Multiline shebang

#!/bin/sh

#`(if running under some shell) {
    eval 'exec /usr/bin/sidef $0 ${1+"[email protected]"} "world"'
}

say "Hello, #{ARGV[0]}!"

Output:

$ ./script.sf
Hello, world!

$ ./script.sf Sidef
Hello, Sidef!

$ sidef script.sf RosettaCode
Hello, RosettaCode!