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While learning Ruby I've come across the "=>" operator on occasion. Usually I see it in the form of
:symbol => value and it seems to be used frequently when passing values to functions. What exactly is that operator called? What does it do/mean? Is it built into Ruby or is it something that different frameworks like Rails and DataMapper add to the symbol class? Is it only used in conjunction with the symbol class? Thanks.
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select { array. count } is a nested loop, you're doing an O(n^2) complex algorithm for something which can be done in O(n). You're right, to solve this Skizit's question we can use in O(n); but in order to find out which elements are duplicated an O(n^2) algo is the only way I can think of so far.
Short answer is no, hashes need to have unique keys.
each is just another method on an object. That means that if you want to iterate over an array with each , you're calling the each method on that array object. It takes a list as it's first argument and a block as the second argument.
=> separates the keys from the values in a hashmap literal. It is not overloadable and not specifically connected to symbols.
A hashmap literal has the form {key1 => value1, key2 => value2, ...}, but when used as the last parameter of a function, you can leave off the curly braces. So when you see a function call like f(:a => 1, :b => 2), f is called with one argument, which is a hashmap that has the keys :a and :b and the values 1 and 2.
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