diff --git a/src/ytdl_sub/script/types/array.py b/src/ytdl_sub/script/types/array.py
index 768aac38..182f575f 100644
--- a/src/ytdl_sub/script/types/array.py
+++ b/src/ytdl_sub/script/types/array.py
@@ -18,6 +18,10 @@ from ytdl_sub.script.types.variable_dependency import VariableDependency
 class Array(NonHashable):
     value: List[Resolvable]
 
+    @classmethod
+    def human_readable_name(cls) -> str:
+        return "Array"
+
 
 @dataclass(frozen=True)
 class UnresolvedArray(Array, VariableDependency, FutureResolvable):
diff --git a/src/ytdl_sub/script/types/function.py b/src/ytdl_sub/script/types/function.py
index 4d23447a..7fc7d49a 100644
--- a/src/ytdl_sub/script/types/function.py
+++ b/src/ytdl_sub/script/types/function.py
@@ -207,7 +207,13 @@ class BuiltInFunction(Function):
         received_type_names: List[str] = []
         for arg in self.args:
             if isinstance(arg, BuiltInFunction):
-                received_type_names.append(f"%{arg.name}(...)->{arg.output_type.__name__}")
+                if is_union(arg.output_type):
+                    # TODO: Move naming to separate function, deal with Union input naming
+                    received_type_names.append(
+                        f"%{arg.name}(...)->Union[{', '.join(arg_type.human_readable_name() for arg_type in arg.output_type.__args__)}]"
+                    )
+                else:
+                    received_type_names.append(f"%{arg.name}(...)->{arg.output_type.__name__}")
             else:
                 received_type_names.append(arg.__class__.__name__)
 
diff --git a/src/ytdl_sub/script/types/map.py b/src/ytdl_sub/script/types/map.py
index b014228c..b29c91a2 100644
--- a/src/ytdl_sub/script/types/map.py
+++ b/src/ytdl_sub/script/types/map.py
@@ -20,6 +20,10 @@ from ytdl_sub.utils.exceptions import StringFormattingException
 class Map(NonHashable):
     value: Dict[Hashable, Resolvable]
 
+    @classmethod
+    def human_readable_name(cls) -> str:
+        return "Map"
+
 
 @dataclass(frozen=True)
 class UnresolvedMap(Map, VariableDependency, FutureResolvable):
diff --git a/src/ytdl_sub/script/types/resolvable.py b/src/ytdl_sub/script/types/resolvable.py
index 3a475c79..463eb5e3 100644
--- a/src/ytdl_sub/script/types/resolvable.py
+++ b/src/ytdl_sub/script/types/resolvable.py
@@ -15,7 +15,9 @@ class ArgumentType(ABC):
     Any possible argument type that has not been resolved yet
     """
 
-    pass
+    @classmethod
+    def human_readable_name(cls) -> str:
+        return cls.__name__
 
 
 class AnyType_0(ABC):