List repetition xx

Repeat a value into a list — the list cousin of string repetition x.

xx repeats its left side into a list of that many copies. It's distinct from x (which repeats a string into a longer string): xx builds a list, x concatenates.

Building a list of copies #

say "ab" xx 3;
my @a = 0 xx 5;
say @a;

(ab ab ab)
[0 0 0 0 0]

"ab" xx 3 is a three-element list (not the string "ababab" that x would give); 0 xx 5 is the idiom for a zero-filled array.

Notes #

• Compare with string repetition x: "ab" x 3 is "ababab", while "ab" xx 3 is ("ab", "ab", "ab").
• The left side is re-evaluated each time if it's a block, so { rand } xx 3 gives three different numbers — handy for generating a list of computed values.
• Combined with a range: "-" xx $n then .join draws a separator line of length $n from list pieces.