Merge pull request #1 from minneelyyyy/dev

push dev changes to main branch

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "lamm"
-version = "0.1.0"
+version = "0.2.0"
 edition = "2021"
 license = "MIT"
 description = "a simple, functional paradigm programming language which uses Polish notation"

README.md

@@ -0,0 +1,206 @@
+# Lamm
+
+A small, functional programming language.
+
+# Syntax
+
+Lamm uses [Polish Notation](https://en.wikipedia.org/wiki/Polish_notation).
+That means that instead of writing `5 + 6`, you would instead write `+ 5 6`.
+
+Since we're here, we might as well cover some operators.
+
+## Math Operators
+
+```
++ 5 6   # => 11
+- 5 6   # => -1
+* 5 6   # => 30
+/ 5 6   # => 0 (integer division)
+** 5 6  # => 15625
+% 6 5   # => 1
+```
+
+There is no order of operations to worry about, you essentially write your code in the order it should be evaluated in.
+
+## Variables
+
+Variables are **constant** in Lamm, there is no mutation. Here are some examples of defining variables.
+
+```
+= pi 3.1415926    # immediately evaluated
+. sqrt2 ** 2 0.5  # lazy evaluated
+```
+
+Variables are **scoped** in Lamm, meaning they only exist in the single expression that they are defined for. That means that the following code is an **error**.
+
+```
+= pi 3.1415926
+= r 16
+* pi ** r 2       # OK
+= deg 60
+* deg / pi 360.0  # ERROR: `pi` was undefined
+```
+
+## Scope
+
+Scope in Lamm consists of a single expression, such as `sqrt + ** a 2 ** b 2`. So then, what do I do when I need a variable for more than a single expression? There are multiple solutions depending on your needs.
+
+### Multi-Statement Expression
+
+You can create a multi-statement expression using either `()` syntax or the `~` operator, which `()` is simple syntactic sugar for. In these, only the value of the last expression is returned, the rest get ignored. This is the perfect place to put stateful function calls.
+
+```
+. x 12 (
+	print + "My favorite number is " string x
+	print + "Auf Wiedersehen! Ich werde aber meine Lieblingsnummer " + string x " vermissen."
+)
+```
+
+### Global Scope
+
+You can introduce a variable to global scope using the `export` builtin function.
+
+```
+# A very useful constant
+= pi 3.1415926
+export ["pi"]
+
+# Some more useful constants
+= e 2.71828
+= phi 1.6180339887
+export ["e" "phi"]
+```
+
+## Functions
+
+All functions in Lamm are **scoped** similarly to variables. Functions are declared using the `:` operator, which can be extended with more `:` and `.` characters to let Lamm know how many arguments the function takes.
+
+```
+: inc x + x 1
+	inc 24  # => 25
+
+:. pythag a b sqrt + ** a 2.0 ** b 2.0
+	pythag 3 4  # => 5
+
+:::::. ten'args a b c d e f g h i j
+	[a b c d e f g h i j]
+```
+
+The parameter types and return type of functions can be declared using a special syntax unique to function and lambda definitions.
+
+```
+# Takes an x of `Any` type
+: inc x + x 1
+	inc 12  # => 13
+
+# Takes an x of `Int` and returns an `Int`
+: inc ?. x Int -> Int + x 1
+	inc 9  # => 10
+```
+
+The `?.` operator is unique to function declarations and is used to specify the type of an argument. There are also first class functions, here is the syntax for it.
+
+```
+# Applies a function to any value
+:. apply : f x f x
+	apply 'sqrt 9  # => 3
+
+# Applies a function f which maps an Int to an Int to x
+:. apply'int ?: f Int -> Int ?. x Int -> Int f x
+	apply'int 'sqrt 36  # => 6
+```
+
+The `:` operator inside of a function prototype tells Lamm that this argument must be a function where every argument and it's return type are all `Any`. This means that `: f` is essentially syntactic sugar for `?: f Any -> Any`. Also, in order to pass a function to a function, you must use the `'` operator, which tells Lamm not to call the function.
+
+And off course, `:` and `?:` in function prototypes can also be extended depending on the number of arguments the function must take.
+
+## Branching
+
+Lamm has the following boolean expressions
+
+```
+== 1 2         # => false
+!= 1 2         # => true
+>  1 2         # => false
+<  1 2         # => true
+>= 1 2         # => false
+<= 1 2         # => true
+!true          # => false
+true && false  # => false
+true || false  # => true
+```
+
+These can be used inside of `?` (if) and `??` (if-else) statements.
+
+```
+. n 12
+	?? < 12 10
+		print "n is less than 10"
+		print "n is greater than 10"
+```
+
+An `?` if statement where it's condition is false simply returns `nil`, as do `print` and other functions without a return value. `?` is mostly useful inside of blocks.
+
+```
+: times'twelve ?. n Int -> Int (
+	? == n 0
+		print "n is 0"
+
+	* n 12
+)
+```
+
+## Arrays
+
+Lamm offers a few fundamental array operations.
+
+```
++ 1 [2 3 4]     # => [1 2 3 4]
++ [1 2 3] 4     # => [1 2 3 4]
++ [1 2] [3 4]   # => [1 2 3 4]
+head [1 2 3 4]  # => 1
+tail [1 2 3 4]  # => [2 3 4]
+init [1 2 3 4]  # => [1 2 3]
+fini [1 2 3 4]  # => 4
+bool [1 2 3 4]  # => true
+bool empty      # => false
+```
+
+Using these, you can build a lot of fundamental functional paradigm functions.
+
+```
+:. map ?: f Any -> Any ?. x [Any] -> [Any]
+	?? bool x
+		+ f head x map 'f tail x
+		empty
+map ;y ** y 2 [1 2 3 4 5 6 7 8 9 10]  # => [1 4 9 16 25 36 49 64 81 100]
+
+:: iterate : f i count -> [Any]
+	?? > count 0 
+		+ i iterate 'f f i - count 1
+		empty
+iterate ;x + 1 x 0 10  # => [0 1 2 3 4 5 6 7 8 9]
+
+:. take ?. n Int ?. x [Any] -> [Any]
+	?? > n 0
+		+ head x take - n 1 tail x
+		empty
+take 3 [1 2 3 4 5]  # => [1 2 3]
+
+:. take'while : pred Any -> Bool ?. x [Any] -> [Any]
+	?? && bool x pred head x
+		+ head x take'while 'pred tail x
+		empty
+take'while ;y < y 10 [1 3 5 7 9 11 13 15 16]  # => [1 3 5 7 9]
+```
+
+## Lambdas
+
+Lambdas are created using the `;` operator, and they are always passed as a value, so no `'` is necessary.
+
+
+```
+map ;x * x 12 [1 2 3]  # => [12 24 36]
+```
+
+They follow the same prototype syntax as regular functions, with the notable lack of an identifier.

src/executor.rs

@@ -1,10 +1,12 @@
-use super::{Value, Type, FunctionDeclaration};
+use super::{Value, Type, Object};
 use super::parser::{ParseTree, ParseError};
 
 use std::collections::HashMap;
-use std::borrow::Cow;
 use std::fmt::Display;
 use std::error::Error;
+use std::io;
+use std::sync::{Arc, Mutex};
+use std::cell::RefCell;
 
 #[derive(Debug)]
 pub enum RuntimeError {
@@ -16,14 +18,17 @@ pub enum RuntimeError {
     FunctionUndefined(String),
     NotAVariable(String),
     ParseFail(String, Type),
+    TypeError(Type, Type),
+    EmptyArray,
+    IO(io::Error),
 }
 
 impl Display for RuntimeError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Self::ParseError(e) => write!(f, "{e}"),
+            Self::ParseError(e) => write!(f, "Parser Error: {e}"),
             Self::NoOverloadForTypes(op, values)
-                => write!(f, "No overload of `{op}` exists for the operands `[{}]`", 
+                => write!(f, "No overload of `{op}` exists for the operands `{}`", 
                     values.iter().map(|x| format!("{}({x})", x.get_type())).collect::<Vec<_>>().join(", ")),
             Self::ImmutableError(ident) => write!(f, "`{ident}` already exists and cannot be redefined"),
             Self::VariableUndefined(ident) => write!(f, "variable `{ident}` was not defined"),
@@ -31,70 +36,137 @@ impl Display for RuntimeError {
             Self::FunctionUndefined(ident) => write!(f, "function `{ident}` was not defined"),
             Self::NotAVariable(ident) => write!(f, "`{ident}` is a function but was attempted to be used like a variable"),
             Self::ParseFail(s, t) => write!(f, "`\"{s}\"` couldn't be parsed into {}", t),
+            Self::IO(e) => write!(f, "{e}"),
+            Self::TypeError(left, right) => write!(f, "expected type `{left}` but got type `{right}`"),
+            Self::EmptyArray => write!(f, "attempt to access element from an empty array"),
         }
     }
 }
 
 impl Error for RuntimeError {}
 
-#[derive(Clone, Debug)]
-enum Evaluation {
-    // at this point, it's type is set in stone
-    Computed(Value),
-
-    // at this point, it's type is unknown, and may contradict a variable's type
-    // or not match the expected value of the expression, this is a runtime error
-    Uncomputed(Box<ParseTree>),
-}
-
-#[derive(Clone, Debug)]
-struct Function {
-    decl: FunctionDeclaration,
-    body: Option<Box<ParseTree>>,
-}
-
-#[derive(Clone, Debug)]
-enum Object {
-    Variable(Evaluation),
-    Function(Function),
-}
-
 /// Executes an input of ParseTrees
-pub struct Executor<I: Iterator<Item = Result<ParseTree, ParseError>>> {
-    exprs: I,
-    globals: HashMap<String, Object>,
+pub struct Executor<'a, I>
+where
+    I: Iterator<Item = Result<ParseTree, ParseError>>
+{
+    exprs: &'a mut I,
+    globals: &'a mut HashMap<String, Arc<Mutex<Object>>>,
+    locals: HashMap<String, Arc<Mutex<Object>>>,
 }
 
-impl<I: Iterator<Item = Result<ParseTree, ParseError>>> Executor<I> {
-    pub fn new(exprs: I) -> Self {
+impl<'a, I> Executor<'a, I>
+where
+    I: Iterator<Item = Result<ParseTree, ParseError>>,
+{
+    pub fn new(exprs: &'a mut I, globals: &'a mut HashMap<String, Arc<Mutex<Object>>>) -> Self {
         Self {
             exprs,
-            globals: HashMap::new(),
+            globals,
+            locals: HashMap::new(),
         }
     }
 
-    fn exec(
-        &mut self,
-        tree: ParseTree,
-        locals: &mut Cow<HashMap<String, Object>>) -> Result<Value, RuntimeError>
-    {
-        match tree {
-            ParseTree::Add(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+    pub fn _add_global(self, k: String, v: Arc<Mutex<Object>>) -> Self {
+        self.globals.insert(k, v);
+        self
+    }
+
+    pub fn locals(mut self, locals: HashMap<String, Arc<Mutex<Object>>>) -> Self {
+        self.locals = locals;
+        self
+    }
+
+    pub fn add_local(mut self, k: String, v: Arc<Mutex<Object>>) -> Self {
+        self.locals.insert(k, v);
+        self
+    }
+
+    fn _get_object(&self, ident: &String) -> Result<&Arc<Mutex<Object>>, RuntimeError> {
+        self.locals.get(ident).or(self.globals.get(ident))
+            .ok_or(RuntimeError::VariableUndefined(ident.clone()))
+    }
+
+    fn get_object_mut(&mut self, ident: &String) -> Result<&mut Arc<Mutex<Object>>, RuntimeError> {
+        self.locals.get_mut(ident).or(self.globals.get_mut(ident))
+            .ok_or(RuntimeError::VariableUndefined(ident.clone()))
+    }
+
+    fn variable_exists(&self, ident: &String) -> bool {
+        self.locals.contains_key(ident) || self.globals.contains_key(ident)
+    }
+
+    fn eval(obj: &mut Arc<Mutex<Object>>) -> Result<Value, RuntimeError> {
+        let mut guard = obj.lock().unwrap();
+
+        let v = guard.eval()?;
+
+        Ok(v)
+    }
+
+    fn obj_locals(obj: &Arc<Mutex<Object>>) -> HashMap<String, Arc<Mutex<Object>>> {
+        let guard = obj.lock().unwrap();
+
+        let locals = guard.locals();
+
+        locals
+    }
+
+    fn obj_globals(obj: &Arc<Mutex<Object>>) -> HashMap<String, Arc<Mutex<Object>>> {
+        let guard = obj.lock().unwrap();
+
+        let locals = guard.globals();
+
+        locals
+    }
+
+    pub fn exec(&mut self, tree: Box<ParseTree>) -> Result<Value, RuntimeError> {
+        match *tree {
+            ParseTree::Add(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Int(x + y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Float(x + y as f64)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Float(x as f64 + y)),
                 (Value::Float(x), Value::Float(y)) => Ok(Value::Float(x + y)),
                 (Value::String(x), Value::String(y)) => Ok(Value::String(format!("{x}{y}"))),
+                (Value::Array(xtype, x), Value::Array(ytype, y)) => {
+                    if xtype != ytype {
+                        return Err(RuntimeError::TypeError(xtype, ytype));
+                    }
+
+                    Ok(Value::Array(xtype, [x, y].concat()))
+                },
+                (Value::Array(t, x), y) => {
+                    let ytype = y.get_type();
+
+                    if t != ytype {
+                        return Err(RuntimeError::TypeError(t, ytype));
+                    }
+
+                    // NOTE: use y's type instead of the arrays type.
+                    // an `empty` array has Any type, but any value will have a fixed type.
+                    // this converts the empty array into a typed array.
+                    Ok(Value::Array(ytype, [x, vec![y]].concat()))
+                },
+                (x, Value::Array(t, y)) => {
+                    let xtype = x.get_type();
+
+                    if t != xtype {
+                        return Err(RuntimeError::TypeError(t, xtype));
+                    }
+
+                    // NOTE: read above
+                    Ok(Value::Array(xtype, [vec![x], y].concat()))
+                },
                 (x, y) => Err(RuntimeError::NoOverloadForTypes("+".into(), vec![x, y]))
             },
-            ParseTree::Sub(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::Sub(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Int(x - y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Float(x - y as f64)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Float(x as f64 - y)),
                 (Value::Float(x), Value::Float(y)) => Ok(Value::Float(x - y)),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes("-".into(), vec![x, y]))
             },
-            ParseTree::Mul(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::Mul(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Int(x * y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Float(x * y as f64)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Float(x as f64 * y)),
@@ -102,28 +174,28 @@ impl<I: Iterator<Item = Result<ParseTree, ParseError>>> Executor<I> {
                 (Value::String(x), Value::Int(y)) => Ok(Value::String(x.repeat(y as usize))),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes("*".into(), vec![x, y]))
             },
-            ParseTree::Div(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::Div(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Int(x / y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Float(x / y as f64)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Float(x as f64 / y)),
                 (Value::Float(x), Value::Float(y)) => Ok(Value::Float(x / y)),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes("*".into(), vec![x, y]))
             },
-            ParseTree::Exp(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::Exp(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Int(x.pow(y as u32))),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Float((x as f64).powf(y))),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Float(x.powf(y as f64))),
                 (Value::Float(x), Value::Float(y)) => Ok(Value::Float(x.powf(y))),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes("**".into(), vec![x, y])),
             },
-            ParseTree::Mod(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::Mod(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Int(x % y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Float(x % y as f64)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Float(x as f64 % y)),
                 (Value::Float(x), Value::Float(y)) => Ok(Value::Float(x % y)),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes("%".into(), vec![x, y])),
             },
-            ParseTree::EqualTo(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::EqualTo(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Bool(x == y)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Bool(x as f64 == y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Bool(x == y as f64)),
@@ -132,140 +204,143 @@ impl<I: Iterator<Item = Result<ParseTree, ParseError>>> Executor<I> {
                 (Value::String(x), Value::String(y)) => Ok(Value::Bool(x == y)),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes("==".into(), vec![x, y])),
             },
-            ParseTree::GreaterThan(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::NotEqualTo(x, y) => match (self.exec(x)?, self.exec(y)?) {
+                (Value::Int(x), Value::Int(y)) => Ok(Value::Bool(x != y)),
+                (Value::Int(x), Value::Float(y)) => Ok(Value::Bool(x as f64 != y)),
+                (Value::Float(x), Value::Int(y)) => Ok(Value::Bool(x != y as f64)),
+                (Value::Float(x), Value::Float(y)) => Ok(Value::Bool(x != y)),
+                (Value::Bool(x), Value::Bool(y)) => Ok(Value::Bool(x != y)),
+                (Value::String(x), Value::String(y)) => Ok(Value::Bool(x != y)),
+                (x, y) => Err(RuntimeError::NoOverloadForTypes("!=".into(), vec![x, y])),
+            },
+            ParseTree::GreaterThan(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Bool(x > y)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Bool(x as f64 > y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Bool(x > y as f64)),
                 (Value::Float(x), Value::Float(y)) => Ok(Value::Bool(x > y)),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes(">".into(), vec![x, y])),
             },
-            ParseTree::GreaterThanOrEqualTo(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::GreaterThanOrEqualTo(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Bool(x >= y)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Bool(x as f64 >= y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Bool(x >= y as f64)),
                 (Value::Float(x), Value::Float(y)) => Ok(Value::Bool(x >= y)),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes(">=".into(), vec![x, y])),
             },
-            ParseTree::LessThan(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::LessThan(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Bool(x < y)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Bool((x as f64) < y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Bool(x < y as f64)),
                 (Value::Float(x), Value::Float(y)) => Ok(Value::Bool(x < y)),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes("<".into(), vec![x, y])),
             },
-            ParseTree::LessThanOrEqualTo(x, y) => match (self.exec(*x, locals)?, self.exec(*y, locals)?) {
+            ParseTree::LessThanOrEqualTo(x, y) => match (self.exec(x)?, self.exec(y)?) {
                 (Value::Int(x), Value::Int(y)) => Ok(Value::Bool(x <= y)),
                 (Value::Int(x), Value::Float(y)) => Ok(Value::Bool(x as f64 <= y)),
                 (Value::Float(x), Value::Int(y)) => Ok(Value::Bool(x <= y as f64)),
                 (Value::Float(x), Value::Float(y)) => Ok(Value::Bool(x <= y)),
                 (x, y) => Err(RuntimeError::NoOverloadForTypes("<=".into(), vec![x, y])),
             },
-            ParseTree::Not(x) => match self.exec(*x, locals)? {
+            ParseTree::Not(x) => match self.exec(x)? {
                 Value::Bool(x) => Ok(Value::Bool(!x)),
                 x => Err(RuntimeError::NoOverloadForTypes("not".into(), vec![x]))
             },
+            ParseTree::And(x, y) => match (self.exec(x)?, self.exec(y)?) {
+                (Value::Bool(x), Value::Bool(y)) => Ok(Value::Bool(x && y)),
+                (x, y) => Err(RuntimeError::NoOverloadForTypes("&&".into(), vec![x, y]))
+            },
+            ParseTree::Or(x, y) => match (self.exec(x)?, self.exec(y)?) {
+                (Value::Bool(x), Value::Bool(y)) => Ok(Value::Bool(x || y)),
+                (x, y) => Err(RuntimeError::NoOverloadForTypes("||".into(), vec![x, y]))
+            },
             ParseTree::Equ(ident, body, scope) => {
-                if self.globals.contains_key(&ident) || locals.contains_key(&ident) {
+                if self.variable_exists(&ident) {
                     Err(RuntimeError::ImmutableError(ident.clone()))
                 } else {
-                    let locals = locals.to_mut();
-                    let value = self.exec(*body, &mut Cow::Borrowed(&locals))?;
-                    locals.insert(ident.clone(), Object::Variable(Evaluation::Computed(value)));
+                    let value = self.exec(body)?;
+                    let g = self.globals.clone();
 
-                    self.exec(*scope, &mut Cow::Borrowed(&locals))
+                    Executor::new(self.exprs, &mut self.globals)
+                        .locals(self.locals.clone())
+                        .add_local(ident, Arc::new(Mutex::new(Object::value(value, g, self.locals.to_owned()))))
+                        .exec(scope)
                 }
             },
             ParseTree::LazyEqu(ident, body, scope) => {
-                if self.globals.contains_key(&ident) || locals.contains_key(&ident) {
+                if self.variable_exists(&ident) {
                     Err(RuntimeError::ImmutableError(ident.clone()))
                 } else {
-                    let locals = locals.to_mut();
-                    locals.insert(ident.clone(), Object::Variable(Evaluation::Uncomputed(body)));
-
-                    self.exec(*scope, &mut Cow::Borrowed(&locals))
+                    let g = self.globals.clone();
+                    Executor::new(self.exprs, &mut self.globals)
+                        .locals(self.locals.clone())
+                        .add_local(ident, Arc::new(Mutex::new(Object::variable(*body, g, self.locals.to_owned()))))
+                        .exec(scope)
                 }
             },
-            ParseTree::FunctionDefinition(ident, args, r, body, scope) => {
-                let existing = locals.get(&ident).or(self.globals.get(&ident)).cloned();
-
-                match existing {
-                    Some(_) => Err(RuntimeError::ImmutableError(ident.clone())),
-                    None => {
-                        let locals = locals.to_mut();
-
-                        locals.insert(ident.clone(), Object::Function(Function {
-                            decl: FunctionDeclaration { _name: ident.clone(), _r: r, args },
-                            body: Some(body)
-                        }));
-
-                        self.exec(*scope, &mut Cow::Borrowed(&locals))
-                    }
-                }
+            ParseTree::FunctionDefinition(func, scope) => {
+                let g = self.globals.clone();
+                Executor::new(self.exprs, &mut self.globals)
+                    .locals(self.locals.clone())
+                    .add_local(func.name().unwrap().to_string(), Arc::new(Mutex::new(Object::function(func, g, self.locals.clone()))))
+                    .exec(scope)
             },
             ParseTree::Compose(x, y) => {
-                self.exec(*x, locals)?;
-                self.exec(*y, locals)
+                self.exec(x)?;
+                self.exec(y)
             },
-            ParseTree::Id(x) => self.exec(*x, locals),
-            ParseTree::If(cond, body) => if match self.exec(*cond, locals)? {
+            ParseTree::Id(x) => self.exec(x),
+            ParseTree::If(cond, body) => if match self.exec(cond)? {
                     Value::Float(f) => f != 0.0,
                     Value::Int(i) => i != 0,
                     Value::Bool(b) => b,
                     Value::String(s) => !s.is_empty(),
+                    Value::Array(_, vec) => !vec.is_empty(),
                     Value::Nil => false,
+                    x => return Err(RuntimeError::NoOverloadForTypes("?".into(), vec![x])),
                 } {
-                    self.exec(*body, locals)
+                    self.exec(body)
                 } else {
                     Ok(Value::Nil)
                 },
-            ParseTree::IfElse(cond, istrue, isfalse) => if match self.exec(*cond, locals)? {
+            ParseTree::IfElse(cond, istrue, isfalse) => if match self.exec(cond)? {
                 Value::Float(f) => f != 0.0,
                 Value::Int(i) => i != 0,
                 Value::Bool(b) => b,
                 Value::String(s) => !s.is_empty(),
+                Value::Array(_, vec) => !vec.is_empty(),
                 Value::Nil => false,
+                x => return Err(RuntimeError::NoOverloadForTypes("??".into(), vec![x])),
             } {
-                self.exec(*istrue, locals)
+                self.exec(istrue)
             } else {
-                self.exec(*isfalse, locals)
+                self.exec(isfalse)
             },
             ParseTree::FunctionCall(ident, args) => {
-                let obj = locals.get(&ident).or(self.globals.get(&ident)).cloned();
+                let obj = self.get_object_mut(&ident)?;
+                let globals = Self::obj_globals(obj);
+                let locals = Self::obj_locals(obj);
+                let v = Self::eval(obj)?;
 
-                if let Some(Object::Function(f)) = obj {
-                    let locals = locals.to_mut();
-                    let body = f.body.ok_or(RuntimeError::FunctionUndefined(ident.clone()))?;
+                match v {
+                    Value::Function(mut f) => {
+                        let args = args.into_iter()
+                            .map(|x| Object::variable(x, self.globals.clone(), self.locals.clone()))
+                            .collect();
 
-                    for ((name, _), tree) in std::iter::zip(f.decl.args, args) {
-                        locals.insert(name.clone(), Object::Variable(Evaluation::Computed(self.exec(tree, &mut Cow::Borrowed(locals))?)));
-                    }
-
-                    self.exec(*body, &mut Cow::Borrowed(&locals))
-                } else {
-                    Err(RuntimeError::FunctionUndeclared(ident.clone()))
+                        f.call(globals, locals, args)
+                    },
+                    _ => Err(RuntimeError::FunctionUndefined(ident.clone()))
                 }
             },
             ParseTree::Variable(ident) => {
-                let locals = locals.to_mut();
+                let obj = self.get_object_mut(&ident)?;
 
-                let obj = locals.get(&ident).or(self.globals.get(&ident)).cloned();
-
-                if let Some(Object::Variable(eval)) = obj {
-                    match eval {
-                        Evaluation::Computed(v) => Ok(v),
-                        Evaluation::Uncomputed(tree) => {
-                            let v = self.exec(*tree, &mut Cow::Borrowed(&locals))?;
-                            locals.insert(ident, Object::Variable(Evaluation::Computed(v.clone())));
+                let v = obj.lock().unwrap().eval()?;
 
                 Ok(v)
-                        }
-                    }
-                } else {
-                    Err(RuntimeError::VariableUndefined(ident.clone()))
-                }
             },
             ParseTree::Constant(value) => Ok(value),
-            ParseTree::ToInt(x) => match self.exec(*x, locals)? {
+            ParseTree::IntCast(x) => match self.exec(x)? {
                 Value::Int(x) => Ok(Value::Int(x)),
                 Value::Float(x) => Ok(Value::Int(x as i64)),
                 Value::Bool(x) => Ok(Value::Int(if x { 1 } else { 0 })),
@@ -275,7 +350,7 @@ impl<I: Iterator<Item = Result<ParseTree, ParseError>>> Executor<I> {
                 }
                 x => Err(RuntimeError::NoOverloadForTypes("int".into(), vec![x])),
             },
-            ParseTree::ToFloat(x) => match self.exec(*x, locals)? {
+            ParseTree::FloatCast(x) => match self.exec(x)? {
                 Value::Int(x) => Ok(Value::Float(x as f64)),
                 Value::Float(x) => Ok(Value::Float(x)),
                 Value::Bool(x) => Ok(Value::Float(if x { 1.0 } else { 0.0 })),
@@ -285,26 +360,70 @@ impl<I: Iterator<Item = Result<ParseTree, ParseError>>> Executor<I> {
                 }
                 x => Err(RuntimeError::NoOverloadForTypes("float".into(), vec![x])),
             },
-            ParseTree::ToBool(x) => match self.exec(*x, locals)? {
+            ParseTree::BoolCast(x) => match self.exec(x)? {
                 Value::Int(x) => Ok(Value::Bool(x != 0)),
                 Value::Float(x) => Ok(Value::Bool(x != 0.0)),
                 Value::Bool(x) => Ok(Value::Bool(x)),
                 Value::String(x) => Ok(Value::Bool(!x.is_empty())),
+                Value::Array(_, vec) => Ok(Value::Bool(!vec.is_empty())),
                 x => Err(RuntimeError::NoOverloadForTypes("bool".into(), vec![x])),
             },
-            ParseTree::ToString(x) => Ok(Value::String(format!("{}", self.exec(*x, locals)?))),
+            ParseTree::StringCast(x) => Ok(Value::String(format!("{}", self.exec(x)?))),
+            ParseTree::Print(x) => match self.exec(x)? {
+                Value::String(s) => {
+                    println!("{s}");
+                    Ok(Value::Nil)
+                }
+                x => {
+                    println!("{x}");
+                    Ok(Value::Nil)
+                }
+            }
+            ParseTree::LambdaDefinition(func) => Ok(Value::Function(func)),
+            ParseTree::NonCall(name) => {
+                let obj = self.get_object_mut(&name)?;
+
+                let v = obj.lock().unwrap().eval()?;
+
+                Ok(v)
+            }
+            ParseTree::Head(x) => match self.exec(x)? {
+                Value::Array(_, x) => Ok(x.first().ok_or(RuntimeError::EmptyArray)?.clone()),
+                t => Err(RuntimeError::NoOverloadForTypes("head".into(), vec![t]))
+            },
+            ParseTree::Tail(x) => match self.exec(x)? {
+                Value::Array(t, x) => Ok(Value::Array(t, if x.len() > 0 { x[1..].to_vec() } else { vec![] })),
+                t => Err(RuntimeError::NoOverloadForTypes("tail".into(), vec![t]))
+            },
+            ParseTree::Init(x) => match self.exec(x)? {
+                Value::Array(t, x) => Ok(Value::Array(t, if x.len() > 0 { x[..x.len() - 1].to_vec() } else { vec![] })),
+                t => Err(RuntimeError::NoOverloadForTypes("init".into(), vec![t]))
+            },
+            ParseTree::Fini(x) => match self.exec(x)? {
+                Value::Array(_, x) => Ok(x.last().ok_or(RuntimeError::EmptyArray)?.clone()),
+                t => Err(RuntimeError::NoOverloadForTypes("fini".into(), vec![t]))
+            },
+            ParseTree::Nop => Ok(Value::Nil),
+            ParseTree::Export(names) => {
+                for name in names {
+                    let obj = self.locals.remove(&name).ok_or(RuntimeError::VariableUndefined(name.clone()))?;
+                    self.globals.insert(name, obj);
+                }
+
+                Ok(Value::Nil)
+            }
         }
     }
 }
 
-impl<I: Iterator<Item = Result<ParseTree, ParseError>>> Iterator for Executor<I> {
+impl<'a, I: Iterator<Item = Result<ParseTree, ParseError>>> Iterator for Executor<'a, I> {
     type Item = Result<Value, RuntimeError>;
 
     fn next(&mut self) -> Option<Self::Item> {
         let expr = self.exprs.next();
 
         match expr {
-            Some(Ok(expr)) => Some(self.exec(expr, &mut Cow::Borrowed(&HashMap::new()))),
+            Some(Ok(expr)) => Some(self.exec(Box::new(expr))),
             Some(Err(e)) => Some(Err(RuntimeError::ParseError(e))),
             None => None,
         }

src/function.rs

@@ -0,0 +1,81 @@
+use std::cell::RefCell;
+use crate::parser::ParseTree;
+use crate::executor::{Executor, RuntimeError};
+use crate::{Type, Object, Value};
+
+use std::collections::HashMap;
+use std::fmt::{self, Display};
+use std::sync::{Arc, Mutex};
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct FunctionType(pub Box<Type>, pub Vec<Type>);
+
+impl Display for FunctionType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Function({}, {})", self.0, self.1.iter().map(|x| format!("{x}")).collect::<Vec<_>>().join(", "))
+    }
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Function {
+    pub(crate) name: Option<String>,
+    t: FunctionType,
+    arg_names: Vec<String>,
+    body: Box<ParseTree>,
+}
+
+impl Function {
+    pub(crate) fn lambda(t: FunctionType, arg_names: Vec<String>, body: Box<ParseTree>) -> Self {
+        Self {
+            name: None,
+            t,
+            arg_names,
+            body
+        }
+    }
+
+    pub(crate) fn named(name: &str, t: FunctionType, arg_names: Vec<String>, body: Box<ParseTree>) -> Self {
+        Self {
+            name: Some(name.to_string()),
+            t,
+            arg_names,
+            body
+        }
+    }
+
+	pub(crate) fn name(&self) -> Option<&str> {
+		self.name.as_ref().map(|x| x.as_str())
+	}
+
+	pub(crate) fn get_type(&self) -> FunctionType {
+		self.t.clone()
+	}
+
+	pub(crate) fn call(&mut self,
+                mut globals: HashMap<String, Arc<Mutex<Object>>>,
+                locals: HashMap<String, Arc<Mutex<Object>>>,
+                args: Vec<Object>) -> Result<Value, RuntimeError>
+    {
+        let mut tree = vec![Ok(*self.body.clone())].into_iter();
+        let g = globals.clone();
+
+        let mut exec = Executor::new(&mut tree, &mut globals)
+            .locals(locals.clone());
+
+        for (obj, name) in std::iter::zip(args.into_iter(), self.arg_names.clone().into_iter()) {
+            exec = exec.add_local(name.clone(), Arc::new(Mutex::new(obj)));
+        }
+
+        if let Some(name) = self.name().map(|x| x.to_string()) {
+            exec = exec.add_local(name, Arc::new(Mutex::new(Object::function(self.clone(), g, locals))));
+        }
+
+        exec.next().unwrap()
+	}
+}
+
+impl Display for Function {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.t)
+    }
+}

src/lib.rs

@@ -1,10 +1,20 @@
-
 mod tokenizer;
 mod parser;
 mod executor;
+mod function;
 
+use executor::{Executor, RuntimeError};
+use parser::{ParseTree, Parser};
+use tokenizer::Tokenizer;
+use function::{FunctionType, Function};
+
+use std::collections::HashMap;
 use std::fmt::Display;
 use std::io::BufRead;
+use std::fmt;
+use std::iter::Peekable;
+use std::sync::{Arc, Mutex};
+use std::cell::RefCell;
 
 #[derive(Clone, Debug)]
 pub enum Type {
@@ -12,21 +22,35 @@ pub enum Type {
     Int,
     Bool,
     String,
+    Array(Box<Type>),
+    Function(FunctionType),
     Nil,
     Any,
-    _Function(Box<Type>, Vec<Type>),
+}
+
+impl PartialEq for Type {
+    fn eq(&self, other: &Type) -> bool {
+        match (self, other) {
+            (Self::Any, _) => true,
+            (_, Self::Any) => true,
+            (Self::Array(l0), Self::Array(r0)) => l0 == r0,
+            (Self::Function(l0), Self::Function(r0)) => l0 == r0,
+            _ => core::mem::discriminant(self) == core::mem::discriminant(other),
+        }
+    }
 }
 
 impl Display for Type {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{}", match self {
             Self::Float => "Float".into(),
             Self::Int => "Int".into(),
             Self::Bool => "Bool".into(),
             Self::String => "String".into(),
+            Self::Array(t) => format!("[{t}]"),
+            Self::Function(r) => format!("{r}"),
             Self::Nil => "Nil".into(),
             Self::Any => "Any".into(),
-            Self::_Function(r, _) => format!("Function -> {}", *r)
         })
     }
 }
@@ -38,6 +62,8 @@ pub enum Value {
     Int(i64),
     Bool(bool),
     String(String),
+    Array(Type, Vec<Value>),
+    Function(Function),
     Nil,
 }
 
@@ -48,7 +74,9 @@ impl Value {
             Self::Int(_) => Type::Int,
             Self::Bool(_) => Type::Bool,
             Self::String(_) => Type::String,
+            Self::Array(t, _) => Type::Array(Box::new(t.clone())),
             Self::Nil => Type::Nil,
+            Self::Function(f) => Type::Function(f.get_type()),
         }
     }
 }
@@ -59,19 +87,105 @@ impl Display for Value {
             Self::Float(x) => write!(f, "{x}"),
             Self::Int(x) => write!(f, "{x}"),
             Self::Bool(x) => write!(f, "{}", if *x { "true" } else { "false" }),
-            Self::String(x) => write!(f, "{x}"),
+            Self::String(x) => write!(f, "\"{x}\""),
+            Self::Array(_t, v) => write!(f, "[{}]", v.iter().map(|x| format!("{x}")).collect::<Vec<_>>().join(" ")),
+            Self::Function(func) => write!(f, "{func}"),
             Self::Nil => write!(f, "nil"),
         }
     }
 }
 
-#[derive(Clone, Debug)]
-pub(crate) struct FunctionDeclaration {
-    _name: String,
-    _r: Type,
-    args: Vec<(String, Type)>,
+#[derive(Clone, Debug, PartialEq)]
+enum Cache {
+    Cached(Value),
+    Uncached(ParseTree),
 }
 
-pub fn evaluate<R: BufRead>(r: R) -> impl Iterator<Item = Result<Value, executor::RuntimeError>> {
-    executor::Executor::new(parser::Parser::new(tokenizer::Tokenizer::new(r)))
+#[derive(Clone, Debug)]
+struct Object {
+    locals: HashMap<String, Arc<Mutex<Object>>>,
+    globals: HashMap<String, Arc<Mutex<Object>>>,
+    value: Cache,
+}
+
+impl PartialEq for Object {
+    fn eq(&self, other: &Self) -> bool {
+        self.value == other.value
+    }
+}
+
+impl Object {
+    pub fn variable(tree: ParseTree, globals: HashMap<String, Arc<Mutex<Object>>>, locals: HashMap<String, Arc<Mutex<Object>>>) -> Self {
+        Self {
+            locals,
+            globals,
+            value: Cache::Uncached(tree),
+        }
+    }
+
+    pub fn value(v: Value, globals: HashMap<String, Arc<Mutex<Object>>>, locals: HashMap<String, Arc<Mutex<Object>>>) -> Self {
+        Self {
+            locals,
+            globals,
+            value: Cache::Cached(v),
+        }
+    }
+
+    pub fn function(func: Function, globals: HashMap<String, Arc<Mutex<Object>>>, locals: HashMap<String, Arc<Mutex<Object>>>) -> Self {
+        Self {
+            locals,
+            globals,
+            value: Cache::Cached(Value::Function(func)),
+        }
+    }
+
+    /// evaluate the tree inside of an object if it isn't evaluated yet, returns the value
+    pub fn eval(&mut self) -> Result<Value, RuntimeError> {
+        match self.value.clone() {
+            Cache::Cached(v) => Ok(v),
+            Cache::Uncached(tree) => {
+                let mut tree = vec![Ok(tree)].into_iter();
+
+                let mut exec = Executor::new(&mut tree, &mut self.globals)
+                    .locals(self.locals.clone());
+
+                let v = exec.next().unwrap()?;
+
+                self.value = Cache::Cached(v.clone());
+
+                Ok(v)
+            }
+        }
+    }
+
+    pub fn locals(&self) -> HashMap<String, Arc<Mutex<Object>>> {
+        self.locals.clone()
+    }
+
+    pub fn globals(&self) -> HashMap<String, Arc<Mutex<Object>>> {
+        self.globals.clone()
+    }
+}
+
+pub struct Runtime<'a, R: BufRead> {
+    tokenizer: Peekable<Tokenizer<R>>,
+    global_types: HashMap<String, Type>,
+    globals: HashMap<String, Arc<Mutex<Object>>>,
+    parser: Option<Parser<'a, Tokenizer<R>>>,
+}
+
+impl<'a, R: BufRead> Runtime<'a, R> {
+    pub fn new(reader: R) -> Self {
+        Self {
+            tokenizer: Tokenizer::new(reader).peekable(),
+            global_types: HashMap::new(),
+            globals: HashMap::new(),
+            parser: None,
+        }
+    }
+
+    pub fn values(&'a mut self) -> impl Iterator<Item = Result<Value, RuntimeError>> + 'a {
+        self.parser = Some(Parser::new(&mut self.tokenizer, &mut self.global_types));
+        Executor::new(self.parser.as_mut().unwrap(), &mut self.globals)
+    }
 }

src/main.rs

@@ -1,7 +1,9 @@
 use std::io::{self, BufReader};
 
 fn main() {
-	for value in lamm::evaluate(BufReader::new(io::stdin())) {
+	let mut runtime = lamm::Runtime::new(BufReader::new(io::stdin()));
+
+	for value in runtime.values() {
 		match value {
 			Ok(v) => println!("{v}"),
 			Err(e) => eprintln!("{e}"),

src/parser.rs

@@ -1,39 +1,45 @@
-use super::{Type, Value, FunctionDeclaration};
+
+use crate::executor::Executor;
+
+use super::{Value, Type, Function, FunctionType};
 use super::tokenizer::{Token, TokenizeError, Op};
 
+use std::borrow::BorrowMut;
 use std::error;
 use std::collections::HashMap;
 use std::fmt::Display;
-use std::borrow::Cow;
+use std::iter::Peekable;
 
 #[derive(Debug)]
 pub enum ParseError {
     NoInput,
     UnexpectedEndInput,
     IdentifierUndefined(String),
-    InvalidIdentifier,
-    FunctionUndefined(String),
-    VariableUndefined(String),
+    InvalidIdentifier(Token),
+    UnmatchedArrayClose,
+    UnwantedToken(Token),
     TokenizeError(TokenizeError),
+    ImmutableError(String),
 }
 
 impl Display for ParseError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             ParseError::UnexpectedEndInput => write!(f, "Input ended unexpectedly"),
-            ParseError::IdentifierUndefined(name) => write!(f, "Undefined variable `{name}`"),
-            ParseError::InvalidIdentifier => write!(f, "Invalid identifier"),
-            ParseError::FunctionUndefined(name) => write!(f, "Undefined function `{name}`"),
-            ParseError::VariableUndefined(name) => write!(f, "Undefined variable `{name}`"),
+            ParseError::IdentifierUndefined(name) => write!(f, "Undefined identifier `{name}`"),
+            ParseError::InvalidIdentifier(t) => write!(f, "Invalid identifier `{t:?}`"),
             ParseError::NoInput => write!(f, "No input given"),
-            ParseError::TokenizeError(e) => write!(f, "{e}"),
+            ParseError::UnmatchedArrayClose => write!(f, "there was an unmatched array closing operator `]`"),
+            ParseError::TokenizeError(e) => write!(f, "Tokenizer Error: {e}"),
+            ParseError::ImmutableError(i) => write!(f, "attempt to redeclare {i} met with force"),
+            ParseError::UnwantedToken(t) => write!(f, "unexpected token {t:?}"),
         }
     }
 }
 
 impl error::Error for ParseError {}
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub(crate) enum ParseTree {
     // Mathematical Operators
     Add(Box<ParseTree>, Box<ParseTree>),
@@ -45,20 +51,28 @@ pub(crate) enum ParseTree {
 
     // Boolean Operations
     EqualTo(Box<ParseTree>, Box<ParseTree>),
+    NotEqualTo(Box<ParseTree>, Box<ParseTree>),
     GreaterThan(Box<ParseTree>, Box<ParseTree>),
     GreaterThanOrEqualTo(Box<ParseTree>, Box<ParseTree>),
     LessThan(Box<ParseTree>, Box<ParseTree>),
     LessThanOrEqualTo(Box<ParseTree>, Box<ParseTree>),
     Not(Box<ParseTree>),
+    And(Box<ParseTree>, Box<ParseTree>),
+    Or(Box<ParseTree>, Box<ParseTree>),
 
     // Defining Objects
     Equ(String, Box<ParseTree>, Box<ParseTree>),
     LazyEqu(String, Box<ParseTree>, Box<ParseTree>),
-    FunctionDefinition(String, Vec<(String, Type)>, Type, Box<ParseTree>, Box<ParseTree>),
+    FunctionDefinition(Function, Box<ParseTree>),
+    LambdaDefinition(Function),
 
     // Functional Operations
     Compose(Box<ParseTree>, Box<ParseTree>),
     Id(Box<ParseTree>),
+    Head(Box<ParseTree>),
+    Tail(Box<ParseTree>),
+    Init(Box<ParseTree>),
+    Fini(Box<ParseTree>),
 
     // Branching
     If(Box<ParseTree>, Box<ParseTree>),
@@ -68,195 +82,430 @@ pub(crate) enum ParseTree {
     FunctionCall(String, Vec<ParseTree>),
     Variable(String),
     Constant(Value),
+    NonCall(String),
 
     // Type Casts
-    ToInt(Box<ParseTree>),
-    ToFloat(Box<ParseTree>),
-    ToBool(Box<ParseTree>),
-    ToString(Box<ParseTree>),
+    IntCast(Box<ParseTree>),
+    FloatCast(Box<ParseTree>),
+    BoolCast(Box<ParseTree>),
+    StringCast(Box<ParseTree>),
+
+    // Misc
+    Print(Box<ParseTree>),
+    Nop,
+    Export(Vec<String>),
 }
 
-impl ParseTree {
-    fn parse<I>(
-        tokens: &mut I,
-        globals: &HashMap<String, FunctionDeclaration>,
-        locals: &mut Cow<HashMap<String, FunctionDeclaration>>) -> Result<Self, ParseError>
-    where
-        I: Iterator<Item = Result<Token, TokenizeError>>,
-    {
-        match tokens.next() {
-            Some(Ok(token)) => {
-                match token {
-                    Token::Constant(c) => Ok(Self::Constant(c)),
-                    Token::Identifier(ident) => {
-                        // If it is found to be a function, get its argument count.
-                        // During parsing, we only keep track of function definitions
-                        // so that we know how many arguments it takes
-                        if let Some(decl) = locals.clone().get(&ident).or(globals.clone().get(&ident)) {
-                            let args = decl.args.iter()
-                                .map(|_| ParseTree::parse(tokens, globals, locals)).collect::<Result<Vec<_>, ParseError>>()?;
+/// Parses input tokens and produces ParseTrees for an Executor
+pub(crate) struct Parser<'a, I: Iterator<Item = Result<Token, TokenizeError>>> {
+    tokens: &'a mut Peekable<I>,
+    globals: &'a mut HashMap<String, Type>,
+    locals: HashMap<String, Type>,
+}
 
-                            Ok(ParseTree::FunctionCall(ident.clone(), args))
-                        } else {
-                            Ok(ParseTree::Variable(ident.clone()))
+impl<'a, I: Iterator<Item = Result<Token, TokenizeError>>> Parser<'a, I> {
+    pub fn new(tokens: &'a mut Peekable<I>, globals: &'a mut HashMap<String, Type>) -> Self {
+        Self {
+            tokens,
+            globals,
+            locals: HashMap::new()
+        }
+    }
+
+
+    pub fn add_global(self, k: String, v: Type) -> Self {
+        self.globals.insert(k, v);
+        self
+    }
+
+    pub fn add_globals<Items: Iterator<Item = (String, Type)>>(self, items: Items) -> Self {
+        items.for_each(|(name, t)| {
+            self.globals.insert(name, t);
+        });
+        self
+    }
+
+    pub fn locals(mut self, locals: HashMap<String, Type>) -> Self {
+        self.locals = locals;
+        self
+    }
+
+    pub fn add_local(mut self, k: String, v: Type) -> Self {
+        self.locals.insert(k, v);
+        self
+    }
+
+    pub fn add_locals<Items: Iterator<Item = (String, Type)>>(mut self, items: Items) -> Self {
+        items.for_each(|(name, t)| {
+            self.locals.insert(name, t);
+        });
+        self
+    }
+
+    fn get_object_type(&self, ident: &String) -> Result<&Type, ParseError> {
+        self.locals.get(ident).or(self.globals.get(ident))
+            .ok_or(ParseError::IdentifierUndefined(ident.clone()))
+    }
+
+    fn get_object_types<Names: Iterator<Item = String>>(&self, items: Names) -> impl Iterator<Item = Result<&Type, ParseError>> {
+        items.map(|x| self.get_object_type(&x))
+    }
+
+    fn parse(&mut self) -> Result<ParseTree, ParseError> {
+        match self.tokens.next().ok_or(ParseError::NoInput)?.map_err(|e| ParseError::TokenizeError(e))? {
+            Token::Constant(c) => Ok(ParseTree::Constant(c)),
+            Token::Identifier(ident) => {
+                match self.get_object_type(&ident)? {
+                    Type::Function(f) => {
+                        let args = f.1.clone().iter()
+                            .map(|_| self.parse()).collect::<Result<Vec<_>, ParseError>>()?;
+
+                        Ok(ParseTree::FunctionCall(ident, args))
+                    }
+                    _ => Ok(ParseTree::Variable(ident)),
                 }
             }
             Token::Operator(op) => {
                 match op {
-                            Op::Add => Ok(ParseTree::Add(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::Sub => Ok(ParseTree::Sub(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::Mul => Ok(ParseTree::Mul(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::Div => Ok(ParseTree::Div(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::Exp => Ok(ParseTree::Exp(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::Mod => Ok(ParseTree::Mod(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
+                    Op::Add => Ok(ParseTree::Add(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::Sub => Ok(ParseTree::Sub(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::Mul => Ok(ParseTree::Mul(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::Div => Ok(ParseTree::Div(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::Exp => Ok(ParseTree::Exp(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::Mod => Ok(ParseTree::Mod(Box::new(self.parse()?), Box::new(self.parse()?))),
                     Op::Equ | Op::LazyEqu => {
-                                let token = tokens.next()
+                        let token = self.tokens.next()
                             .ok_or(ParseError::UnexpectedEndInput)?
                             .map_err(|e| ParseError::TokenizeError(e))?;
 
+                        let body = Box::new(self.parse()?);
+
                         if let Token::Identifier(ident) = token {
                             match op {
                                 Op::Equ => Ok(ParseTree::Equ(ident.clone(),
-                                            Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                            Box::new(ParseTree::parse(tokens, globals, locals)?)
-                                        )),
+                                    body,
+                                    Box::new(Parser::new(self.tokens.by_ref(), self.globals.borrow_mut())
+                                        .locals(self.locals.clone())
+                                        .add_local(ident, Type::Any)
+                                        .parse()?))
+                                ),
                                 Op::LazyEqu => Ok(ParseTree::LazyEqu(ident.clone(),
-                                            Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                            Box::new(ParseTree::parse(tokens, globals, locals)?)
-                                        )),
-                                        _ => panic!("Operator literally changed under your nose"),
+                                    body,
+                                    Box::new(Parser::new(self.tokens.by_ref(), self.globals.borrow_mut())
+                                        .locals(self.locals.clone())
+                                        .add_local(ident, Type::Any)
+                                        .parse()?))
+                                ),
+                                _ => unreachable!(),
                             }
                         } else {
-                                    Err(ParseError::InvalidIdentifier)
+                            Err(ParseError::InvalidIdentifier(token))
                         }
                     }
-                            Op::FunctionDeclare(nargs) => {
-                                let token = tokens.next()
-                                    .ok_or(ParseError::UnexpectedEndInput)?
-                                    .map_err(|e| ParseError::TokenizeError(e))?;
+                    Op::FunctionDefine(arg_count) => {
+                        let f = self.parse_function(arg_count)?;
 
-                                    if let Token::Identifier(ident) = token {
-                                        let args: Vec<(String, Type)> = tokens.take(nargs)
-                                            .map(|token| match token {
-                                                Ok(Token::Identifier(ident)) => Ok((ident, Type::Any)),
-                                                Ok(_) => Err(ParseError::InvalidIdentifier),
-                                                Err(e) => Err(ParseError::TokenizeError(e)),
-                                            })
-                                            .collect::<Result<Vec<_>, ParseError>>()?;
+                        Ok(ParseTree::FunctionDefinition(f.clone(),
+                            Box::new(
+                                Parser::new(self.tokens, self.globals.borrow_mut())
+                                .locals(self.locals.clone())
+                                .add_local(f.name().unwrap().to_string(), Type::Function(f.get_type()))
+                                .parse()?
+                            )))
+                    },
+                    Op::Compose => Ok(ParseTree::Compose(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::Id => Ok(ParseTree::Id(Box::new(self.parse()?))),
+                    Op::IfElse => Ok(ParseTree::IfElse(Box::new(self.parse()?), Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::If => Ok(ParseTree::If(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::EqualTo => Ok(ParseTree::EqualTo(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::GreaterThan => Ok(ParseTree::GreaterThan(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::LessThan => Ok(ParseTree::LessThan(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::GreaterThanOrEqualTo => Ok(ParseTree::GreaterThanOrEqualTo(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::LessThanOrEqualTo => Ok(ParseTree::LessThanOrEqualTo(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::Not => Ok(ParseTree::Not(Box::new(self.parse()?))),
+                    Op::IntCast => Ok(ParseTree::IntCast(Box::new(self.parse()?))),
+                    Op::FloatCast => Ok(ParseTree::FloatCast(Box::new(self.parse()?))),
+                    Op::BoolCast => Ok(ParseTree::BoolCast(Box::new(self.parse()?))),
+                    Op::StringCast => Ok(ParseTree::StringCast(Box::new(self.parse()?))),
+                    Op::Print => Ok(ParseTree::Print(Box::new(self.parse()?))),
+                    Op::OpenArray => {
+                        let mut depth = 1;
 
-                                        let locals = locals.to_mut();
+                        // take tokens until we reach the end of this array
+                        // if we don't collect them here it causes rust to overflow computing the types
+                        let array_tokens = self.tokens.by_ref().take_while(|t| match t {
+                            Ok(Token::Operator(Op::OpenArray)) => {
+                                depth += 1;
+                                true
+                            },
+                            Ok(Token::Operator(Op::CloseArray)) => {
+                                depth -= 1;
+                                depth > 0
+                            }
+                            _ => true,
+                        }).collect::<Result<Vec<_>, TokenizeError>>().map_err(|e| ParseError::TokenizeError(e))?;
 
-                                        locals.insert(ident.clone(), FunctionDeclaration {
-                                            _name: ident.clone(),
-                                            _r: Type::Any,
-                                            args: args.clone(),
+                        let mut array_tokens = array_tokens
+                            .into_iter()
+                            .map(|t| Ok(t))
+                            .collect::<Vec<Result<Token, TokenizeError>>>()
+                            .into_iter()
+                            .peekable();
+
+                        let trees: Vec<ParseTree> = Parser::new(&mut array_tokens, self.globals.borrow_mut())
+                            .locals(self.locals.to_owned())
+                            .collect::<Result<_, ParseError>>()?;
+
+                        let tree = trees.into_iter().fold(
+                            ParseTree::Constant(Value::Array(Type::Any, vec![])),
+                            |acc, x| ParseTree::Add(Box::new(acc), Box::new(x.clone())),
+                        );
+
+                        Ok(tree)
+                    }
+                    Op::OpenStatement => {
+                        let mut depth = 1;
+
+                        // take tokens until we reach the end of this array
+                        // if we don't collect them here it causes rust to overflow computing the types
+                        let tokens = self.tokens.by_ref().take_while(|t| match t {
+                            Ok(Token::Operator(Op::OpenStatement)) => {
+                                depth += 1;
+                                true
+                            },
+                            Ok(Token::Operator(Op::CloseStatement)) => {
+                                depth -= 1;
+                                depth > 0
+                            }
+                            _ => true,
+                        }).collect::<Result<Vec<_>, TokenizeError>>().map_err(|e| ParseError::TokenizeError(e))?;
+
+                        let mut tokens = tokens
+                            .into_iter()
+                            .map(|t| Ok(t))
+                            .collect::<Vec<Result<Token, TokenizeError>>>()
+                            .into_iter()
+                            .peekable();
+
+                        let trees: Vec<ParseTree> = Parser::new(&mut tokens, self.globals.borrow_mut())
+                            .locals(self.locals.to_owned())
+                            .collect::<Result<_, ParseError>>()?;
+
+                        let tree = trees.into_iter().fold(
+                            ParseTree::Nop,
+                            |acc, x| ParseTree::Compose(Box::new(acc), Box::new(x.clone())),
+                        );
+
+                        Ok(tree)
+                    }
+                    Op::Empty => Ok(ParseTree::Constant(Value::Array(Type::Any, vec![]))),
+                    Op::CloseArray => Err(ParseError::UnmatchedArrayClose),
+                    Op::NotEqualTo => Ok(ParseTree::NotEqualTo(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::And => Ok(ParseTree::And(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::Or => Ok(ParseTree::Or(Box::new(self.parse()?), Box::new(self.parse()?))),
+                    Op::LambdaDefine(arg_count) => {
+                        let f = self.parse_lambda(arg_count)?;
+                        Ok(ParseTree::LambdaDefinition(f))
+                    }
+                    Op::NonCall => {
+                        let name = Self::get_identifier(self.tokens.next())?;
+                        Ok(ParseTree::NonCall(name))
+                    },
+                    Op::Head => Ok(ParseTree::Head(Box::new(self.parse()?))),
+                    Op::Tail => Ok(ParseTree::Tail(Box::new(self.parse()?))),
+                    Op::Init => Ok(ParseTree::Init(Box::new(self.parse()?))),
+                    Op::Fini => Ok(ParseTree::Fini(Box::new(self.parse()?))),
+                    Op::Export => {
+                        let list = self.parse()?;
+                        let mut g = HashMap::new();
+                        let list = Executor::new(&mut vec![Ok(list)].into_iter(), &mut g).next().unwrap().map_err(|_| ParseError::NoInput)?;
+
+                        if let Value::Array(Type::String, items) = list {
+                            let names = items.into_iter().map(|x| match x {
+                                Value::String(s) => s,
+                                _ => unreachable!(),
                             });
 
-                                        Ok(ParseTree::FunctionDefinition(
-                                            ident,
-                                            args,
-                                            Type::Any,
-                                            Box::new(ParseTree::parse(tokens, globals, &mut Cow::Borrowed(&*locals))?),
-                                            Box::new(ParseTree::parse(tokens, globals, &mut Cow::Borrowed(&*locals))?)))
+                            for name in names.clone() {
+                                let t = self.locals.remove(&name).ok_or(ParseError::IdentifierUndefined(name.clone()))?;
+                                self.globals.insert(name, t);
+                            }
+
+                            Ok(ParseTree::Export(names.collect()))
                         } else {
-                                        Err(ParseError::InvalidIdentifier)
+                            Err(ParseError::NoInput)
                         }
                     }
-                            Op::Compose => Ok(ParseTree::Compose(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::Id => Ok(ParseTree::Id(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::If => Ok(ParseTree::If(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::IfElse => Ok(ParseTree::IfElse(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::EqualTo => Ok(ParseTree::EqualTo(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::GreaterThan => Ok(ParseTree::GreaterThan(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::LessThan => Ok(ParseTree::LessThan(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::GreaterThanOrEqualTo => Ok(ParseTree::GreaterThanOrEqualTo(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::LessThanOrEqualTo => Ok(ParseTree::LessThanOrEqualTo(
-                                Box::new(ParseTree::parse(tokens, globals, locals)?),
-                                Box::new(ParseTree::parse(tokens, globals, locals)?)
-                            )),
-                            Op::Not => Ok(ParseTree::Not(Box::new(ParseTree::parse(tokens, globals, locals)?))),
-                            Op::IntCast => Ok(ParseTree::ToInt(Box::new(ParseTree::parse(tokens, globals, locals)?))),
-                            Op::FloatCast => Ok(ParseTree::ToFloat(Box::new(ParseTree::parse(tokens, globals, locals)?))),
-                            Op::BoolCast => Ok(ParseTree::ToBool(Box::new(ParseTree::parse(tokens, globals, locals)?))),
-                            Op::StringCast => Ok(ParseTree::ToString(Box::new(ParseTree::parse(tokens, globals, locals)?))),
+                    op => Err(ParseError::UnwantedToken(Token::Operator(op))),
                 }
             }
+            t => Err(ParseError::UnwantedToken(t)),
         }
-            },
+    }
+
+    fn parse_lambda(&mut self, arg_count: usize) -> Result<Function, ParseError> {
+        let (t, args) = Self::parse_function_declaration(self.tokens, arg_count)?;
+
+        let mut locals = self.locals.clone();
+
+        for (name, t) in std::iter::zip(args.iter(), t.1.iter()) {
+            locals.insert(name.clone(), t.clone());
+        }
+
+        Ok(Function::lambda(t, args, Box::new(
+            Parser::new(self.tokens, &mut self.globals)
+                .locals(locals).parse()?)))
+    }
+
+    fn parse_function(&mut self, arg_count: usize) -> Result<Function, ParseError> {
+        let name = Self::get_identifier(self.tokens.next())?;
+        let (t, args) = Self::parse_function_declaration(self.tokens, arg_count)?;
+
+        let mut locals = self.locals.clone();
+
+        for (name, t) in std::iter::zip(args.iter(), t.1.iter()) {
+            locals.insert(name.clone(), t.clone());
+        }
+
+        locals.insert(name.clone(), Type::Function(t.clone()));
+
+        Ok(Function::named(&name, t, args, Box::new(
+            Parser::new(self.tokens, &mut self.globals)
+                .locals(locals).parse()?)))
+    }
+
+    fn parse_function_declaration(
+        tokens: &mut Peekable<I>,
+        arg_count: usize) -> Result<(FunctionType, Vec<String>), ParseError>
+    {
+        let args: Vec<(Type, String)> = (0..arg_count)
+            .map(|_| Self::parse_function_declaration_parameter(tokens))
+            .collect::<Result<_, _>>()?;
+
+        let (types, names): (Vec<_>, Vec<_>) = args.into_iter().unzip();
+        let ret = if tokens.next_if(|x| matches!(x, Ok(Token::Operator(Op::Arrow)))).is_some() {
+            Self::parse_type(tokens)?
+        } else {
+            Type::Any
+        };
+
+        Ok((FunctionType(Box::new(ret), types), names))
+    }
+
+    fn parse_function_declaration_parameter(
+        mut tokens: &mut Peekable<I>) -> Result<(Type, String), ParseError>
+    {
+        match tokens.next() {
+            // untyped variable
+            Some(Ok(Token::Identifier(x))) => Ok((Type::Any, x)),
+
+            // typed variable
+            Some(Ok(Token::Operator(Op::TypeDeclaration))) => {
+                let name = Self::get_identifier(tokens.next())?;
+                let t = Self::parse_type(&mut tokens)?;
+
+                Ok((t, name))
+            }
+
+            // untyped function (all args Any, return type Any)
+            Some(Ok(Token::Operator(Op::FunctionDefine(n)))) => {
+                let name = Self::get_identifier(tokens.next())?;
+                let args = (0..n).map(|_| Type::Any).collect();
+
+                Ok((Type::Function(FunctionType(Box::new(Type::Any), args)), name))
+            }
+
+            // typed function
+            Some(Ok(Token::Operator(Op::FunctionDeclare(n)))) => {
+                let name = Self::get_identifier(tokens.next())?;
+                let args = (0..n).map(|_| Self::parse_type(&mut tokens)).collect::<Result<_, _>>()?;
+                let mut ret = Type::Any;
+
+                // this is annoying
+                // inside the next_if closure, we already can know that its an error
+                // and return it, but we cannot return out of a closure
+                if let Some(t) = tokens.next_if(|x| matches!(x, Ok(Token::Operator(Op::Arrow))))
+                {
+                    // so we just check for an error here. this is the only reason t exists.
+                    if let Err(e) = t {
+                        return Err(ParseError::TokenizeError(e));
+                    }
+
+                    ret = Self::parse_type(&mut tokens)?;
+                }
+
+                Ok((Type::Function(FunctionType(Box::new(ret), args)), name))
+            }
+
+            Some(Ok(t)) => Err(ParseError::UnwantedToken(t)),
             Some(Err(e)) => Err(ParseError::TokenizeError(e)),
-            None => Err(ParseError::NoInput),
+            None => Err(ParseError::UnexpectedEndInput),
+        }
+    }
+
+    // for some dumbass reason,
+    // this is the only code that breaks if it doesn't take an impl Iterator instead of simply I ...
+    fn parse_type(tokens: &mut Peekable<impl Iterator<Item = Result<Token, TokenizeError>>>) -> Result<Type, ParseError> {
+        match tokens.next() {
+            Some(Ok(Token::Type(t))) => Ok(t),
+            Some(Ok(Token::Operator(Op::OpenArray))) => {
+                let mut depth = 1;
+
+                // take tokens until we reach the end of this array
+                // if we don't collect them here it causes rust to overflow computing the types
+                let array_tokens = tokens.by_ref().take_while(|t| match t {
+                    Ok(Token::Operator(Op::OpenArray)) => {
+                        depth += 1;
+                        true
+                    },
+                    Ok(Token::Operator(Op::CloseArray)) => {
+                        depth -= 1;
+                        depth > 0
+                    }
+                    _ => true,
+                }).collect::<Result<Vec<_>, TokenizeError>>().map_err(|e| ParseError::TokenizeError(e))?;
+
+                // ... thanks to this conversion here. The compiler complains that the types don't
+                // match. there is code elsewhere in this codebase that looks exactly like this and
+                // still simply uses &mut Peekable<I> as the type. I don't understand why this code
+                // is special, but we have to do horribleness for it to work.
+                let mut array_tokens = array_tokens
+                    .into_iter()
+                    .map(|t| Ok(t))
+                    .collect::<Vec<Result<Token, TokenizeError>>>()
+                    .into_iter()
+                    .peekable();
+
+                let t = match Self::parse_type(&mut array_tokens) {
+                    Ok(t) => t,
+                    Err(ParseError::UnexpectedEndInput) => Type::Any,
+                    Err(e) => return Err(e),
+                };
+
+                Ok(Type::Array(Box::new(t)))
+            },
+            Some(Ok(t)) => Err(ParseError::UnwantedToken(t.clone())),
+            Some(Err(e)) => Err(ParseError::TokenizeError(e)),
+            None => Err(ParseError::UnexpectedEndInput),
+        }
+    }
+
+    fn get_identifier(t: Option<Result<Token, TokenizeError>>) -> Result<String, ParseError> {
+        match t.ok_or(ParseError::UnexpectedEndInput)?
+            .map_err(|e| ParseError::TokenizeError(e))
+        {
+            Ok(Token::Identifier(ident)) => Ok(ident),
+            Ok(t) => Err(ParseError::InvalidIdentifier(t)),
+            Err(e) => Err(e),
         }
     }
 }
 
-/// Parses input tokens and produces ParseTrees for an Executor
-pub(crate) struct Parser<I: Iterator<Item = Result<Token, TokenizeError>>> {
-    tokens: I,
-
-    // These are used to keep track of functions in the current context
-    // by the parser. otherwise the parser would have no way to tell
-    // if the program `* a b 12` is supposed to be ((* a b) (12)) or (* (a b) 12)
-    globals: HashMap<String, FunctionDeclaration>,
-    locals: HashMap<String, FunctionDeclaration>,
-}
-
-impl<I: Iterator<Item = Result<Token, TokenizeError>>> Parser<I> {
-    pub fn new(tokens: I) -> Self {
-        Self {
-            tokens,
-            globals: HashMap::new(),
-            locals: HashMap::new()
-        }
-    }
-}
-
-impl<I: Iterator<Item = Result<Token, TokenizeError>>> Iterator for Parser<I> {
+impl<'a, I: Iterator<Item = Result<Token, TokenizeError>>> Iterator for Parser<'a, I> {
     type Item = Result<ParseTree, ParseError>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        let tree = ParseTree::parse(&mut self.tokens, &self.globals, &mut Cow::Borrowed(&self.locals));
+        let tree = self.parse();
 
         match tree {
             Ok(tree) => Some(Ok(tree)),

src/tokenizer.rs

@@ -1,6 +1,8 @@
 use std::iter::Peekable;
 use std::{error, io};
-use std::collections::VecDeque;
+use std::collections::{VecDeque, HashMap};
+
+use crate::Type;
 
 use super::Value;
 use std::fmt::{Display, Formatter};
@@ -39,8 +41,8 @@ impl Display for TokenizeError {
 
 impl error::Error for TokenizeError {}
 
-#[derive(Debug, Clone)]
-pub(crate) enum Op {
+#[derive(Debug, Clone, PartialEq)]
+pub enum Op {
     Add,
     Sub,
     Mul,
@@ -49,7 +51,11 @@ pub(crate) enum Op {
     Equ,
     Mod,
     LazyEqu,
+    TypeDeclaration,
+    FunctionDefine(usize),
     FunctionDeclare(usize),
+    LambdaDefine(usize),
+    Arrow,
     Compose,
     Id,
     If,
@@ -57,6 +63,7 @@ pub(crate) enum Op {
     GreaterThan,
     LessThan,
     EqualTo,
+    NotEqualTo,
     GreaterThanOrEqualTo,
     LessThanOrEqualTo,
     Not,
@@ -64,35 +71,76 @@ pub(crate) enum Op {
     FloatCast,
     BoolCast,
     StringCast,
+    Print,
+    OpenArray,
+    CloseArray,
+    OpenStatement,
+    CloseStatement,
+    Empty,
+    And,
+    Or,
+    NonCall,
+    Head,
+    Tail,
+    Init,
+    Fini,
+    Export,
 }
 
-#[derive(Debug, Clone)]
-pub(crate) enum Token {
+#[derive(Debug, Clone, PartialEq)]
+pub enum Token {
     Identifier(String),
     Operator(Op),
     Constant(Value),
+    Type(Type),
 }
 
-fn get_dot_count(s: &str) -> Option<usize> {
-    s.chars().fold(Some(0), |acc, c|
-        match c {
-            ':' => acc.map(|acc| acc + 2),
-            '.' => acc.map(|acc| acc + 1),
-            _ => None,
+fn get_dot_count<I: Iterator<Item = char>>(s: &mut Peekable<I>) -> Option<usize> {
+    let mut total = 0;
+
+    while let Some(n) = s.next_if(|&c| c == ':' || c == '.').map(|c| match c {
+        ':' => 2,
+        '.' => 1,
+        _ => 0,
+    }) {
+        total += n;
     }
-    )
+
+    Some(total)
 }
 
 impl Token {
     /// Parse a single token
     fn parse(s: &str) -> Result<Self, TokenizeError> {
-        let string = regex::Regex::new(r#"".+""#).map_err(|e| TokenizeError::Regex(e))?;
         let identifier = regex::Regex::new(r#"[A-Za-z_][A-Za-z0-9_']*"#).map_err(|e| TokenizeError::Regex(e))?;
         let number = regex::Regex::new(r#"([0-9]+\.?[0-9]*)|(\.[0-9])"#).map_err(|e| TokenizeError::Regex(e))?;
 
-        if string.is_match(s) {
-            Ok(Token::Constant(Value::String(s[1..s.len() - 1].to_string())))
-        } else if identifier.is_match(s) {
+        match s {
+            // Match keywords first
+            "true"  => Ok(Token::Constant(Value::Bool(true))),
+            "false" => Ok(Token::Constant(Value::Bool(false))),
+            "int"    => Ok(Token::Operator(Op::IntCast)),
+            "float"  => Ok(Token::Operator(Op::FloatCast)),
+            "bool"   => Ok(Token::Operator(Op::BoolCast)),
+            "string" => Ok(Token::Operator(Op::StringCast)),
+            "print" => Ok(Token::Operator(Op::Print)),
+            "empty" => Ok(Token::Operator(Op::Empty)),
+            "head" => Ok(Token::Operator(Op::Head)),
+            "tail" => Ok(Token::Operator(Op::Tail)),
+            "init" => Ok(Token::Operator(Op::Init)),
+            "fini" => Ok(Token::Operator(Op::Fini)),
+            "export" => Ok(Token::Operator(Op::Export)),
+
+            // Types
+            "Any" => Ok(Token::Type(Type::Any)),
+            "Int" => Ok(Token::Type(Type::Int)),
+            "Float" => Ok(Token::Type(Type::Float)),
+            "Bool" => Ok(Token::Type(Type::Bool)),
+            "String" => Ok(Token::Type(Type::String)),
+
+            // then identifiers and numbers
+            _ => {
+                if identifier.is_match(s) {
                     Ok(Token::Identifier(s.to_string()))
                 } else if number.is_match(s) {
                     if let Ok(int) = s.parse::<i64>() {
@@ -102,44 +150,6 @@ impl Token {
                     } else {
                         Err(TokenizeError::InvalidNumericConstant(s.to_string()))
                     }
-        } else {
-            match s {
-                // First check if s is an operator
-                "+"  => Ok(Token::Operator(Op::Add)),
-                "-"  => Ok(Token::Operator(Op::Sub)),
-                "*"  => Ok(Token::Operator(Op::Mul)),
-                "/"  => Ok(Token::Operator(Op::Div)),
-                "**" => Ok(Token::Operator(Op::Exp)),
-                "%"  => Ok(Token::Operator(Op::Mod)),
-                "="  => Ok(Token::Operator(Op::Equ)),
-                "."  => Ok(Token::Operator(Op::LazyEqu)),
-                "~"  => Ok(Token::Operator(Op::Compose)),
-                ","  => Ok(Token::Operator(Op::Id)),
-                "?"  => Ok(Token::Operator(Op::If)),
-                "??" => Ok(Token::Operator(Op::IfElse)),
-                ">"  => Ok(Token::Operator(Op::GreaterThan)),
-                "<"  => Ok(Token::Operator(Op::LessThan)),
-                ">=" => Ok(Token::Operator(Op::GreaterThanOrEqualTo)),
-                "<=" => Ok(Token::Operator(Op::LessThanOrEqualTo)),
-                "==" => Ok(Token::Operator(Op::EqualTo)),
-    
-                // then some keywords
-                "true"  => Ok(Token::Constant(Value::Bool(true))),
-                "false" => Ok(Token::Constant(Value::Bool(false))),
-                "not"   => Ok(Token::Operator(Op::Not)),
-    
-                // Type casting
-                "int"    => Ok(Token::Operator(Op::IntCast)),
-                "float"  => Ok(Token::Operator(Op::FloatCast)),
-                "bool"   => Ok(Token::Operator(Op::BoolCast)),
-                "string" => Ok(Token::Operator(Op::StringCast)),
-    
-                // then variable length keywords
-                _ => {
-                    if s.starts_with(":") {
-                        Ok(Token::Operator(Op::FunctionDeclare(
-                            get_dot_count(s).map(|x| x - 1).ok_or(TokenizeError::InvalidDynamicOperator(s.to_string()))?
-                        )))
                 } else {
                     Err(TokenizeError::UnableToMatchToken(s.to_string()))
                 }
@@ -147,7 +157,6 @@ impl Token {
         }
     }
 }
-}
 
 /// Tokenize an input stream of source code for a Parser
 pub(crate) struct Tokenizer<R: BufRead> {
@@ -165,7 +174,39 @@ impl<R: BufRead> Tokenizer<R> {
 
     /// Tokenizes more input and adds them to the internal queue
     fn tokenize<I: Iterator<Item = char>>(&mut self, mut iter: Peekable<I>) {
-        const OPERATOR_CHARS: &'static str = "!@$%^&*()-=+[]{}|;:,<.>/?";
+        let operators: HashMap<&'static str, Op> = HashMap::from([
+            ("+", Op::Add),
+            ("-", Op::Sub),
+            ("*", Op::Mul),
+            ("/", Op::Div),
+            ("**", Op::Exp),
+            ("%", Op::Mod),
+            ("=", Op::Equ),
+            (".", Op::LazyEqu),
+            ("?.", Op::TypeDeclaration),
+            (":", Op::FunctionDefine(1)),
+            ("?:", Op::FunctionDeclare(1)),
+            (";", Op::LambdaDefine(1)),
+            ("->", Op::Arrow),
+            ("~", Op::Compose),
+            (",", Op::Id),
+            ("?", Op::If),
+            ("??", Op::IfElse),
+            (">", Op::GreaterThan),
+            ("<", Op::LessThan),
+            (">=", Op::GreaterThanOrEqualTo),
+            ("<=", Op::LessThanOrEqualTo),
+            ("==", Op::EqualTo),
+            ("!=", Op::NotEqualTo),
+            ("[", Op::OpenArray),
+            ("]", Op::CloseArray),
+            ("(", Op::OpenStatement),
+            (")", Op::CloseStatement),
+            ("!", Op::Not),
+            ("&&", Op::And),
+            ("||", Op::Or),
+            ("'", Op::NonCall),
+        ]);
 
         let c = if let Some(c) = iter.next() {
             c
@@ -173,26 +214,16 @@ impl<R: BufRead> Tokenizer<R> {
             return;
         };
 
-        if c.is_alphanumeric() || c == '.' {
+        if c.is_alphanumeric() {
             let mut token = String::from(c);
 
             while let Some(c) = iter.next_if(|&c| c.is_alphanumeric() || c == '.' || c == '\'') {
                 token.push(c);
             }
 
-            self.tokens.push_back(Token::parse(&token));
-            self.tokenize(iter)
-        } else if OPERATOR_CHARS.contains(c) {
-            let mut token = String::from(c);
-
-            while let Some(c) = iter.next_if(|&c| OPERATOR_CHARS.contains(c)) {
-                token.push(c);
-            }
-
             self.tokens.push_back(Token::parse(&token));
             self.tokenize(iter)
         } else if c == '#' {
-            // consume comments
             let _: String = iter.by_ref().take_while(|&c| c != '\n').collect();
         } else if c == '\"' {
             let mut token = String::new();
@@ -221,11 +252,136 @@ impl<R: BufRead> Tokenizer<R> {
             }
 
             self.tokens.push_back(Ok(Token::Constant(Value::String(token))));
+            self.tokenize(iter)
+        } else if operators.keys().any(|x| x.starts_with(c)) {
+            let mut token = String::from(c);
+
+            loop {
+                // get a list of all tokens this current token could possibly be
+                let possible: HashMap<&'static str, Op> = operators
+                    .clone().into_iter()
+                    .filter(|(key, _)| key.starts_with(&token))
+                    .collect();
+
+                // checks if a character is "expected", aka based on how many chars
+                // we have eaten so far, which characters out of the current nominees
+                // are expected in the next position
+                let is_expected = |c: &char|
+                    possible.iter().any(|(op, _)| match op.chars().nth(token.len()) {
+                        Some(i) => *c == i,
+                        None => false,
+                    });
+
+                match possible.len() {
+                    1 => {
+                        // if the current operator exists in possible, we push it
+                        // if not, we need to make sure that the next characters
+                        // we grab *actually* match the last operator
+                        if let Some(op) = possible.get(token.as_str()) {
+                            self.tokens.push_back(Ok(Token::Operator(match op {
+                                // special handling for "dynamic" operators
+                                Op::FunctionDefine(n) => {
+                                    let count = match get_dot_count(&mut iter) {
+                                        Some(count) => count,
+                                        None => {
+                                            self.tokens.push_back(Err(TokenizeError::InvalidDynamicOperator(token)));
+                                            return;
+                                        }
+                                    };
+                                    Op::FunctionDefine(n + count)
+                                }
+                                Op::FunctionDeclare(n) => {
+                                    let count = match get_dot_count(&mut iter) {
+                                        Some(count) => count,
+                                        None => {
+                                            self.tokens.push_back(Err(TokenizeError::InvalidDynamicOperator(token)));
+                                            return;
+                                        }
+                                    };
+                                    Op::FunctionDeclare(n + count)
+                                }
+                                Op::LambdaDefine(n) => {
+                                    let count = match get_dot_count(&mut iter) {
+                                        Some(count) => count,
+                                        None => {
+                                            self.tokens.push_back(Err(TokenizeError::InvalidDynamicOperator(token)));
+                                            return;
+                                        }
+                                    };
+                                    Op::LambdaDefine(n + count)
+                                }
+                                op => op.clone(),
+                            })));
+
+                            break;
+                        } else {
+                            let next = match iter.next_if(is_expected) {
+                                Some(c) => c,
+                                None => {
+                                    self.tokens.push_back(Err(TokenizeError::UnableToMatchToken(format!("{token}"))));
+                                    return;
+                                }
+                            };
+    
+                            token.push(next);
+                        }
+                    }
+                    0 => unreachable!(),
+                    _ => {
+                        let next = match iter.next_if(is_expected) {
+                            Some(c) => c,
+                            None => {
+                                // at this point, token must be in the hashmap possible, otherwise it wouldnt have any matches
+                                self.tokens.push_back(Ok(Token::Operator(match possible.get(token.as_str()).unwrap() {
+                                    // special handling for "dynamic" operators
+                                    Op::FunctionDefine(n) => {
+                                        let count = match get_dot_count(&mut iter) {
+                                            Some(count) => count,
+                                            None => {
+                                                self.tokens.push_back(Err(TokenizeError::InvalidDynamicOperator(token)));
+                                                return;
+                                            }
+                                        };
+    
+                                        Op::FunctionDefine(n + count)
+                                    }
+                                    Op::FunctionDeclare(n) => {
+                                        let count = match get_dot_count(&mut iter) {
+                                            Some(count) => count,
+                                            None => {
+                                                self.tokens.push_back(Err(TokenizeError::InvalidDynamicOperator(token)));
+                                                return;
+                                            }
+                                        };
+                                        Op::FunctionDeclare(n + count)
+                                    }
+                                    Op::LambdaDefine(n) => {
+                                        let count = match get_dot_count(&mut iter) {
+                                            Some(count) => count,
+                                            None => {
+                                                self.tokens.push_back(Err(TokenizeError::InvalidDynamicOperator(token)));
+                                                return;
+                                            }
+                                        };
+                                        Op::LambdaDefine(n + count)
+                                    }
+                                    op => op.clone(),
+                                })));
+                                break;
+                            }
+                        };
+
+                        token.push(next);
+                    }
+                }
+            }
+
             self.tokenize(iter)
         } else if c.is_whitespace() {
             self.tokenize(iter)
         } else {
             self.tokens.push_back(Err(TokenizeError::InvalidCharacter(c)));
+            return;
         }
     }
 }
@@ -262,16 +418,29 @@ impl<R: BufRead> std::iter::Iterator for Tokenizer<R> {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use std::str::FromStr;
+    use crate::parser::Parser;
+    use super::*;
 
     #[test]
     fn tokenizer() {
-        let program = ": function x ** x 2 function 1200";
+        let program = ": length ?. x [] -> Int ?? x + 1 length tail x 0 length [ 1 2 3 ]";
 
-        let tok = Tokenizer::from_str(program).unwrap();
-        let tokens: Vec<Token> = tok.collect::<Result<_, TokenizeError>>().expect("tokenizer error");
+        let tokens: Vec<Token> = Tokenizer::from_str(program).unwrap().collect::<Result<_, _>>().unwrap();
 
-        println!("{tokens:?}");
+        println!("{tokens:#?}");
+    }
+
+    #[test]
+    fn a() {
+        let program = ": length ?. x [] -> Int ?? x + 1 length tail x 0 length [ 1 2 3 ]";
+
+        let mut tokenizer = Tokenizer::from_str(program).unwrap().peekable();
+
+        let mut globals = HashMap::new();
+        let mut parser = Parser::new(&mut tokenizer, &mut globals);
+
+        let tree = parser.next();
+        println!("{tree:#?}");
     }
 }