diff --git a/lysp/example0.lysp b/lysp/example0.lysp
new file mode 100644
index 0000000..cb86c54
--- /dev/null
+++ b/lysp/example0.lysp
@@ -0,0 +1,14 @@
+(defun return-1 () 1)
+(assert (= 1 (return-1)))
+(assert (< 1 2 3 4))
+(assert (<= 1 2 2 3))
+(assert (= 6 (+ 1 2 3) (apply + (list 1 2 3))))
+(assert (= (- 4) (- 1 2 3) (apply - (list 1 2 3))))
+(assert (= 6 (* 1 2 3) (apply * (list 1 2 3))))
+(assert (= 2 (/ 6 3 1) (apply / (list 6 3 1))))
+(assert (= 2 (% 6 4) (apply % (list 6 4))))
+(assert (= 7 (| 1 2 4) (apply | (list 1 2 4))))
+(assert (= 1 (& 1 3 5 7) (apply & (list 1 3 5 7))))
+(assert (= 0 (^ 1 3 5 7) (apply ^ (list 1 3 5 7))))
+(assert (= #t (&& #t #t) (apply && (list #t #t))))
+(assert (= #f (|| #f #f) (apply || (list #f #f))))
diff --git a/src/compile/block.rs b/src/compile/block.rs
index e8d124a..7d4a85b 100644
--- a/src/compile/block.rs
+++ b/src/compile/block.rs
@@ -7,12 +7,12 @@ use crate::{
         instruction::Emitted,
         module::CompilationModule,
         syntax::{
-            CallExpression, CondExpression, Expression, FunctionBody, IfExpression,
-            LambdaExpression,
+            CallExpression, CondExpression, DefunExpression, Expression, FunctionBody,
+            IfExpression, LambdaExpression,
         },
         value::{BuiltinFunction, CompileConstant, CompileValue},
     },
-    vm::instruction::{Comparison, Instruction, U},
+    vm::instruction::{Instruction, MathInstruction, U},
 };
 
 pub struct CompiledFunction {
@@ -112,6 +112,20 @@ impl<'a> LocalBlock<'a> {
         }
     }
 
+    fn compile_set_global(
+        &mut self,
+        identifier: &Rc<str>,
+        value: CompileValue,
+    ) -> Result<(), CompileError> {
+        self.compile_push(value)?;
+        let index = self
+            .module
+            .constant(CompileConstant::Identifier(identifier.clone()))?;
+        self.function.emit(Instruction::PushConstant(index));
+        self.function.emit(Instruction::SetGlobal);
+        Ok(())
+    }
+
     fn compile_push(&mut self, value: CompileValue) -> Result<(), CompileError> {
         match value {
             CompileValue::Nil => {
@@ -141,10 +155,10 @@ impl<'a> LocalBlock<'a> {
                 };
                 self.function.emit(Instruction::PushArgument(index));
             }
-            CompileValue::LocalFunction(index) => {
+            CompileValue::LocalFunction(index, required_count) => {
                 let value = self
                     .module
-                    .constant(CompileConstant::LocalFunction(index))?;
+                    .constant(CompileConstant::LocalFunction(index, required_count))?;
                 self.function.emit(Instruction::PushConstant(value));
             }
             // Already on stack
@@ -174,9 +188,6 @@ impl<'a> LocalBlock<'a> {
     }
 
     fn compile_identifier(&mut self, identifier: &Rc<str>) -> Result<CompileValue, CompileError> {
-        if let Some(_builtin) = BuiltinFunction::from_identifier(identifier) {
-            todo!("Illegal");
-        }
         if let Some(argument) = self.function.signature.argument(identifier) {
             return Ok(CompileValue::Argument(argument));
         }
@@ -188,33 +199,27 @@ impl<'a> LocalBlock<'a> {
         let index = self
             .module
             .compile_function(lambda.signature.clone(), &lambda.body, false)?;
-        Ok(CompileValue::LocalFunction(index))
+        Ok(CompileValue::LocalFunction(
+            index,
+            lambda.signature.required_arguments.len(),
+        ))
     }
 
-    fn compile_builtin_add(&mut self, args: &[Expression]) -> Result<CompileValue, CompileError> {
-        // TODO optimize literals
-        for arg in args.iter().rev() {
-            let arg = self.compile_expression(arg)?;
-            self.compile_push(arg)?;
-        }
-        let Some(count) = U::new(args.len() as u32) else {
-            todo!()
-        };
-        self.function.emit(Instruction::Add(count));
-        Ok(CompileValue::Stack)
+    fn compile_defun(&mut self, defun: &DefunExpression) -> Result<CompileValue, CompileError> {
+        let index = self
+            .module
+            .compile_function(defun.signature.clone(), &defun.body, false)?;
+        let value = CompileValue::LocalFunction(index, defun.signature.required_arguments.len());
+        self.compile_set_global(&defun.name, value)?;
+        Ok(CompileValue::Nil)
     }
 
-    fn compile_builtin_sub(&mut self, _args: &[Expression]) -> Result<CompileValue, CompileError> {
-        todo!()
-    }
-
-    fn compile_builtin_cmp(
+    fn compile_builtin_math_generic(
         &mut self,
-        not: bool,
-        cmp: Comparison,
+        math: MathInstruction,
         args: &[Expression],
     ) -> Result<CompileValue, CompileError> {
-        // TODO optimize literals
+        // TODO optimize
         for arg in args.iter().rev() {
             let arg = self.compile_expression(arg)?;
             self.compile_push(arg)?;
@@ -222,7 +227,7 @@ impl<'a> LocalBlock<'a> {
         let Some(count) = U::new(args.len() as u32) else {
             todo!()
         };
-        self.function.emit(Instruction::Compare(not, cmp, count));
+        self.function.emit(Instruction::Math(math, count));
         Ok(CompileValue::Stack)
     }
 
@@ -232,9 +237,7 @@ impl<'a> LocalBlock<'a> {
         args: &[Expression],
     ) -> Result<CompileValue, CompileError> {
         match builtin {
-            BuiltinFunction::Add => self.compile_builtin_add(args),
-            BuiltinFunction::Sub => self.compile_builtin_sub(args),
-            BuiltinFunction::Cmp(not, cmp) => self.compile_builtin_cmp(not, cmp, args),
+            BuiltinFunction::Math(math) => self.compile_builtin_math_generic(math, args),
         }
     }
 
@@ -323,6 +326,7 @@ impl<'a> LocalBlock<'a> {
             Expression::IntegerLiteral(value) => Ok(CompileValue::Integer(*value)),
             Expression::Identifier(identifier) => self.compile_identifier(identifier),
             Expression::Lambda(lambda) => self.compile_lambda(lambda),
+            Expression::Defun(defun) => self.compile_defun(defun),
             Expression::Call(call) => self.compile_call(call),
             Expression::If(condition) => self.compile_if(condition),
             Expression::Cond(condition) => self.compile_cond(condition),
@@ -347,7 +351,7 @@ mod tests {
             },
             value::{CompileConstant, CompileValue},
         },
-        vm::instruction::{Comparison, Instruction, U},
+        vm::instruction::{Instruction, U},
     };
 
     fn test_compile(
diff --git a/src/compile/module.rs b/src/compile/module.rs
index f84d3db..ac7813e 100644
--- a/src/compile/module.rs
+++ b/src/compile/module.rs
@@ -73,9 +73,9 @@ impl CompilationModule {
                         CompileConstant::Identifier(identifier) => {
                             ModuleConstant::Identifier(identifier)
                         }
-                        CompileConstant::LocalFunction(index) => {
+                        CompileConstant::LocalFunction(index, required_count) => {
                             let address = *function_offsets.get(&index).unwrap();
-                            ModuleConstant::LocalFunction(address)
+                            ModuleConstant::LocalFunction(address, required_count)
                         }
                     },
                 )
diff --git a/src/compile/syntax/error.rs b/src/compile/syntax/error.rs
index c805634..536d469 100644
--- a/src/compile/syntax/error.rs
+++ b/src/compile/syntax/error.rs
@@ -40,6 +40,8 @@ pub enum ExpectedWhat {
     ArgumentSpec,
     #[error("a proper list")]
     ProperList,
+    #[error("an identifier")]
+    Identifier,
 }
 
 #[derive(Debug, Clone, PartialEq, thiserror::Error)]
@@ -58,6 +60,8 @@ pub enum ExpectedWhere {
     InConditionList,
     #[error("in the condition arm")]
     InConditionArm,
+    #[error("in the function definition")]
+    InFunctionDefinition,
 }
 
 pub(super) trait CollectErrors<E> {
diff --git a/src/compile/syntax/function.rs b/src/compile/syntax/function.rs
index a4e3d2d..8510c2a 100644
--- a/src/compile/syntax/function.rs
+++ b/src/compile/syntax/function.rs
@@ -14,6 +14,13 @@ pub struct FunctionBody {
     pub tail: Rc<Expression>,
 }
 
+#[derive(Debug, PartialEq)]
+pub struct DefunExpression {
+    pub name: Rc<str>,
+    pub signature: FunctionSignature,
+    pub body: FunctionBody,
+}
+
 impl FunctionSignature {
     pub(super) fn parse(mut value: &Value, input: &Value) -> Result<Self, ParseError> {
         enum Mode {
@@ -164,6 +171,50 @@ impl FunctionBody {
     }
 }
 
+impl DefunExpression {
+    pub(super) fn parse(value: &Value, input: &Value) -> Result<Self, ParseError> {
+        let Value::Cons(value) = value else {
+            return Err(ParseError {
+                input: input.clone(),
+                error: ParseErrorKind::Expected(
+                    ExpectedWhat::ProperList,
+                    ExpectedWhere::InFunctionDefinition,
+                ),
+            });
+        };
+        let ConsCell(identifier, cdr) = value.as_ref();
+
+        let Value::Identifier(identifier) = identifier else {
+            return Err(ParseError {
+                input: input.clone(),
+                error: ParseErrorKind::Expected(
+                    ExpectedWhat::Identifier,
+                    ExpectedWhere::AfterKeyword(Keyword::Defun),
+                ),
+            });
+        };
+
+        let Value::Cons(cdr) = cdr else {
+            return Err(ParseError {
+                input: input.clone(),
+                error: ParseErrorKind::Expected(
+                    ExpectedWhat::ProperList,
+                    ExpectedWhere::InFunctionDefinition,
+                ),
+            });
+        };
+        let ConsCell(car, cdr) = cdr.as_ref();
+
+        let signature = FunctionSignature::parse(car, input)?;
+        let body = FunctionBody::parse(cdr, input, Keyword::Lambda)?;
+        Ok(Self {
+            name: identifier.clone(),
+            signature,
+            body,
+        })
+    }
+}
+
 impl CollectErrors<ParseError> for FunctionBody {
     fn collect_errors(&self, errors: &mut Vec<ParseError>) -> bool {
         let mut r = false;
@@ -175,6 +226,12 @@ impl CollectErrors<ParseError> for FunctionBody {
     }
 }
 
+impl CollectErrors<ParseError> for DefunExpression {
+    fn collect_errors(&self, errors: &mut Vec<ParseError>) -> bool {
+        self.body.collect_errors(errors)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use std::rc::Rc;
diff --git a/src/compile/syntax/mod.rs b/src/compile/syntax/mod.rs
index 09a1a5a..754282d 100644
--- a/src/compile/syntax/mod.rs
+++ b/src/compile/syntax/mod.rs
@@ -21,6 +21,7 @@ pub enum Expression {
     IntegerLiteral(i64),
     Identifier(Rc<str>),
     Lambda(LambdaExpression),
+    Defun(DefunExpression),
     Call(CallExpression),
     If(IfExpression),
     Cond(CondExpression),
@@ -63,6 +64,9 @@ impl Expression {
                     Value::Keyword(Keyword::Cond) => {
                         Self::map_or(CondExpression::parse(cdr, value), Expression::Cond)
                     }
+                    Value::Keyword(Keyword::Defun) => {
+                        Self::map_or(DefunExpression::parse(cdr, value), Expression::Defun)
+                    }
                     _ => Self::map_or(CallExpression::parse(cons, value), Expression::Call),
                 }
             }
@@ -83,7 +87,8 @@ impl CollectErrors<ParseError> for Expression {
             }
             Self::If(condition) => condition.collect_errors(errors),
             Self::Cond(condition) => condition.collect_errors(errors),
-            Self::Lambda(condition) => condition.collect_errors(errors),
+            Self::Lambda(lambda) => lambda.collect_errors(errors),
+            Self::Defun(defun) => defun.collect_errors(errors),
             Self::Call(call) => call.collect_errors(errors),
             Self::Nil | Self::IntegerLiteral(_) | Self::Identifier(_) | Self::BooleanLiteral(_) => {
                 false
diff --git a/src/compile/value.rs b/src/compile/value.rs
index c33cfe0..078a65f 100644
--- a/src/compile/value.rs
+++ b/src/compile/value.rs
@@ -1,12 +1,12 @@
 use std::rc::Rc;
 
-use crate::vm::instruction::Comparison;
+use crate::vm::instruction::MathInstruction;
 
 #[derive(Debug, PartialEq)]
 pub enum CompileValue {
     Integer(i64),
     Boolean(bool),
-    LocalFunction(u32),
+    LocalFunction(u32, usize),
     Argument(usize),
     Global(Rc<str>),
     Stack,
@@ -16,28 +16,34 @@ pub enum CompileValue {
 #[derive(Debug, Hash, PartialEq, Eq)]
 pub enum CompileConstant {
     Integer(i64),
-    LocalFunction(u32),
+    LocalFunction(u32, usize),
     Identifier(Rc<str>),
 }
 
 #[derive(Debug, PartialEq, Clone, Copy)]
 pub enum BuiltinFunction {
-    Add,
-    Sub,
-    Cmp(bool, Comparison),
+    Math(MathInstruction),
 }
 
 impl BuiltinFunction {
     pub fn from_identifier(identifier: &str) -> Option<Self> {
         match identifier {
-            "+" => Some(Self::Add),
-            "-" => Some(Self::Sub),
-            ">" => Some(Self::Cmp(false, Comparison::Gt)),
-            ">=" => Some(Self::Cmp(true, Comparison::Lt)),
-            "=" => Some(Self::Cmp(false, Comparison::Eq)),
-            "/=" => Some(Self::Cmp(true, Comparison::Eq)),
-            "<=" => Some(Self::Cmp(true, Comparison::Gt)),
-            "<" => Some(Self::Cmp(false, Comparison::Lt)),
+            "+" => Some(Self::Math(MathInstruction::Add)),
+            "-" => Some(Self::Math(MathInstruction::Sub)),
+            "*" => Some(Self::Math(MathInstruction::Mul)),
+            "/" => Some(Self::Math(MathInstruction::Div)),
+            "%" => Some(Self::Math(MathInstruction::Mod)),
+            "&" => Some(Self::Math(MathInstruction::BitwiseAnd)),
+            "|" => Some(Self::Math(MathInstruction::BitwiseOr)),
+            "^" => Some(Self::Math(MathInstruction::BitwiseXor)),
+            "&&" => Some(Self::Math(MathInstruction::And)),
+            "||" => Some(Self::Math(MathInstruction::Or)),
+            ">" => Some(Self::Math(MathInstruction::Gt)),
+            ">=" => Some(Self::Math(MathInstruction::Ge)),
+            "=" => Some(Self::Math(MathInstruction::Eq)),
+            "/=" => Some(Self::Math(MathInstruction::Ne)),
+            "<=" => Some(Self::Math(MathInstruction::Le)),
+            "<" => Some(Self::Math(MathInstruction::Lt)),
             _ => None,
         }
     }
diff --git a/src/lib.rs b/src/lib.rs
index e47ae52..b2a9124 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,4 +4,5 @@ pub mod compile;
 pub mod convert;
 pub mod error;
 pub mod parse;
+pub mod util;
 pub mod vm;
diff --git a/src/main.rs b/src/main.rs
index b0fee7a..7b9d8e9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,23 +1,56 @@
-use std::io::stdin;
+use std::{
+    fs::File,
+    io::{self, BufRead, BufReader, Write, stdin, stdout},
+    path::{Path, PathBuf},
+    process::ExitCode,
+    rc::Rc,
+};
 
+use clap::Parser;
 use lysp::{
-    compile::{CompileError, ParseError},
+    compile::{
+        CompilationModule, CompileError, Expression, FunctionBody, FunctionSignature, ParseError,
+    },
     error::EvalError,
     parse::parse_value,
     vm::{
-        machine::{EvalResult, Machine},
+        machine::{EvalResult, Machine, MachineError},
         prelude,
     },
 };
 
-fn main() {
-    let mut vm = Machine::default();
-    prelude::load(&mut vm);
+#[derive(Debug, thiserror::Error)]
+#[error("{0}")]
+enum Error {
+    Machine(#[from] MachineError),
+    Eval(#[from] EvalError),
+    Io(#[from] io::Error),
+    Compile(#[from] CompileError),
+    #[error("Compilation errors ocurred")]
+    CompilationErrors,
+    #[error("Error already printed")]
+    Printed,
+}
 
+#[derive(Debug, Parser)]
+struct Args {
+    module: Option<PathBuf>,
+}
+
+fn run_interactive(vm: &mut Machine) -> Result<(), Error> {
     let mut input = String::new();
     let stdin = stdin();
+    let mut stdout = stdout();
+
     loop {
-        let len = stdin.read_line(&mut input).unwrap();
+        if input.is_empty() {
+            print!("> ");
+        } else {
+            print!(">>> ");
+        }
+        stdout.flush().ok();
+
+        let len = stdin.read_line(&mut input)?;
         if len == 0 {
             break;
         }
@@ -48,7 +81,7 @@ fn main() {
                     eprintln!();
                     eprintln!(":: {error}");
                     eprintln!();
-                    module.dump(ip_address);
+                    module.dump(ip_address, 8);
                     i = "";
                     break;
                 }
@@ -90,4 +123,121 @@ fn main() {
 
         input = i.into();
     }
+
+    Ok(())
+}
+
+fn run_module<P: AsRef<Path>>(vm: &mut Machine, path: P) -> Result<(), Error> {
+    let path = path.as_ref();
+    let mut input = String::new();
+    let mut reader = BufReader::new(File::open(path)?);
+
+    let mut module = CompilationModule::default();
+    let mut body = FunctionBody {
+        head: vec![],
+        tail: Rc::new(Expression::Nil),
+    };
+
+    let mut fail = false;
+
+    loop {
+        let len = reader.read_line(&mut input)?;
+        if len == 0 {
+            break;
+        }
+
+        let mut i = input.trim_start();
+        while !i.is_empty() {
+            let result = parse_value(i);
+            let (o, value) = match result {
+                Ok(r) => r,
+                Err(nom::Err::Incomplete(_)) => {
+                    break;
+                }
+                Err(error) => {
+                    eprintln!("Syntax error: {error}");
+                    i = "";
+                    fail = true;
+                    break;
+                }
+            };
+
+            let expression = match Expression::parse(&value) {
+                Ok(expression) => expression,
+                Err(errors) => {
+                    if errors.len() > 1 {
+                        eprintln!("Syntax errors:");
+                    } else {
+                        eprintln!("Syntax error:");
+                    }
+                    eprintln!();
+                    for error in errors {
+                        let ParseError { input, error } = error;
+                        eprintln!(" * In (sub)expression:");
+                        eprintln!();
+                        eprintln!("     {input}");
+                        eprintln!();
+                        eprintln!("  :: {error}");
+                    }
+                    fail = true;
+                    continue;
+                }
+            };
+
+            body.head.push(expression);
+
+            i = o.trim_start();
+        }
+
+        input = i.into();
+    }
+
+    if fail {
+        return Err(Error::CompilationErrors);
+    }
+
+    module.compile_function(
+        FunctionSignature {
+            required_arguments: vec![],
+            optional_arguments: vec![],
+            rest_argument: None,
+        },
+        &body,
+        true,
+    )?;
+    let module = module.compile_module()?;
+
+    match vm.eval_module(module.into()) {
+        EvalResult::Ok(_) => Ok(()),
+        EvalResult::Err(module, ip, error) => {
+            let ip_address = ip.map(|ip| ip.address);
+            eprintln!("Error in module");
+            eprintln!();
+            eprintln!("  {}:", path.display());
+            eprintln!();
+            eprintln!(":: {error}");
+            eprintln!();
+            module.dump(ip_address, 8);
+            Err(Error::Printed)
+        }
+        EvalResult::LoadErr(error) => Err(error.into()),
+    }
+}
+
+fn main() -> ExitCode {
+    let args = Args::parse();
+    let mut vm = Machine::default();
+    prelude::load(&mut vm);
+    let result = match args.module.as_ref() {
+        Some(module) => run_module(&mut vm, module),
+        None => run_interactive(&mut vm),
+    };
+    match result {
+        Ok(()) => ExitCode::SUCCESS,
+        Err(Error::Printed) => ExitCode::FAILURE,
+        Err(error) => {
+            eprintln!("{error}");
+            ExitCode::FAILURE
+        }
+    }
 }
diff --git a/src/parse.rs b/src/parse.rs
index dccf0ec..e110533 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -19,13 +19,13 @@ struct IdentifierTail;
 
 impl FindToken<char> for IdentifierHead {
     fn find_token(&self, token: char) -> bool {
-        token.is_alphabetic() || "~!@$%^&*-=_+<>?/".contains(token)
+        token.is_alphabetic() || "~!@$%^&*-=_+<>?/|".contains(token)
     }
 }
 
 impl FindToken<char> for IdentifierTail {
     fn find_token(&self, token: char) -> bool {
-        token.is_alphanumeric() || "~!@$%^&*-=_+<>?/".contains(token)
+        token.is_alphanumeric() || "~!@$%^&*-=_+<>?/|".contains(token)
     }
 }
 
diff --git a/src/util.rs b/src/util.rs
new file mode 100644
index 0000000..ed7e004
--- /dev/null
+++ b/src/util.rs
@@ -0,0 +1,60 @@
+pub struct TryFilter<I, E1, E2, T, F>
+where
+    I: Iterator<Item = Result<T, E1>>,
+    F: FnMut(&T) -> Result<bool, E2>,
+    E2: From<E1>,
+{
+    iterator: I,
+    filter: F,
+}
+
+pub trait IteratorExt<I, E1, T> {
+    fn try_filter<E2, F>(self, filter: F) -> impl Iterator<Item = Result<T, E2>>
+    where
+        F: FnMut(&T) -> Result<bool, E2>,
+        E2: From<E1>;
+}
+
+impl<I, E1, T> IteratorExt<I, E1, T> for I
+where
+    I: Iterator<Item = Result<T, E1>>,
+{
+    fn try_filter<E2, F>(self, filter: F) -> impl Iterator<Item = Result<T, E2>>
+    where
+        F: FnMut(&T) -> Result<bool, E2>,
+        E2: From<E1>,
+    {
+        TryFilter {
+            iterator: self,
+            filter,
+        }
+    }
+}
+
+impl<I, E1, E2, T, F> Iterator for TryFilter<I, E1, E2, T, F>
+where
+    I: Iterator<Item = Result<T, E1>>,
+    F: FnMut(&T) -> Result<bool, E2>,
+    E2: From<E1>,
+{
+    type Item = Result<T, E2>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            let value = self.iterator.next()?;
+            let value = match value {
+                Ok(value) => value,
+                Err(error) => return Some(Err(error.into())),
+            };
+            let cond = match (self.filter)(&value) {
+                Ok(value) => value,
+                Err(error) => return Some(Err(error)),
+            };
+
+            match cond {
+                true => return Some(Ok(value)),
+                false => continue,
+            }
+        }
+    }
+}
diff --git a/src/vm/instruction.rs b/src/vm/instruction.rs
index aeda002..430f00c 100644
--- a/src/vm/instruction.rs
+++ b/src/vm/instruction.rs
@@ -14,24 +14,59 @@ pub enum InstructionEncodeError {}
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct U<const N: usize>(u32);
 
-#[derive(Debug, Clone, Copy, PartialEq)]
-#[repr(u32)]
-pub enum Comparison {
-    Eq = 0,
-    Lt = 1,
-    Gt = 2,
+macro_rules! primitive_enum {
+    (
+        $(#[$meta:meta])*
+        $vis:vis enum $ident:ident: $repr:ty {
+            $($variant:ident = $value:literal),* $(,)?
+        }
+    ) => {
+        $(#[$meta])*
+        #[repr($repr)]
+        $vis enum $ident {
+            $($variant = $value),*
+        }
+
+        impl TryFrom<$repr> for $ident {
+            type Error = InstructionError;
+
+            fn try_from(value: $repr) -> Result<Self, Self::Error> {
+                match value {
+                    $($value => Ok(Self::$variant),)*
+                    _ => Err(InstructionError::Invalid)
+                }
+            }
+        }
+
+        impl From<$ident> for $repr {
+            fn from(value: $ident) -> $repr {
+                match value {
+                    $($ident::$variant => $value,)*
+                }
+            }
+        }
+    };
 }
 
-impl TryFrom<u32> for Comparison {
-    type Error = InstructionError;
-
-    fn try_from(value: u32) -> Result<Self, Self::Error> {
-        match value {
-            0 => Ok(Self::Eq),
-            1 => Ok(Self::Lt),
-            2 => Ok(Self::Gt),
-            _ => Err(InstructionError::Invalid),
-        }
+primitive_enum! {
+    #[derive(Debug, Clone, Copy, PartialEq)]
+    pub enum MathInstruction: u32 {
+        Add = 0,
+        Sub = 1,
+        Mul = 2,
+        Div = 3,
+        Mod = 4,
+        And = 5,
+        Or = 6,
+        BitwiseAnd = 7,
+        BitwiseOr = 8,
+        BitwiseXor = 9,
+        Gt = 10,
+        Lt = 11,
+        Eq = 12,
+        Ne = 13,
+        Ge = 14,
+        Le = 15,
     }
 }
 
@@ -47,11 +82,9 @@ pub enum Instruction {
     GetGlobal,
     Call(U<6>),
     Return,
-    Add(U<6>),
-    Sub(U<6>),
+    Math(MathInstruction, U<6>),
     Branch(U<12>),
     Jump(U<12>),
-    Compare(bool, Comparison, U<6>),
 }
 
 pub type ConstantId = U<24>;
@@ -91,15 +124,15 @@ impl<const N: usize> fmt::Debug for U<N> {
     }
 }
 
-impl<const N: usize> Into<usize> for U<N> {
-    fn into(self) -> usize {
-        self.0 as usize
+impl<const N: usize> From<U<N>> for usize {
+    fn from(value: U<N>) -> Self {
+        value.0 as usize
     }
 }
 
-impl<const N: usize> Into<u32> for U<N> {
-    fn into(self) -> u32 {
-        self.0
+impl<const N: usize> From<U<N>> for u32 {
+    fn from(value: U<N>) -> Self {
+        value.0
     }
 }
 
@@ -112,16 +145,14 @@ impl From<Instruction> for u32 {
             Instruction::Return => 0b0000_0000_0000_0100,
             Instruction::SetGlobal => 0b0000_0000_0000_0101,
             Instruction::GetGlobal => 0b0000_0000_0000_0110,
-            Instruction::Add(count) => 0b0000_0001_0000_0000 | count.0,
-            Instruction::Sub(count) => 0b0000_0001_0100_0000 | count.0,
             Instruction::Call(count) => 0b0000_0000_0100_0000 | count.0,
             Instruction::PushInteger(value) => 0b0001_0000_0000_0000 | value.0,
             Instruction::PushConstant(index) => 0b0010_0000_0000_0000 | index.0,
             Instruction::PushArgument(index) => 0b0000_0000_1000_0000 | index.0,
             Instruction::Branch(offset) => 0b0000_1000_0000_0000 | offset.0,
             Instruction::Jump(offset) => 0b0000_1100_0000_0000 | offset.0,
-            Instruction::Compare(not, cmp, count) => {
-                0b0000_0010_0000_0000 | ((not as u32) << 8) | ((cmp as u32) << 6) | count.0
+            Instruction::Math(math, count) => {
+                0b0000_0100_0000_0000 | (u32::from(math) << 6) | count.0
             }
         }
     }
@@ -140,16 +171,26 @@ impl TryFrom<u32> for Instruction {
             "0000_0000_0000_0100" => Ok(Instruction::Return),
             "0000_0000_0000_0101" => Ok(Instruction::SetGlobal),
             "0000_0000_0000_0110" => Ok(Instruction::GetGlobal),
+            "0000_0000_0000_0111" => todo!(),
+            "0000_0000_0000_1???" => todo!(),
+
+            "0000_0000_0001_????" => todo!(),
+            "0000_0000_001?_????" => todo!(),
             "0000_0000_01xx_xxxx" => Ok(Instruction::Call(U(x))),
             "0000_0000_10xx_xxxx" => Ok(Instruction::PushArgument(U(x))),
-            "0000_0001_00xx_xxxx" => Ok(Instruction::Add(U(x))),
-            "0000_0001_01xx_xxxx" => Ok(Instruction::Sub(U(x))),
-            "0000_001x_yyzz_zzzz" => Ok(Instruction::Compare(x != 0, y.try_into()?, U(z))),
+            "0000_0000_11??_????" => todo!(),
+
+            "0000_0001_????_????" => todo!(),
+            "0000_001?_????_????" => todo!(),
+            "0000_01xx_xxyy_yyyy" => Ok(Instruction::Math(x.try_into()?, U(y))),
             "0000_10xx_xxxx_xxxx" => Ok(Instruction::Branch(U(x))),
             "0000_11xx_xxxx_xxxx" => Ok(Instruction::Jump(U(x))),
+
             "0001_xxxx_xxxx_xxxx" => Ok(Instruction::PushInteger(U(x))),
             "0010_xxxx_xxxx_xxxx" => Ok(Instruction::PushConstant(U(x))),
-            _ => todo!(),
+            "0011_????_????_????" => todo!(),
+            "01??_????_????_????" => todo!(),
+            "1???_????_????_????" => todo!(),
         }
     }
 }
diff --git a/src/vm/machine.rs b/src/vm/machine.rs
index 8ee8d72..a220539 100644
--- a/src/vm/machine.rs
+++ b/src/vm/machine.rs
@@ -1,11 +1,12 @@
-use std::{cmp::Ordering, collections::HashMap, fmt, rc::Rc};
+use std::{collections::HashMap, fmt, rc::Rc};
 
 use crate::{
     error::EvalError,
     vm::{
-        instruction::{Comparison, ConstantId, Instruction, InstructionError},
+        instruction::{ConstantId, Instruction, InstructionError, MathInstruction},
         module::{Module, ModuleConstant, ModuleRef},
         native::NativeFunction,
+        prelude,
         stack::Stack,
         value::{BytecodeFunction, Value},
     },
@@ -29,6 +30,8 @@ pub enum MachineError {
     CallStackOverflow,
     #[error("Unbound identifier: {0:?}")]
     UnboundIdentifier(Rc<str>),
+    #[error("Expected at least {0} arguments, got {1}")]
+    ArgumentCountMismatch(usize, usize),
     #[error("Invalid argument provided in a call")]
     InvalidArgument,
 }
@@ -79,6 +82,10 @@ impl Default for Machine {
 }
 
 impl Machine {
+    pub fn ip(&self) -> Option<InstructionPointer> {
+        self.ip.clone()
+    }
+
     pub fn set_global<S: Into<Rc<str>>>(&mut self, identifier: S, value: Value) {
         self.globals.insert(identifier.into(), value);
     }
@@ -111,15 +118,25 @@ impl Machine {
         arguments: Vec<Value>,
     ) -> Result<(), MachineError> {
         let source_ip = self.ip.clone().unwrap();
+        let BytecodeFunction {
+            module,
+            required_count,
+            address,
+        } = bytecode.clone();
+        if required_count > arguments.len() {
+            return Err(MachineError::ArgumentCountMismatch(
+                required_count,
+                arguments.len(),
+            ));
+        }
         let frame = CallFrame {
             arguments,
-            event: ExecutionEvent::BytecodeFunctionExit(bytecode.clone()),
+            event: ExecutionEvent::BytecodeFunctionExit(bytecode),
             return_address: InstructionPointer {
                 module: source_ip.module,
                 address: source_ip.address + 1,
             },
         };
-        let BytecodeFunction { module, address } = bytecode;
         if self.call_stack.push(frame).is_err() {
             return Err(MachineError::CallStackOverflow);
         }
@@ -160,6 +177,19 @@ impl Machine {
         Ok(())
     }
 
+    fn execute_builtin_native<F>(&mut self, function: F, count: usize) -> Result<(), MachineError>
+    where
+        F: Fn(&mut Self, &[Value]) -> Result<Value, MachineError>,
+    {
+        let mut args = vec![];
+        for _ in 0..count {
+            args.push(self.pop()?);
+        }
+        let value = function(self, &args)?;
+        self.push(value)?;
+        Ok(())
+    }
+
     fn execute_return(&mut self) -> Result<ExecutionEvent, MachineError> {
         let ip = self.ip.clone().unwrap();
         if let Some(frame) = self.call_stack.pop() {
@@ -171,59 +201,49 @@ impl Machine {
         }
     }
 
-    fn execute_add(&mut self, count: usize) -> Result<(), MachineError> {
-        let mut accumulator = 0i64;
-        for _ in 0..count {
-            let arg = self.pop()?;
-            match arg {
-                Value::Integer(value) => {
-                    accumulator = accumulator.wrapping_add(value);
-                }
-                _ => todo!("{arg:?}"),
-            }
-        }
-        self.push(Value::Integer(accumulator))?;
-        Ok(())
-    }
+    //fn execute_add(&mut self, count: usize) -> Result<(), MachineError> {
+    //}
 
-    fn execute_sub(&mut self, _count: usize) -> Result<(), MachineError> {
-        todo!()
-    }
+    // fn execute_sub(&mut self, _count: usize) -> Result<(), MachineError> {
+    //     todo!()
+    // }
 
-    fn execute_compare(
-        &mut self,
-        not: bool,
-        cmp: Comparison,
-        count: usize,
-    ) -> Result<(), MachineError> {
-        fn ordering(a: &Value, b: &Value) -> Ordering {
-            match (a, b) {
-                (Value::Integer(a), Value::Integer(b)) => Ord::cmp(a, b),
-                _ => todo!(),
-            }
-        }
-
-        // TODO checks
-        let values = (0..count)
-            .map(|_| self.pop())
-            .collect::<Result<Vec<_>, _>>()?;
-        let mut accumulator = true;
-        for i in 0..values.len() - 1 {
-            let a = &values[i];
-            let b = &values[i + 1];
-            let ord = ordering(a, b);
-            let check = match (not, cmp) {
-                (true, Comparison::Gt) => ord.is_le(),
-                (false, Comparison::Gt) => ord.is_gt(),
-                (true, Comparison::Eq) => ord.is_ne(),
-                (false, Comparison::Eq) => ord.is_eq(),
-                (true, Comparison::Lt) => ord.is_ge(),
-                (false, Comparison::Lt) => ord.is_lt(),
-            };
-            accumulator &= check;
-        }
-        self.push(Value::Boolean(accumulator))?;
-        Ok(())
+    // fn execute_compare(
+    //     &mut self,
+    //     not: bool,
+    //     cmp: Comparison,
+    //     count: usize,
+    // ) -> Result<(), MachineError> {
+    //     let f = match (not, cmp) {
+    //         (true, Comparison::Gt) => prelude::builtin_cmp_le,
+    //         (false, Comparison::Gt) => prelude::builtin_cmp_gt,
+    //         (true, Comparison::Eq) => prelude::builtin_cmp_eq,
+    //         (false, Comparison::Eq) => prelude::builtin_cmp_ne,
+    //         (true, Comparison::Lt) => prelude::builtin_cmp_ge,
+    //         (false, Comparison::Lt) => prelude::builtin_cmp_lt,
+    //     };
+    //     self.execute_builtin_native(f, count)
+    // }
+    fn execute_math(&mut self, math: MathInstruction, count: usize) -> Result<(), MachineError> {
+        let function = match math {
+            MathInstruction::Add => prelude::builtin_add,
+            MathInstruction::Sub => prelude::builtin_sub,
+            MathInstruction::Mul => prelude::builtin_mul,
+            MathInstruction::Div => prelude::builtin_div,
+            MathInstruction::Mod => prelude::builtin_mod,
+            MathInstruction::And => prelude::builtin_and,
+            MathInstruction::Or => prelude::builtin_or,
+            MathInstruction::BitwiseAnd => prelude::builtin_bitwise_and,
+            MathInstruction::BitwiseOr => prelude::builtin_bitwise_or,
+            MathInstruction::BitwiseXor => prelude::builtin_bitwise_xor,
+            MathInstruction::Gt => prelude::builtin_cmp_gt,
+            MathInstruction::Lt => prelude::builtin_cmp_lt,
+            MathInstruction::Eq => prelude::builtin_cmp_eq,
+            MathInstruction::Ne => prelude::builtin_cmp_ne,
+            MathInstruction::Ge => prelude::builtin_cmp_ge,
+            MathInstruction::Le => prelude::builtin_cmp_le,
+        };
+        self.execute_builtin_native(function, count)
     }
 
     fn execute_branch(&mut self, offset: usize) -> Result<bool, MachineError> {
@@ -253,10 +273,13 @@ impl Machine {
         let ip = self.ip.as_ref().unwrap();
         let constant = ip.module.constant(index).expect("TODO");
         let value = match constant {
-            ModuleConstant::LocalFunction(address) => Value::BytecodeFunction(BytecodeFunction {
-                module: ip.module.clone(),
-                address,
-            }),
+            ModuleConstant::LocalFunction(address, required_count) => {
+                Value::BytecodeFunction(BytecodeFunction {
+                    module: ip.module.clone(),
+                    required_count,
+                    address,
+                })
+            }
             ModuleConstant::Integer(value) => Value::Integer(value),
             ModuleConstant::Identifier(identifier) => Value::Identifier(identifier),
         };
@@ -281,7 +304,7 @@ impl Machine {
                     .globals
                     .get(&ident)
                     .cloned()
-                    .ok_or_else(|| MachineError::UnboundIdentifier(ident))?;
+                    .ok_or(MachineError::UnboundIdentifier(ident))?;
                 self.push(value)
             }
             _ => todo!(),
@@ -341,11 +364,8 @@ impl Machine {
                 advance = false;
                 self.execute_call(count.into())?;
             }
-            Instruction::Add(count) => {
-                self.execute_add(count.into())?;
-            }
-            Instruction::Sub(count) => {
-                self.execute_sub(count.into())?;
+            Instruction::Math(math, count) => {
+                self.execute_math(math, count.into())?;
             }
             Instruction::Branch(offset) => {
                 advance = self.execute_branch(offset.into())?;
@@ -354,9 +374,6 @@ impl Machine {
                 advance = false;
                 self.execute_jump(offset.into())?;
             }
-            Instruction::Compare(not, cmp, count) => {
-                self.execute_compare(not, cmp, count.into())?;
-            }
         }
         if advance {
             self.ip = Some(InstructionPointer {
diff --git a/src/vm/module.rs b/src/vm/module.rs
index b1c03a8..cf96976 100644
--- a/src/vm/module.rs
+++ b/src/vm/module.rs
@@ -12,7 +12,7 @@ use crate::{
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum ModuleConstant {
     Integer(i64),
-    LocalFunction(usize),
+    LocalFunction(usize, usize),
     Identifier(Rc<str>),
 }
 
@@ -120,15 +120,22 @@ impl Module {
         module.compile_module()
     }
 
-    pub fn dump(&self, highlight: Option<usize>) {
-        for (i, instruction) in self.instructions.iter().enumerate() {
-            if highlight.is_some_and(|a| a == i) {
+    pub fn dump(&self, highlight: Option<usize>, context: usize) {
+        let window = highlight
+            .map(|end| (end + 1).min(self.instructions.len()))
+            .map(|end| end.saturating_sub(context)..end)
+            .unwrap_or(0..self.instructions.len());
+
+        let start = window.start;
+        for (i, instruction) in self.instructions[window].iter().enumerate() {
+            let offset = i + start;
+            if highlight.is_some_and(|a| a == offset) {
                 print!(">");
             } else {
                 print!(" ");
             }
 
-            print!("{i:4}: {instruction:08x}");
+            print!("{offset:4}: {instruction:08x}");
             if let Ok(instruction) = Instruction::try_from(*instruction) {
                 print!(" {instruction:?}");
 
@@ -183,7 +190,7 @@ impl fmt::Display for ModuleConstant {
         match self {
             Self::Integer(value) => fmt::Display::fmt(value, f),
             Self::Identifier(ident) => write!(f, "ident {ident:?}"),
-            Self::LocalFunction(address) => write!(f, "label {address}"),
+            Self::LocalFunction(address, _) => write!(f, "label {address}"),
         }
     }
 }
diff --git a/src/vm/native.rs b/src/vm/native.rs
index eeb5e29..b3771c5 100644
--- a/src/vm/native.rs
+++ b/src/vm/native.rs
@@ -5,10 +5,13 @@ use crate::vm::{
     value::Value,
 };
 
+pub type NativeFunctionImpl =
+    Rc<dyn Fn(&mut Machine, &[Value]) -> Result<Value, MachineError> + 'static>;
+
 #[derive(Clone)]
 pub struct NativeFunction {
     name: Rc<str>,
-    inner: Rc<dyn Fn(&mut Machine, &[Value]) -> Result<Value, MachineError> + 'static>,
+    inner: NativeFunctionImpl,
 }
 
 impl NativeFunction {
diff --git a/src/vm/prelude.rs b/src/vm/prelude.rs
index 16f104d..ce46631 100644
--- a/src/vm/prelude.rs
+++ b/src/vm/prelude.rs
@@ -1,29 +1,289 @@
+use std::{
+    cmp::Ordering,
+    ops::{BitAnd, BitOr, BitXor},
+    slice,
+};
+
 use crate::{
     convert::{AnyFunction, TryFromValue},
+    util::IteratorExt,
     vm::{
         machine::{Machine, MachineError},
         value::Value,
     },
 };
 
+pub(crate) enum CompareOperation {
+    Eq,
+    Ne,
+    Lt,
+    Gt,
+    Le,
+    Ge,
+}
+
+fn builtin_fold_integer<F>(
+    fold: F,
+    mut accumulator: i64,
+    args: &[Value],
+) -> Result<Value, MachineError>
+where
+    F: Fn(i64, i64) -> i64,
+{
+    for arg in args {
+        match arg {
+            &Value::Integer(value) => {
+                accumulator = fold(accumulator, value);
+            }
+            _ => todo!("Math for {arg}"),
+        }
+    }
+    Ok(Value::Integer(accumulator))
+}
+fn builtin_fold_bool<F>(
+    fold: F,
+    mut accumulator: bool,
+    args: &[Value],
+) -> Result<Value, MachineError>
+where
+    F: Fn(bool, bool) -> bool,
+{
+    for arg in args {
+        let arg = bool::try_from_value(arg)?;
+        accumulator = fold(accumulator, arg);
+    }
+    Ok(Value::Boolean(accumulator))
+}
+
+pub(crate) fn builtin_add(_vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_fold_integer(i64::wrapping_add, 0, args)
+}
+pub(crate) fn builtin_sub(_vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    match args {
+        [] => Err(MachineError::InvalidArgument),
+        [x] if let &Value::Integer(x) = x => Ok(Value::Integer(-x)),
+        [x] => todo!("Math for {x}"),
+        [x, rest @ ..] => {
+            let &Value::Integer(x) = x else {
+                todo!("Math for {x}");
+            };
+            let mut accumulator = x;
+            for arg in rest {
+                match arg {
+                    &Value::Integer(arg) => {
+                        accumulator = accumulator.saturating_sub(arg);
+                    }
+                    _ => todo!("Math for {arg}"),
+                }
+            }
+            Ok(Value::Integer(accumulator))
+        }
+    }
+}
+pub(crate) fn builtin_mul(_vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_fold_integer(i64::wrapping_mul, 1, args)
+}
+pub(crate) fn builtin_mod(_vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    let [x, y] = args else {
+        return Err(MachineError::InvalidArgument);
+    };
+    let (&Value::Integer(x), &Value::Integer(y)) = (x, y) else {
+        return Err(MachineError::InvalidArgument);
+    };
+    Ok(Value::Integer(x % y))
+}
+pub(crate) fn builtin_div(_vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    match args {
+        [] => Err(MachineError::InvalidArgument),
+        [x] if let &Value::Integer(_x) = x => todo!("Fractionals"),
+        [x] => todo!("Math for {x}"),
+        [x, rest @ ..] => {
+            let &Value::Integer(x) = x else {
+                todo!("Math for {x}");
+            };
+            let mut accumulator = x;
+            for arg in rest {
+                match arg {
+                    &Value::Integer(arg) => {
+                        accumulator = accumulator.saturating_div(arg);
+                    }
+                    _ => todo!("Math for {arg}"),
+                }
+            }
+            Ok(Value::Integer(accumulator))
+        }
+    }
+}
+
+pub(crate) fn builtin_and(_vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_fold_bool(BitAnd::bitand, true, args)
+}
+pub(crate) fn builtin_or(_vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_fold_bool(BitOr::bitor, false, args)
+}
+pub(crate) fn builtin_bitwise_and(
+    _vm: &mut Machine,
+    args: &[Value],
+) -> Result<Value, MachineError> {
+    builtin_fold_integer(BitAnd::bitand, 1, args)
+}
+pub(crate) fn builtin_bitwise_or(_vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_fold_integer(BitOr::bitor, 0, args)
+}
+pub(crate) fn builtin_bitwise_xor(
+    _vm: &mut Machine,
+    args: &[Value],
+) -> Result<Value, MachineError> {
+    builtin_fold_integer(BitXor::bitxor, 0, args)
+}
+
+pub(crate) fn builtin_cmp(
+    _vm: &mut Machine,
+    args: &[Value],
+    op: CompareOperation,
+) -> Result<Value, MachineError> {
+    fn ordering(a: &Value, b: &Value) -> Ordering {
+        match (a, b) {
+            (Value::Integer(a), Value::Integer(b)) => Ord::cmp(a, b),
+            (Value::Boolean(a), Value::Boolean(b)) => Ord::cmp(a, b),
+            _ => todo!(),
+        }
+    }
+
+    let mut accumulator = true;
+    if !args.is_empty() {
+        for i in 0..args.len() - 1 {
+            let a = &args[i];
+            let b = &args[i + 1];
+            let ord = ordering(a, b);
+
+            let check = match op {
+                CompareOperation::Eq => ord.is_eq(),
+                CompareOperation::Ne => ord.is_ne(),
+                CompareOperation::Lt => ord.is_lt(),
+                CompareOperation::Gt => ord.is_gt(),
+                CompareOperation::Le => ord.is_le(),
+                CompareOperation::Ge => ord.is_ge(),
+            };
+            accumulator &= check;
+        }
+    }
+    Ok(Value::Boolean(accumulator))
+}
+pub(crate) fn builtin_cmp_eq(vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_cmp(vm, args, CompareOperation::Eq)
+}
+pub(crate) fn builtin_cmp_ne(vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_cmp(vm, args, CompareOperation::Ne)
+}
+pub(crate) fn builtin_cmp_gt(vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_cmp(vm, args, CompareOperation::Gt)
+}
+pub(crate) fn builtin_cmp_lt(vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_cmp(vm, args, CompareOperation::Lt)
+}
+pub(crate) fn builtin_cmp_ge(vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_cmp(vm, args, CompareOperation::Ge)
+}
+pub(crate) fn builtin_cmp_le(vm: &mut Machine, args: &[Value]) -> Result<Value, MachineError> {
+    builtin_cmp(vm, args, CompareOperation::Le)
+}
+
 pub fn load(vm: &mut Machine) {
+    // math
+    vm.defun_native("+", builtin_add);
+    vm.defun_native("-", builtin_sub);
+    vm.defun_native("*", builtin_mul);
+    vm.defun_native("%", builtin_mod);
+    vm.defun_native("/", builtin_div);
+
+    vm.defun_native("&&", builtin_and);
+    vm.defun_native("||", builtin_or);
+    vm.defun_native("&", builtin_bitwise_and);
+    vm.defun_native("|", builtin_bitwise_or);
+    vm.defun_native("^", builtin_bitwise_xor);
+
+    vm.defun_native(">", builtin_cmp_gt);
+    vm.defun_native("<", builtin_cmp_lt);
+    vm.defun_native("=", builtin_cmp_eq);
+    vm.defun_native("/=", builtin_cmp_ne);
+    vm.defun_native(">=", builtin_cmp_ge);
+    vm.defun_native("<=", builtin_cmp_le);
+
+    // lists
     vm.defun_native("map", |vm, args| {
         let [f, xs] = args else {
             return Err(MachineError::InvalidArgument);
         };
         let f = AnyFunction::try_from_value(f)?;
         let xs = xs.proper_iter();
-        let out = Value::try_list_or_nil(xs.map(|v| f.invoke(vm, &[v?.clone()])))?;
+        let out = Value::try_list_or_nil(xs.map(|v| f.invoke(vm, slice::from_ref(v?))))?;
         Ok(out)
     });
+    vm.defun_native("filter", |vm, args| {
+        let [f, xs] = args else {
+            return Err(MachineError::InvalidArgument);
+        };
+        let f = AnyFunction::try_from_value(f)?;
+        let xs = xs.proper_iter().map(|x| x.cloned());
+        let out = Value::try_list_or_nil(xs.try_filter(|v| {
+            let result = f.invoke(vm, slice::from_ref(v))?;
+            bool::try_from_value(&result)
+        }))?;
+        Ok(out)
+    });
+    vm.defun_native("list", |_, args| {
+        let out = Value::list_or_nil(args.iter().cloned());
+        Ok(out)
+    });
+
+    // functional
     vm.defun_native("identity", |_, args| {
         let [arg] = args else {
             return Err(MachineError::InvalidArgument);
         };
         Ok(arg.clone())
     });
-    vm.defun_native("list", |_, args| {
-        let out = Value::list_or_nil(args.iter().cloned());
-        Ok(out)
+
+    // eval
+    vm.defun_native("apply", |vm, args| {
+        let [f, xs] = args else {
+            return Err(MachineError::InvalidArgument);
+        };
+        let f = AnyFunction::try_from_value(f)?;
+        let args = xs
+            .proper_iter()
+            .map(|x| x.cloned())
+            .collect::<Result<Vec<_>, _>>()?;
+        f.invoke(vm, &args[..])
+    });
+    vm.defun_native("assert", |vm, args| match args {
+        [] => Err(MachineError::InvalidArgument),
+        [cond] => {
+            let cond = bool::try_from_value(cond)?;
+            if !cond {
+                let ip = vm.ip();
+                if let Some(ip) = ip {
+                    eprintln!("Assertion failed at {ip}:");
+                    eprintln!();
+                    ip.module.dump(Some(ip.address), 8);
+                }
+                panic!("Assertion failed");
+            }
+            Ok(Value::Nil)
+        }
+        _ => todo!(),
+    });
+
+    // io
+    vm.defun_native("print", |_, args| {
+        for (i, arg) in args.iter().enumerate() {
+            if i != 0 {
+                print!(" ");
+            }
+            print!("{arg}");
+        }
+        println!();
+        Ok(Value::Nil)
     });
 }
diff --git a/src/vm/value.rs b/src/vm/value.rs
index 9ff6154..3dbd8a8 100644
--- a/src/vm/value.rs
+++ b/src/vm/value.rs
@@ -5,6 +5,7 @@ use crate::vm::{machine::MachineError, module::ModuleRef, native::NativeFunction
 #[derive(Debug, Clone, PartialEq)]
 pub struct BytecodeFunction {
     pub module: ModuleRef,
+    pub required_count: usize,
     pub address: usize,
 }