CODEWITHSUNDEEP
rebolred-lang
Wolfram Kriesing
Wolfram Kriesing

Reputation: 1527

How can I pass around a function with args, in red?

How can I pass a function as an argument in red? Or would I not need that in red?

Using does I can define a function "with no arguments or local variables"

f: does [print 1] do f
>> 1

How can I make this work with (multiple) args? does is no the way, what is?

I want something like: (the following does NOT work):

; does NOT work
f: does-with-args [x][print x] do f 23
>> 1

In the last paragraph of this article http://blog.revolucent.net/2009/05/javascript-rebol.html the author says "allow functions to be passed as arguments" so I got excited, but it's also just using does :). But I learned it's possible.

Upvotes: 3

Views: 199

Answers (1)

rgchris
rgchris

Reputation: 3718

How can I pass a function as an argument in red?

It doesn't seem this is the essence of your question, but you can pass a function as an argument in a couple of ways:

my-func: func [their-func [any-function!]][their-func "Stuff"]

my-func :print
my-func func [thing][probe uppercase thing]

How can I make this work with (multiple) args?

There are two possibilities here. One is APPLY:

my-func: func [thing][print uppercase thing]
apply :my-func ["Foo"]

Another is to build up a block and DO it:

do collect [keep 'my-func keep "Bar"]
do collect [keep :my-func keep "Baz"] ; keeps the function itself

Upvotes: 3

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