrasing ruby programmers) gets executed in the "yield operation" line, you pass the method a block of code to be executed inside the method defined. This makes Ruby pretty versatile language.

In this case yield receives an argument called "operation". I wrote it that way because you asked for a way to implement a callback.

but you could just wrote

def method()
  puts "I'm inside the method"
  yield
end

method(){puts "I'm inside a block"}

and it would output

I'm inside the method   
I'm inside a block

Functional programming with Ruby

1 Answers1