Where and when to use Lambda?

Question

I am trying to understand why do we really need lambda or proc in ruby (or any other language for that matter)?

#method
def add a,b
  c = a+b
end

#using proc
de         


        

Answer 1

It comes down to style. Lambdas are a a declarative style, methods are an imperative style. Consider this:

Lambda, blocks, procs, are all different types of closure. Now the question is, when and why to use an anonymous closure. I can answer that - at least in ruby!

Closures contain the lexical context of where they were called from. If you call a method from within a method, you do not get the context of where the method was called. This is due to the way the object chain is stored in the AST.

A Closure (lambda) on the other hand, can be passed WITH lexical context through a method, allowing for lazy evaluation.

Also lambdas naturally lend themselves to recursion and enumeration.