diff --git a/lib/base/CMakeLists.txt b/lib/base/CMakeLists.txt
index 59e836443..1cdf0a409 100644
--- a/lib/base/CMakeLists.txt
+++ b/lib/base/CMakeLists.txt
@@ -37,6 +37,11 @@ set(base_SOURCES
   fifo.cpp fifo.hpp
   filelogger.cpp filelogger.hpp filelogger-ti.hpp
   function.cpp function.hpp function-ti.hpp function-script.cpp functionwrapper.hpp
+  generator.cpp generator.hpp generator-script.cpp
+  generator-array.cpp generator-array.hpp
+  generator-filter.cpp generator-filter.hpp
+  generator-map.cpp generator-map.hpp
+  generator-unique.cpp generator-unique.hpp
   initialize.cpp initialize.hpp
   intrusive-ptr.hpp
   io-engine.cpp io-engine.hpp
diff --git a/lib/base/array-script.cpp b/lib/base/array-script.cpp
index a97668350..f656b2fab 100644
--- a/lib/base/array-script.cpp
+++ b/lib/base/array-script.cpp
@@ -3,6 +3,8 @@
 #include "base/array.hpp"
 #include "base/function.hpp"
 #include "base/functionwrapper.hpp"
+#include "base/generator.hpp"
+#include "base/generator-array.hpp"
 #include "base/scriptframe.hpp"
 #include "base/objectlock.hpp"
 #include "base/exception.hpp"
@@ -233,6 +235,15 @@ static void ArrayFreeze()
 	self->Freeze();
 }
 
+static Generator::Ptr ArrayIter()
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Array::Ptr self = static_cast<Array::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	return new GeneratorArray(self);
+}
+
 Object::Ptr Array::GetPrototype()
 {
 	static Dictionary::Ptr prototype = new Dictionary({
@@ -253,7 +264,8 @@ Object::Ptr Array::GetPrototype()
 		{ "any", new Function("Array#any", ArrayAny, { "func" }, true) },
 		{ "all", new Function("Array#all", ArrayAll, { "func" }, true) },
 		{ "unique", new Function("Array#unique", ArrayUnique, {}, true) },
-		{ "freeze", new Function("Array#freeze", ArrayFreeze, {}) }
+		{ "freeze", new Function("Array#freeze", ArrayFreeze, {}) },
+		{ "iter", new Function("Array#iter", ArrayIter, {}, true) }
 	});
 
 	return prototype;
diff --git a/lib/base/generator-array.cpp b/lib/base/generator-array.cpp
new file mode 100644
index 000000000..04f2d7d31
--- /dev/null
+++ b/lib/base/generator-array.cpp
@@ -0,0 +1,19 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#include "base/generator-array.hpp"
+#include "base/objectlock.hpp"
+#include "base/value.hpp"
+
+using namespace icinga;
+
+bool GeneratorArray::GetNext(Value& out)
+{
+	ObjectLock oLock (m_Source);
+
+	if (m_Next < m_Source->GetLength()) {
+		out = m_Source->Get(m_Next++);
+		return true;
+	}
+
+	return false;
+}
diff --git a/lib/base/generator-array.hpp b/lib/base/generator-array.hpp
new file mode 100644
index 000000000..6b3d3f2f0
--- /dev/null
+++ b/lib/base/generator-array.hpp
@@ -0,0 +1,37 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#ifndef GENERATOR_ARRAY_H
+#define GENERATOR_ARRAY_H
+
+#include "base/array.hpp"
+#include "base/generator.hpp"
+#include "base/value.hpp"
+#include <cstddef>
+#include <utility>
+
+namespace icinga
+{
+
+/**
+ * A lazy Value supplier of Array items.
+ *
+ * @ingroup base
+ */
+class GeneratorArray final : public Generator
+{
+public:
+	inline GeneratorArray(Array::Ptr source)
+		: m_Source(std::move(source)), m_Next(0)
+	{
+	}
+
+	bool GetNext(Value& out) override;
+
+private:
+	Array::Ptr m_Source;
+	size_t m_Next;
+};
+
+}
+
+#endif /* GENERATOR_ARRAY_H */
diff --git a/lib/base/generator-filter.cpp b/lib/base/generator-filter.cpp
new file mode 100644
index 000000000..2b32b684c
--- /dev/null
+++ b/lib/base/generator-filter.cpp
@@ -0,0 +1,21 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#include "base/generator-filter.hpp"
+#include "base/value.hpp"
+#include <utility>
+
+using namespace icinga;
+
+bool GeneratorFilter::GetNext(Value& out)
+{
+	Value buf;
+
+	while (m_Source->GetNext(buf)) {
+		if (m_Function->Invoke({ buf })) {
+			out = std::move(buf);
+			return true;
+		}
+	}
+
+	return false;
+}
diff --git a/lib/base/generator-filter.hpp b/lib/base/generator-filter.hpp
new file mode 100644
index 000000000..f6ec6008e
--- /dev/null
+++ b/lib/base/generator-filter.hpp
@@ -0,0 +1,36 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#ifndef GENERATOR_FILTER_H
+#define GENERATOR_FILTER_H
+
+#include "base/function.hpp"
+#include "base/generator.hpp"
+#include "base/value.hpp"
+#include <utility>
+
+namespace icinga
+{
+
+/**
+ * Filters another generator's items based on a function.
+ *
+ * @ingroup base
+ */
+class GeneratorFilter final : public Generator
+{
+public:
+	inline GeneratorFilter(Generator::Ptr source, Function::Ptr function)
+		: m_Source(std::move(source)), m_Function(std::move(function))
+	{
+	}
+
+	bool GetNext(Value& out) override;
+
+private:
+	Generator::Ptr m_Source;
+	Function::Ptr m_Function;
+};
+
+}
+
+#endif /* GENERATOR_FILTER_H */
diff --git a/lib/base/generator-map.cpp b/lib/base/generator-map.cpp
new file mode 100644
index 000000000..dd245d603
--- /dev/null
+++ b/lib/base/generator-map.cpp
@@ -0,0 +1,19 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#include "base/generator-map.hpp"
+#include "base/value.hpp"
+#include <utility>
+
+using namespace icinga;
+
+bool GeneratorMap::GetNext(Value& out)
+{
+	Value buf;
+
+	if (m_Source->GetNext(buf)) {
+		out = m_Function->Invoke({ std::move(buf) });
+		return true;
+	}
+
+	return false;
+}
diff --git a/lib/base/generator-map.hpp b/lib/base/generator-map.hpp
new file mode 100644
index 000000000..b4e963b42
--- /dev/null
+++ b/lib/base/generator-map.hpp
@@ -0,0 +1,36 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#ifndef GENERATOR_MAP_H
+#define GENERATOR_MAP_H
+
+#include "base/function.hpp"
+#include "base/generator.hpp"
+#include "base/value.hpp"
+#include <utility>
+
+namespace icinga
+{
+
+/**
+ * Applies a function to another generator's items.
+ *
+ * @ingroup base
+ */
+class GeneratorMap final : public Generator
+{
+public:
+	inline GeneratorMap(Generator::Ptr source, Function::Ptr function)
+		: m_Source(std::move(source)), m_Function(std::move(function))
+	{
+	}
+
+	bool GetNext(Value& out) override;
+
+private:
+	Generator::Ptr m_Source;
+	Function::Ptr m_Function;
+};
+
+}
+
+#endif /* GENERATOR_MAP_H */
diff --git a/lib/base/generator-script.cpp b/lib/base/generator-script.cpp
new file mode 100644
index 000000000..16dceb956
--- /dev/null
+++ b/lib/base/generator-script.cpp
@@ -0,0 +1,227 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#include "base/array.hpp"
+#include "base/exception.hpp"
+#include "base/function.hpp"
+#include "base/generator.hpp"
+#include "base/generator-filter.hpp"
+#include "base/generator-map.hpp"
+#include "base/objectlock.hpp"
+#include "base/reference.hpp"
+#include "base/scriptframe.hpp"
+#include "base/value.hpp"
+#include <algorithm>
+#include <functional>
+#include <utility>
+#include <vector>
+
+using namespace icinga;
+
+static bool GeneratorNext(const Reference::Ptr& out)
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	Value buf;
+
+	if (self->GetNext(buf)) {
+		if (out) {
+			out->Set(std::move(buf));
+		}
+
+		return true;
+	}
+
+	return false;
+}
+
+static double GeneratorLen()
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	return self->GetLength();
+}
+
+static bool GeneratorContains(const Value& value)
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	return self->Contains(value);
+}
+
+static Array::Ptr GeneratorSort(const std::vector<Value>& args)
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	auto arr (self->ToArray());
+
+	if (args.empty()) {
+		ObjectLock olock(arr);
+		std::sort(arr->Begin(), arr->End());
+	} else {
+		Function::Ptr function = args[0];
+
+		if (vframe->Sandboxed && !function->IsSideEffectFree())
+			BOOST_THROW_EXCEPTION(ScriptError("Sort function must be side-effect free."));
+
+		ObjectLock olock(arr);
+		std::sort(arr->Begin(), arr->End(), [&args](const Value& a, const Value& b) -> bool {
+			Function::Ptr cmp = args[0];
+			return cmp->Invoke({ a, b });
+		});
+	}
+
+	return arr;
+}
+
+static Value GeneratorJoin(const Value& separator)
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	return self->Join(separator);
+}
+
+static Array::Ptr GeneratorReverse()
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	return self->Reverse();
+}
+
+static Generator::Ptr GeneratorMap(const Function::Ptr& function)
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	if (vframe->Sandboxed && !function->IsSideEffectFree())
+		BOOST_THROW_EXCEPTION(ScriptError("Map function must be side-effect free."));
+
+	return new icinga::GeneratorMap(std::move(self), function);
+}
+
+static Value GeneratorReduce(const Function::Ptr& function)
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	if (vframe->Sandboxed && !function->IsSideEffectFree())
+		BOOST_THROW_EXCEPTION(ScriptError("Reduce function must be side-effect free."));
+
+	Value result;
+
+	if (!self->GetNext(result)) {
+		return Empty;
+	}
+
+	Value buf;
+
+	while (self->GetNext(buf)) {
+		result = function->Invoke({ std::move(result), std::move(buf) });
+	}
+
+	return result;
+}
+
+static Generator::Ptr GeneratorFilter(const Function::Ptr& function)
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	if (vframe->Sandboxed && !function->IsSideEffectFree())
+		BOOST_THROW_EXCEPTION(ScriptError("Filter function must be side-effect free."));
+
+	return new icinga::GeneratorFilter(std::move(self), function);
+}
+
+static bool GeneratorAny(const Function::Ptr& function)
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	if (vframe->Sandboxed && !function->IsSideEffectFree())
+		BOOST_THROW_EXCEPTION(ScriptError("Filter function must be side-effect free."));
+
+	Value buf;
+
+	while (self->GetNext(buf)) {
+		if (function->Invoke({ std::move(buf) })) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static bool GeneratorAll(const Function::Ptr& function)
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	if (vframe->Sandboxed && !function->IsSideEffectFree())
+		BOOST_THROW_EXCEPTION(ScriptError("Filter function must be side-effect free."));
+
+	Value buf;
+
+	while (self->GetNext(buf)) {
+		if (!function->Invoke({ std::move(buf) })) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+static Generator::Ptr GeneratorUnique()
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	return self->Unique();
+}
+
+static Array::Ptr GeneratorToArray()
+{
+	ScriptFrame *vframe = ScriptFrame::GetCurrentFrame();
+	Generator::Ptr self = static_cast<Generator::Ptr>(vframe->Self);
+	REQUIRE_NOT_NULL(self);
+
+	return self->ToArray();
+}
+
+Object::Ptr Generator::GetPrototype()
+{
+	static Dictionary::Ptr prototype = new Dictionary({
+		{ "next", new Function("Generator#next", GeneratorNext, { "out" }) },
+		{ "len", new Function("Generator#len", GeneratorLen, {}, true) },
+		{ "contains", new Function("Generator#contains", GeneratorContains, { "value" }, true) },
+		{ "sort", new Function("Generator#sort", GeneratorSort, { "less_cmp" }, true) },
+		{ "join", new Function("Generator#join", GeneratorJoin, { "separator" }, true) },
+		{ "reverse", new Function("Generator#reverse", GeneratorReverse, {}, true) },
+		{ "map", new Function("Generator#map", ::GeneratorMap, { "func" }, true) },
+		{ "reduce", new Function("Generator#reduce", GeneratorReduce, { "reduce" }, true) },
+		{ "filter", new Function("Generator#filter", ::GeneratorFilter, { "func" }, true) },
+		{ "any", new Function("Generator#any", GeneratorAny, { "func" }, true) },
+		{ "all", new Function("Generator#all", GeneratorAll, { "func" }, true) },
+		{ "unique", new Function("Generator#unique", ::GeneratorUnique, {}, true) },
+		{ "to_array", new Function("Generator#to_array", GeneratorToArray, {}, true) }
+	});
+
+	return prototype;
+}
diff --git a/lib/base/generator-unique.cpp b/lib/base/generator-unique.cpp
new file mode 100644
index 000000000..e5d6f6362
--- /dev/null
+++ b/lib/base/generator-unique.cpp
@@ -0,0 +1,26 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#include "base/generator-unique.hpp"
+#include "base/objectlock.hpp"
+#include "base/value.hpp"
+#include <utility>
+
+using namespace icinga;
+
+bool GeneratorUnique::GetNext(Value& out)
+{
+	ObjectLock oLock (this);
+
+	Value buf;
+
+	while (m_Source->GetNext(buf)) {
+		auto res (m_Unique.emplace(std::move(buf)));
+
+		if (res.second) {
+			out = *res.first;
+			return true;
+		}
+	}
+
+	return false;
+}
diff --git a/lib/base/generator-unique.hpp b/lib/base/generator-unique.hpp
new file mode 100644
index 000000000..69ed503ea
--- /dev/null
+++ b/lib/base/generator-unique.hpp
@@ -0,0 +1,36 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#ifndef GENERATOR_UNIQUE_H
+#define GENERATOR_UNIQUE_H
+
+#include "base/generator.hpp"
+#include "base/value.hpp"
+#include <set>
+#include <utility>
+
+namespace icinga
+{
+
+/**
+ * Filters another generator's unique items.
+ *
+ * @ingroup base
+ */
+class GeneratorUnique final : public Generator
+{
+public:
+	inline GeneratorUnique(Generator::Ptr source)
+		: m_Source(std::move(source))
+	{
+	}
+
+	bool GetNext(Value& out) override;
+
+private:
+	Generator::Ptr m_Source;
+	std::set<Value> m_Unique;
+};
+
+}
+
+#endif /* GENERATOR_UNIQUE_H */
diff --git a/lib/base/generator.cpp b/lib/base/generator.cpp
new file mode 100644
index 000000000..6b9301499
--- /dev/null
+++ b/lib/base/generator.cpp
@@ -0,0 +1,100 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#include "base/array.hpp"
+#include "base/generator.hpp"
+#include "base/generator-unique.hpp"
+#include "base/objectlock.hpp"
+#include "base/primitivetype.hpp"
+#include <algorithm>
+#include <utility>
+
+using namespace icinga;
+
+REGISTER_PRIMITIVE_TYPE(Generator, Object, Generator::GetPrototype());
+
+bool Generator::GetNext(Value& out)
+{
+	return false;
+}
+
+/**
+ * Counts the items.
+ *
+ * @returns Amount of items.
+ */
+size_t Generator::GetLength()
+{
+	size_t len = 0;
+	Value buf;
+
+	while (GetNext(buf)) {
+		++len;
+	}
+
+	return len;
+}
+
+/**
+ * Checks whether the items include the specified value.
+ *
+ * @param value The value.
+ * @returns true if the items include the value, false otherwise.
+ */
+bool Generator::Contains(const Value& value)
+{
+	Value buf;
+
+	while (GetNext(buf)) {
+		if (buf == value) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+Array::Ptr Generator::Reverse()
+{
+	auto result (ToArray());
+	ObjectLock oLock (result);
+
+	std::reverse(result->Begin(), result->End());
+
+	return std::move(result);
+}
+
+Value Generator::Join(const Value& separator)
+{
+	Value result;
+	Value buf;
+	bool first = true;
+
+	while (GetNext(buf)) {
+		if (first) {
+			first = false;
+		} else {
+			result = std::move(result) + separator;
+		}
+
+		result = std::move(result) + std::move(buf);
+	}
+
+	return std::move(result);
+}
+
+Generator::Ptr Generator::Unique()
+{
+	return new GeneratorUnique(this);
+}
+
+Array::Ptr Generator::ToArray()
+{
+	Array::Ptr result (new Array());
+	Value buf;
+
+	while (GetNext(buf)) {
+		result->Add(std::move(buf));
+	}
+
+	return std::move(result);
+}
diff --git a/lib/base/generator.hpp b/lib/base/generator.hpp
new file mode 100644
index 000000000..ec23ecf9b
--- /dev/null
+++ b/lib/base/generator.hpp
@@ -0,0 +1,47 @@
+/* Icinga 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+#ifndef GENERATOR_H
+#define GENERATOR_H
+
+#include "base/array.hpp"
+#include "base/object.hpp"
+#include "base/value.hpp"
+#include <cstddef>
+
+namespace icinga
+{
+
+/**
+ * A lazy Value items supplier.
+ *
+ * @ingroup base
+ */
+class Generator : public Object
+{
+public:
+	DECLARE_OBJECT(Generator);
+
+	static Object::Ptr GetPrototype();
+
+	Generator() = default;
+
+	Generator(const Generator&) = delete;
+	Generator(Generator&&) = delete;
+	Generator& operator=(const Generator&) = delete;
+	Generator& operator=(Generator&&) = delete;
+
+	virtual ~Generator() = default;
+
+	virtual bool GetNext(Value& out);
+
+	size_t GetLength();
+	bool Contains(const Value& value);
+	Array::Ptr Reverse();
+	Value Join(const Value& separator);
+	Generator::Ptr Unique();
+	Array::Ptr ToArray();
+};
+
+}
+
+#endif /* GENERATOR_H */