diff --git a/src/ytdl_sub/script/functions/array_functions.py b/src/ytdl_sub/script/functions/array_functions.py
index b75a6ade..9a2bf2fb 100644
--- a/src/ytdl_sub/script/functions/array_functions.py
+++ b/src/ytdl_sub/script/functions/array_functions.py
@@ -1,6 +1,7 @@
 from typing import List
 
-from ytdl_sub.script.types.resolvable import Array
+from ytdl_sub.script.types.array import Array
+from ytdl_sub.script.types.resolvable import Integer
 from ytdl_sub.script.types.resolvable import Resolvable
 
 
@@ -12,3 +13,18 @@ class ArrayFunctions:
             output.extend(array.value)
 
         return Array(output)
+
+    @staticmethod
+    def at(array: Array, idx: Integer) -> Resolvable:
+        return array.value[idx.value]
+
+    @staticmethod
+    def flatten_array(array: Array) -> Array:
+        output: List[Resolvable] = []
+        for elem in array.value:
+            if isinstance(elem, Array):
+                output.extend(ArrayFunctions.flatten_array(elem).value)
+            else:
+                output.append(elem)
+
+        return Array(output)
diff --git a/src/ytdl_sub/script/functions/map_functions.py b/src/ytdl_sub/script/functions/map_functions.py
index d5ef7010..51f4828c 100644
--- a/src/ytdl_sub/script/functions/map_functions.py
+++ b/src/ytdl_sub/script/functions/map_functions.py
@@ -1,6 +1,8 @@
-from typing import List, Dict
+from typing import Dict
+from typing import List
 
-from ytdl_sub.script.types.resolvable import Array, Map
+from ytdl_sub.script.types.array import Array
+from ytdl_sub.script.types.resolvable import Map
 from ytdl_sub.script.types.resolvable import Resolvable
 from ytdl_sub.utils.exceptions import StringFormattingException
 
diff --git a/src/ytdl_sub/script/parser.py b/src/ytdl_sub/script/parser.py
index f11185a4..8566ae58 100644
--- a/src/ytdl_sub/script/parser.py
+++ b/src/ytdl_sub/script/parser.py
@@ -2,9 +2,10 @@ from typing import List
 from typing import Optional
 
 from ytdl_sub.script.syntax_tree import SyntaxTree
+from ytdl_sub.script.types.array import Array
+from ytdl_sub.script.types.array import UnresolvedArray
 from ytdl_sub.script.types.function import ArgumentType
 from ytdl_sub.script.types.function import Function
-from ytdl_sub.script.types.resolvable import Array
 from ytdl_sub.script.types.resolvable import Boolean
 from ytdl_sub.script.types.resolvable import Float
 from ytdl_sub.script.types.resolvable import Integer
@@ -20,7 +21,7 @@ class _Parser:
     def __init__(self, text: str):
         self._text = text
         self._pos = 0
-        self._ast: List[String | Variable | Function] = []
+        self._ast: List[ArgumentType] = []
 
         self._syntax_tree = self._parse()
 
@@ -157,7 +158,7 @@ class _Parser:
         Begin parsing a function after reading the first ``%``
         """
         function_name: str = ""
-        function_args: List[String | Variable | "Function"] = []
+        function_args: List[ArgumentType] = []
 
         while ch := self._read():
             if ch == ")":
@@ -170,16 +171,16 @@ class _Parser:
 
         raise StringFormattingException("Invalid function")
 
-    def _parse_array(self) -> Array:
+    def _parse_array(self) -> UnresolvedArray:
         """
         Begin parsing an array after reading the first ``[``
         """
-        function_args: List[String | Variable | "Function"] = []
+        function_args: List[ArgumentType] = []
 
         while ch := self._read(increment_pos=False):
             if ch == "]":
                 self._pos += 1
-                return Array(value=function_args)
+                return UnresolvedArray(value=function_args)
             else:
                 function_args = self._parse_args(breaking_char="]")
 
diff --git a/src/ytdl_sub/script/syntax_tree.py b/src/ytdl_sub/script/syntax_tree.py
index a24621c7..317d701a 100644
--- a/src/ytdl_sub/script/syntax_tree.py
+++ b/src/ytdl_sub/script/syntax_tree.py
@@ -1,20 +1,20 @@
 from dataclasses import dataclass
 from typing import Dict
 from typing import List
-from typing import Optional
 from typing import Set
 
 from ytdl_sub.script.types.function import Function
-from ytdl_sub.script.types.function import VariableDependency
+from ytdl_sub.script.types.resolvable import ArgumentType
 from ytdl_sub.script.types.resolvable import Resolvable
 from ytdl_sub.script.types.resolvable import String
 from ytdl_sub.script.types.variable import Variable
+from ytdl_sub.script.types.variable_dependency import VariableDependency
 from ytdl_sub.utils.exceptions import StringFormattingException
 
 
 @dataclass(frozen=True)
 class SyntaxTree(VariableDependency):
-    ast: List[String | Variable | Function]
+    ast: List[ArgumentType]
 
     @property
     def variables(self) -> Set[Variable]:
@@ -35,14 +35,9 @@ class SyntaxTree(VariableDependency):
     def resolve(self, resolved_variables: Dict[Variable, Resolvable]) -> Resolvable:
         resolved: List[Resolvable] = []
         for token in self.ast:
-            if isinstance(token, Resolvable):
-                resolved.append(token)
-            elif isinstance(token, Variable):
-                resolved.append(resolved_variables[token])
-            elif isinstance(token, Function):
-                resolved.append(token.resolve(resolved_variables=resolved_variables))
-            else:
-                assert False, "should never reach"
+            resolved.append(
+                self._resolve_argument_type(resolved_variables=resolved_variables, arg=token)
+            )
 
         # If only one resolvable resides in the AST, return as that
         if len(resolved) == 1:
diff --git a/src/ytdl_sub/script/types/array.py b/src/ytdl_sub/script/types/array.py
new file mode 100644
index 00000000..a2aaa77c
--- /dev/null
+++ b/src/ytdl_sub/script/types/array.py
@@ -0,0 +1,36 @@
+from dataclasses import dataclass
+from typing import Dict
+from typing import List
+from typing import Set
+
+from ytdl_sub.script.types.resolvable import ArgumentType
+from ytdl_sub.script.types.resolvable import Resolvable
+from ytdl_sub.script.types.variable import Variable
+from ytdl_sub.script.types.variable_dependency import VariableDependency
+
+
+@dataclass(frozen=True)
+class Array:
+    value: List[Resolvable]
+
+
+@dataclass(frozen=True)
+class UnresolvedArray(Array, VariableDependency, ArgumentType):
+    value: List[ArgumentType]
+
+    @property
+    def variables(self) -> Set[Variable]:
+        return {value for value in self.value if isinstance(value, Variable)}
+
+    def resolve(self, resolved_variables: Dict[Variable, Resolvable]) -> Resolvable:
+        return ResolvedArray(
+            [
+                self._resolve_argument_type(resolved_variables=resolved_variables, arg=arg)
+                for arg in self.value
+            ]
+        )
+
+
+@dataclass(frozen=True)
+class ResolvedArray(Array, Resolvable):
+    pass
diff --git a/src/ytdl_sub/script/types/function.py b/src/ytdl_sub/script/types/function.py
index b3367819..c524e01c 100644
--- a/src/ytdl_sub/script/types/function.py
+++ b/src/ytdl_sub/script/types/function.py
@@ -1,7 +1,5 @@
 import functools
 import inspect
-from abc import ABC
-from abc import abstractmethod
 from dataclasses import dataclass
 from inspect import FullArgSpec
 from typing import Callable
@@ -11,45 +9,18 @@ from typing import Optional
 from typing import Set
 from typing import Type
 from typing import Union
-from typing import final
 from typing import get_origin
 
 from ytdl_sub.script.functions import Functions
-from ytdl_sub.script.types.resolvable import Array
-from ytdl_sub.script.types.resolvable import Boolean
-from ytdl_sub.script.types.resolvable import Float
-from ytdl_sub.script.types.resolvable import Integer
+from ytdl_sub.script.types.resolvable import ArgumentType
 from ytdl_sub.script.types.resolvable import Resolvable
 from ytdl_sub.script.types.resolvable import Resolvable_0
 from ytdl_sub.script.types.resolvable import Resolvable_1
 from ytdl_sub.script.types.resolvable import Resolvable_2
-from ytdl_sub.script.types.resolvable import String
 from ytdl_sub.script.types.variable import Variable
+from ytdl_sub.script.types.variable_dependency import VariableDependency
 from ytdl_sub.utils.exceptions import StringFormattingException
 
-ArgumentType = Union[Integer, Float, String, Boolean, Variable, "Function", Array]
-
-
-@dataclass(frozen=True)
-class VariableDependency(ABC):
-    @property
-    @abstractmethod
-    def variables(self) -> Set[Variable]:
-        raise NotImplemented()
-
-    @abstractmethod
-    def resolve(self, resolved_variables: Dict[Variable, Resolvable]) -> str:
-        raise NotImplemented()
-
-    @final
-    def has_variable_dependency(self, resolved_variables: Dict[Variable, Resolvable]) -> bool:
-        """
-        Returns
-        -------
-        True if variable dependency. False otherwise.
-        """
-        return not self.variables.issubset(set(resolved_variables.keys()))
-
 
 def is_union(arg_type: Type) -> bool:
     return get_origin(arg_type) is Union
@@ -151,7 +122,7 @@ class FunctionInputSpec:
 
 
 @dataclass(frozen=True)
-class Function(VariableDependency):
+class Function(VariableDependency, ArgumentType):
     name: str
     args: List[ArgumentType]
 
@@ -227,13 +198,9 @@ class Function(VariableDependency):
         return variables
 
     def resolve(self, resolved_variables: Dict[Variable, Resolvable]) -> Resolvable:
-        resolved_args: List[Resolvable] = []
-        for arg in self.args:
-            if arg in resolved_variables:
-                resolved_args.append(resolved_variables[arg])
-            elif isinstance(arg, Function):
-                resolved_args.append(arg.resolve(resolved_variables))
-            else:
-                resolved_args.append(arg)
+        resolved_args = [
+            self._resolve_argument_type(resolved_variables=resolved_variables, arg=arg)
+            for arg in self.args
+        ]
 
         return self.callable(*resolved_args)
diff --git a/src/ytdl_sub/script/types/resolvable.py b/src/ytdl_sub/script/types/resolvable.py
index 62630215..9f4016db 100644
--- a/src/ytdl_sub/script/types/resolvable.py
+++ b/src/ytdl_sub/script/types/resolvable.py
@@ -1,15 +1,18 @@
 from abc import ABC
-from abc import abstractmethod
 from dataclasses import dataclass
-from typing import Any, Dict
+from typing import Any
+from typing import Dict
 from typing import Generic
-from typing import List
 from typing import TypeVar
 
 T = TypeVar("T")
 NumericT = TypeVar("NumericT", bound=int | float)
 
 
+class ArgumentType(ABC):
+    pass
+
+
 class Resolvable_0(ABC):
     pass
 
@@ -41,35 +44,28 @@ class Numeric(ResolvableT[NumericT], ABC, Generic[NumericT]):
 
 
 @dataclass(frozen=True)
-class Integer(Numeric[int]):
+class Integer(Numeric[int], ArgumentType):
     pass
 
 
 @dataclass(frozen=True)
-class Float(Numeric[float]):
+class Float(Numeric[float], ArgumentType):
     pass
 
 
 @dataclass(frozen=True)
-class Boolean(ResolvableT[bool]):
+class Boolean(ResolvableT[bool], ArgumentType):
     pass
 
 
 @dataclass(frozen=True)
-class String(ResolvableT[str]):
+class String(ResolvableT[str], ArgumentType):
     pass
 
 
 @dataclass(frozen=True)
-class Array(Resolvable):
-    value: List[Resolvable]
-
-    def __str__(self) -> str:
-        return f"[{', '.join([val.value for val in self.value])}]"
-
-@dataclass(frozen=True)
-class Map(Resolvable):
+class Map(Resolvable, ArgumentType):
     value: Dict[Resolvable, Resolvable]
 
     def __str__(self) -> str:
-        return f"[{', '.join([val.value for val in self.value])}]"
\ No newline at end of file
+        return f"[{', '.join([val.value for val in self.value])}]"
diff --git a/src/ytdl_sub/script/types/variable.py b/src/ytdl_sub/script/types/variable.py
index 4bcb8b63..af723724 100644
--- a/src/ytdl_sub/script/types/variable.py
+++ b/src/ytdl_sub/script/types/variable.py
@@ -1,6 +1,8 @@
 from dataclasses import dataclass
 
+from ytdl_sub.script.types.resolvable import ArgumentType
+
 
 @dataclass(frozen=True)
-class Variable:
+class Variable(ArgumentType):
     name: str
diff --git a/src/ytdl_sub/script/types/variable_dependency.py b/src/ytdl_sub/script/types/variable_dependency.py
new file mode 100644
index 00000000..b08f821b
--- /dev/null
+++ b/src/ytdl_sub/script/types/variable_dependency.py
@@ -0,0 +1,46 @@
+from abc import ABC
+from abc import abstractmethod
+from dataclasses import dataclass
+from typing import Dict
+from typing import Set
+from typing import final
+
+from ytdl_sub.script.types.resolvable import ArgumentType
+from ytdl_sub.script.types.resolvable import Resolvable
+from ytdl_sub.script.types.variable import Variable
+from ytdl_sub.utils.exceptions import StringFormattingException
+
+
+@dataclass(frozen=True)
+class VariableDependency(ABC):
+    @property
+    @abstractmethod
+    def variables(self) -> Set[Variable]:
+        raise NotImplemented()
+
+    @abstractmethod
+    def resolve(self, resolved_variables: Dict[Variable, Resolvable]) -> Resolvable:
+        raise NotImplemented()
+
+    def _resolve_argument_type(
+        self, resolved_variables: Dict[Variable, Resolvable], arg: ArgumentType
+    ) -> Resolvable:
+        if isinstance(arg, Resolvable):
+            return arg
+        if isinstance(arg, Variable):
+            if arg not in resolved_variables:
+                raise StringFormattingException("should never reach@")
+            return resolved_variables[arg]
+        if isinstance(arg, VariableDependency):
+            return arg.resolve(resolved_variables)
+
+        assert False, "never reach here"
+
+    @final
+    def has_variable_dependency(self, resolved_variables: Dict[Variable, Resolvable]) -> bool:
+        """
+        Returns
+        -------
+        True if variable dependency. False otherwise.
+        """
+        return not self.variables.issubset(set(resolved_variables.keys()))
diff --git a/tests/unit/script/test_parser.py b/tests/unit/script/test_parser.py
index 7a50113a..f638bd30 100644
--- a/tests/unit/script/test_parser.py
+++ b/tests/unit/script/test_parser.py
@@ -32,7 +32,10 @@ class TestParser:
         parsed = parse("hello {['elem1', 'elem2']}")
         parsed_empty = parse("hello {[]}")
         parsed_with_var = parse("hello {['elem1', variable_name]}")
-        parsed_extend = parse("hi {%extend(['elem1', 'elem2'], ['elem3'], [],   ['elem4'])}")
+        parsed_extend = parse(
+            "hi {%at(%flatten_array(%extend(['elem1', 'elem2'], ['elem3'], [['elem4'], ['elem5', 'elem6']],   ['elem7'])), 1)}"
+        )
+        parsed_extend.resolve({})
         assert False
 
     def test_map(self):