diff --git a/src/A.php b/src/A.php
index 3123a9d..f4062de 100644
--- a/src/A.php
+++ b/src/A.php
@@ -191,4 +191,21 @@ class A {
     return $values;
   }
 
+  static final function filter_if(&$dest, callable $cond): void {
+    self::ensure_narray($dest);
+    $dest = cl::filter_if($dest, $cond);
+  }
+
+  static final function filter_z(?array $dest): void { self::filter_if($dest, [cv::class, "z"]);}
+  static final function filter_nz(?array $dest): void { self::filter_if($dest, [cv::class, "nz"]);}
+  static final function filter_n(?array $dest): void { self::filter_if($dest, [cv::class, "n"]);}
+  static final function filter_nn(?array $dest): void { self::filter_if($dest, [cv::class, "nn"]);}
+  static final function filter_t(?array $dest): void { self::filter_if($dest, [cv::class, "t"]);}
+  static final function filter_f(?array $dest): void { self::filter_if($dest, [cv::class, "f"]);}
+  static final function filter_pt(?array $dest): void { self::filter_if($dest, [cv::class, "pt"]);}
+  static final function filter_pf(?array $dest): void { self::filter_if($dest, [cv::class, "pf"]);}
+  static final function filter_equals(?array $dest, $value): void { self::filter_if($dest, cv::equals($value)); }
+  static final function filter_not_equals(?array $dest, $value): void { self::filter_if($dest, cv::not_equals($value)); }
+  static final function filter_same(?array $dest, $value): void { self::filter_if($dest, cv::same($value)); }
+  static final function filter_not_same(?array $dest, $value): void { self::filter_if($dest, cv::not_same($value)); }
 }