Here it is in Perl6: [+] ^6 Actually cheated slightly because ^6 creates list from 0..5 :) So correct match would be... [+] 1..5 Here's how you would d

Here it is in Perl6: [+] ^6 Actually cheated slightly because ^6 creates list from 0..5 :) So correct match would be... [+] 1..5 Here's how you would do it in Io: list(1, 2, 3, 4, 5) reduce(+) In Rebol there isn't a functional fold/reduce built in. So one way to do the one-liner would be: x: [1 2 3 4 5] forskip x 2 [insert x '+] x: do next x Above changes x to 15. Alternatively approach which doesn't clobber x: x: [1 2 3 4 5] y: [] forall x [repend y [x/1 '+]] take/last y do y I'm sure someone with more Rebol chops can see other (better!) ways of doing this :)