How to pass functions as parameters in REBOL

Question

I have attempted to pass a function as a parameter in the REBOL programming language, but I haven't figured out the correct syntax yet:

doSomething: func [a b] [
    a b
    a b
]

doSomething print "hello" {This should pass print as the first argument and "hello" as the second argument.}

This produces an error, since the print function is being called instead of being passed:

hello
*** ERROR
** Script error: doSomething does not allow unset! for its a argument
** Where: try do either either either -apply-
** Near: try load/all join %/users/try-REBOL/data/ system/script/args...

Is it possible to pass the print function as a parameter instead of calling the print function?

Answer 1

I've found the solution: I only need to add : before the name of the function that is being passed as a parameter.

Here, the :print function is being passed as a parameter instead of being invoked with "hello" as its argument:

doSomething: func [a b] [
    a b
    a b
]

doSomething :print "hello" {This should pass print as the first argument and "hello" as the second argument.}