[winterlight]

The interface is the same. For example, in C# you have an interface Collection, which offers a lookup method, and which both HashSet and Lists implement.

The point of the OP is that among different implementations for the same interface, choose the simplest one unless you have empirical evidence that compels you to do otherwise.

[seanmcdirmid]

Arrays didn't implement interfaces in C# until the Linq release. But the main problem is that arrays have an interface st is much more complex than just ICollection, they have functionality you don't want to be used and that should be properly encapsulated.

[smegel]

> which offers a lookup method, and which both HashSet and Lists implement

How does a List map values to key? How does it even represent them?

[winterlight]

The lookup method just checks whether an element exists in a collection or not. List and HashSet implement non-indexable collections, which have no notion of key. The Collection interface is very thin, and it's mostly used when you need to keep track of a set of elements. E.g. storing the nodes already visited in a dfs.

[smegel]

OK I know more about C# now than I ever planned on knowing.

The problem with OP comment is that KISS and premature optimization are not diametrically opposed. Thet are two separate principles that mean different things.

Premature optimization is bad, but not because it necessarily violates KISS. Similarly, many people overcomplicate code for reasons nothing to do with optimization.

His argument reminds me of people who argue against free speech generally because we already ban people shouting fire in a cinema.

[coldtea]

As tuples? You can very easily traverse the list, check for the key in the 0 index of the tuple, and get the value on the 1 index.

Not efficient, but very much possible.