DRYing up Rock Paper Scissors

Question

I\'m a novice ruby programmer and although this code works, I\'m wondering how I can improve it. I have very limited knowledge on lambdas and procs and the like, but any advice

Answer 1

Here are a couple of ways:

#1 Use Array#cycle

OPS = %w[rock paper scissors]

def rps(roll)
  pick = OPS.sample
  enum = OPS.cycle
  (prev = enum.next) until enum.peek == roll
  return [pick, "lose"] if prev == pick
  enum.next
  return [pick, "win"] if enum.peek == pick
  [pick, "tie"]
end

rps "scissors" #=> ["scissors", "tie"] 
rps "scissors" #=> ["scissors", "tie"] 
rps "scissors" #=> ["rock", "win"] 
rps "scissors" #=> ["paper", "lose"] 

#2 Take @MurifoX's answer one step farther

def rps(roll)
  roll_ops = %w|rock paper scissors|
  h = (roll_ops + [roll_ops.first]).each_cons(2).
    with_object(Hash.new("tie")) { |(a,b),h| h[[a,b]]="lose"; h[[b,a]]="win" }
  pick = roll_ops.sample
  [pick, h[[roll,pick]]]
end

rps "scissors" #=> ["rock", "lose"] 
rps "scissors" #=> ["scissors", "tie"] 
rps "scissors" #=> ["paper", "win"] 

Here:

h #=> {["rock", "paper"]=>"lose", ["paper", "rock"]=>"win",
  #    ["paper", "scissors"]=>"lose", ["scissors", "paper"]=>"win",
  #    ["scissors", "rock"]=>"lose", ["rock", "scissors"]=>"win"} 

and because of the default value "tie":

h[["rock", "rock"]]         #=> "tie"
h[["paper", "paper"]]       #=> "tie"
h[["scissors", "scissors"]] #=> "tie"