added comparisons, builtin functions, while loops

examples/cat.cxpr

@@ -0,0 +1,3 @@
+while true { 
+    print(input());
+}

examples/collatz.cxpr

@@ -0,0 +1,10 @@
+let n = 29;
+while n != 1 {
+    println(n);
+    if n % 2 == 0 {
+        n = n/2;
+    } else {
+        n = 3*n+1;
+    }
+}
+println(n);

examples/fib.cxpr

@@ -0,0 +1,9 @@
+let x = 0;
+let y = 0;
+let z = 1;
+while z < 1000000 {
+    x = y + z;
+    z = y;
+    y = x;
+    println(z);
+}

examples/helloworld.cxpr

@@ -0,0 +1,2 @@
+# Prints the string "Hello, world!" followed by a newline
+println("Hello, world!");

src/bin/main.rs

@@ -1,6 +1,6 @@
-use std::{rc::Rc, cell::RefCell, fs::{File, self}, io::{BufReader, Read}};
+use std::{rc::Rc, cell::RefCell, fs};
 
-use complexpr::{eval::Environment, interpreter::interpret, value::Value};
+use complexpr::{eval::Environment, interpreter::interpret, value::Value, stdlib};
 use rustyline::{self, error::ReadlineError};
 
 const C_RESET: &'static str = "\x1b[0m";
@@ -26,6 +26,7 @@ fn repl() -> Result<(), Box<dyn std::error::Error>> {
     println!("Press {}Ctrl+D{} to exit.", C_BLUE, C_RESET);
     let mut rl = rustyline::Editor::<()>::new()?;
     let env = Rc::new(RefCell::new(Environment::new()));
+    stdlib::load(&mut env.borrow_mut());
     loop {
         let readline = rl.readline(PROMPT);
         match readline {
@@ -33,7 +34,7 @@ fn repl() -> Result<(), Box<dyn std::error::Error>> {
                 let result = interpret(&line, None, Some(env.clone()), true);
                 match result {
                     Ok(Value::Nil) => (),
-                    Ok(value) => println!("{:?}", value),
+                    Ok(value) => println!("{}", value.repr()),
                     Err(e) => println!("{}", e)
                 }
             }

src/eval.rs

@@ -1,17 +1,14 @@
 use std::{collections::HashMap, rc::Rc, cell::RefCell};
 
-use num_complex::Complex64;
-
-use crate::{value::Value, expr::{Stmt, Expr}, token::{TokenType, Token, OpType}, RuntimeError};
-
+use crate::{value::{Value, Complex}, expr::{Stmt, Expr}, token::{TokenType, Token, OpType}, RuntimeError};
 
 #[derive(Debug)]
 pub struct Environment {
     parent: Option<EnvRef>,
-    map: HashMap<Rc<str>, Value>
+    map: HashMap<Rc<str>, Value>,
 }
 
-type EnvRef = Rc<RefCell<Environment>>;
+pub type EnvRef = Rc<RefCell<Environment>>;
 
 impl Environment {
     pub fn new() -> Self {
@@ -27,24 +24,20 @@ impl Environment {
     }
 
     pub fn get(&self, name: &str) -> Result<Value,()> {
-        let x = match self.map.get(name) {
+        match self.map.get(name) {
             Some(v) => Ok(v.clone()),
             None => match self.parent {
                 Some(ref p) => p.borrow().get(name),
                 None => Err(())
             }
-        };
-        println!("get {}: {:?}", name, x);
-        x
+        }
     }
 
     pub fn declare(&mut self, name: Rc<str>, value: Value) {
-        println!("declare {}: {:?}", name, value);
         self.map.insert(name, value);
     }
 
     pub fn set(&mut self, name: Rc<str>, value: Value) -> Result<(),()> {
-        println!("set {}: {:?}", name, value);
         match self.map.contains_key(&name) {
             true => { self.map.insert(name, value); Ok(()) },
             false => match self.parent {
@@ -104,7 +97,15 @@ pub fn eval_stmt(stmt: &Stmt, env: EnvRef) -> Result<(), RuntimeError> {
                 return Err(RuntimeError { message: "Cannot iterate this type".into(), pos: var.pos.clone() })
             };
         },
-        _ => unreachable!()
+        Stmt::While { expr, stmt } => {
+            loop {
+                let cond = eval_expr(expr, env.clone())?;
+                if !cond.truthy() {
+                    break
+                }
+                eval_stmt(&stmt, env.clone())?;
+            }
+        },
     }
     Ok(())
 }
@@ -118,8 +119,26 @@ pub fn eval_expr(expr: &Expr, env: EnvRef) -> Result<Value, RuntimeError> {
                 => eval_assignment(lhs, rhs, op, env),
             Some(OpType::Additive) | Some(OpType::Multiplicative) 
                 => eval_binary(lhs, rhs, op, env),
+            Some(OpType::Comparison)
+                => eval_comp(lhs, rhs, op, env),
             o => todo!("{:?}", o) // TODO other operations
         },
+        Expr::List { items } => {
+            let mut list = Vec::with_capacity(items.len());
+            for item in items {
+                list.push(eval_expr(item, env.clone())?);
+            }
+            Ok(Value::List(Rc::new(list)))
+        },
+        Expr::FuncCall { func, args, pos } => {
+            let func = eval_expr(&func, env.clone())?;
+            let mut arg_values = Vec::with_capacity(args.len());
+            for arg in args {
+                let result = eval_expr(arg, env.clone())?;
+                arg_values.push(result);
+            }
+            func.call(arg_values, pos)
+        }
         e => todo!("{:?}", e) // TODO other expression types
     }
 }
@@ -131,7 +150,7 @@ pub fn eval_literal(token: &Token) -> Value {
         TokenType::False => Value::Bool(false),
         TokenType::Int(n) => Value::Int(*n),
         TokenType::Float(f) => Value::Float(*f),
-        TokenType::ImFloat(f) => Value::Complex(Complex64::new(0.0, *f)),
+        TokenType::ImFloat(f) => Value::Complex(Complex::new(0.0, *f)),
         TokenType::String(s) => Value::String(s.clone()),
         TokenType::Char(c) => Value::Char(*c),
         _ => todo!()
@@ -194,4 +213,33 @@ pub fn eval_binary(lhs: &Box<Expr>, rhs: &Box<Expr>, op: &Token, env: EnvRef) ->
         TokenType::Percent => &l % &r,
         _ => todo!() // TODO other operations
     }.map_err(|e| RuntimeError { message: e, pos: op.pos.clone() })
+}
+
+pub fn eval_comp(lhs: &Box<Expr>, rhs: &Box<Expr>, op: &Token, env: EnvRef) -> Result<Value, RuntimeError> {
+    let l = eval_expr(lhs, env.clone())?;
+    let r = eval_expr(rhs, env)?;
+    let mk_err = || RuntimeError {
+        message: format!("Cannot compare {:?} with {:?}", l, r),
+        pos: op.pos.clone()
+    };
+    match op.ty {
+        TokenType::DoubleEqual => Ok(Value::Bool(l == r)),
+        TokenType::BangEqual => Ok(Value::Bool(l != r)),
+        TokenType::Greater => l.partial_cmp(&r)
+            .ok_or_else(mk_err)
+            .map(|o| Value::from(o.is_gt())),
+        TokenType::Less => l.partial_cmp(&r)
+            .ok_or_else(mk_err)
+            .map(|o| Value::from(o.is_lt())),
+        TokenType::GreaterEqual => l.partial_cmp(&r)
+            .ok_or_else(mk_err)
+            .map(|o| Value::from(o.is_ge())),
+        TokenType::LessEqual => l.partial_cmp(&r)
+            .ok_or_else(mk_err)
+            .map(|o| Value::from(o.is_le())),
+        TokenType::Spaceship => l.partial_cmp(&r)
+            .ok_or_else(mk_err)
+            .map(|o| Value::from(o as i8)),
+        _ => unreachable!()
+    }
 }

src/expr.rs

@@ -1,13 +1,14 @@
 use std::fmt;
 
-use crate::{token::{Token, OpType}};
+use crate::{token::{Token, OpType}, Position};
 
 pub enum Stmt {
     Expr { expr: Expr },
     Let { lhs: Token, rhs: Option<Expr> },
     Block { stmts: Vec<Stmt> },
     If { if_clauses: Vec<(Expr, Stmt)>, else_clause: Option<Box<Stmt>> },
-    For { var: Token, expr: Expr, stmt: Box<Stmt> }
+    For { var: Token, expr: Expr, stmt: Box<Stmt> },
+    While { expr: Expr, stmt: Box<Stmt> },
 }
 
 impl fmt::Debug for Stmt {
@@ -26,18 +27,18 @@ pub enum Expr {
     Ident { value: Token },
     Literal { value: Token },
     List { items: Vec<Expr> },
-    FuncCall { func: Box<Expr>, args: Vec<Expr> }
+    FuncCall { func: Box<Expr>, args: Vec<Expr>, pos: Position }
 }
 
 impl fmt::Debug for Expr {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             Self::Binary { lhs: left, rhs: right, op} => write!(f, "({:?} {:?} {:?})", op, left, right),
-            Self::Unary { arg, op} => write!(f, "({:?} {:?})", op, arg),
-            Self::Ident { value, .. } => write!(f, "(ident {:?})", value),
-            Self::Literal { value, .. } => write!(f, "(lit {:?})", value),
+            Self::Unary { arg, op } => write!(f, "({:?} {:?})", op, arg),
+            Self::Ident { value } => write!(f, "(ident {:?})", value),
+            Self::Literal { value } => write!(f, "(lit {:?})", value),
             Self::List { items } => write!(f, "(list {:?})", items),
-            Self::FuncCall { func, args } => write!(f, "(call {:?} {:?})", func, args),
+            Self::FuncCall { func, args, .. } => write!(f, "(call {:?} {:?})", func, args),
         }
     }
 }

src/interpreter.rs

@@ -1,8 +1,8 @@
 use std::{cell::RefCell, rc::Rc};
 
-use crate::{value::Value, lexer::Lexer, parser::Parser, eval::{Environment, eval_stmt, eval_expr}, expr::Stmt};
+use crate::{value::Value, lexer::Lexer, parser::Parser, eval::{Environment, eval_stmt, eval_expr, EnvRef}, expr::Stmt, stdlib};
 
-pub fn interpret(src: &str, fname: Option<String>, env: Option<Rc<RefCell<Environment>>>, repl: bool) -> Result<Value, Box<dyn std::error::Error>> {
+pub fn interpret(src: &str, fname: Option<String>, env: Option<EnvRef>, repl: bool) -> Result<Value, Box<dyn std::error::Error>> {
     let mut lexer = Lexer::new(src, fname);
     lexer.lex()?;
     let mut parser = Parser::new(lexer.into_tokens(), repl);
@@ -11,8 +11,10 @@ pub fn interpret(src: &str, fname: Option<String>, env: Option<Rc<RefCell<Enviro
     if let Some(env) = env {
         environ = env;
     } else {
-        environ = Rc::new(RefCell::new(Environment::new()))
+        environ = Rc::new(RefCell::new(Environment::new()));
+        stdlib::load(&mut environ.borrow_mut());
     }
+
     let mut result = Value::Nil;
     for stmt in ast {
         if let Stmt::Expr{expr} = stmt {

src/lexer.rs

@@ -29,6 +29,7 @@ impl Lexer {
     }
 
     fn expect(&mut self, chars: &[char]) -> Option<char> {
+        if self.at_end() { return None }
         for c in chars {
             if self.code[self.current] == *c {
                 self.advance(*c == '\n');
@@ -126,7 +127,10 @@ impl Lexer {
                     _ => self.add_token(TokenType::Greater, ">")
                 },
                 '<' => match self.expect(&['=']) {
-                    Some('=') => self.add_token(TokenType::LessEqual, "<="),
+                    Some('=') => match self.expect(&['>']) {
+                        Some('>') => self.add_token(TokenType::Spaceship, "<=>"),
+                        _ => self.add_token(TokenType::LessEqual, "<="),
+                    }
                     _ => self.add_token(TokenType::Less, "<")
                 },
                 '&' => match self.expect(&['&']) {
@@ -176,6 +180,7 @@ impl Lexer {
             if self.at_end() { return Err(self.mk_error("Unexpected EOF in character literal")) }
             // TODO Escapes
         }
+        if self.at_end() { return Err(self.mk_error("Unexpected EOF in character literal")) }
         self.expect(&['\'']).ok_or(self.mk_error("Expected ' to terminate character literal"))?;
         self.add_token(TokenType::Char(c), self.collect_literal());
         Ok(())
@@ -186,6 +191,9 @@ impl Lexer {
         while !self.at_end() && self.peek() != '"' {
             if self.peek() == '\\' {
                 self.advance(false);
+                if self.at_end() { 
+                    return Err(self.mk_error("Unexpected EOF in string literal")) 
+                }
                 // TODO more escape codes! \xHH, \u{HH..} or maybe \uhhhh \Uhhhhhhhh
                 match self.peek() {
                     '0' => s.push('\0'),
@@ -205,7 +213,7 @@ impl Lexer {
             }
         }
         if self.at_end() {
-            return Err(self.mk_error("Unexpected EOF while parsing string"))
+            return Err(self.mk_error("Unexpected EOF in string literal"))
         }
         self.advance(false);
         self.add_token(TokenType::String(Rc::from(s)), self.collect_literal());
@@ -217,7 +225,7 @@ impl Lexer {
         while !self.at_end() && (self.peek().is_numeric() || self.peek() == '.') {
             if self.peek() == '.' {
                 if has_dot {
-                    return Err(self.mk_error("Numeric literals cannot contain two decimal points"))
+                    break;
                 } else {
                     has_dot = true;
                 }

src/lib.rs

@@ -7,6 +7,7 @@ pub mod parser;
 pub mod value;
 pub mod eval;
 pub mod interpreter;
+pub mod stdlib;
 
 #[derive(Clone, Debug)]
 pub struct Position {

src/parser.rs

@@ -70,10 +70,15 @@ impl Parser {
                 self.ifstmt()
             },
             TokenType::For => {
-                // for statement
+                // for loop
                 self.next();
                 self.forstmt()
             },
+            TokenType::While => {
+                // while loop
+                self.next();
+                self.whilestmt()
+            },
             _ => {
                 // fallback to an expression terminated with a semicolon
                 let expr = self.assignment()?;
@@ -177,6 +182,14 @@ impl Parser {
         }
     }
 
+    fn whilestmt(&mut self) -> Result<Stmt, ParserError> {
+        self.err_on_eof()?;
+        let expr = self.assignment()?;
+        self.err_on_eof()?;
+        let stmt = self.statement()?;
+        Ok(Stmt::While{ expr, stmt: Box::new(stmt) })
+    }
+
     fn block(&mut self) -> Result<Stmt, ParserError> {
         let mut stmts = vec![];
         while !self.at_end() && self.peek().ty != TokenType::RBrace {
@@ -200,9 +213,10 @@ impl Parser {
 
     fn commalist(&mut self, terminator: TokenType, parse_item: fn(&mut Parser) -> Result<Expr, ParserError>) -> Result<Vec<Expr>, ParserError> {
         let mut items = vec![];
-        while self.peek().ty != terminator {
+        while !self.at_end() && self.peek().ty != terminator {
             let expr = parse_item(self)?;
             items.push(expr);
+            self.err_on_eof()?;
             if self.peek().ty == TokenType::Comma {
                 self.next();
             } else if self.peek().ty == terminator {
@@ -211,6 +225,7 @@ impl Parser {
                 return Err(self.mk_error(format!("Expected Comma or {:?} after list", terminator)))
             }
         }
+        self.err_on_eof()?;
         self.next();
         Ok(items)
     }
@@ -233,7 +248,11 @@ impl Parser {
     }
 
     fn pipeline(&mut self) -> Result<Expr, ParserError> {
-        self.expr(OpType::Pipeline, Self::additive)
+        self.expr(OpType::Pipeline, Self::comparison)
+    }
+
+    fn comparison(&mut self) -> Result<Expr, ParserError> {
+        self.expr(OpType::Comparison, Self::additive)
     }
 
     fn additive(&mut self) -> Result<Expr, ParserError> {
@@ -272,9 +291,9 @@ impl Parser {
     fn fncall(&mut self) -> Result<Expr, ParserError> {
         let expr = self.expr_base()?;
         if !self.at_end() && self.peek().ty == TokenType::LParen {
-            self.next();
+            let lparen = self.next();
             let args = self.commalist(TokenType::RParen, Self::assignment)?;
-            Ok(Expr::FuncCall { func: Box::new(expr), args })
+            Ok(Expr::FuncCall { func: Box::new(expr), args, pos: lparen.pos.clone() })
         } else {
             Ok(expr)
         }
@@ -298,6 +317,9 @@ impl Parser {
             } else {
                 Ok(expr)
             }
+        } else if next.ty == TokenType::LBrack {
+            let items = self.commalist(TokenType::RBrack, Self::assignment)?;
+            Ok(Expr::List { items })
         } else {
             Err(self.mk_error(format!("Unexpected token: {:?}", next.ty)))
         }

src/stdlib/mod.rs

@@ -0,0 +1,43 @@
+use std::{rc::Rc, io::Write};
+
+use crate::{value::{Value, BuiltinFn}, eval::Environment};
+
+pub fn load(env: &mut Environment) {
+    let mut name: Rc<str>;
+    name = Rc::from("str");
+    env.declare(name.clone(), Value::BuiltinFn(BuiltinFn { func: fn_str, arg_count: 1, name }));
+    name = Rc::from("repr");
+    env.declare(name.clone(), Value::BuiltinFn(BuiltinFn { func: fn_repr, arg_count: 1, name }));
+    name = Rc::from("print");
+    env.declare(name.clone(), Value::BuiltinFn(BuiltinFn { func: fn_print, arg_count: 1, name }));
+    name = Rc::from("println"); 
+    env.declare(name.clone(), Value::BuiltinFn(BuiltinFn { func: fn_println, arg_count: 1, name }));
+    name = Rc::from("input"); 
+    env.declare(name.clone(), Value::BuiltinFn(BuiltinFn { func: fn_input, arg_count: 0, name }));
+}
+
+fn fn_str(args: Vec<Value>) -> Result<Value, String> {
+    Ok(Value::String(args[0].to_string()))
+}
+
+fn fn_repr(args: Vec<Value>) -> Result<Value, String> {
+    Ok(Value::String(args[0].repr()))
+}
+
+fn fn_print(args: Vec<Value>) -> Result<Value, String> {
+    print!("{}", args[0].to_string());
+    std::io::stdout().flush().map_err(|e| e.to_string())?;
+    Ok(Value::Nil)
+}
+
+fn fn_println(args: Vec<Value>) -> Result<Value, String> {
+    println!("{}", args[0].to_string());
+    Ok(Value::Nil)
+}
+
+fn fn_input(_: Vec<Value>) -> Result<Value, String> {
+    let mut buffer = String::new();
+    let stdin = std::io::stdin();
+    stdin.read_line(&mut buffer).map_err(|e| e.to_string())?;
+    Ok(Value::from(buffer))
+}

src/token.rs

@@ -25,7 +25,7 @@ pub enum TokenType {
     Bang, Amper, Pipe, DoubleAmper, DoublePipe,
 
     Equal, PlusEqual, MinusEqual, StarEqual, SlashEqual, PercentEqual, DoubleSlashEqual, CaretEqual,
-    DoubleEqual, BangEqual, Greater, GreaterEqual, Less, LessEqual,
+    DoubleEqual, BangEqual, Greater, GreaterEqual, Less, LessEqual, Spaceship,
 
     Arrow, PipeColon, PipePoint, PipeQuestion, PipeAmper,
 
@@ -49,6 +49,9 @@ impl TokenType {
             Self::PipeColon | Self::PipeAmper | Self::PipePoint 
             | Self::PipeQuestion => Some(OpType::Pipeline),
 
+            Self::Greater | Self::GreaterEqual | Self::Less | Self::LessEqual
+            | Self::DoubleEqual | Self::BangEqual | Self::Spaceship => Some(OpType::Comparison),
+
             Self::Equal | Self::PlusEqual | Self::MinusEqual
             | Self::StarEqual | Self::SlashEqual | Self::DoubleSlashEqual
             | Self::CaretEqual | Self::PercentEqual => Some(OpType::Assignment),
@@ -60,7 +63,7 @@ impl TokenType {
 
 #[derive(Clone,Copy,Debug,PartialEq)]
 pub enum OpType {
-    Assignment, Pipeline, Additive, Multiplicative, Exponential
+    Assignment, Comparison, Pipeline, Additive, Multiplicative, Exponential
 }
 
 impl OpType {

src/value.rs

@@ -1,62 +1,49 @@
-use std::{rc::Rc, collections::HashMap, ops::*, ascii::AsciiExt};
+use std::{rc::Rc, collections::HashMap, ops::*, fmt, cmp::Ordering};
 
-use num_traits::Zero;
+use num_traits::{Zero, ToPrimitive};
 
-type Rational = num_rational::Ratio<i64>;
-type Complex = num_complex::Complex64;
+use crate::{RuntimeError, Position};
 
-macro_rules! value_from {
-    ($variant:ident, $($kind:ty)*) => {
-        $(
-            impl From<$kind> for Value {
-                fn from(x: $kind) -> Self {
-                    Self::$variant(x.into())
-                }
-            }
-        )*
-    };
+pub type Rational = num_rational::Ratio<i64>;
+pub type Complex = num_complex::Complex64;
+
+#[derive(Clone)]
+pub struct BuiltinFn {
+    pub name: Rc<str>,
+    pub func: fn(Vec<Value>) -> Result<Value, String>,
+    pub arg_count: usize
 }
 
-macro_rules! impl_numeric_op {
-    ($optrait:ty, $fnname:ident, { $($bonus:tt)* }) => {
-        impl $optrait for &Value {
-            type Output = Result<Value, String>;
-            fn $fnname(self, other: Self) -> Self::Output {
-                use Value::*;
-                use num_traits::ToPrimitive;
-                const RATIO_CAST_FAIL: &'static str = "Failed to cast Rational to Float";
-                match (self, other) {
-                    (Int(a),      Int(b))      => Ok(a.$fnname(b).into()),
-                    (Rational(a), Int(b))      => Ok(a.$fnname(b).into()),
-                    (Int(a),      Rational(b)) => Ok(self::Rational::from(*a).$fnname(b).into()),
-                    (Float(a),    Int(b))      => Ok(a.$fnname(*b as f64).into()),
-                    (Int(a),      Float(b))    => Ok((*a as f64).$fnname(b).into()),
-                    (Float(a),    Rational(b)) => Ok(a.$fnname(b.to_f64().ok_or(RATIO_CAST_FAIL)?).into()),
-                    (Rational(a), Float(b))    => Ok(a.to_f64().ok_or(RATIO_CAST_FAIL)?.$fnname(b).into()),
-                    (Float(a),    Float(b))    => Ok(a.$fnname(b).into()),
-                    (Int(a),      Complex(b))  => Ok(self::Complex::from(*a as f64).$fnname(b).into()),
-                    (Complex(a),  Int(b))      => Ok(a.$fnname(self::Complex::from(*b as f64)).into()),
-                    (Float(a),    Complex(b))  => Ok(self::Complex::from(a).$fnname(b).into()),
-                    (Complex(a),  Float(b))    => Ok(a.$fnname(self::Complex::from(b)).into()),
-                    (Rational(a), Complex(b))  => Ok(self::Complex::from(a.to_f64().ok_or(RATIO_CAST_FAIL)?).$fnname(b).into()),
-                    (Complex(a),  Rational(b)) => Ok(a.$fnname(self::Complex::from(b.to_f64().ok_or(RATIO_CAST_FAIL)?)).into()),
-                    (Complex(a),  Complex(b))  => Ok(a.$fnname(b).into()),
-                    $($bonus)*
-                    (lhs, rhs) => Err(format!("Unsupported operation '{}' between {:?} and {:?}", stringify!($fnname), lhs, rhs))
-                }
-            }
-        }
+impl fmt::Debug for BuiltinFn {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("BuiltinFn").field("name", &self.name).field("arg_count", &self.arg_count).finish()
     }
 }
 
 #[derive(Clone, Debug)]
+pub struct Data {
+    pub ty: usize,
+    // TODO user-defined data types
+}
+
+#[derive(Clone, Debug)]
+pub struct Type {
+    pub name: Rc<str>,
+    pub id: usize
+}
+
+#[derive(Clone, Debug)]
+#[repr(u8)]
 pub enum Value {
     Nil,
+    Type(usize),
     Int(i64), Float(f64), Complex(Complex), Rational(Rational),
     Bool(bool), 
     Char(char),
     String(Rc<str>), 
     List(Rc<Vec<Value>>), Map(Rc<HashMap<Value,Value>>),
+    BuiltinFn(BuiltinFn),
+    Data(Data),
 }
 
 impl Value {
@@ -83,8 +70,170 @@ impl Value {
             _ => Err(())
         }
     }
+
+    pub fn call(&self, args: Vec<Value>, pos: &Position) -> Result<Value, RuntimeError> {
+        match self {
+            Value::BuiltinFn(f) => {
+                if args.len() == f.arg_count {
+                    (f.func)(args).map_err(|e| RuntimeError { message: e, pos: pos.clone() })
+                } else if args.len() < f.arg_count {
+                    Err(RuntimeError { 
+                        message: format!("Not enough arguments for function: expected {}, got {}", f.arg_count, args.len()), 
+                        pos: pos.clone() 
+                    })
+                } else {
+                    Err(RuntimeError { 
+                        message: format!("Too many arguments for function: expected {}, got {}", f.arg_count, args.len()), 
+                        pos: pos.clone() 
+                    })
+                }
+            }
+            _ => Err(RuntimeError { message: "Cannot call".into(), pos: pos.clone() })
+        }
+    }
+
+    pub fn to_string(&self) -> Rc<str> {
+        match self {
+            Self::Nil => Rc::from("nil"),
+            Self::Bool(b) => Rc::from(b.to_string()),
+            Self::Int(n) => Rc::from(n.to_string()),
+            Self::Float(f) => Rc::from(f.to_string()),
+            Self::Rational(r) => Rc::from(r.to_string()),
+            Self::Complex(z) => Rc::from(z.to_string()),
+            Self::Char(c) => Rc::from(c.to_string()),
+            Self::String(s) => s.clone(),
+            Self::List(l) => Rc::from(format!("{:?}", l)), // TODO fix
+            Self::Map(m) => Rc::from(format!("{:?}", m)), // TODO fix
+            Self::Type(_) => todo!(),
+            Self::BuiltinFn(bf) => Rc::from(format!("<builtin fn {} at {:?}>", bf.name, bf.func as *const ())),
+            Self::Data(_) => todo!(),
+        }
+    }
+    
+    pub fn repr(&self) -> Rc<str> {
+        match self {
+            Self::Nil => Rc::from("nil"),
+            Self::Bool(b) => Rc::from(b.to_string()),
+            Self::Int(n) => Rc::from(n.to_string()),
+            Self::Float(f) => Rc::from(f.to_string()),
+            Self::Rational(r) => Rc::from(r.to_string()),
+            Self::Complex(z) => Rc::from(z.to_string()),
+            Self::Char(c) => Rc::from(format!("'{}'", c)), // TODO escaping
+            Self::String(s) => Rc::from(format!("\"{}\"", s)), // TODO escaping
+            Self::List(l) => Rc::from(format!("{:?}", l)), // TODO fix
+            Self::Map(m) => Rc::from(format!("{:?}", m)), // TODO fix
+            Self::Type(_) => todo!(),
+            Self::BuiltinFn(bf) => Rc::from(format!("<builtin fn {} at {:?}>", bf.name, bf.func as *const ())),
+            Self::Data(_) => todo!(),
+        }
+    }
 }
 
+impl PartialEq for Value {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Self::Nil, Self::Nil)                 => true,
+            (Self::Type(a), Self::Type(b))         => a == b,
+
+            (Self::Int(a), Self::Int(b))           => a == b,
+            (Self::Rational(a), Self::Int(b))      => *a == Rational::from(*b),
+            (Self::Int(a), Self::Rational(b))      => Rational::from(*a) == *b,
+            (Self::Rational(a), Self::Rational(b)) => a == b,
+            (Self::Float(a), Self::Int(b))         => *a == *b as f64,
+            (Self::Int(a), Self::Float(b))         => *a as f64 == *b,
+            (Self::Float(a), Self::Rational(b))    => *a == b.to_f64().unwrap(),
+            (Self::Rational(a), Self::Float(b))    => a.to_f64().unwrap() == *b,
+            (Self::Float(a), Self::Float(b))       => a == b,
+
+            (Self::Complex(a), Self::Int(b))       => *a == Complex::from(*b as f64),
+            (Self::Int(a), Self::Complex(b))       => Complex::from(*a as f64) == *b,
+            (Self::Complex(a), Self::Rational(b))  => *a == Complex::from(b.to_f64().unwrap()),
+            (Self::Rational(a), Self::Complex(b))  => Complex::from(a.to_f64().unwrap()) == *b,
+            (Self::Complex(a), Self::Float(b))     => *a == Complex::from(*b),
+            (Self::Float(a), Self::Complex(b))     => Complex::from(*a) == *b,
+            (Self::Complex(a), Self::Complex(b))   => a == b,
+
+            (Self::Bool(a), Self::Bool(b)) => a == b,
+            (Self::Char(a), Self::Char(b)) => a == b,
+            (Self::String(a), Self::String(b)) => a == b,
+            (Self::List(a), Self::List(b)) => a == b,
+            (Self::Map(_), Self::Map(_)) => todo!("Can't test maps for equality yet"),
+            (Self::BuiltinFn(a), Self::BuiltinFn(b)) 
+                => (a.func as *const ()) == (b.func as *const ()) && a.arg_count == b.arg_count,
+            (Self::Data(_), Self::Data(_)) => todo!("Can't compare data yet"),
+            _ => false
+        }
+    }
+}
+
+impl PartialOrd for Value {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        if self == other {
+            return Some(Ordering::Equal)
+        }
+        match (self, other) {
+            (Self::Int(a), Self::Int(b)) => a.partial_cmp(b),
+            (Self::Int(a), Self::Float(b)) => (*a as f64).partial_cmp(b),
+            (Self::Float(a), Self::Int(b)) => a.partial_cmp(&(*b as f64)),
+            (Self::Float(a), Self::Float(b)) => a.partial_cmp(b),
+            (Self::Int(a), Self::Rational(b)) => Rational::from(*a).partial_cmp(b),
+            (Self::Rational(a), Self::Int(b)) => a.partial_cmp(&Rational::from(*b)),
+            (Self::Float(a), Self::Rational(b)) => a.partial_cmp(&b.to_f64().unwrap()),
+            (Self::Rational(a), Self::Float(b)) => a.to_f64().unwrap().partial_cmp(b),
+            (Self::Rational(a), Self::Rational(b)) => a.partial_cmp(b),
+
+            (Self::Char(a), Self::Char(b)) => a.partial_cmp(b),
+            (Self::String(a), Self::String(b)) => a.partial_cmp(b),
+            (Self::List(a), Self::List(b)) => a.partial_cmp(b),
+            _ => None
+        }
+    }
+}
+
+macro_rules! value_from {
+    ($variant:ident, $($kind:ty)*) => {
+        $(
+            impl From<$kind> for Value {
+                fn from(x: $kind) -> Self {
+                    Self::$variant(x.into())
+                }
+            }
+        )*
+    };
+}
+
+macro_rules! impl_numeric_op {
+    ($optrait:ty, $fnname:ident, { $($bonus:tt)* }) => {
+        impl $optrait for &Value {
+            type Output = Result<Value, String>;
+            fn $fnname(self, other: Self) -> Self::Output {
+                use Value::*;
+                use num_traits::ToPrimitive;
+                const RATIO_CAST_FAIL: &'static str = "Failed to cast Rational to Float";
+                match (self, other) {
+                    (Int(a),      Int(b))      => Ok(a.$fnname(b).into()),
+                    (Rational(a), Int(b))      => Ok(a.$fnname(b).into()),
+                    (Int(a),      Rational(b)) => Ok(self::Rational::from(*a).$fnname(b).into()),
+                    (Rational(a), Rational(b)) => Ok(a.$fnname(b).into()),
+                    (Float(a),    Int(b))      => Ok(a.$fnname(*b as f64).into()),
+                    (Int(a),      Float(b))    => Ok((*a as f64).$fnname(b).into()),
+                    (Float(a),    Rational(b)) => Ok(a.$fnname(b.to_f64().ok_or(RATIO_CAST_FAIL)?).into()),
+                    (Rational(a), Float(b))    => Ok(a.to_f64().ok_or(RATIO_CAST_FAIL)?.$fnname(b).into()),
+                    (Float(a),    Float(b))    => Ok(a.$fnname(b).into()),
+                    (Int(a),      Complex(b))  => Ok(self::Complex::from(*a as f64).$fnname(b).into()),
+                    (Complex(a),  Int(b))      => Ok(a.$fnname(self::Complex::from(*b as f64)).into()),
+                    (Float(a),    Complex(b))  => Ok(self::Complex::from(a).$fnname(b).into()),
+                    (Complex(a),  Float(b))    => Ok(a.$fnname(self::Complex::from(b)).into()),
+                    (Rational(a), Complex(b))  => Ok(self::Complex::from(a.to_f64().ok_or(RATIO_CAST_FAIL)?).$fnname(b).into()),
+                    (Complex(a),  Rational(b)) => Ok(a.$fnname(self::Complex::from(b.to_f64().ok_or(RATIO_CAST_FAIL)?)).into()),
+                    (Complex(a),  Complex(b))  => Ok(a.$fnname(b).into()),
+                    $($bonus)*
+                    (lhs, rhs) => Err(format!("Unsupported operation '{}' between {:?} and {:?}", stringify!($fnname), lhs, rhs))
+                }
+            }
+        }
+    }
+}
 
 value_from!(Int, u8 u16 u32 i8 i16 i32 i64);
 value_from!(Float, f32 f64);

tests/code.cxpr

@@ -1,4 +0,0 @@
-
-for c: "asdfghjkl" {
-    let b = 'q' + c;
-}

tests/test.rs

@@ -1,19 +0,0 @@
-#![cfg(test)]
-
-use std::{cell::RefCell, rc::Rc};
-
-use complexpr::{lexer::Lexer, parser::Parser, eval::{Environment, eval_stmt}};
-
-#[test]
-pub fn test() {
-    let mut lexer = Lexer::new("let a = 1 + 1; let b = a + 1;", None);
-    lexer.lex().unwrap();
-    let mut parser = Parser::new(lexer.into_tokens(), false);
-    let ast = parser.parse().unwrap();
-    let env = Rc::new(RefCell::new(Environment::new()));
-    for stmt in ast {
-        eval_stmt(&stmt, env.clone()).unwrap();
-    }
-    println!("{:?}", env);
-    todo!("end of tests")
-}