Tuples are a fixed-order, fixed-size collection of values which do not all have to be of the same type.

var myPair: tuple<int, string> = (1, "one");

# Claro will interprate literal int subscripts at compile-time for type validation.
var myInt: int = myPair[0]; 
var myStr: string = myPair[1]; 

# Claro requires a type cast for non-literal index.
var index: int = ...;
myInt = myPair[index]; # Compile Error
myInt = (int) myPair[index]; # OK, opting into runtime type validation.

You can see in the example above, tuples interact w/ type validation in an interesting way worth making note of. When you index into a tuple, you should generally prefer to use a literal int constant. When you do, Claro can statically determine the type of the value you're accessing at compile time, which allows cleaner, safer code. If your index value is hidden behind some indirection, Claro can't know the type at compile-time and will require a runtime type cast (which is slow & unsafe).