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Scala's mutable HashMap allocates a Some\[T] object for every successful get(key) call.
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We need lots of stacks, and since Scala's general stacks are generic collections, we created our own non-boxing flavors:
- MStack.Of\[T] - generic
- MStack.OfInt - stack of Int - non-boxing
- MStack.OfMaybe\[T] - doesn't create box for the Maybe object. Uses null for Nope, and a regular object reference for One.
- However, MStackOfMaybe\[Int] will box and unbox the Int
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If you consider that we have to avoid scala's nice generic collection functional operations like foreach and map, one might be tempted to just use the Iterator\[T] class.
However, if the generic type T here is a value type (e.g., Int, or Long or Boolean) then calling next() will return a boxed object. Whether that box is saved somewhere or is being created and discarded immediately depends on what you are iterating over.
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