Perl6

Fibonacci in Perl6.

my @fib := (0, 1, *+* ... *);

Can your toy language do this?

>>1
The right question would be: "Should it be able to do it?"

How often do you need a specialised sequence operator distinct from the normal ".." range operator. The operator isn't bad per se and I'm sure if you do need it it's very useful but I think it belongs into a math library, not the core language.