Perl6 search then replace with output of subroutine

Question

I've combed the docs but I can't seem to find how to do this in perl6.

In perl5 I would have done (just an example):

sub func { ... }

$str =~ s/needle/func($1)/e;

i.e. to replace 'needle' with the output of a call to 'func'

Answer 1

Ok so we'll start by making a function that just returns our input repeated 5 times

sub func($a) { $a x 5 };

Make our string

my $s = "Here is a needle";

And here's the replace

$s ~~ s/"needle"/{func($/)}/;

Couple of things to notice. As we just want to match a string we quote it. And our output is effectively a double quoted string so to run a function in it we use {}. No need for the e modifier as all strings allow for that kind of escaping.

The docs on substitution mention that the Match object is put in $/ so we pass that to our function. In this case the Match object when cast to a String just returns the matched string. And we get as our final result.

Here is a needleneedleneedleneedleneedle