In Regexes§
See primary documentation in context for Disable backtracking: :
The :
metacharacter disables backtracking for the previous atom. Thus, / .*: a/
does not match " a"
because the .*
matches the entire string, leaving nothing for the a
to match without backtracking.
In Variables§
See primary documentation in context for The : twigil
The :
twigil declares a formal named parameter to a block or subroutine. Variables declared using this form are a type of placeholder variable too. Therefore the same things that apply to variables declared using the ^
twigil also apply here (with the exception that they are not positional and therefore not ordered using Unicode order). For instance:
say ( 4, 5 ) :!add# OUTPUT: «-1»
See ^ for more details about placeholder variables.