[REBOL] Re: Functional programming in REBOL
From: g:santilli:tiscalinet:it at: 8-Aug-2001 23:40
Hello Larry!
On 08-Ago-01, you wrote:
LP>> pa2: func [f x] [
LP>> use [ff xx] [
LP>> xx: :x
LP>> ff: :f
LP>> func [y] [ff xx y]
LP>> ]
LP>> ]
LP> Yes, I have a set of higher-order funcs written in exactly
LP> that fashion. But I don't like it. Renaming all the variables
LP> in the code block is ugly, and it seemed to me the approach
LP> would be cumbersome (and perhaps diffcult) to generalize for
LP> creating the generic cfunc. I think changing only the spec
LP> blocks as in cfunc or Ladislav's e-func is preferable.
Yes, of course you can also write:
pa2: func [f x /local w] [
w: use [f x] ['f]
set bind [f x] w reduce [:f :x]
func [y] bind [f x y] w
]
Of course all this can be generalized.
LP> I really liked that one. Unfortunately, it doesn't pass the
LP> mystery test as shown in the console session below where I
LP> have renamed your version to pa4.
[...]
LP>>> type? mystery4 :+
LP> ** Script Error: y expected value1 argument of type: number
LP> pair char mone y date time tuple
So that would need to be changed to:
pa4: func [f x] [
func [y] reduce [:f :x to-get-word 'y]
]
or (will have problems with blocks):
pa4: func [f x] [
func [y] compose [(:f) (:x) :y]
]
or even:
pa4: func [f x] [
func [y] reduce [get 'f get 'x 'get to-lit-word 'y]
]
or any other variant.
Regards,
Gabriele.
--
Gabriele Santilli <[giesse--writeme--com]> - Amigan - REBOL programmer
Amiga Group Italia sez. L'Aquila -- http://www.amyresource.it/AGI/
