Implement is_odd and length functions; Pass all tests

dust-lang/src/abstract_tree.rs

@@ -5,7 +5,7 @@ use std::{
 
 use serde::{Deserialize, Serialize};
 
-use crate::{Identifier, ReservedIdentifier, Type, Value};
+use crate::{Identifier, Type, Value};
 
 #[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
 pub struct AbstractSyntaxTree<P> {
@@ -40,6 +40,16 @@ pub enum Statement<P> {
 
     // Expressions
     Add(Box<Node<P>>, Box<Node<P>>),
+    BuiltInFunctionCall {
+        function: BuiltInFunction,
+        type_arguments: Option<Vec<Node<P>>>,
+        value_arguments: Option<Vec<Node<P>>>,
+    },
+    FunctionCall {
+        function: Box<Node<P>>,
+        type_arguments: Option<Vec<Node<P>>>,
+        value_arguments: Option<Vec<Node<P>>>,
+    },
     PropertyAccess(Box<Node<P>>, Box<Node<P>>),
     List(Vec<Node<P>>),
     Multiply(Box<Node<P>>, Box<Node<P>>),
@@ -47,7 +57,6 @@ pub enum Statement<P> {
     // Hard-coded values
     Constant(Value),
     Identifier(Identifier),
-    ReservedIdentifier(ReservedIdentifier),
 }
 
 impl<P> Statement<P> {
@@ -55,17 +64,15 @@ impl<P> Statement<P> {
         match self {
             Statement::Add(left, _) => left.statement.expected_type(variables),
             Statement::Assign(_, _) => None,
+            Statement::BuiltInFunctionCall { function, .. } => function.expected_type(),
             Statement::Constant(value) => Some(value.r#type(variables)),
+            Statement::FunctionCall { function, .. } => function.statement.expected_type(variables),
             Statement::Identifier(identifier) => variables
                 .get(identifier)
                 .map(|value| value.r#type(variables)),
             Statement::List(_) => None,
             Statement::Multiply(left, _) => left.statement.expected_type(variables),
             Statement::PropertyAccess(_, _) => None,
-            Statement::ReservedIdentifier(reserved) => match reserved {
-                ReservedIdentifier::IsEven | ReservedIdentifier::IsOdd => Some(Type::Boolean),
-                ReservedIdentifier::Length => Some(Type::Integer),
-            },
         }
     }
 }
@@ -75,6 +82,76 @@ impl<P> Display for Statement<P> {
         match self {
             Statement::Assign(left, right) => write!(f, "{left} = {right}"),
             Statement::Add(left, right) => write!(f, "{left} + {right}"),
+            Statement::BuiltInFunctionCall {
+                function,
+                type_arguments: type_parameters,
+                value_arguments: value_parameters,
+            } => {
+                write!(f, "{function}")?;
+
+                if let Some(type_parameters) = type_parameters {
+                    write!(f, "<")?;
+
+                    for (i, type_parameter) in type_parameters.iter().enumerate() {
+                        if i > 0 {
+                            write!(f, ", ")?;
+                        }
+
+                        write!(f, "{type_parameter}")?;
+                    }
+
+                    write!(f, ">")?;
+                }
+
+                write!(f, "(")?;
+
+                if let Some(value_parameters) = value_parameters {
+                    for (i, value_parameter) in value_parameters.iter().enumerate() {
+                        if i > 0 {
+                            write!(f, ", ")?;
+                        }
+
+                        write!(f, "{value_parameter}")?;
+                    }
+                }
+
+                write!(f, ")")
+            }
+            Statement::FunctionCall {
+                function,
+                type_arguments: type_parameters,
+                value_arguments: value_parameters,
+            } => {
+                write!(f, "{function}")?;
+
+                if let Some(type_parameters) = type_parameters {
+                    write!(f, "<")?;
+
+                    for (i, type_parameter) in type_parameters.iter().enumerate() {
+                        if i > 0 {
+                            write!(f, ", ")?;
+                        }
+
+                        write!(f, "{type_parameter}")?;
+                    }
+
+                    write!(f, ">")?;
+                }
+
+                write!(f, "(")?;
+
+                if let Some(value_parameters) = value_parameters {
+                    for (i, value_parameter) in value_parameters.iter().enumerate() {
+                        if i > 0 {
+                            write!(f, ", ")?;
+                        }
+
+                        write!(f, "{value_parameter}")?;
+                    }
+                }
+
+                write!(f, ")")
+            }
             Statement::PropertyAccess(left, right) => write!(f, "{left}.{right}"),
             Statement::List(nodes) => {
                 write!(f, "[")?;
@@ -89,7 +166,97 @@ impl<P> Display for Statement<P> {
             Statement::Multiply(left, right) => write!(f, "{left} * {right}"),
             Statement::Constant(value) => write!(f, "{value}"),
             Statement::Identifier(identifier) => write!(f, "{identifier}"),
-            Statement::ReservedIdentifier(identifier) => write!(f, "{identifier}"),
         }
     }
 }
+
+#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
+pub enum BuiltInFunction {
+    IsEven,
+    IsOdd,
+    Length,
+}
+
+impl BuiltInFunction {
+    pub fn name(&self) -> &'static str {
+        match self {
+            BuiltInFunction::IsEven => "is_even",
+            BuiltInFunction::IsOdd => "is_odd",
+            BuiltInFunction::Length => "length",
+        }
+    }
+
+    pub fn call(
+        &self,
+        _type_arguments: Option<Vec<Type>>,
+        value_arguments: Option<Vec<Value>>,
+    ) -> Result<Value, BuiltInFunctionError> {
+        match self {
+            BuiltInFunction::IsEven => {
+                if let Some(value_arguments) = value_arguments {
+                    if value_arguments.len() == 1 {
+                        if let Some(integer) = value_arguments[0].as_integer() {
+                            Ok(Value::boolean(integer % 2 == 0))
+                        } else {
+                            Err(BuiltInFunctionError::ExpectedInteger)
+                        }
+                    } else {
+                        Err(BuiltInFunctionError::WrongNumberOfValueArguments)
+                    }
+                } else {
+                    Err(BuiltInFunctionError::WrongNumberOfValueArguments)
+                }
+            }
+            BuiltInFunction::IsOdd => {
+                if let Some(value_arguments) = value_arguments {
+                    if value_arguments.len() == 1 {
+                        if let Some(integer) = value_arguments[0].as_integer() {
+                            Ok(Value::boolean(integer % 2 != 0))
+                        } else {
+                            Err(BuiltInFunctionError::ExpectedInteger)
+                        }
+                    } else {
+                        Err(BuiltInFunctionError::WrongNumberOfValueArguments)
+                    }
+                } else {
+                    Err(BuiltInFunctionError::WrongNumberOfValueArguments)
+                }
+            }
+            BuiltInFunction::Length => {
+                if let Some(value_arguments) = value_arguments {
+                    if value_arguments.len() == 1 {
+                        if let Some(list) = value_arguments[0].as_list() {
+                            Ok(Value::integer(list.len() as i64))
+                        } else {
+                            Err(BuiltInFunctionError::ExpectedInteger)
+                        }
+                    } else {
+                        Err(BuiltInFunctionError::WrongNumberOfValueArguments)
+                    }
+                } else {
+                    Err(BuiltInFunctionError::WrongNumberOfValueArguments)
+                }
+            }
+        }
+    }
+
+    pub fn expected_type(&self) -> Option<Type> {
+        match self {
+            BuiltInFunction::IsEven => Some(Type::Boolean),
+            BuiltInFunction::IsOdd => Some(Type::Boolean),
+            BuiltInFunction::Length => Some(Type::Integer),
+        }
+    }
+}
+
+impl Display for BuiltInFunction {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "{}", self.name())
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum BuiltInFunctionError {
+    ExpectedInteger,
+    WrongNumberOfValueArguments,
+}

dust-lang/src/analyzer.rs

@@ -103,7 +103,17 @@ impl<'a, P: Clone> Analyzer<'a, P> {
 
                 self.analyze_node(right)?;
             }
+            Statement::BuiltInFunctionCall { .. } => {}
             Statement::Constant(_) => {}
+            Statement::FunctionCall { function, .. } => {
+                if let Statement::Identifier(_) = &function.statement {
+                    // Function is in the correct position
+                } else {
+                    return Err(AnalyzerError::ExpectedIdentifier {
+                        actual: function.as_ref().clone(),
+                    });
+                }
+            }
             Statement::Identifier(_) => {
                 return Err(AnalyzerError::UnexpectedIdentifier {
                     identifier: node.clone(),
@@ -149,7 +159,6 @@ impl<'a, P: Clone> Analyzer<'a, P> {
 
                 self.analyze_node(right)?;
             }
-            Statement::ReservedIdentifier(_) => {}
         }
 
         Ok(())
@@ -158,6 +167,7 @@ impl<'a, P: Clone> Analyzer<'a, P> {
 
 #[derive(Clone, Debug, PartialEq)]
 pub enum AnalyzerError<P> {
+    ExpectedFunction { position: P },
     ExpectedIdentifier { actual: Node<P> },
     ExpectedIntegerOrFloat { actual: Node<P> },
     UnexpectedIdentifier { identifier: Node<P> },

dust-lang/src/lex.rs

@@ -5,7 +5,7 @@
 //! - [`Lexer`], which lexes the input a token at a time
 use std::num::{ParseFloatError, ParseIntError};
 
-use crate::{Identifier, ReservedIdentifier, Span, Token};
+use crate::{Identifier, Span, Token};
 
 /// Lexes the input and return a vector of tokens and their positions.
 ///
@@ -245,9 +245,9 @@ impl<'a> Lexer<'a> {
         let token = match string {
             "true" => Token::Boolean(true),
             "false" => Token::Boolean(false),
-            "is_even" => Token::ReservedIdentifier(ReservedIdentifier::IsEven),
-            "is_odd" => Token::ReservedIdentifier(ReservedIdentifier::IsOdd),
-            "length" => Token::ReservedIdentifier(ReservedIdentifier::Length),
+            "is_even" => Token::IsEven,
+            "is_odd" => Token::IsOdd,
+            "length" => Token::Length,
             _ => Token::Identifier(Identifier::new(string)),
         };
 
@@ -298,19 +298,18 @@ mod tests {
     }
 
     #[test]
-    fn integer_property_access() {
-        let input = "42.is_even";
+    fn property_access_function_call() {
+        let input = "42.is_even()";
 
         assert_eq!(
             lex(input),
             Ok(vec![
                 (Token::Integer(42), (0, 2)),
                 (Token::Dot, (2, 3)),
-                (
-                    Token::ReservedIdentifier(ReservedIdentifier::IsEven),
-                    (3, 10)
-                ),
-                (Token::Eof, (10, 10)),
+                (Token::IsEven, (3, 10)),
+                (Token::LeftParenthesis, (10, 11)),
+                (Token::RightParenthesis, (11, 12)),
+                (Token::Eof, (12, 12)),
             ])
         )
     }
@@ -328,13 +327,7 @@ mod tests {
 
         assert_eq!(
             lex(input),
-            Ok(vec![
-                (
-                    Token::ReservedIdentifier(ReservedIdentifier::Length),
-                    (0, 6)
-                ),
-                (Token::Eof, (6, 6)),
-            ])
+            Ok(vec![(Token::Length, (0, 6)), (Token::Eof, (6, 6)),])
         )
     }
 

dust-lang/src/lib.rs

@@ -15,13 +15,13 @@ pub mod r#type;
 pub mod value;
 pub mod vm;
 
-pub use abstract_tree::{AbstractSyntaxTree, Node, Statement};
+pub use abstract_tree::{AbstractSyntaxTree, BuiltInFunction, Node, Statement};
 pub use analyzer::{analyze, Analyzer, AnalyzerError};
 pub use identifier::Identifier;
 pub use lex::{lex, LexError, Lexer};
 pub use parse::{parse, ParseError, Parser};
 pub use r#type::Type;
-pub use token::{ReservedIdentifier, Token};
+pub use token::Token;
 pub use value::{Value, ValueError};
 pub use vm::{run, Vm, VmError};
 

dust-lang/src/parse.rs

@@ -5,7 +5,10 @@
 /// - `Parser` struct, which parses the input a statement at a time
 use std::collections::VecDeque;
 
-use crate::{AbstractSyntaxTree, LexError, Lexer, Node, Span, Statement, Token, Value};
+use crate::{
+    abstract_tree::BuiltInFunction, AbstractSyntaxTree, LexError, Lexer, Node, Span, Statement,
+    Token, Value,
+};
 
 /// Parses the input into an abstract syntax tree.
 ///
@@ -206,15 +209,12 @@ impl<'src> Parser<'src> {
             (Token::LeftParenthesis, left_span) => {
                 self.next_token()?;
 
-                let instruction = self.parse_node(0)?;
+                let node = self.parse_node(0)?;
 
                 if let (Token::RightParenthesis, right_span) = self.current {
                     self.next_token()?;
 
-                    Ok(Node::new(
-                        instruction.statement,
-                        (left_span.0, right_span.1),
-                    ))
+                    Ok(Node::new(node.statement, (left_span.0, right_span.1)))
                 } else {
                     Err(ParseError::ExpectedClosingParenthesis {
                         actual: self.current.0.clone(),
@@ -225,14 +225,14 @@ impl<'src> Parser<'src> {
             (Token::LeftSquareBrace, left_span) => {
                 self.next_token()?;
 
-                let mut instructions = Vec::new();
+                let mut nodes = Vec::new();
 
                 loop {
                     if let (Token::RightSquareBrace, right_span) = self.current {
                         self.next_token()?;
 
                         return Ok(Node::new(
-                            Statement::List(instructions),
+                            Statement::List(nodes),
                             (left_span.0, right_span.1),
                         ));
                     }
@@ -244,7 +244,7 @@ impl<'src> Parser<'src> {
                     }
 
                     if let Ok(instruction) = self.parse_node(0) {
-                        instructions.push(instruction);
+                        nodes.push(instruction);
                     } else {
                         return Err(ParseError::ExpectedClosingSquareBrace {
                             actual: self.current.0.clone(),
@@ -253,12 +253,94 @@ impl<'src> Parser<'src> {
                     }
                 }
             }
-            (Token::ReservedIdentifier(reserved), _) => {
+            (Token::IsEven, left_span) => {
                 self.next_token()?;
 
+                if let (Token::LeftParenthesis, _) = self.current {
+                    self.next_token()?;
+                } else {
+                    return Err(ParseError::ExpectedOpeningParenthesis {
+                        actual: self.current.0.clone(),
+                        span: self.current.1,
+                    });
+                }
+
+                if let (Token::RightParenthesis, _) = self.current {
+                    self.next_token()?;
+                } else {
+                    return Err(ParseError::ExpectedClosingParenthesis {
+                        actual: self.current.0.clone(),
+                        span: self.current.1,
+                    });
+                }
+
                 Ok(Node::new(
-                    Statement::ReservedIdentifier(reserved),
-                    self.current.1,
+                    Statement::BuiltInFunctionCall {
+                        function: BuiltInFunction::IsEven,
+                        type_arguments: None,
+                        value_arguments: None,
+                    },
+                    left_span,
+                ))
+            }
+            (Token::IsOdd, left_span) => {
+                self.next_token()?;
+
+                if let (Token::LeftParenthesis, _) = self.current {
+                    self.next_token()?;
+                } else {
+                    return Err(ParseError::ExpectedOpeningParenthesis {
+                        actual: self.current.0.clone(),
+                        span: self.current.1,
+                    });
+                }
+
+                if let (Token::RightParenthesis, _) = self.current {
+                    self.next_token()?;
+                } else {
+                    return Err(ParseError::ExpectedClosingParenthesis {
+                        actual: self.current.0.clone(),
+                        span: self.current.1,
+                    });
+                }
+
+                Ok(Node::new(
+                    Statement::BuiltInFunctionCall {
+                        function: BuiltInFunction::IsOdd,
+                        type_arguments: None,
+                        value_arguments: None,
+                    },
+                    left_span,
+                ))
+            }
+            (Token::Length, left_span) => {
+                self.next_token()?;
+
+                if let (Token::LeftParenthesis, _) = self.current {
+                    self.next_token()?;
+                } else {
+                    return Err(ParseError::ExpectedOpeningParenthesis {
+                        actual: self.current.0.clone(),
+                        span: self.current.1,
+                    });
+                }
+
+                if let (Token::RightParenthesis, _) = self.current {
+                    self.next_token()?;
+                } else {
+                    return Err(ParseError::ExpectedClosingParenthesis {
+                        actual: self.current.0.clone(),
+                        span: self.current.1,
+                    });
+                }
+
+                Ok(Node::new(
+                    Statement::BuiltInFunctionCall {
+                        function: BuiltInFunction::Length,
+                        type_arguments: None,
+                        value_arguments: None,
+                    },
+                    left_span,
                 ))
             }
             _ => Err(ParseError::UnexpectedToken(self.current.0.clone())),
@@ -280,6 +362,7 @@ impl<'src> Parser<'src> {
 pub enum ParseError {
     ExpectedClosingParenthesis { actual: Token, span: Span },
     ExpectedClosingSquareBrace { actual: Token, span: Span },
+    ExpectedOpeningParenthesis { actual: Token, span: Span },
     LexError(LexError),
     UnexpectedToken(Token),
 }
@@ -308,6 +391,32 @@ mod tests {
         );
     }
 
+    #[test]
+    fn property_access_function_call() {
+        let input = "42.is_even()";
+
+        assert_eq!(
+            parse(input),
+            Ok(AbstractSyntaxTree {
+                nodes: [Node::new(
+                    Statement::PropertyAccess(
+                        Box::new(Node::new(Statement::Constant(Value::integer(42)), (0, 2))),
+                        Box::new(Node::new(
+                            Statement::BuiltInFunctionCall {
+                                function: BuiltInFunction::IsEven,
+                                type_arguments: None,
+                                value_arguments: None
+                            },
+                            (3, 10)
+                        )),
+                    ),
+                    (0, 10),
+                )]
+                .into()
+            })
+        );
+    }
+
     #[test]
     fn list_access() {
         let input = "[1, 2, 3].0";

dust-lang/src/token.rs

@@ -1,44 +1,57 @@
-use std::fmt::Display;
+use std::fmt::{self, Display, Formatter};
 
 use serde::{Deserialize, Serialize};
 
 use crate::Identifier;
 
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
 pub enum Token {
+    Eof,
+
+    Identifier(Identifier),
+
+    // Hard-coded values
     Boolean(bool),
+    Float(f64),
+    Integer(i64),
+
+    // Keywords
+    IsEven,
+    IsOdd,
+    Length,
+
+    // Symbols
     Comma,
     Dot,
-    Eof,
     Equal,
-    Identifier(Identifier),
-    ReservedIdentifier(ReservedIdentifier),
-    Integer(i64),
     Plus,
     Star,
     LeftParenthesis,
     RightParenthesis,
     LeftSquareBrace,
     RightSquareBrace,
-    Float(f64),
 }
 
-#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
-pub enum ReservedIdentifier {
-    // Number properties
-    IsEven,
-    IsOdd,
-
-    // List properties
-    Length,
-}
-
-impl Display for ReservedIdentifier {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+impl Display for Token {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         match self {
-            ReservedIdentifier::IsEven => write!(f, "is_even"),
-            ReservedIdentifier::IsOdd => write!(f, "is_odd"),
-            ReservedIdentifier::Length => write!(f, "length"),
+            Token::Eof => write!(f, "EOF"),
+            Token::Identifier(identifier) => write!(f, "{identifier}"),
+            Token::Boolean(boolean) => write!(f, "{boolean}"),
+            Token::Float(float) => write!(f, "{float}"),
+            Token::Integer(integer) => write!(f, "{integer}"),
+            Token::IsEven => write!(f, "is_even"),
+            Token::IsOdd => write!(f, "is_odd"),
+            Token::Length => write!(f, "length"),
+            Token::Comma => write!(f, ","),
+            Token::Dot => write!(f, "."),
+            Token::Equal => write!(f, "="),
+            Token::Plus => write!(f, "+"),
+            Token::Star => write!(f, "*"),
+            Token::LeftParenthesis => write!(f, "("),
+            Token::RightParenthesis => write!(f, ")"),
+            Token::LeftSquareBrace => write!(f, "["),
+            Token::RightSquareBrace => write!(f, "]"),
         }
     }
 }

dust-lang/src/value.rs

@@ -12,7 +12,7 @@ use serde::{
     Deserialize, Deserializer, Serialize,
 };
 
-use crate::{identifier::Identifier, Statement, Type};
+use crate::{identifier::Identifier, AbstractSyntaxTree, Type, Vm, VmError};
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct Value(Arc<ValueInner>);
@@ -30,6 +30,10 @@ impl Value {
         Value(Arc::new(ValueInner::Float(float)))
     }
 
+    pub fn function(function: Function) -> Self {
+        Value(Arc::new(ValueInner::Function(function)))
+    }
+
     pub fn integer(integer: i64) -> Self {
         Value(Arc::new(ValueInner::Integer(integer)))
     }
@@ -62,6 +66,14 @@ impl Value {
         }
     }
 
+    pub fn as_function(&self) -> Option<&Function> {
+        if let ValueInner::Function(function) = self.0.as_ref() {
+            Some(function)
+        } else {
+            None
+        }
+    }
+
     pub fn as_list(&self) -> Option<&Vec<Value>> {
         if let ValueInner::List(list) = self.inner().as_ref() {
             Some(list)
@@ -539,12 +551,39 @@ pub struct Function {
     pub name: Identifier,
     pub type_parameters: Option<Vec<Type>>,
     pub value_parameters: Option<Vec<(Identifier, Type)>>,
-    pub body: Vec<Statement<()>>,
+    pub body: AbstractSyntaxTree<()>,
 }
 
 impl Function {
+    pub fn call(
+        self,
+        type_arguments: Option<Vec<Type>>,
+        value_arguments: Option<Vec<Value>>,
+        variables: &HashMap<Identifier, Value>,
+    ) -> Result<Option<Value>, VmError<()>> {
+        let mut new_variables = variables.clone();
+
+        if let (Some(value_parameters), Some(value_arguments)) =
+            (self.value_parameters, value_arguments)
+        {
+            for ((identifier, _), value) in value_parameters.into_iter().zip(value_arguments) {
+                new_variables.insert(identifier, value);
+            }
+        }
+
+        let mut vm = Vm::new(self.body);
+
+        vm.run(&mut new_variables)
+    }
+
     pub fn return_type(&self, variables: &HashMap<Identifier, Value>) -> Option<Type> {
-        self.body.last().unwrap().expected_type(variables)
+        self.body
+            .nodes
+            .iter()
+            .last()
+            .unwrap()
+            .statement
+            .expected_type(variables)
     }
 }
 
@@ -580,7 +619,7 @@ impl Display for Function {
 
         write!(f, ") {{")?;
 
-        for statement in &self.body {
+        for statement in &self.body.nodes {
             write!(f, "{}", statement)?;
         }
 

dust-lang/src/vm.rs

@@ -1,8 +1,8 @@
 use std::collections::HashMap;
 
 use crate::{
-    parse, AbstractSyntaxTree, Analyzer, AnalyzerError, Identifier, Node, ParseError,
-    ReservedIdentifier, Span, Statement, Value, ValueError,
+    abstract_tree::BuiltInFunctionError, parse, AbstractSyntaxTree, Analyzer, AnalyzerError,
+    Identifier, Node, ParseError, Span, Statement, Value, ValueError,
 };
 
 pub fn run(
@@ -47,9 +47,6 @@ impl<P: Copy> Vm<P> {
         variables: &mut HashMap<Identifier, Value>,
     ) -> Result<Option<Value>, VmError<P>> {
         match node.statement {
-            Statement::Constant(value) => Ok(Some(value.clone())),
-            Statement::Identifier(_) => Ok(None),
-            Statement::ReservedIdentifier(_) => Ok(None),
             Statement::Add(left, right) => {
                 let left_span = left.position;
                 let left = if let Some(value) = self.run_node(*left, variables)? {
@@ -92,6 +89,84 @@ impl<P: Copy> Vm<P> {
 
                 Ok(None)
             }
+            Statement::BuiltInFunctionCall {
+                function,
+                type_arguments: _,
+                value_arguments: value_nodes,
+            } => {
+                let mut values = if let Some(nodes) = value_nodes {
+                    let mut values = Vec::new();
+
+                    for node in nodes {
+                        let position = node.position;
+                        let value = if let Some(value) = self.run_node(node, variables)? {
+                            value
+                        } else {
+                            return Err(VmError::ExpectedValue { position });
+                        };
+
+                        values.push(value);
+                    }
+
+                    Some(values)
+                } else {
+                    None
+                };
+                let function_call_return = function.call(None, values)?;
+
+                Ok(Some(function_call_return))
+            }
+            Statement::Constant(value) => Ok(Some(value.clone())),
+            Statement::FunctionCall {
+                function: function_node,
+                type_arguments: type_parameter_nodes,
+                value_arguments: value_parameter_nodes,
+            } => {
+                let function_position = function_node.position;
+                let function_value =
+                    if let Some(value) = self.run_node(*function_node, variables)? {
+                        value
+                    } else {
+                        return Err(VmError::ExpectedValue {
+                            position: function_position,
+                        });
+                    };
+                let function = if let Some(function) = function_value.as_function() {
+                    function
+                } else {
+                    return Err(VmError::AnaylyzerError(AnalyzerError::ExpectedFunction {
+                        position: function_position,
+                    }));
+                };
+
+                let value_parameters = if let Some(value_nodes) = value_parameter_nodes {
+                    let mut value_parameters = Vec::new();
+
+                    for node in value_nodes {
+                        let position = node.position;
+                        let value = if let Some(value) = self.run_node(node, variables)? {
+                            value
+                        } else {
+                            return Err(VmError::ExpectedValue { position });
+                        };
+
+                        value_parameters.push(value);
+                    }
+
+                    Some(value_parameters)
+                } else {
+                    None
+                };
+
+                Ok(function
+                    .clone()
+                    .call(None, value_parameters, variables)
+                    .map_err(|error| VmError::FunctionCallFailed {
+                        error: Box::new(error),
+                        position: function_position,
+                    })?)
+            }
+            Statement::Identifier(_) => Ok(None),
             Statement::List(nodes) => {
                 let values = nodes
                     .into_iter()
@@ -110,7 +185,7 @@ impl<P: Copy> Vm<P> {
             Statement::Multiply(_, _) => todo!(),
             Statement::PropertyAccess(left, right) => {
                 let left_span = left.position;
-                let left = if let Some(value) = self.run_node(*left, variables)? {
+                let left_value = if let Some(value) = self.run_node(*left, variables)? {
                     value
                 } else {
                     return Err(VmError::ExpectedValue {
@@ -119,39 +194,8 @@ impl<P: Copy> Vm<P> {
                 };
                 let right_span = right.position;
 
-                if let Statement::ReservedIdentifier(reserved) = &right.statement {
-                    match reserved {
-                        ReservedIdentifier::IsEven => {
-                            if let Some(integer) = left.as_integer() {
-                                return Ok(Some(Value::boolean(integer % 2 == 0)));
-                            } else {
-                                return Err(VmError::ExpectedInteger {
-                                    position: right_span,
-                                });
-                            }
-                        }
-                        ReservedIdentifier::IsOdd => {
-                            if let Some(integer) = left.as_integer() {
-                                return Ok(Some(Value::boolean(integer % 2 != 0)));
-                            } else {
-                                return Err(VmError::ExpectedInteger {
-                                    position: right_span,
-                                });
-                            }
-                        }
-                        ReservedIdentifier::Length => {
-                            if let Some(list) = left.as_list() {
-                                return Ok(Some(Value::integer(list.len() as i64)));
-                            } else {
-                                return Err(VmError::ExpectedList {
-                                    position: right_span,
-                                });
-                            }
-                        }
-                    }
-                }
-
-                if let (Some(list), Statement::Constant(value)) = (left.as_list(), &right.statement)
+                if let (Some(list), Statement::Constant(value)) =
+                    (left_value.as_list(), &right.statement)
                 {
                     if let Some(index) = value.as_integer() {
                         let value = list.get(index as usize).cloned();
@@ -160,6 +204,37 @@ impl<P: Copy> Vm<P> {
                     }
                 }
 
+                if let (
+                    value,
+                    Statement::BuiltInFunctionCall {
+                        function,
+                        type_arguments,
+                        value_arguments: mut value_argument_nodes,
+                    },
+                ) = (left_value, right.statement)
+                {
+                    let mut value_arguments = Vec::new();
+
+                    value_arguments.push(value);
+
+                    if let Some(value_nodes) = value_argument_nodes {
+                        for node in value_nodes {
+                            let position = node.position;
+                            let value = if let Some(value) = self.run_node(node, variables)? {
+                                value
+                            } else {
+                                return Err(VmError::ExpectedValue { position });
+                            };
+
+                            value_arguments.push(value);
+                        }
+                    }
+
+                    let function_call_return = function.call(None, Some(value_arguments))?;
+
+                    return Ok(Some(function_call_return));
+                }
+
                 Err(VmError::ExpectedIdentifierOrInteger {
                     position: right_span,
                 })
@@ -176,11 +251,32 @@ pub enum VmError<P> {
 
     // Anaylsis Failures
     // These should be prevented by running the analyzer before the VM
-    ExpectedIdentifier { position: P },
-    ExpectedIdentifierOrInteger { position: P },
-    ExpectedInteger { position: P },
-    ExpectedList { position: P },
-    ExpectedValue { position: P },
+    BuiltInFunctionCallFailed(BuiltInFunctionError),
+    ExpectedIdentifier {
+        position: P,
+    },
+    ExpectedIdentifierOrInteger {
+        position: P,
+    },
+    ExpectedInteger {
+        position: P,
+    },
+    ExpectedList {
+        position: P,
+    },
+    ExpectedValue {
+        position: P,
+    },
+    FunctionCallFailed {
+        error: Box<VmError<()>>,
+        position: P,
+    },
+}
+
+impl<P> From<BuiltInFunctionError> for VmError<P> {
+    fn from(v: BuiltInFunctionError) -> Self {
+        Self::BuiltInFunctionCallFailed(v)
+    }
 }
 
 impl<P> From<AnalyzerError<P>> for VmError<P> {
@@ -217,7 +313,7 @@ mod tests {
 
     #[test]
     fn is_even() {
-        let input = "42.is_even";
+        let input = "42.is_even()";
 
         assert_eq!(
             run(input, &mut HashMap::new()),
@@ -227,7 +323,7 @@ mod tests {
 
     #[test]
     fn is_odd() {
-        let input = "42.is_odd";
+        let input = "42.is_odd()";
 
         assert_eq!(
             run(input, &mut HashMap::new()),
@@ -235,6 +331,13 @@ mod tests {
         );
     }
 
+    #[test]
+    fn length() {
+        let input = "[1, 2, 3].length()";
+
+        assert_eq!(run(input, &mut HashMap::new()), Ok(Some(Value::integer(3))));
+    }
+
     #[test]
     fn list_access() {
         let input = "[1, 2, 3].1";
@@ -242,13 +345,6 @@ mod tests {
         assert_eq!(run(input, &mut HashMap::new()), Ok(Some(Value::integer(2))));
     }
 
-    #[test]
-    fn property_access() {
-        let input = "[1, 2, 3].length";
-
-        assert_eq!(run(input, &mut HashMap::new()), Ok(Some(Value::integer(3))));
-    }
-
     #[test]
     fn add() {
         let input = "1 + 2";