Add more types

src/Standard.php

@@ -59,7 +59,7 @@ class Standard implements IteratorAggregate, Countable
      *
      * @var ?iterable
      */
-    private $pipeline;
+    private ?iterable $pipeline;
 
     /**
      * Contructor with an optional source of data.
@@ -289,14 +289,15 @@ public function map(?callable $func = null): self
         }
 
         // Let's check what we got for a start.
-        $this->pipeline = $func();
+        $value = $func();
 
         // Generator is a generator, moving along
-        if ($this->pipeline instanceof Generator) {
+        if ($value instanceof Generator) {
             // It is possible to detect if callback is a generator like so:
             // (new \ReflectionFunction($func))->isGenerator();
             // Yet this will restrict users from replacing the pipeline and has unknown performance impact.
             // But, again, we could add a direct internal method to replace the pipeline, e.g. as done by unpack()
+            $this->pipeline = $value;
 
             return $this;
         }
@@ -305,7 +306,7 @@ public function map(?callable $func = null): self
         // We do not cast to an array here because casting a null to an array results in
         // an empty array; that's surprising and not how it works for other values.
         $this->pipeline = [
-            $this->pipeline,
+            $value,
         ];
 
         return $this;