add shortcut to specify the constraint of each element of a list

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- `Is::list()->and(Each::of(Constraint))` has been shortened to `Is::list(Constraint)`
+
 ### Changed
 
 - `Is::array()->and(Is::list())` has been shortened to `Is::list()`

proofs/is.php

@@ -370,6 +370,45 @@ static function($assert, $array, $other) {
         },
     );
 
+    yield proof(
+        'Is::list() with inner type',
+        given(
+            Set\Sequence::of(
+                Set\Strings::any(),
+            )->atLeast(1),
+            Set\Sequence::of(
+                Set\Integers::any(),
+            )->atLeast(1),
+        ),
+        static function($assert, $strings, $ints) {
+            $assert->true(
+                Is::list(Is::string())->asPredicate()($strings),
+            );
+            $assert->same(
+                $strings,
+                Is::list(Is::string())($strings)->match(
+                    static fn($value) => $value,
+                    static fn() => null,
+                ),
+            );
+            $assert->false(
+                Is::list(Is::string())->asPredicate()($ints),
+            );
+            $assert->same(
+                [['$', 'Value is not of type string']],
+                Is::list(Is::string())($ints)->match(
+                    static fn() => null,
+                    static fn($failures) => $failures
+                        ->map(static fn($failure) => [
+                            $failure->path()->toString(),
+                            $failure->message(),
+                        ])
+                        ->toList(),
+                ),
+            );
+        },
+    );
+
     yield proof(
         'Is::shape()',
         given(

src/Is.php

@@ -109,14 +109,23 @@ public static function null(): self
     /**
      * @psalm-pure
      *
-     * @return Constraint<mixed, list>
+     * @template E
+     *
+     * @param Constraint<mixed, E> $each
+     *
+     * @return Constraint<mixed, list<E>>
      */
-    public static function list(): Constraint
+    public static function list(Constraint $each = null): Constraint
     {
-        /** @var self<array, list> */
+        /** @var self<array, list<mixed>> */
         $list = new self(\array_is_list(...), 'list');
 
-        return self::array()->and($list);
+        $constraint = self::array()->and($list);
+
+        return match ($each) {
+            null => $constraint,
+            default => $constraint->and(Each::of($each)),
+        };
     }
 
     /**