Add .NET's Tuples data type

[ghost]

.NET's System.Tuple.

[IsaacShelton]

Right now only fixed-number of type parameters are allowed, so a single Tuple type would not be possible without adding the ability to handle variadic type parameters.

However something as simple as this could do the job in the meantime:

record <$A, $B> Tuple2 (a $A, b $B)
record <$A, $B, $C> Tuple3 (a $A, b $B, c $C)
record <$A, $B, $C, $D> Tuple4 (a $A, b $B, c $C, d $D)
record <$A, $B, $C, $D, $E> Tuple5 (a $A, b $B, c $C, d $D, e $E)
record <$A, $B, $C, $D, $E, $F> Tuple6 (a $A, b $B, c $C, d $D, e $E, f $F)

or whatever your preference for naming is, and then you can use them like this:

import basics

func main {
    values <int, int, String> Tuple3 = Tuple3(10, 11, "Hello")
    printf("a=%d b=%d c=%S\n", values.a, values.b, values.c)
}