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Programming-Idioms

Produce a new list y containing the result of the function T applied to all elements e of the list x that match the predicate P.
New implementation

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Be useful.

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Other implementations
(def y 
  (eduction (filter P)
            (map T))
            x)
#include <ranges>
#include <iterator>
constexpr auto transform_matches(const auto& x, auto p, auto t) {
    auto result = x 
	| std::views::filter(p)
        | std::views::transform(t);

    std::vector<std::ranges::range_value_t<decltype(result)>> y;
    std::copy(result.begin(), result.end(), std::back_inserter(y));
    return y;
}
template <typename SeqT>
auto transform_copy_if(const SeqT i, auto p, auto f)
{
 using namespace std;

 SeqT o;

 for_each(begin(i), end(i),
          [&](const auto& x) {
              if(p(x))
               o.push_back(f(x));
          }
         );

 return o;
}
using System.Linq;
var y = x.Where(P).Select(T).ToList();
import std.algorithm;
y = x.filter!(P).map!(T);
var y = x.where(P).map(T).toList();
y = x
|> Enum.filter(&P/1)
|> Enum.map(&P(&T/1)
y = pack (t(x), mask=p(x))
var y []Result
for _, e := range x {
	if P(e) {
		y = append(y, T(e))
	}
}
def y = x.findAll(p).collect(t)
y = (map t . filter p) x
y = x.filter(e => P(e)).map(e => T(e))
import java.util.stream.Collectors;
x.stream().filter(P).map(T).collect(Collectors.toList());
(defvar y (mapcar #'T (remove-if-not p x)))
$y = array_map('T', array_filter($x, 'P'));
uses classes;
type
  TListPredicate = function(e: pointer): Boolean;
  TListElementFunc = function(e: pointer): pointer;

function NewList(X: TList; P: TListPredicate; T: TListElementFunc): TList;
var
  e: pointer;
begin
  Result := TList.Create;
  for e in X do
  begin
    if P(e) then
      Result.Add(T(e));
  end;
end;
my @y = map { T($_) } grep { P($_) } @x;
y = [T(e) for e in x if P(e)]
y = list(map(T, filter(P, x)))
y = x.each_with_object([]){|e, ar| ar << t(e) if p(e)}
y = x.filter_map{|e| t(e) if p(e)}
let y = x.iter()
	.filter(P)
        .map(T)
	.collect::<Vec<_>>();
val y = x.collect { case e if P(e) => T(e) }
y := x 
  collect: [:ea | ea t]
  thenSelect: [:ea | ea p].
y := x 
  select: [:ea | ea p]
  thenCollect: [:ea | ea t].