Ruby Hash Tricks
Some really cool tricks with Ruby hashes–if you supply a block to Hash.new, that will act as a default value for a given key. For example, here’s a Fibonacci hash I put together which caches the values (making it pretty quick):
fibonacci = Hash.new do |h,k|
if k < 2
h[k] = k
else
h[k] = h[k-1] + h[k-2]
end
end
fibonacci[6] # => 8
fibonacci[100] # => 354224848179261915075