diff --git a/examples/clue_solver.ds b/examples/clue_solver.ds
index 1d18d85..dce0d5e 100644
--- a/examples/clue_solver.ds
+++ b/examples/clue_solver.ds
@@ -11,8 +11,8 @@ is_ready_to_solve = (fn cards <map>) <bool> {
 }
 
 take_turn = (fn cards <map>, opponent_card <str>, current_room <str>) <map> {
-	cards = (remove_card opponent_card cards)
-	cards = (make_guess current_room cards)
+	cards = (remove_card cards opponent_card)
+	cards = (make_guess cards current_room)
 	cards
 }
 
@@ -23,7 +23,7 @@ remove_card = (fn cards <map>, opponent_card <str>) <map> {
 	cards
 }
 
-make_guess = (fn cards <map> current_room <str>) <map> {
+make_guess = (fn cards <map>, current_room <str>) <map> {
 	if (is_ready_to_solve cards) {
 		(output 'It was '
 			+ cards:suspects:0
diff --git a/src/abstract_tree/function_call.rs b/src/abstract_tree/function_call.rs
index 80a188c..388dbd3 100644
--- a/src/abstract_tree/function_call.rs
+++ b/src/abstract_tree/function_call.rs
@@ -102,7 +102,15 @@ impl AbstractTree for FunctionCall {
             Expression::Yield(r#yield) => r#yield.run(source, context)?,
         };
 
-        value.as_function()?.call(&self.arguments, source, context)
+        let mut arguments = Vec::with_capacity(self.arguments.len());
+
+        for expression in &self.arguments {
+            let value = expression.run(source, context)?;
+
+            arguments.push(value);
+        }
+
+        value.as_function()?.call(&arguments, source, context)
     }
 
     fn expected_type(&self, context: &Map) -> Result<Type> {
diff --git a/src/abstract_tree/value_node.rs b/src/abstract_tree/value_node.rs
index ae02655..bc57c67 100644
--- a/src/abstract_tree/value_node.rs
+++ b/src/abstract_tree/value_node.rs
@@ -50,19 +50,36 @@ impl AbstractTree for ValueNode {
                     }
                 }
 
+                let function_context = Map::clone_from(context)?;
+
+                for (parameter_name, parameter_type) in
+                    parameters.iter().zip(parameter_types.iter())
+                {
+                    function_context.set(
+                        parameter_name.inner().clone(),
+                        Value::Empty,
+                        Some(parameter_type.clone()),
+                    )?;
+                }
+
                 let return_type_node = child.child(child_count - 2).unwrap();
                 let return_type =
                     TypeDefinition::from_syntax_node(source, return_type_node, context)?;
 
                 let body_node = child.child(child_count - 1).unwrap();
-                let body = Block::from_syntax_node(source, body_node, context)?;
+                let body = Block::from_syntax_node(source, body_node, &function_context)?;
 
                 let r#type = Type::Function {
                     parameter_types,
                     return_type: Box::new(return_type.take_inner()),
                 };
 
-                ValueNode::Function(Function::new(parameters, body, Some(r#type)))
+                ValueNode::Function(Function::new(
+                    parameters,
+                    body,
+                    Some(r#type),
+                    function_context,
+                ))
             }
             "integer" => ValueNode::Integer(source[child.byte_range()].to_string()),
             "string" => {
diff --git a/src/value/function.rs b/src/value/function.rs
index 498bda6..e7199b2 100644
--- a/src/value/function.rs
+++ b/src/value/function.rs
@@ -2,17 +2,23 @@ use std::fmt::{self, Display, Formatter};
 
 use serde::{Deserialize, Serialize};
 
-use crate::{AbstractTree, Block, Error, Expression, Identifier, Map, Result, Type, Value};
+use crate::{AbstractTree, Block, Error, Identifier, Map, Result, Type, Value};
 
-#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
+#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialOrd, Ord)]
 pub struct Function {
     parameters: Vec<Identifier>,
     body: Block,
     r#type: Type,
+    context: Map,
 }
 
 impl Function {
-    pub fn new(parameters: Vec<Identifier>, body: Block, r#type: Option<Type>) -> Self {
+    pub fn new(
+        parameters: Vec<Identifier>,
+        body: Block,
+        r#type: Option<Type>,
+        context: Map,
+    ) -> Self {
         let r#type = r#type.unwrap_or(Type::Function {
             parameter_types: vec![Type::Any; parameters.len()],
             return_type: Box::new(Type::Any),
@@ -22,6 +28,7 @@ impl Function {
             parameters,
             body,
             r#type,
+            context,
         }
     }
 
@@ -47,9 +54,7 @@ impl Function {
         }
     }
 
-    pub fn call(&self, arguments: &[Expression], source: &str, context: &Map) -> Result<Value> {
-        let function_context = Map::clone_from(context)?;
-
+    pub fn call(&self, arguments: &[Value], source: &str, context: &Map) -> Result<Value> {
         if self.parameters.len() != arguments.len() {
             return Err(Error::ExpectedArgumentAmount {
                 function_name: "",
@@ -58,22 +63,37 @@ impl Function {
             });
         }
 
-        let parameter_argument_pairs = self.parameters.iter().zip(arguments.iter());
+        for (key, (value, r#type)) in context.variables()?.iter() {
+            if self.context.variables()?.contains_key(key) {
+                continue;
+            }
 
-        for (identifier, expression) in parameter_argument_pairs {
-            let value = expression.run(source, context)?;
-
-            let key = identifier.inner().clone();
-
-            function_context.set(key, value, None)?;
+            self.context
+                .set(key.clone(), value.clone(), Some(r#type.clone()))?;
         }
 
-        let return_value = self.body.run(source, &function_context)?;
+        let parameter_argument_pairs = self.parameters.iter().zip(arguments.iter());
+
+        for (identifier, value) in parameter_argument_pairs {
+            let key = identifier.inner().clone();
+
+            self.context.set(key, value.clone(), None)?;
+        }
+
+        let return_value = self.body.run(source, &self.context)?;
 
         Ok(return_value)
     }
 }
 
+impl PartialEq for Function {
+    fn eq(&self, other: &Self) -> bool {
+        self.r#type.eq(&other.r#type)
+            && self.parameters.eq(&other.parameters)
+            && self.body.eq(&other.body)
+    }
+}
+
 impl Display for Function {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         write!(
diff --git a/src/value/map.rs b/src/value/map.rs
index d7f3799..e56a2c3 100644
--- a/src/value/map.rs
+++ b/src/value/map.rs
@@ -1,4 +1,4 @@
-use serde::{ser::SerializeMap, Serialize};
+use serde::{ser::SerializeMap, Deserialize, Deserializer, Serialize};
 use std::{
     cmp::Ordering,
     collections::BTreeMap,
@@ -120,3 +120,12 @@ impl Serialize for Map {
         map.end()
     }
 }
+
+impl<'de> Deserialize<'de> for Map {
+    fn deserialize<D>(_deserializer: D) -> std::result::Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        todo!()
+    }
+}