implemented more nodes

src/cli-repl.rs

@@ -2,7 +2,7 @@ use std::io::{self, StdoutLock, Write, stdout};
 
 use libopenbirch::environment::Environment;
 use libopenbirch::node::Node;
-use libopenbirch::parser::{Lexer, Parser};
+use libopenbirch::parser::{Lexer, Parser, ParserError};
 #[cfg(feature = "async")]
 use termion::AsyncReader;
 use termion::color;
@@ -133,8 +133,13 @@ impl Input {
     }
 }
 
-fn print_err(i: usize, exp: String) {
-    println!("\r{}{}^", " ".repeat(i + 2), color::Fg(color::Yellow));
+fn print_err(i: usize, len: usize, exp: String) {
+    println!(
+        "\r{}{}{}",
+        " ".repeat(i + 3 - len),
+        color::Fg(color::Yellow),
+        "^".repeat(len)
+    );
     println!(
         "\r{}{}{}",
         color::Fg(color::Red),
@@ -154,7 +159,7 @@ fn main() -> Result<(), io::Error> {
 
         if tokens_result.is_err() {
             match tokens_result.err().unwrap() {
-                libopenbirch::parser::LexerError::UnexpectedChar(i, exp) => print_err(i, exp),
+                libopenbirch::parser::LexerError::UnexpectedChar(i, exp) => print_err(i, 1, exp),
             }
             continue;
         }
@@ -163,7 +168,7 @@ fn main() -> Result<(), io::Error> {
         input.disable_raw();
 
         let tokens = tokens_result.unwrap();
-        let mut parser = Parser::new(tokens);
+        let mut parser = Parser::new(tokens, &mut env);
 
         #[cfg(debug_assertions)]
         input.enable_raw();
@@ -172,10 +177,10 @@ fn main() -> Result<(), io::Error> {
             Ok(nodes) => nodes,
             Err(err) => {
                 match err {
-                    libopenbirch::parser::ParserError::UnexpectedEndOfTokens(exp) => {
-                        print_err(source.len(), exp)
-                    }
-                    libopenbirch::parser::ParserError::UnexpectedToken(i, exp) => print_err(i, exp),
+                    ParserError::UnexpectedEndOfTokens(exp) => print_err(source.len(), 1, exp),
+                    ParserError::UnexpectedToken(i, len, exp)
+                    | ParserError::Unimplemented(i, len, exp) => print_err(i, len, exp),
+                    ParserError::UnexpectedNode(i, exp) => print_err(i, 1, exp),
                 }
                 continue;
             }
@@ -186,8 +191,8 @@ fn main() -> Result<(), io::Error> {
         for node in nodes {
             let evaluated = node.evaluate(&mut env);
             match evaluated {
-                Ok(result) => println!("\r\t{}", result.as_string(None)),
-                Err(exp) => print_err(0, exp),
+                Ok(result) => println!("\r\t{}", result.as_string(Some(&env))),
+                Err(exp) => print_err(0, 1, exp),
             }
         }
 

src/lib/environment.rs

@@ -3,4 +3,51 @@ use std::{collections::HashMap, rc::Rc};
 use crate::node::NodeEnum;
 
 pub type EnvironmentInternalSymbolKey = u16;
-pub type Environment = HashMap<EnvironmentInternalSymbolKey, Rc<NodeEnum>>;
+// pub type Environment = HashMap<EnvironmentInternalSymbolKey, Rc<NodeEnum>>;
+
+pub struct Environment {
+    map: HashMap<EnvironmentInternalSymbolKey, Rc<NodeEnum>>,
+
+    symbol_to_id: HashMap<String, EnvironmentInternalSymbolKey>,
+    id_to_symbol: HashMap<EnvironmentInternalSymbolKey, String>,
+    unique_keys: EnvironmentInternalSymbolKey
+}
+
+impl Environment {
+    pub fn new() -> Self {
+        Self {
+            map: HashMap::new(),
+
+            symbol_to_id: HashMap::new(),
+            id_to_symbol: HashMap::new(),
+            unique_keys: 0
+        }
+    }
+
+    pub fn get(&self, key: &EnvironmentInternalSymbolKey) -> Option<&Rc<NodeEnum>> {
+        self.map.get(key)
+    }
+
+    pub fn insert(&mut self, key: EnvironmentInternalSymbolKey, value: Rc<NodeEnum>) {
+        self.map.insert(key, value);
+    }
+
+    pub fn str_to_id(&self, value: &String) -> Option<&EnvironmentInternalSymbolKey> {
+        self.symbol_to_id.get(value)
+    }
+    pub fn id_to_str(&self, value: &EnvironmentInternalSymbolKey) -> Option<&String> {
+        self.id_to_symbol.get(value)
+    }
+    pub fn insert_str_to_id(&mut self, key: String, value: EnvironmentInternalSymbolKey) {
+        self.symbol_to_id.insert(key.clone(), value);
+        self.id_to_symbol.insert(value, key);
+    }
+    pub fn insert_id_to_str(&mut self, key: EnvironmentInternalSymbolKey, value: String) {
+        self.id_to_symbol.insert(key, value.clone());
+        self.symbol_to_id.insert(value, key);
+    }
+    pub fn get_new_id(&mut self) -> EnvironmentInternalSymbolKey {
+        self.unique_keys += 1;
+        self.unique_keys
+    }
+}

src/lib/node/add.rs

@@ -14,10 +14,26 @@ impl Node for Add {
         let evaluated_right = self.right.evaluate(env)?;
 
         match (evaluated_left.as_ref(), evaluated_right.as_ref()) {
+            // Zero rule
+            (NodeEnum::Constant(zero), _) if zero.get_value() == 0. => Ok(evaluated_right),
+            (_, NodeEnum::Constant(zero)) if zero.get_value() == 0. => Ok(evaluated_left),
+
+            // Constant + Constant = Constant
             (NodeEnum::Constant(a), NodeEnum::Constant(b)) => {
                 Ok(Rc::new(Constant::new(a.get_value() + b.get_value()).into()))
             }
-            _ => Err(format!("Invalid Add operation: {:?}", self)),
+
+            // Symbol + Constant we just return the same
+            (NodeEnum::Symbol(_), NodeEnum::Constant(_)) => {
+                Ok(Rc::new(Add::new(evaluated_left, evaluated_right).into()))
+            }
+
+            // Constant + Symbol we switch them around so the constant is last
+            (NodeEnum::Constant(_), NodeEnum::Symbol(_)) => {
+                Ok(Rc::new(Add::new(evaluated_right, evaluated_left).into()))
+            }
+
+            _ => Ok(Rc::new(Add::new(evaluated_left, evaluated_right).into())),
         }
     }
 
@@ -42,10 +58,7 @@ impl Node for Add {
 
 impl Add {
     pub fn new(left: Rc<NodeEnum>, right: Rc<NodeEnum>) -> Self {
-        Self {
-            left,
-            right,
-        }
+        Self { left, right }
     }
 
     pub fn get_left(&self) -> Rc<NodeEnum> {

src/lib/node/assign.rs

@@ -11,8 +11,17 @@ pub struct Assign {
 impl Node for Assign {
     fn evaluate(&self, env: &mut Environment) -> Result<Rc<NodeEnum>, String> {
         if let NodeEnum::Symbol(symbol) = self.left.as_ref() {
-            env.insert(symbol.get_value(), self.right.clone());
-            Ok(Empty::EMPTY.clone())
+            let name = env
+                .id_to_str(&symbol.get_value())
+                .expect("Unknown symbol")
+                .clone();
+            let right = self.right.evaluate(env)?;
+
+            env.insert(symbol.get_value(), right.clone());
+            Ok(Empty::new(format!(
+                "{name} := {}",
+                right.as_string(Some(env))
+            )))
         } else {
             Err(format!(
                 "Cannot assign to a {}",
@@ -35,6 +44,10 @@ impl Node for Assign {
 }
 
 impl Assign {
+    pub fn new(left: Rc<NodeEnum>, right: Rc<NodeEnum>) -> Self {
+        Self { left, right }
+    }
+
     pub fn get_left(&self) -> Rc<NodeEnum> {
         self.left.clone()
     }

src/lib/node/call.rs

@@ -7,7 +7,7 @@ use super::{Node, NodeEnum, Precedence, symbol::Symbol};
 #[derive(Debug, Clone, PartialEq, PartialOrd)]
 pub struct Call {
     function: Rc<NodeEnum>,
-    arguments: Vec<Rc<NodeEnum>>,
+    arguments: Rc<NodeEnum>,
 }
 
 impl Node for Call {
@@ -23,29 +23,34 @@ impl Node for Call {
             ));
         };
 
+        let arguments = if let NodeEnum::Set(set) = self.arguments.as_ref() {
+            set.get_values()
+        } else {
+            panic!(
+                "This shoulnd not be possible, but call constructed with arguments of type that is not set"
+            );
+        };
+
         // Check if argument counts match
         let fargs = func.get_arguments();
-        if fargs.len() != self.arguments.len() {
+        if fargs.len() != arguments.len() {
             return Err(format!(
                 "Error calling function. Expected {} arguments, but got {}",
                 func.get_arguments().len(),
-                self.arguments.len()
+                arguments.len()
             ));
         }
 
         // Call function body with arguments
         match func.get_body() {
             // Pass arguments to native function
-            FunctionType::Native(_name, native_function) => native_function(&self.arguments),
+            FunctionType::Native(_name, native_function) => native_function(arguments),
             FunctionType::UserFunction(node_enum) => {
                 // TODO: Push scope
                 // Define variables
-                fargs
-                    .iter()
-                    .zip(&self.arguments)
-                    .for_each(|(symbol, value)| {
-                        env.insert(symbol.get_value(), value.clone());
-                    });
+                fargs.iter().zip(arguments).for_each(|(symbol, value)| {
+                    env.insert(symbol.get_value(), value.clone());
+                });
                 let ev = node_enum.evaluate(env);
                 // TODO: Pop scope
                 // Return evaluated return value for function
@@ -55,12 +60,7 @@ impl Node for Call {
     }
 
     fn as_string(&self, env: Option<&Environment>) -> String {
-        let arguments = self
-            .arguments
-            .iter()
-            .map(|x| x.as_string(env))
-            .reduce(|a, b| a + ", " + &b)
-            .unwrap();
+        let arguments = self.arguments.as_string(env);
         format!("{}({})", self.function.as_string(env), arguments)
     }
 
@@ -68,3 +68,15 @@ impl Node for Call {
         Precedence::Call
     }
 }
+
+impl Call {
+    pub fn new(function: Rc<NodeEnum>, arguments: Rc<NodeEnum>) -> Rc<NodeEnum> {
+        Rc::new(
+            Self {
+                function,
+                arguments,
+            }
+            .into(),
+        )
+    }
+}

src/lib/node/constant.rs

@@ -9,6 +9,12 @@ pub struct Constant {
     value: ConstantValue,
 }
 
+impl From<ConstantValue> for Constant {
+    fn from(value: ConstantValue) -> Self {
+        Self::new(value)
+    }
+}
+
 impl Node for Constant {
     fn evaluate(&self, _: &mut super::Environment) -> Result<Rc<super::NodeEnum>, String> {
         Ok(Rc::new(self.clone().into()))

src/lib/node/divide.rs

@@ -1,6 +1,6 @@
 use std::rc::Rc;
 
-use super::{Node, NodeEnum, Precedence, constant::Constant};
+use super::{constant::Constant, set::Set, Node, NodeEnum, Precedence};
 
 #[derive(Clone, Debug, PartialEq, PartialOrd)]
 pub struct Divide {
@@ -14,10 +14,55 @@ impl Node for Divide {
         let evaluated_right = self.right.evaluate(env)?;
 
         match (evaluated_left.as_ref(), evaluated_right.as_ref()) {
+            // Error if dividing by zero
+            (_, NodeEnum::Constant(zero)) if zero.get_value() == 0. => {
+                Err("Division by Zero".into())
+            }
+
+            // Zero rule
+            (NodeEnum::Constant(zero), _) if zero.get_value() == 0. => {
+                Ok(evaluated_left)
+            }
+
+            // Constant + Constant = Constant
             (NodeEnum::Constant(a), NodeEnum::Constant(b)) => {
                 Ok(Rc::new(Constant::new(a.get_value() / b.get_value()).into()))
             }
-            _ => Err(format!("Invalid Divide operation: {:?}", self)),
+            // Symbol + Constant we just return the same
+            (NodeEnum::Symbol(_), NodeEnum::Constant(_)) => {
+                Ok(Rc::new(Divide::new(evaluated_left, evaluated_right).into()))
+            }
+            // Constant + Symbol we switch them around so the constant is last
+            (NodeEnum::Constant(_), NodeEnum::Symbol(_)) => {
+                Ok(Rc::new(Divide::new(evaluated_right, evaluated_left).into()))
+            }
+            // Divide a set with a constant
+            (NodeEnum::Set(s), NodeEnum::Constant(c)) => {
+                let old_values = s.get_values();
+                let mut values = Vec::with_capacity(old_values.len());
+                let c: Rc<NodeEnum> = Rc::new(c.clone().into());
+
+                for value in old_values.iter() {
+                    let new_value = Divide::new(c.clone(), value.clone());
+                    values.push(new_value.evaluate(env)?);
+                }
+
+                Ok(Set::new(values))
+            }
+            // Divide a set with a symbol
+            (NodeEnum::Set(s), NodeEnum::Symbol(c)) => {
+                let old_values = s.get_values();
+                let mut values = Vec::with_capacity(old_values.len());
+                let c: Rc<NodeEnum> = Rc::new(c.clone().into());
+
+                for value in old_values.iter() {
+                    let new_value = Divide::new(c.clone(), value.clone());
+                    values.push(new_value.evaluate(env)?);
+                }
+
+                Ok(Set::new(values))
+            }
+            _ => Ok(Rc::new(Divide::new(evaluated_left, evaluated_right).into())),
         }
     }
 
@@ -42,10 +87,7 @@ impl Node for Divide {
 
 impl Divide {
     pub fn new(left: Rc<NodeEnum>, right: Rc<NodeEnum>) -> Self {
-        Self {
-            left,
-            right
-        }
+        Self { left, right }
     }
 
     pub fn get_left(&self) -> Rc<NodeEnum> {

src/lib/node/empty.rs

@@ -3,14 +3,20 @@ use std::{rc::Rc, sync::LazyLock};
 use super::{Environment, Node, NodeEnum, Precedence};
 
 #[derive(Debug, Clone, PartialEq, PartialOrd)]
-pub struct Empty;
+pub struct Empty {
+    message: Option<String>,
+}
+
 impl Node for Empty {
     fn evaluate(&self, _: &mut Environment) -> Result<Rc<NodeEnum>, String> {
         Ok(Empty::EMPTY.clone())
     }
 
     fn as_string(&self, _: Option<&Environment>) -> String {
-        String::from("{{#VOID}}")
+        match &self.message {
+            Some(m) => m.clone(),
+            None => String::from("{{#VOID}}"),
+        }
     }
 
     fn precedence(&self) -> Precedence {
@@ -19,5 +25,15 @@ impl Node for Empty {
 }
 
 impl Empty {
-    pub const EMPTY: LazyLock<Rc<NodeEnum>> = LazyLock::new(|| Rc::new(Empty{}.into()));
+    pub const EMPTY: LazyLock<Rc<NodeEnum>> =
+        LazyLock::new(|| Rc::new(Empty { message: None }.into()));
+
+    pub fn new(message: impl Into<String>) -> Rc<NodeEnum> {
+        Rc::new(
+            Self {
+                message: Some(message.into()),
+            }
+            .into(),
+        )
+    }
 }

src/lib/node/equals.rs

@@ -0,0 +1,39 @@
+use std::rc::Rc;
+
+use super::{Environment, Node, NodeEnum, Precedence, if_else::Bool};
+
+#[derive(Clone, Debug, PartialEq, PartialOrd)]
+pub struct Equals {
+    left: Rc<NodeEnum>,
+    right: Rc<NodeEnum>,
+}
+
+impl Node for Equals {
+    fn evaluate(&self, env: &mut Environment) -> Result<Rc<NodeEnum>, String> {
+        let left = self.left.evaluate(env)?;
+        let right = self.right.evaluate(env)?;
+
+        match left == right {
+            true => Ok(Rc::new(Bool::True.into())),
+            false => Ok(Rc::new(Bool::False.into())),
+        }
+    }
+
+    fn as_string(&self, env: Option<&Environment>) -> String {
+        format!(
+            "({}={})",
+            self.left.as_string(env),
+            self.right.as_string(env)
+        )
+    }
+
+    fn precedence(&self) -> Precedence {
+        Precedence::Primary
+    }
+}
+
+impl Equals {
+    pub fn new(left: Rc<NodeEnum>, right: Rc<NodeEnum>) -> Self {
+        Self { left, right }
+    }
+}

src/lib/node/function.rs

@@ -30,7 +30,7 @@ impl Node for Function {
         let args = self
             .arguments
             .iter()
-            .map(|x| Node::as_string(x, None))
+            .map(|x| Node::as_string(x, env))
             .reduce(|acc, e| format!("{acc}, {e}"))
             .unwrap_or("()".to_owned());
 
@@ -46,10 +46,15 @@ impl Node for Function {
 }
 
 impl Function {
-    // TODO: Implement new.
-    // pub fn new(t: FunctionType, ) -> Self {
-    //
-    // }
+    pub fn new(t: FunctionType, args: Vec<Symbol>) -> Rc<NodeEnum> {
+        Rc::new(
+            Self {
+                function: t,
+                arguments: args,
+            }
+            .into(),
+        )
+    }
 
     pub fn get_body(&self) -> &FunctionType {
         &self.function

src/lib/node/mod.rs

@@ -12,6 +12,8 @@ use if_else::{Bool, IfElse};
 use multiply::Multiply;
 use subtract::Subtract;
 use symbol::Symbol;
+use equals::Equals;
+use set::Set;
 
 use crate::environment::Environment;
 
@@ -21,12 +23,14 @@ pub mod divide;
 pub mod multiply;
 pub mod subtract;
 pub mod symbol;
-mod node_ref;
-mod assign;
-mod empty;
-mod function;
-mod call;
-mod if_else;
+pub mod node_ref;
+pub mod assign;
+pub mod empty;
+pub mod function;
+pub mod call;
+pub mod if_else;
+pub mod equals;
+pub mod set;
 
 #[enum_dispatch]
 #[enum_dispatch(Debug, Clone, PartialEq, PartialOrd, ToString)]
@@ -50,6 +54,14 @@ pub enum NodeEnum {
     Bool,
     IfElse,
 
+    Set,
+
+    Equals,
+    // Greater,
+    // GreaterEquals,
+    // Less,
+    // LessEquals
+
     // Logical operators
     // In,
     // Where,

src/lib/node/multiply.rs

@@ -1,6 +1,8 @@
 use std::rc::Rc;
 
-use super::{Node, NodeEnum, Precedence, constant::Constant};
+use crate::environment::Environment;
+
+use super::{Node, NodeEnum, Precedence, constant::Constant, set::Set};
 
 #[derive(Clone, Debug, PartialEq, PartialOrd)]
 pub struct Multiply {
@@ -14,10 +16,70 @@ impl Node for Multiply {
         let evaluated_right = self.right.evaluate(env)?;
 
         match (evaluated_left.as_ref(), evaluated_right.as_ref()) {
+            // Zero rule
+            (NodeEnum::Constant(zero), _) | (_, NodeEnum::Constant(zero))
+                if zero.get_value() == 0. =>
+            {
+                Ok(Rc::new(Constant::new(0.).into()))
+            }
+
+            // Constant + Constant = Constant
             (NodeEnum::Constant(a), NodeEnum::Constant(b)) => {
                 Ok(Rc::new(Constant::new(a.get_value() * b.get_value()).into()))
             }
-            _ => Err(format!("Invalid Multiply operation: {:?}", self)),
+
+            // Symbol + Constant we just return the same
+            (NodeEnum::Symbol(_), NodeEnum::Constant(_)) => Ok(Rc::new(
+                Multiply::new(evaluated_right, evaluated_left).into(),
+            )),
+
+            // Constant + Symbol we switch them around so the constant is last
+            (NodeEnum::Constant(_), NodeEnum::Symbol(_)) => Ok(Rc::new(
+                Multiply::new(evaluated_left, evaluated_right).into(),
+            )),
+
+            // Multiply a set with a constant
+            (NodeEnum::Set(s), NodeEnum::Constant(c))
+            | (NodeEnum::Constant(c), NodeEnum::Set(s)) => {
+                let old_values = s.get_values();
+                let mut values = Vec::with_capacity(old_values.len());
+                let c: Rc<NodeEnum> = Rc::new(c.clone().into());
+
+                for value in old_values.iter() {
+                    let new_value = Multiply::new(c.clone(), value.clone());
+                    values.push(new_value.evaluate(env)?);
+                }
+
+                Ok(Set::new(values))
+            }
+
+            // Multiply a set with a constant
+            (NodeEnum::Set(s), NodeEnum::Symbol(c)) | (NodeEnum::Symbol(c), NodeEnum::Set(s)) => {
+                let old_values = s.get_values();
+                let mut values = Vec::with_capacity(old_values.len());
+                let c: Rc<NodeEnum> = Rc::new(c.clone().into());
+
+                for value in old_values.iter() {
+                    let new_value = Multiply::new(c.clone(), value.clone());
+                    values.push(new_value.evaluate(env)?);
+                }
+
+                Ok(Set::new(values))
+            }
+
+            (NodeEnum::Constant(c), NodeEnum::Multiply(m))
+            | (NodeEnum::Multiply(m), NodeEnum::Constant(c)) => {
+                Self::collapse_nested_multiply(c, m, env)?.evaluate(env)
+            }
+
+            // (NodeEnum::Multiply(m1), NodeEnum::Multiply(m2)) => {
+            //     Self::move_constants_to_left(evaluated_left.clone(), evaluated_right.clone())
+            // }
+
+            // Default to returning with left and right evaluated
+            _ => Ok(Rc::new(
+                Multiply::new(evaluated_left, evaluated_right).into(),
+            )),
         }
     }
 
@@ -41,13 +103,79 @@ impl Node for Multiply {
 }
 
 impl Multiply {
-    pub fn new(left: Rc<NodeEnum>, right: Rc<NodeEnum>) -> Self {
-        Self {
-            left,
-            right
+    fn collapse_nested_multiply(
+        constant: &Constant,
+        multiply: &Multiply,
+        env: &mut Environment,
+    ) -> Result<Rc<NodeEnum>, String> {
+        match (multiply.left.as_ref(), multiply.right.as_ref()) {
+            (NodeEnum::Constant(c2), _) => {
+                let new_const = Constant::new(constant.get_value() * c2.get_value()).into();
+                Ok(Rc::new(
+                    Multiply::new(Rc::new(new_const), multiply.right.clone()).into(),
+                ))
+            }
+
+            (_, NodeEnum::Constant(c2)) => {
+                let new_const = Constant::new(constant.get_value() * c2.get_value()).into();
+                Ok(Rc::new(
+                    Multiply::new(Rc::new(new_const), multiply.right.clone()).into(),
+                ))
+            }
+
+            (_, NodeEnum::Multiply(inner_mul)) => {
+                let expr = Self::collapse_nested_multiply(constant, inner_mul, env)?;
+                Ok(Rc::new(Multiply::new(expr, multiply.left.clone()).into()))
+            }
+
+            (NodeEnum::Multiply(inner_mul), _) => {
+                let expr = Self::collapse_nested_multiply(constant, inner_mul, env)?;
+                Ok(Rc::new(Multiply::new(expr, multiply.right.clone()).into()))
+            }
+
+            _ => Ok(Rc::new(
+                Multiply::new(
+                    Rc::new(constant.clone().into()),
+                    Rc::new(multiply.clone().into()),
+                )
+                .into(),
+            )),
         }
     }
 
+    fn move_constants_to_left(
+        left: Rc<NodeEnum>,
+        right: Rc<NodeEnum>,
+    ) -> Result<Rc<NodeEnum>, String> {
+        match (left.as_ref(), right.as_ref()) {
+            // Default cases that returns
+            (NodeEnum::Constant(_), NodeEnum::Multiply(_))
+            | (NodeEnum::Symbol(_), NodeEnum::Symbol(_)) => Ok(Self::new_rc(left, right)),
+
+            (NodeEnum::Multiply(m), NodeEnum::Constant(c)) => Ok(Self::new_rc(
+                right.clone(),
+                Self::move_constants_to_left(m.left.clone(), m.right.clone())?,
+            )),
+
+            (NodeEnum::Multiply(m1), NodeEnum::Multiply(m2)) => Ok(Self::new_rc(
+                Self::move_constants_to_left(m1.left.clone(), m1.right.clone())?,
+                Self::move_constants_to_left(m2.left.clone(), m2.right.clone())?,
+            )),
+
+            _ => Ok(Self::new_rc(left, right)),
+        }
+    }
+}
+
+impl Multiply {
+    pub fn new(left: Rc<NodeEnum>, right: Rc<NodeEnum>) -> Self {
+        Self { left, right }
+    }
+
+    pub fn new_rc(left: Rc<NodeEnum>, right: Rc<NodeEnum>) -> Rc<NodeEnum> {
+        Rc::new(Self::new(left, right).into())
+    }
+
     pub fn get_left(&self) -> Rc<NodeEnum> {
         self.left.clone()
     }

src/lib/node/set.rs

@@ -0,0 +1,49 @@
+use std::rc::Rc;
+
+use super::{Environment, Node, NodeEnum, Precedence};
+
+#[derive(Clone, Debug, PartialEq, PartialOrd)]
+pub struct Set {
+    values: Vec<Rc<NodeEnum>>,
+}
+
+impl Node for Set {
+    fn evaluate(&self, env: &mut super::Environment) -> Result<Rc<NodeEnum>, String> {
+        let mut values = Vec::with_capacity(self.values.len());
+
+        for value in self.values.iter() {
+            values.push(value.evaluate(env)?);
+        }
+
+        Ok(Self::new(values))
+    }
+
+    fn as_string(&self, env: Option<&Environment>) -> String {
+        format!(
+            "({})",
+            self.values
+                .iter()
+                .map(|x| x.as_string(env))
+                .reduce(|a, b| a + ", " + &b)
+                .unwrap()
+        )
+    }
+
+    fn precedence(&self) -> Precedence {
+        Precedence::Primary
+    }
+}
+
+impl Set {
+    pub fn new(values: Vec<Rc<NodeEnum>>) -> Rc<NodeEnum> {
+        Rc::new(Self { values }.into())
+    }
+
+    pub fn get_values(&self) -> &Vec<Rc<NodeEnum>> {
+        &self.values
+    }
+
+    pub fn set_value(&mut self, values: Vec<Rc<NodeEnum>>) {
+        self.values = values;
+    }
+}

src/lib/node/subtract.rs

@@ -14,10 +14,25 @@ impl Node for Subtract {
         let evaluated_right = self.right.evaluate(env)?;
 
         match (evaluated_left.as_ref(), evaluated_right.as_ref()) {
+            // Zero rule
+            (NodeEnum::Constant(zero), _) if zero.get_value() == 0. => Ok(evaluated_right),
+            (_, NodeEnum::Constant(zero)) if zero.get_value() == 0. => Ok(evaluated_left),
+
+            // Constant + Constant = Constant
             (NodeEnum::Constant(a), NodeEnum::Constant(b)) => {
                 Ok(Rc::new(Constant::new(a.get_value() - b.get_value()).into()))
             }
-            _ => Err(format!("Invalid Add operation: {:?}", self)),
+            // Symbol + Constant we just return the same
+            (NodeEnum::Symbol(_), NodeEnum::Constant(_)) => {
+                Ok(Rc::new(Subtract::new(evaluated_left, evaluated_right).into()))
+            }
+            // Constant + Symbol we switch them around so the constant is last
+            (NodeEnum::Constant(_), NodeEnum::Symbol(_)) => {
+                Ok(Rc::new(Subtract::new(evaluated_right, evaluated_left).into()))
+            }
+            _ => {
+                Ok(Rc::new(Subtract::new(evaluated_left, evaluated_right).into()))
+            }
         }
     }
 

src/lib/node/symbol.rs

@@ -28,20 +28,12 @@ impl Node for Symbol {
             if let Some(value) = env.get(&self.value) {
                 value.as_string(Some(env))
             } else {
-                Symbol::ID_TO_STR_MAP
-                    .lock()
-                    .unwrap()
-                    .get(&self.value)
-                    .unwrap_or(&format!("{{#SYMBOL {}}}", self.value))
-                    .clone()
+                env.id_to_str(&self.value)
+                    .cloned()
+                    .unwrap_or(format!("{{#SYMBOL {}}}", self.value))
             }
         } else {
-            Symbol::ID_TO_STR_MAP
-                .lock()
-                .unwrap()
-                .get(&self.value)
-                .unwrap_or(&format!("{{#SYMBOL {}}}", self.value))
-                .clone()
+            format!("{{#SYMBOL {}}}", self.value)
         }
     }
 
@@ -51,32 +43,17 @@ impl Node for Symbol {
 }
 
 impl Symbol {
-    const STR_TO_ID_MAP: LazyLock<Mutex<HashMap<String, EnvironmentInternalSymbolKey>>> =
-        LazyLock::new(|| HashMap::new().into());
-    const ID_TO_STR_MAP: LazyLock<Mutex<HashMap<EnvironmentInternalSymbolKey, String>>> =
-        LazyLock::new(|| HashMap::new().into());
-
     pub fn new(value: EnvironmentInternalSymbolKey) -> Self {
         Self { value }
     }
 
-    pub fn new_from_str(str: impl Into<String>) -> Self {
+    pub fn new_from_str(str: impl Into<String>, env: &mut Environment) -> Self {
         let str = str.into();
-        if let Some(value) = Symbol::STR_TO_ID_MAP.lock().unwrap().get(str.as_str()) {
+        if let Some(value) = env.str_to_id(&str) {
             Self::new(value.clone())
         } else {
-            let id = Symbol::STR_TO_ID_MAP
-                .lock()
-                .unwrap()
-                .len()
-                .try_into()
-                .unwrap();
-            Symbol::STR_TO_ID_MAP
-                .lock()
-                .unwrap()
-                .insert(str.clone(), id);
-            Symbol::ID_TO_STR_MAP.lock().unwrap().insert(id, str);
-
+            let id = env.get_new_id();
+            env.insert_str_to_id(str.clone(), id);
             Self::new(id)
         }
     }

src/lib/parser/mod.rs

@@ -1,29 +1,45 @@
-use std::{collections::HashMap, iter::Peekable, rc::Rc, slice::Iter, vec::IntoIter};
+use std::{collections::HashMap, iter::Peekable, rc::Rc, slice::Iter, str::Chars, vec::IntoIter};
 
-use crate::node::{
-    NodeEnum,
-    add::Add,
-    constant::{Constant, ConstantValue},
-    divide::Divide,
-    multiply::Multiply,
-    subtract::Subtract,
+use crate::{
+    environment::Environment,
+    node::{
+        NodeEnum,
+        add::Add,
+        assign::Assign,
+        call::Call,
+        constant::{Constant, ConstantValue},
+        divide::Divide,
+        equals::Equals,
+        function::{Function, FunctionType},
+        multiply::Multiply,
+        set::Set,
+        subtract::Subtract,
+        symbol::Symbol,
+    },
 };
 
 #[derive(Debug)]
 pub struct Token(usize, TokenType);
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq, Clone)]
 pub enum TokenType {
     // Space,
     Number(ConstantValue),
+    Identifier(String),
 
     Plus,
     Minus,
     Star,
     Slash,
 
+    Equals,
+
+    ColonEquals,
+    LeftArrow,
+
     RParen,
     LParen,
+    Comma,
 
     If,
     Then,
@@ -31,8 +47,35 @@ pub enum TokenType {
     End,
 }
 
+impl TokenType {
+    pub fn len(&self) -> usize {
+        match self {
+            TokenType::Number(n) => n.to_string().len(),
+            TokenType::Identifier(s) => s.len(),
+
+            TokenType::Plus => 1,
+            TokenType::Minus => 1,
+            TokenType::Star => 1,
+            TokenType::Slash => 1,
+            TokenType::Equals => 1,
+
+            TokenType::ColonEquals => 2,
+            TokenType::LeftArrow => 2,
+
+            TokenType::RParen => 1,
+            TokenType::LParen => 1,
+            TokenType::Comma => 1,
+
+            TokenType::If => 2,
+            TokenType::Then => 4,
+            TokenType::Else => 4,
+            TokenType::End => 3,
+        }
+    }
+}
+
 pub struct Lexer<'a> {
-    source: &'a String,
+    source: Peekable<Chars<'a>>,
 }
 
 #[derive(Debug)]
@@ -42,40 +85,41 @@ pub enum LexerError {
 
 impl<'a> Lexer<'a> {
     pub fn new(source: &'a String) -> Self {
-        Self { source }
+        Self {
+            source: source.chars().peekable(),
+        }
     }
 
     pub fn lex(&'a mut self) -> Result<Vec<Token>, LexerError> {
-        let mut src = self.source.chars().peekable();
         let mut i = 0;
         let mut tokens = vec![];
 
-        while let Some(c) = src.next() {
+        while let Some(c) = self.source.next() {
             match c {
                 // Collapse spaces into a single Space token
                 ' ' => {
-                    while src.peek() == Some(&' ') {
-                        src.next();
+                    while self.source.peek() == Some(&' ') {
+                        self.source.next();
                         i += 1;
                     }
                     // tokens.push(Token(i, TokenType::Space));
                 }
                 // Comments with //
-                '/' if src.peek() == Some(&'/') => {
-                    while src.next() != Some('\n') {
+                '/' if self.source.peek() == Some(&'/') => {
+                    while self.source.next() != Some('\n') {
                         i += 1;
                     }
                 }
                 // Numbers with decimal points
-                '0'..'9' | '.' => {
+                '0'..='9' | '.' => {
                     let mut digit = String::from(c);
                     loop {
-                        let d = src.peek();
+                        let d = self.source.peek();
                         let mut has_decimal = c == '.';
                         match d {
-                            Some('0'..'9') => {
+                            Some('0'..='9') => {
                                 digit.push(*d.unwrap());
-                                src.next();
+                                self.source.next();
                                 i += 1;
                             }
                             #[allow(unused_assignments)] // For some reason it thinks has_decimal
@@ -101,14 +145,33 @@ impl<'a> Lexer<'a> {
                     tokens.push(Token(i, TokenType::Number(number)));
                 }
 
+                // LeftArrow (->)
+                '-' if self.source.peek() == Some(&'>') => {
+                    self.source.next();
+                    i += 1;
+                    tokens.push(Token(i, TokenType::LeftArrow));
+                }
+
                 '+' => tokens.push(Token(i, TokenType::Plus)),
                 '-' => tokens.push(Token(i, TokenType::Minus)),
                 '*' => tokens.push(Token(i, TokenType::Star)),
                 '/' => tokens.push(Token(i, TokenType::Slash)),
+                '=' => tokens.push(Token(i, TokenType::Equals)),
+                ',' => tokens.push(Token(i, TokenType::Comma)),
+
+                ':' if self.source.peek() == Some(&'=') => {
+                    self.source.next();
+                    i += 1;
+                    tokens.push(Token(i, TokenType::ColonEquals));
+                }
 
                 '(' => tokens.push(Token(i, TokenType::LParen)),
                 ')' => tokens.push(Token(i, TokenType::RParen)),
 
+                _ if c.is_alphabetic() || c == '_' => {
+                    tokens.push(self.lex_identifier(&mut i, c)?);
+                }
+
                 _ => {
                     return Err(LexerError::UnexpectedChar(
                         i,
@@ -121,26 +184,57 @@ impl<'a> Lexer<'a> {
 
         Ok(tokens)
     }
+
+    fn lex_identifier<'b>(&'b mut self, i: &mut usize, c: char) -> Result<Token, LexerError> {
+        let mut identifier = c.to_string();
+
+        while let Some(c) = self.source.peek() {
+            if c.is_alphanumeric() || c == &'_' || c == &'\'' {
+                identifier.push(*c);
+                self.source.next();
+                *i += 1;
+            } else {
+                break;
+            }
+        }
+
+        Ok(Token(
+            *i,
+            match identifier.to_lowercase().as_str() {
+                "if" => TokenType::If,
+                "then" => TokenType::Then,
+                "else" => TokenType::Else,
+                "end" => TokenType::End,
+                _ => TokenType::Identifier(identifier),
+            },
+        ))
+    }
 }
 
 pub enum ParserError {
     UnexpectedEndOfTokens(String),
-    UnexpectedToken(usize, String),
+    UnexpectedToken(usize, usize, String),
+    Unimplemented(usize, usize, String),
+    UnexpectedNode(usize, String),
 }
 
 /// Recursive descent parser
-pub struct Parser {
+pub struct Parser<'a> {
     tokens: Peekable<IntoIter<Token>>,
+    environment: &'a mut Environment,
+    previous: Option<&'a Token>,
 }
 
 type Tokens<'a> = Peekable<Iter<'a, Token>>;
 
-impl Parser {
-    pub fn new(tokens: Vec<Token>) -> Self {
+impl<'a> Parser<'a> {
+    pub fn new(tokens: Vec<Token>, env: &'a mut Environment) -> Self {
         // #[cfg(debug_assertions)]
-        // println!("\r{tokens:#?}");
+        // println!("\r{tokens:?}");
         Self {
             tokens: tokens.into_iter().peekable(),
+            environment: env,
+            previous: None,
         }
     }
 
@@ -155,13 +249,61 @@ impl Parser {
         Ok(expressions)
     }
 
+    #[inline]
+    fn matchType<'b>(&'b mut self, t: TokenType) -> bool {
+        if let Some(Token(_, token_type)) = self.tokens.peek() {
+            if *token_type == t {
+                self.tokens.next();
+                return true;
+            }
+        }
+
+        false
+    }
+
+    #[inline]
+    fn matchOrErr(&mut self, t: TokenType) -> Result<bool, ParserError> {
+        let (i, tt) = if let Some(Token(i, tt)) = self.tokens.peek() {
+            (*i, tt.clone())
+        } else {
+            return Err(ParserError::UnexpectedEndOfTokens(format!(
+                "Expected {t:?} but found nothing instead"
+            )));
+        };
+
+        if self.matchType(t.clone()) {
+            Ok(true)
+        } else {
+            Err(ParserError::UnexpectedToken(
+                i,
+                tt.len(),
+                format!("Expected {t:?} but found {tt:?} instead"),
+            ))
+        }
+    }
+
     fn expression(&mut self) -> Result<Rc<NodeEnum>, ParserError> {
-        self.equality()
+        self.assignment()
+    }
+
+    fn assignment(&mut self) -> Result<Rc<NodeEnum>, ParserError> {
+        let expr = self.equality();
+
+        if let Some(Token(_, TokenType::ColonEquals)) = self.tokens.peek() {
+            self.tokens.next();
+            return Ok(Rc::new(Assign::new(expr?, self.equality()?).into()));
+        }
+
+        expr
     }
 
     fn equality(&mut self) -> Result<Rc<NodeEnum>, ParserError> {
         // TODO: Implement equality
-        self.comparison()
+        let expr = self.comparison();
+        if self.matchType(TokenType::Equals) {
+            return Ok(Rc::new(Equals::new(expr?, self.equality()?).into()));
+        }
+        expr
     }
 
     fn comparison(&mut self) -> Result<Rc<NodeEnum>, ParserError> {
@@ -171,8 +313,7 @@ impl Parser {
 
     fn term(&mut self) -> Result<Rc<NodeEnum>, ParserError> {
         let expr = self.factor()?;
-        if let Some(Token(_, TokenType::Plus)) = self.tokens.peek() {
-            self.tokens.next();
+        if self.matchType(TokenType::Plus) {
             Ok(Rc::new(Add::new(expr, self.comparison()?).into()))
         } else if let Some(Token(_, TokenType::Minus)) = self.tokens.peek() {
             self.tokens.next();
@@ -204,11 +345,83 @@ impl Parser {
     }
 
     fn call(&mut self) -> Result<Rc<NodeEnum>, ParserError> {
-        self.function()
+        let mut expr = self.function();
+
+        loop {
+            let (i, t) = if let Some(Token(i, x)) = self.tokens.peek() {
+                (*i, x.clone())
+            } else {
+                return expr;
+            };
+
+            if t == TokenType::LParen {
+                let potential_parameters = self.primary()?;
+                let parameters = if let NodeEnum::Set(set) = potential_parameters.as_ref() {
+                    potential_parameters
+                } else {
+                    // return Err(ParserError::UnexpectedNode(
+                    //     i,
+                    //     format!("Expected a Set here, but got a {potential_parameters:?}"),
+                    // ));
+                    Set::new(vec![potential_parameters])
+                };
+
+             expr = Ok(Call::new(expr?, parameters));
+            } else {
+                break;
+            }
+        }
+
+        expr
     }
 
     fn function(&mut self) -> Result<Rc<NodeEnum>, ParserError> {
-        self.primary()
+        let error_loc = if let Some(Token(i, _)) = self.tokens.peek() {
+            *i
+        } else {
+            0
+        };
+
+        let expr = self.primary()?;
+
+        if self.matchType(TokenType::LeftArrow) {
+            let right = self.equality()?;
+            match expr.clone().as_ref() {
+                NodeEnum::Symbol(symbol) => {
+                    return Ok(Function::new(
+                        FunctionType::UserFunction(right),
+                        vec![symbol.clone()],
+                    ));
+                }
+                NodeEnum::Set(set) => {
+                    let mut symbols = vec![];
+                    for (i, value) in set.get_values().into_iter().enumerate() {
+                        match value.as_ref() {
+                            _ => {
+                                return Err(ParserError::UnexpectedNode(
+                                    error_loc,
+                                    format!(
+                                        "Expected set of Identifiers, but argument #{i} is a {value:?}"
+                                    ),
+                                ));
+                            }
+
+                            NodeEnum::Symbol(symbol) => symbols.push(symbol.clone()),
+                        }
+                    }
+
+                    return Ok(Function::new(FunctionType::UserFunction(right), symbols));
+                }
+                _ => {
+                    return Err(ParserError::UnexpectedNode(
+                        error_loc,
+                        format!("Expected Set, got {:?}", expr),
+                    ));
+                }
+            }
+        }
+
+        Ok(expr)
     }
 
     fn primary(&mut self) -> Result<Rc<NodeEnum>, ParserError> {
@@ -222,8 +435,73 @@ impl Parser {
 
         match token {
             TokenType::Number(value) => Ok(Rc::new(Constant::new(value).into())),
+            TokenType::Identifier(string) => Ok(Rc::new(
+                Symbol::new_from_str(string, self.environment).into(),
+            )),
+            TokenType::LParen => {
+                let expr = self.expression()?;
+                let (i, t) = if let Some(Token(i, x)) = self.tokens.peek() {
+                    (i, x)
+                } else {
+                    return Err(ParserError::UnexpectedEndOfTokens(
+                        "Unclosed right parenthesis".into(),
+                    ));
+                };
+
+                match t {
+                    TokenType::RParen => {
+                        self.tokens.next();
+                        Ok(expr)
+                    }
+                    TokenType::Comma => {
+                        let mut values = vec![expr];
+                        while {
+                            if let Some(Token(_, TokenType::RParen)) = self.tokens.peek() {
+                                self.tokens.next();
+                                false
+                            } else {
+                                true
+                            }
+                        } {
+                            let (i, token) = if let Some(Token(i, x)) = self.tokens.peek() {
+                                (i, x)
+                            } else {
+                                return Err(ParserError::UnexpectedEndOfTokens(
+                                    "Expected comma here".into(),
+                                ));
+                            };
+
+                            if *token == TokenType::Comma {
+                                self.tokens.next();
+                            } else {
+                                return Err(ParserError::UnexpectedToken(
+                                    *i,
+                                    token.len(),
+                                    format!("Expected comma here, but got {token:?}"),
+                                ));
+                            }
+
+                            values.push(self.equality()?);
+                        }
+
+                        Ok(Set::new(values))
+                    }
+                    _ => Err(ParserError::Unimplemented(
+                        *i,
+                        t.len(),
+                        format!("Expected either a comma or a right parenthesis here. Got {t:?}"),
+                    )),
+                }
+
+                // if t != TokenType::RParen {
+                //     Err(ParserError::UnexpectedToken(i, t.len(), format!("")))
+                // } else {
+                //     Ok(expr)
+                // }
+            }
             _ => Err(ParserError::UnexpectedToken(
                 i,
+                token.len(),
                 format!("Unexpected token {token:?}"),
             )),
         }