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Groups > comp.lang.forth > #49545

Simple filtering

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Barry Margolin wrote:

> In article ... (Christopher Dollin) writes:
> >So suppose someone says "please implement 'remove-if-not'. I would like
> >your solution to generate no garbage if possible and to be reasonably
> >efficient".
> 
> Here's a version I threw together quickly (note that it doesn't take
> any options as the CL version does, and it only accepts a list, not
> any sequence):
> 
> (defun simple-remove-if-not (test list)
>   (let ((result nil))
>     (dolist (item list)
>       (unless (funcall test item)
>         (push item result)))
>     (nreverse result)))

OCaml:

open List ;;

let my_filter test list =
  rev (fold_left
        (fun result x -> if test x then x::result else result)
        []
        list) ;;

my_filter (fun x -> 0=x mod 2) [0;2;3;4;5];;
 ===>
0; 2; 4]

my_filter (fun s -> String.length s > 2)
  ["a";"or";"and";"morose";"soar"] ;;
 ===>
["and"; "morose"; "soar"]

In Forth?

-- 
The former leader of the National Front Jean-Marie Le Pen was fined 30,000
euros for exposing the Jews Holocaust gas chamber hoax.
infostormer.com/jean-marie-le-pen-fined-30000-euros-for-exposing-jewish-holocaust-gas-chamber-hoax

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Simple filtering "WJ" <w_a_x_man@yahoo.com> - 2016-07-26 18:37 +0000

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