Release 0.2

Reviewed-on: https://git.ablecorp.us:443/AbleScript/able-script/pulls/1

able-script-test/by-arity-chain.able

@@ -0,0 +1,44 @@
+functio arity_0() {
+   "this function has arity 0" print;
+}
+
+functio arity_1(arg1) {
+   "this function has arity 1" print;
+   arg1 print;
+}
+
+functio arity_2(arg1, arg2) {
+   "this function has arity 2" print;
+   arg1 print;
+   arg2 print;
+}
+
+functio arity_3(arg1, arg2, arg3) {
+   "this function has arity 3" print;
+   arg1 print;
+   arg2 print;
+   arg3 print;
+}
+
+owo arity_0();
+owo arity_1("foo");
+owo arity_2("foo", "bar");
+owo arity_3("foo", "bar", "baz");
+
+var i1 = arity_0 * arity_1;
+i1("second");
+
+"----" print;
+
+var i2 = arity_1 * arity_0;
+i2("first");
+
+"----" print;
+
+var ifancy = arity_3 * arity_3;
+ifancy("left1", "right1", "left2", "right2", "left3", "right3");
+
+"----" print;
+
+var another = arity_0 * arity_3;
+another("right1", "right2", "right3");

able-script-test/carts.able

@@ -1,5 +1,5 @@
 functio helloable() {
-    "Hello, Able!" print;
+   "Hello, Able!" print;
 }
 
 var cart = ["able" <= 42, helloable <= "hello"];

ablescript/src/ast.rs

@@ -15,26 +15,71 @@ use crate::variables::Value;
 type Span = std::ops::Range<usize>;
 
 #[derive(Debug, Clone)]
-pub struct Iden {
+pub struct Ident {
-    pub iden: String,
+    pub ident: String,
     pub span: Span,
 }
 
-impl Iden {
+impl Ident {
-    pub fn new(iden: String, span: Span) -> Self {
+    pub fn new(ident: String, span: Span) -> Self {
-        Self { iden, span }
+        Self { ident, span }
     }
 }
 
-impl PartialEq for Iden {
+impl PartialEq for Ident {
     fn eq(&self, other: &Self) -> bool {
-        self.iden == other.iden
+        self.ident == other.ident
     }
 }
 
-impl Hash for Iden {
+impl Hash for Ident {
     fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
-        self.iden.hash(state)
+        self.ident.hash(state)
+    }
+}
+
+#[derive(Debug, PartialEq, Clone, Hash)]
+pub struct Assignable {
+    pub ident: Ident,
+    pub kind: AssignableKind,
+}
+
+#[derive(Debug, PartialEq, Clone, Hash)]
+pub enum AssignableKind {
+    Variable,
+    Index { indices: Vec<Expr> },
+}
+
+impl Assignable {
+    pub fn from_expr(expr: Expr) -> Result<Assignable, ()> {
+        match expr.kind {
+            ExprKind::Variable(ident) => Ok(Assignable {
+                ident: Ident::new(ident, expr.span),
+                kind: AssignableKind::Variable,
+            }),
+            ExprKind::Index { expr, index } => Self::from_index(*expr, *index),
+            _ => Err(()),
+        }
+    }
+
+    fn from_index(mut buf: Expr, index: Expr) -> Result<Assignable, ()> {
+        let mut indices = vec![index];
+        let ident = loop {
+            match buf.kind {
+                ExprKind::Variable(ident) => break ident,
+                ExprKind::Index { expr, index } => {
+                    indices.push(*index);
+                    buf = *expr;
+                }
+                _ => return Err(()),
+            }
+        };
+
+        indices.reverse();
+        Ok(Assignable {
+            ident: Ident::new(ident, buf.span),
+            kind: AssignableKind::Index { indices },
+        })
     }
 }
 
@@ -76,21 +121,21 @@ pub enum StmtKind {
     HopBack,
 
     Var {
-        iden: Iden,
+        ident: Ident,
         init: Option<Expr>,
     },
     Assign {
-        iden: Iden,
+        assignable: Assignable,
         value: Expr,
     },
 
     Functio {
-        iden: Iden,
+        ident: Ident,
-        params: Vec<Iden>,
+        params: Vec<Ident>,
         body: Block,
     },
     BfFunctio {
-        iden: Iden,
+        ident: Ident,
         tape_len: Option<Expr>,
         code: Vec<u8>,
     },
@@ -99,8 +144,8 @@ pub enum StmtKind {
         args: Vec<Expr>,
     },
     Print(Expr),
-    Read(Iden),
+    Read(Assignable),
-    Melo(Iden),
+    Melo(Ident),
     Rlyeh,
     Rickroll,
 }
@@ -142,7 +187,7 @@ pub enum ExprKind {
     Literal(Value),
     Cart(Vec<(Expr, Expr)>),
     Index {
-        cart: Box<Expr>,
+        expr: Box<Expr>,
         index: Box<Expr>,
     },
     Variable(String),
@@ -164,8 +209,6 @@ pub enum BinOpKind {
     Less,
     Equal,
     NotEqual,
-    And,
-    Or,
 }
 
 impl BinOpKind {
@@ -181,8 +224,6 @@ impl BinOpKind {
             Token::LessThan => Ok(Self::Less),
             Token::EqualEqual => Ok(Self::Equal),
             Token::NotEqual => Ok(Self::NotEqual),
-            Token::And => Ok(Self::And),
-            Token::Or => Ok(Self::Or),
             t => Err(crate::error::ErrorKind::UnexpectedToken(t)),
         }
     }

ablescript/src/base_55.rs

@@ -60,68 +60,6 @@ pub fn char2num(character: char) -> i32 {
         _ => 0,
     }
 }
-pub fn num2char(number: i32) -> char {
-    match number {
-        -26 => 'Z',
-        -25 => 'Y',
-        -24 => 'X',
-        -23 => 'W',
-        -22 => 'V',
-        -210 => 'U',
-        -20 => 'T',
-        -18 => 'R',
-        -19 => 'S',
-        -17 => 'Q',
-        -16 => 'P',
-        -15 => 'O',
-        -14 => 'N',
-        -13 => 'M',
-        -12 => 'L',
-        -11 => 'K',
-        -10 => 'J',
-        -9 => 'I',
-        -8 => 'H',
-        -7 => 'G',
-        -6 => 'F',
-        -5 => 'E',
-        -4 => 'D',
-        -3 => 'C',
-        -2 => 'B',
-        -1 => 'A',
-        0 => ' ',
-        1 => 'a',
-        2 => 'b',
-        3 => 'c',
-        4 => 'd',
-        5 => 'e',
-        6 => 'f',
-        7 => 'g',
-        8 => 'h',
-        9 => 'i',
-        10 => 'j',
-        11 => 'k',
-        12 => 'l',
-        13 => 'm',
-        14 => 'n',
-        15 => 'o',
-        16 => 'p',
-        17 => 'q',
-        18 => 'r',
-        19 => 's',
-        20 => 't',
-        21 => 'u',
-        22 => 'v',
-        23 => 'w',
-        24 => 'x',
-        25 => 'y',
-        26 => 'z',
-        //         NOTE(Able): Why does it jump to 53 here? MY REASONS ARE BEYOND YOUR UNDERSTANDING MORTAL
-        53 => '/',
-        54 => '\\',
-        55 => '.',
-        _ => ' ',
-    }
-}
 
 #[cfg(test)]
 mod tests {

ablescript/src/brian.rs

@@ -17,6 +17,8 @@
 //! [`interpret_with_output`]: Interpreter::interpret_with_output
 
 #![deny(missing_docs)]
+// Putting this here because we still don't use the entire capabilities of this module. ~~Alex
+#![allow(dead_code)]
 
 use std::{
     collections::VecDeque,
@@ -30,6 +32,8 @@ use std::{
 /// The default limit for the tape size. This is the value used by methods that don't take it as a parameter
 pub const DEFAULT_TAPE_SIZE_LIMIT: usize = 30_000;
 
+/// Mappings from integers to BF instructions
+pub const INSTRUCTION_MAPPINGS: &[u8] = b"[]+-,.<>";
 #[derive(Debug, Clone, PartialEq, Eq)]
 /// A brainfuck interpreter. Read the [module level documentation](self) for more
 pub struct Interpreter<'a, I> {

ablescript/src/interpret.rs

@@ -9,8 +9,10 @@
 #![deny(missing_docs)]
 use std::{
     cell::RefCell,
+    cmp::Ordering,
     collections::{HashMap, VecDeque},
     io::{stdin, stdout, Read, Write},
+    mem::take,
     ops::Range,
     process::exit,
     rc::Rc,
@@ -19,9 +21,9 @@ use std::{
 use rand::random;
 
 use crate::{
-    ast::{Expr, ExprKind, Iden, Stmt, StmtKind},
+    ast::{Assignable, AssignableKind, Expr, ExprKind, Ident, Stmt, StmtKind},
     base_55,
-    consts::{self, ablescript_consts},
+    consts::ablescript_consts,
     error::{Error, ErrorKind},
     variables::{Functio, Value, Variable},
 };
@@ -134,66 +136,23 @@ impl ExecEnv {
     fn eval_expr(&self, expr: &Expr) -> Result<Value, Error> {
         use crate::ast::BinOpKind::*;
         use crate::ast::ExprKind::*;
-        use Value::*;
 
         Ok(match &expr.kind {
             BinOp { lhs, rhs, kind } => {
                 let lhs = self.eval_expr(lhs)?;
                 let rhs = self.eval_expr(rhs)?;
                 match kind {
-                    // Arithmetic operators.
+                    Add => lhs + rhs,
-                    Add | Subtract | Multiply | Divide => {
+                    Subtract => lhs - rhs,
-                        let lhs = lhs.to_i32();
+                    Multiply => lhs * rhs,
-                        let rhs = rhs.to_i32();
+                    Divide => lhs / rhs,
-
+                    Greater => Value::Bool(lhs > rhs),
-                        let res = match kind {
+                    Less => Value::Bool(lhs < rhs),
-                            Add => lhs.checked_add(rhs),
+                    Equal => Value::Bool(lhs == rhs),
-                            Subtract => lhs.checked_sub(rhs),
+                    NotEqual => Value::Bool(lhs != rhs),
-                            Multiply => lhs.checked_mul(rhs),
-                            Divide => lhs.checked_div(rhs),
-                            _ => unreachable!(),
-                        }
-                        .unwrap_or(consts::ANSWER);
-                        Int(res)
-                    }
-
-                    // Numeric comparisons.
-                    Less | Greater => {
-                        let lhs = lhs.to_i32();
-                        let rhs = rhs.to_i32();
-
-                        let res = match kind {
-                            Less => lhs < rhs,
-                            Greater => lhs > rhs,
-                            _ => unreachable!(),
-                        };
-                        Bool(res)
-                    }
-
-                    // General comparisons.
-                    Equal | NotEqual => {
-                        let res = match kind {
-                            Equal => lhs == rhs,
-                            NotEqual => lhs != rhs,
-                            _ => unreachable!(),
-                        };
-                        Bool(res)
-                    }
-
-                    // Logical connectives.
-                    And | Or => {
-                        let lhs = lhs.to_bool();
-                        let rhs = rhs.to_bool();
-                        let res = match kind {
-                            And => lhs && rhs,
-                            Or => lhs || rhs,
-                            _ => unreachable!(),
-                        };
-                        Bool(res)
-                    }
                 }
             }
-            Not(expr) => Bool(!self.eval_expr(expr)?.to_bool()),
+            Not(expr) => !self.eval_expr(expr)?,
             Literal(value) => value.clone(),
             ExprKind::Cart(members) => Value::Cart(
                 members
@@ -206,18 +165,21 @@ impl ExecEnv {
                     })
                     .collect::<Result<HashMap<_, _>, _>>()?,
             ),
-            Index { cart, index } => {
+            Index { expr, index } => {
-                let cart = self.eval_expr(cart)?;
+                let value = self.eval_expr(expr)?;
                 let index = self.eval_expr(index)?;
 
-                // TODO: this probably shouldn't be cloned
+                value
-                cart.index(&index).borrow().clone()
+                    .into_cart()
+                    .get(&index)
+                    .map(|x| x.borrow().clone())
+                    .unwrap_or(Value::Nul)
             }
 
             // TODO: not too happy with constructing an artificial
-            // Iden here.
+            // Ident here.
-            Variable(name) => self.get_var(&Iden {
+            Variable(name) => self.get_var(&Ident {
-                iden: name.to_owned(),
+                ident: name.to_owned(),
                 span: expr.span.clone(),
             })?,
         })
@@ -229,52 +191,52 @@ impl ExecEnv {
             StmtKind::Print(expr) => {
                 println!("{}", self.eval_expr(expr)?);
             }
-            StmtKind::Var { iden, init } => {
+            StmtKind::Var { ident, init } => {
                 let init = match init {
                     Some(e) => self.eval_expr(e)?,
                     None => Value::Nul,
                 };
 
-                self.decl_var(&iden.iden, init);
+                self.decl_var(&ident.ident, init);
             }
-            StmtKind::Functio { iden, params, body } => {
+            StmtKind::Functio {
+                ident,
+                params,
+                body,
+            } => {
                 self.decl_var(
-                    &iden.iden,
+                    &ident.ident,
-                    Value::Functio(Functio::AbleFunctio {
+                    Value::Functio(Functio::Able {
-                        params: params.iter().map(|iden| iden.iden.to_string()).collect(),
+                        params: params.iter().map(|ident| ident.ident.to_owned()).collect(),
                         body: body.block.to_owned(),
                     }),
                 );
             }
             StmtKind::BfFunctio {
-                iden,
+                ident,
                 tape_len,
                 code,
             } => {
                 self.decl_var(
-                    &iden.iden,
+                    &ident.ident,
-                    Value::Functio(Functio::BfFunctio {
+                    Value::Functio(Functio::Bf {
                         instructions: code.to_owned(),
                         tape_len: tape_len
                             .as_ref()
-                            .map(|tape_len| self.eval_expr(tape_len).map(|v| v.to_i32() as usize))
+                            .map(|tape_len| self.eval_expr(tape_len).map(|v| v.into_i32() as usize))
                             .unwrap_or(Ok(crate::brian::DEFAULT_TAPE_SIZE_LIMIT))?,
                     }),
                 );
             }
             StmtKind::If { cond, body } => {
-                if self.eval_expr(cond)?.to_bool() {
+                if self.eval_expr(cond)?.into_bool() {
                     return self.eval_stmts_hs(&body.block, true);
                 }
             }
             StmtKind::Call { expr, args } => {
-                let func = self.eval_expr(expr)?;
+                let func = self.eval_expr(expr)?.into_functio();
 
-                if let Value::Functio(func) = func {
+                self.fn_call(func, args, &stmt.span)?;
-                    self.fn_call(func, args, &stmt.span)?;
-                } else {
-                    // Fail silently for now.
-                }
             }
             StmtKind::Loop { body } => loop {
                 let res = self.eval_stmts_hs(&body.block, true)?;
@@ -284,9 +246,8 @@ impl ExecEnv {
                     HaltStatus::Hopback(_) => continue,
                 }
             },
-            StmtKind::Assign { iden, value } => {
+            StmtKind::Assign { assignable, value } => {
-                let value = self.eval_expr(value)?;
+                self.assign(assignable, self.eval_expr(value)?)?;
-                self.get_var_mut(iden)?.value.replace(value);
             }
             StmtKind::Break => {
                 return Ok(HaltStatus::Break(stmt.span.clone()));
@@ -294,8 +255,8 @@ impl ExecEnv {
             StmtKind::HopBack => {
                 return Ok(HaltStatus::Hopback(stmt.span.clone()));
             }
-            StmtKind::Melo(iden) => {
+            StmtKind::Melo(ident) => {
-                self.get_var_mut(iden)?.melo = true;
+                self.get_var_mut(ident)?.melo = true;
             }
             StmtKind::Rlyeh => {
                 // Maybe print a creepy error message or something
@@ -307,20 +268,69 @@ impl ExecEnv {
                     .write_all(include_str!("rickroll").as_bytes())
                     .expect("Failed to write to stdout");
             }
-            StmtKind::Read(iden) => {
+            StmtKind::Read(assignable) => {
                 let mut value = 0;
                 for _ in 0..READ_BITS {
                     value <<= 1;
                     value += self.get_bit()? as i32;
                 }
 
-                self.get_var_mut(iden)?.value.replace(Value::Int(value));
+                self.assign(assignable, Value::Int(value))?;
             }
         }
 
         Ok(HaltStatus::Finished)
     }
 
+    /// Assign a value to an Assignable.
+    fn assign(&mut self, dest: &Assignable, value: Value) -> Result<(), Error> {
+        match dest.kind {
+            AssignableKind::Variable => {
+                self.get_var_mut(&dest.ident)?.value.replace(value);
+            }
+            AssignableKind::Index { ref indices } => {
+                let mut cell = self.get_var_rc(&dest.ident)?;
+                for index in indices {
+                    let index = self.eval_expr(index)?;
+
+                    let next_cell = match &mut *cell.borrow_mut() {
+                        Value::Cart(c) => {
+                            // cell is a cart, so we can do simple
+                            // indexing.
+                            if let Some(x) = c.get(&index) {
+                                // cell[index] exists, get a shared
+                                // reference to it.
+                                Rc::clone(x)
+                            } else {
+                                // cell[index] does not exist, so we
+                                // insert an empty cart by default
+                                // instead.
+                                let next_cell =
+                                    Rc::new(RefCell::new(Value::Cart(Default::default())));
+                                c.insert(index, Rc::clone(&next_cell));
+                                next_cell
+                            }
+                        }
+                        x => {
+                            // cell is not a cart; `take` it, convert
+                            // it into a cart, and write the result
+                            // back into it.
+                            let mut cart = take(x).into_cart();
+                            let next_cell = Rc::new(RefCell::new(Value::Cart(Default::default())));
+                            cart.insert(index, Rc::clone(&next_cell));
+                            *x = Value::Cart(cart);
+                            next_cell
+                        }
+                    };
+                    cell = next_cell;
+                }
+                cell.replace(value);
+            }
+        }
+
+        Ok(())
+    }
+
     /// Call a function with the given arguments (i.e., actual
     /// parameters). If the function invocation fails for some reason,
     /// report the error at `span`.
@@ -331,8 +341,8 @@ impl ExecEnv {
             .iter()
             .map(|arg| {
                 if let ExprKind::Variable(name) = &arg.kind {
-                    self.get_var_rc(&Iden {
+                    self.get_var_rc(&Ident {
-                        iden: name.to_owned(),
+                        ident: name.to_owned(),
                         span: arg.span.clone(),
                     })
                 } else {
@@ -341,8 +351,17 @@ impl ExecEnv {
             })
             .collect::<Result<Vec<_>, Error>>()?;
 
+        self.fn_call_with_values(func, &args, span)
+    }
+
+    fn fn_call_with_values(
+        &mut self,
+        func: Functio,
+        args: &[Rc<RefCell<Value>>],
+        span: &Range<usize>,
+    ) -> Result<(), Error> {
         match func {
-            Functio::BfFunctio {
+            Functio::Bf {
                 instructions,
                 tape_len,
             } => {
@@ -368,7 +387,7 @@ impl ExecEnv {
                     .write_all(&output)
                     .expect("Failed to write to stdout");
             }
-            Functio::AbleFunctio { params, body } => {
+            Functio::Able { params, body } => {
                 if params.len() != args.len() {
                     return Err(Error {
                         kind: ErrorKind::MismatchedArgumentError,
@@ -387,10 +406,74 @@ impl ExecEnv {
                 self.stack.pop();
                 res?;
             }
+            Functio::Chain { functios, kind } => {
+                let (left_functio, right_functio) = *functios;
+                match kind {
+                    crate::variables::FunctioChainKind::Equal => {
+                        let (l, r) = args.split_at(args.len() / 2);
+
+                        self.fn_call_with_values(left_functio, l, span)?;
+                        self.fn_call_with_values(right_functio, r, span)?;
+                    }
+                    crate::variables::FunctioChainKind::ByArity => {
+                        let (l, r) =
+                            Self::deinterlace(args, (left_functio.arity(), right_functio.arity()));
+
+                        self.fn_call_with_values(left_functio, &l, span)?;
+                        self.fn_call_with_values(right_functio, &r, span)?;
+                    }
+                };
+            }
+            Functio::Eval(code) => {
+                if !args.is_empty() {
+                    return Err(Error {
+                        kind: ErrorKind::MismatchedArgumentError,
+                        span: span.to_owned(),
+                    });
+                }
+
+                let stmts = crate::parser::Parser::new(&code).init()?;
+                self.eval_stmts(&stmts)?;
+            }
         }
         Ok(())
     }
 
+    fn deinterlace(
+        args: &[Rc<RefCell<Value>>],
+        arities: (usize, usize),
+    ) -> (Vec<Rc<RefCell<Value>>>, Vec<Rc<RefCell<Value>>>) {
+        let n_alternations = usize::min(arities.0, arities.1);
+        let (extra_l, extra_r) = match Ord::cmp(&arities.0, &arities.1) {
+            Ordering::Less => (0, arities.1 - arities.0),
+            Ordering::Equal => (0, 0),
+            Ordering::Greater => (arities.0 - arities.1, 0),
+        };
+
+        (
+            args.chunks(2)
+                .take(n_alternations)
+                .map(|chunk| Rc::clone(&chunk[0]))
+                .chain(
+                    args[2 * n_alternations..]
+                        .iter()
+                        .map(|r| Rc::clone(r))
+                        .take(extra_l),
+                )
+                .collect(),
+            args.chunks(2)
+                .take(n_alternations)
+                .map(|chunk| Rc::clone(&chunk[1]))
+                .chain(
+                    args[2 * n_alternations..]
+                        .iter()
+                        .map(|r| Rc::clone(r))
+                        .take(extra_r),
+                )
+                .collect(),
+        )
+    }
+
     /// Get a single bit from the bit buffer, or refill it from
     /// standard input if it is empty.
     fn get_bit(&mut self) -> Result<bool, Error> {
@@ -413,9 +496,9 @@ impl ExecEnv {
 
     /// Get the value of a variable. Throw an error if the variable is
     /// inaccessible or banned.
-    fn get_var(&self, name: &Iden) -> Result<Value, Error> {
+    fn get_var(&self, name: &Ident) -> Result<Value, Error> {
         // One-letter names are reserved as base55 numbers.
-        let mut chars = name.iden.chars();
+        let mut chars = name.ident.chars();
         if let (Some(first), None) = (chars.next(), chars.next()) {
             return Ok(Value::Int(base_55::char2num(first)));
         }
@@ -426,20 +509,20 @@ impl ExecEnv {
             .stack
             .iter()
             .rev()
-            .find_map(|scope| scope.variables.get(&name.iden))
+            .find_map(|scope| scope.variables.get(&name.ident))
         {
             Some(var) => {
                 if !var.melo {
                     Ok(var.value.borrow().clone())
                 } else {
                     Err(Error {
-                        kind: ErrorKind::MeloVariable(name.iden.to_owned()),
+                        kind: ErrorKind::MeloVariable(name.ident.to_owned()),
                         span: name.span.clone(),
                     })
                 }
             }
             None => Err(Error {
-                kind: ErrorKind::UnknownVariable(name.iden.to_owned()),
+                kind: ErrorKind::UnknownVariable(name.ident.to_owned()),
                 span: name.span.clone(),
             }),
         }
@@ -447,27 +530,27 @@ impl ExecEnv {
 
     /// Get a mutable reference to a variable. Throw an error if the
     /// variable is inaccessible or banned.
-    fn get_var_mut(&mut self, name: &Iden) -> Result<&mut Variable, Error> {
+    fn get_var_mut(&mut self, name: &Ident) -> Result<&mut Variable, Error> {
         // This function has a lot of duplicated code with `get_var`,
         // which I feel like is a bad sign...
         match self
             .stack
             .iter_mut()
             .rev()
-            .find_map(|scope| scope.variables.get_mut(&name.iden))
+            .find_map(|scope| scope.variables.get_mut(&name.ident))
         {
             Some(var) => {
                 if !var.melo {
                     Ok(var)
                 } else {
                     Err(Error {
-                        kind: ErrorKind::MeloVariable(name.iden.to_owned()),
+                        kind: ErrorKind::MeloVariable(name.ident.to_owned()),
                         span: name.span.clone(),
                     })
                 }
             }
             None => Err(Error {
-                kind: ErrorKind::UnknownVariable(name.iden.to_owned()),
+                kind: ErrorKind::UnknownVariable(name.ident.to_owned()),
                 span: name.span.clone(),
             }),
         }
@@ -475,7 +558,7 @@ impl ExecEnv {
 
     /// Get an Rc'd pointer to the value of a variable. Throw an error
     /// if the variable is inaccessible or banned.
-    fn get_var_rc(&mut self, name: &Iden) -> Result<Rc<RefCell<Value>>, Error> {
+    fn get_var_rc(&mut self, name: &Ident) -> Result<Rc<RefCell<Value>>, Error> {
         Ok(self.get_var_mut(name)?.value.clone())
     }
 
@@ -571,7 +654,7 @@ mod tests {
                 span: 1..1
             })
             .unwrap(),
-            Value::Int(42)
+            Value::Int(-2147483648)
         );
 
         // And the same for divide by zero.
@@ -579,7 +662,7 @@ mod tests {
             env.eval_expr(&Expr {
                 kind: ExprKind::BinOp {
                     lhs: Box::new(Expr {
-                        kind: ExprKind::Literal(Value::Int(1)),
+                        kind: ExprKind::Literal(Value::Int(84)),
                         span: 1..1,
                     }),
                     rhs: Box::new(Expr {
@@ -591,7 +674,7 @@ mod tests {
                 span: 1..1
             })
             .unwrap(),
-            Value::Int(42)
+            Value::Int(2)
         );
     }
 
@@ -617,8 +700,8 @@ mod tests {
         // Declaring and reading from a variable.
         eval(&mut env, "var foo = 32; var bar = foo + 1;").unwrap();
         assert_eq!(
-            env.get_var(&Iden {
+            env.get_var(&Ident {
-                iden: "bar".to_owned(),
+                ident: "bar".to_owned(),
                 span: 1..1,
             })
             .unwrap(),
@@ -628,8 +711,8 @@ mod tests {
         // Assigning an existing variable.
         eval(&mut env, "foo = \"hi\";").unwrap();
         assert_eq!(
-            env.get_var(&Iden {
+            env.get_var(&Ident {
-                iden: "foo".to_owned(),
+                ident: "foo".to_owned(),
                 span: 1..1,
             })
             .unwrap(),
@@ -654,8 +737,8 @@ mod tests {
         .unwrap();
 
         assert_eq!(
-            env.get_var(&Iden {
+            env.get_var(&Ident {
-                iden: "foo".to_owned(),
+                ident: "foo".to_owned(),
                 span: 1..1,
             })
             .unwrap(),

ablescript/src/lexer.rs

@@ -64,13 +64,7 @@ pub enum Token {
     #[token("!=")]
     NotEqual,
 
-    #[token("&")]
+    #[regex("!|aint")] // also add aint as a not keyword
-    And,
-
-    #[token("|")]
-    Or,
-
-    #[token("!|aint")] // also add aint as a not keyword
     Not,
 
     // Keywords
@@ -123,7 +117,7 @@ pub enum Token {
 
     // Literals
     /// True, False
-    #[regex("true|false", get_bool)]
+    #[regex("true|false", get_value)]
     Bool(bool),
 
     /// Always, Sometimes, Never
@@ -139,11 +133,11 @@ pub enum Token {
     String(String),
 
     /// Integer
-    #[regex(r"-?[0-9]+", get_int)]
+    #[regex(r"-?[0-9]+", get_value)]
     Integer(i32),
 
     /// A C-complaint identifier
-    #[regex(r"[a-zA-Z_][a-zA-Z_0-9]*", get_iden)]
+    #[regex(r"[a-zA-Z_][a-zA-Z_0-9]*", get_ident)]
     Identifier(String),
 
     #[regex(r"owo .*")]
@@ -157,11 +151,7 @@ pub enum Token {
     Error,
 }
 
-fn get_bool(lexer: &mut Lexer<Token>) -> Option<bool> {
+fn get_value<T: std::str::FromStr>(lexer: &mut Lexer<Token>) -> Option<T> {
-    lexer.slice().parse().ok()
-}
-
-fn get_int(lexer: &mut Lexer<Token>) -> Option<i32> {
     lexer.slice().parse().ok()
 }
 
@@ -178,7 +168,7 @@ fn get_abool(lexer: &mut Lexer<Token>) -> Option<Abool> {
     }
 }
 
-fn get_iden(lexer: &mut Lexer<Token>) -> String {
+fn get_ident(lexer: &mut Lexer<Token>) -> String {
     lexer.slice().to_owned()
 }
 

ablescript/src/parser.rs

@@ -37,12 +37,7 @@ impl<'source> Parser<'source> {
                 Token::Comment => continue,
 
                 // T-Dark block (replace `lang` with `script`)
-                Token::TDark => {
+                Token::TDark => ast.extend(self.tdark_flow()?.block),
-                    self.tdark = true;
-                    let mut block = self.get_block()?;
-                    ast.append(&mut block.block);
-                    self.tdark = false;
-                }
                 token => ast.push(self.parse(token)?),
             }
         }
@@ -53,9 +48,16 @@ impl<'source> Parser<'source> {
     ///
     /// If EOF, return Error instead of None
     fn checked_next(&mut self) -> Result<Token, Error> {
-        self.lexer
+        loop {
-            .next()
+            match self
-            .ok_or_else(|| Error::unexpected_eof(self.lexer.span().start))
+                .lexer
+                .next()
+                .ok_or_else(|| Error::unexpected_eof(self.lexer.span().start))?
+            {
+                Token::Comment => (),
+                token => break Ok(token),
+            }
+        }
     }
 
     /// Parse a token
@@ -76,19 +78,19 @@ impl<'source> Parser<'source> {
             Token::Melo => Ok(Stmt::new(self.melo_flow()?, start..self.lexer.span().end)),
             Token::Loop => Ok(Stmt::new(self.loop_flow()?, start..self.lexer.span().end)),
             Token::Break => Ok(Stmt::new(
-                self.semi_terminated(StmtKind::Break)?,
+                self.semicolon_terminated(StmtKind::Break)?,
                 start..self.lexer.span().end,
             )),
             Token::HopBack => Ok(Stmt::new(
-                self.semi_terminated(StmtKind::HopBack)?,
+                self.semicolon_terminated(StmtKind::HopBack)?,
                 start..self.lexer.span().end,
             )),
             Token::Rlyeh => Ok(Stmt::new(
-                self.semi_terminated(StmtKind::Rlyeh)?,
+                self.semicolon_terminated(StmtKind::Rlyeh)?,
                 start..self.lexer.span().end,
             )),
             Token::Rickroll => Ok(Stmt::new(
-                self.semi_terminated(StmtKind::Rickroll)?,
+                self.semicolon_terminated(StmtKind::Rickroll)?,
                 start..self.lexer.span().end,
             )),
 
@@ -98,6 +100,8 @@ impl<'source> Parser<'source> {
             | Token::Integer(_)
             | Token::Abool(_)
             | Token::Bool(_)
+            | Token::Nul
+            | Token::Not
             | Token::LeftBracket
             | Token::LeftParen => Ok(Stmt::new(
                 self.value_flow(token)?,
@@ -114,7 +118,7 @@ impl<'source> Parser<'source> {
     /// Require statement to be semicolon terminated
     ///
     /// Utility function for short statements
-    fn semi_terminated(&mut self, stmt_kind: StmtKind) -> Result<StmtKind, Error> {
+    fn semicolon_terminated(&mut self, stmt_kind: StmtKind) -> Result<StmtKind, Error> {
         self.require(Token::Semicolon)?;
         Ok(stmt_kind)
     }
@@ -129,13 +133,13 @@ impl<'source> Parser<'source> {
     }
 
     /// Get an Identifier
-    fn get_iden(&mut self) -> Result<Iden, Error> {
+    fn get_ident(&mut self) -> Result<Ident, Error> {
         match self.checked_next()? {
-            Token::Identifier(iden) => Ok(Iden {
+            Token::Identifier(ident) => Ok(Ident {
-                iden: if self.tdark {
+                ident: if self.tdark {
-                    iden.replace("lang", "script")
+                    ident.replace("lang", "script")
                 } else {
-                    iden
+                    ident
                 },
                 span: self.lexer.span(),
             }),
@@ -192,7 +196,7 @@ impl<'source> Parser<'source> {
             Token::LeftBracket => match buf.take() {
                 Some(buf) => Ok(Expr::new(
                     ExprKind::Index {
-                        cart: Box::new(buf),
+                        expr: Box::new(buf),
                         index: Box::new(self.expr_flow(Token::RightBracket)?),
                     },
                     start..self.lexer.span().end,
@@ -208,9 +212,7 @@ impl<'source> Parser<'source> {
             | Token::EqualEqual
             | Token::NotEqual
             | Token::LessThan
-            | Token::GreaterThan
+            | Token::GreaterThan => Ok(Expr::new(
-            | Token::And
-            | Token::Or => Ok(Expr::new(
                 self.binop_flow(
                     BinOpKind::from_token(token).map_err(|e| Error::new(e, self.lexer.span()))?,
                     buf,
@@ -322,12 +324,21 @@ impl<'source> Parser<'source> {
         loop {
             match self.checked_next()? {
                 Token::RightCurly => break,
+                Token::TDark => block.extend(self.tdark_flow()?.block),
                 t => block.push(self.parse(t)?),
             }
         }
         Ok(Block { block })
     }
 
+    /// Parse T-Dark block
+    fn tdark_flow(&mut self) -> Result<Block, Error> {
+        self.tdark = true;
+        let block = self.get_block();
+        self.tdark = false;
+        block
+    }
+
     /// If Statement parser gets any kind of value (Identifier or Literal)
     /// It cannot parse it as it do not parse expressions. Instead of it it
     /// will parse it to function call or print statement.
@@ -340,7 +351,7 @@ impl<'source> Parser<'source> {
                     let stmt = StmtKind::Print(buf.take().ok_or_else(|| {
                         Error::new(ErrorKind::UnexpectedToken(Token::Print), self.lexer.span())
                     })?);
-                    break self.semi_terminated(stmt)?;
+                    break self.semicolon_terminated(stmt)?;
                 }
 
                 // Functio call
@@ -355,26 +366,29 @@ impl<'source> Parser<'source> {
 
                 // Variable Assignment
                 Token::Equal => {
-                    if let Some(Expr {
+                    if let Some(Ok(assignable)) = buf.take().map(Assignable::from_expr) {
-                        kind: ExprKind::Variable(iden),
-                        span,
-                    }) = buf
-                    {
                         break StmtKind::Assign {
-                            iden: Iden::new(iden, span),
+                            assignable,
                             value: self.expr_flow(Token::Semicolon)?,
                         };
+                    } else {
+                        return Err(Error::new(
+                            ErrorKind::UnexpectedToken(Token::Equal),
+                            self.lexer.span(),
+                        ));
                     }
                 }
 
                 // Read input
                 Token::Read => {
-                    if let Some(Expr {
+                    if let Some(Ok(assignable)) = buf.take().map(Assignable::from_expr) {
-                        kind: ExprKind::Variable(iden),
+                        self.require(Token::Semicolon)?;
-                        span,
+                        break StmtKind::Read(assignable);
-                    }) = buf
+                    } else {
-                    {
+                        return Err(Error::new(
-                        break self.semi_terminated(StmtKind::Read(Iden::new(iden, span)))?;
+                            ErrorKind::UnexpectedToken(Token::Read),
+                            self.lexer.span(),
+                        ));
                     }
                 }
 
@@ -400,9 +414,9 @@ impl<'source> Parser<'source> {
 
     /// Parse functio flow
     ///
-    /// functio $iden (a, b, c) { ... }
+    /// functio $ident (a, b, c) { ... }
     fn functio_flow(&mut self) -> Result<StmtKind, Error> {
-        let iden = self.get_iden()?;
+        let ident = self.get_ident()?;
 
         self.require(Token::LeftParen)?;
 
@@ -411,7 +425,7 @@ impl<'source> Parser<'source> {
             match self.checked_next()? {
                 Token::RightParen => break,
                 Token::Identifier(i) => {
-                    params.push(Iden::new(i, self.lexer.span()));
+                    params.push(Ident::new(i, self.lexer.span()));
 
                     // Require comma (next) or right paren (end) after identifier
                     match self.checked_next()? {
@@ -431,14 +445,18 @@ impl<'source> Parser<'source> {
 
         let body = self.get_block()?;
 
-        Ok(StmtKind::Functio { iden, params, body })
+        Ok(StmtKind::Functio {
+            ident,
+            params,
+            body,
+        })
     }
 
     /// Parse BF function declaration
     ///
-    /// `bff $iden ([tapelen]) { ... }`
+    /// `bff $ident ([tapelen]) { ... }`
     fn bff_flow(&mut self) -> Result<StmtKind, Error> {
-        let iden = self.get_iden()?;
+        let ident = self.get_ident()?;
 
         let tape_len = match self.checked_next()? {
             Token::LeftParen => {
@@ -472,7 +490,7 @@ impl<'source> Parser<'source> {
         }
 
         Ok(StmtKind::BfFunctio {
-            iden,
+            ident,
             tape_len,
             code,
         })
@@ -513,20 +531,20 @@ impl<'source> Parser<'source> {
 
     /// Parse variable declaration
     fn var_flow(&mut self) -> Result<StmtKind, Error> {
-        let iden = self.get_iden()?;
+        let ident = self.get_ident()?;
         let init = match self.checked_next()? {
             Token::Equal => Some(self.expr_flow(Token::Semicolon)?),
             Token::Semicolon => None,
             t => return Err(Error::new(ErrorKind::UnexpectedToken(t), self.lexer.span())),
         };
 
-        Ok(StmtKind::Var { iden, init })
+        Ok(StmtKind::Var { ident, init })
     }
 
     /// Parse Melo flow
     fn melo_flow(&mut self) -> Result<StmtKind, Error> {
-        let iden = self.get_iden()?;
+        let ident = self.get_ident()?;
-        self.semi_terminated(StmtKind::Melo(iden))
+        self.semicolon_terminated(StmtKind::Melo(ident))
     }
 
     /// Parse loop flow
@@ -558,7 +576,7 @@ mod tests {
                             rhs: Box::new(Expr {
                                 kind: ExprKind::BinOp {
                                     lhs: Box::new(Expr {
-                                        kind: ExprKind::Variable("a".to_string()),
+                                        kind: ExprKind::Variable("a".to_owned()),
                                         span: 5..6,
                                     }),
                                     rhs: Box::new(Expr {
@@ -593,8 +611,8 @@ mod tests {
         let code = r#"var a = 42;"#;
         let expected = &[Stmt {
             kind: StmtKind::Var {
-                iden: Iden {
+                ident: Ident {
-                    iden: "a".to_string(),
+                    ident: "a".to_owned(),
                     span: 4..5,
                 },
                 init: Some(Expr {
@@ -631,7 +649,7 @@ mod tests {
                 body: Block {
                     block: vec![Stmt {
                         kind: StmtKind::Print(Expr {
-                            kind: ExprKind::Literal(Value::Str("Buy Able products!".to_string())),
+                            kind: ExprKind::Literal(Value::Str("Buy Able products!".to_owned())),
                             span: 19..39,
                         }),
                         span: 19..46,
@@ -650,18 +668,18 @@ mod tests {
         let code = r#"T-Dark { var lang = "lang" + lang; }"#;
         let expected = &[Stmt {
             kind: StmtKind::Var {
-                iden: Iden {
+                ident: Ident {
-                    iden: "script".to_string(),
+                    ident: "script".to_owned(),
                     span: 13..17,
                 },
                 init: Some(Expr {
                     kind: ExprKind::BinOp {
                         lhs: Box::new(Expr {
-                            kind: ExprKind::Literal(Value::Str("script".to_string())),
+                            kind: ExprKind::Literal(Value::Str("script".to_owned())),
                             span: 20..26,
                         }),
                         rhs: Box::new(Expr {
-                            kind: ExprKind::Variable("script".to_string()),
+                            kind: ExprKind::Variable("script".to_owned()),
                             span: 29..33,
                         }),
                         kind: BinOpKind::Add,
@@ -684,7 +702,7 @@ mod tests {
                 kind: ExprKind::Cart(vec![
                     (
                         Expr {
-                            kind: ExprKind::Literal(Value::Str("able".to_string())),
+                            kind: ExprKind::Literal(Value::Str("able".to_owned())),
                             span: 1..7,
                         },
                         Expr {
@@ -694,7 +712,7 @@ mod tests {
                     ),
                     (
                         Expr {
-                            kind: ExprKind::Literal(Value::Str("script".to_string())),
+                            kind: ExprKind::Literal(Value::Str("script".to_owned())),
                             span: 14..22,
                         },
                         Expr {
@@ -728,14 +746,14 @@ mod tests {
         let expected = &[Stmt {
             kind: StmtKind::Print(Expr {
                 kind: ExprKind::Index {
-                    cart: Box::new(Expr {
+                    expr: Box::new(Expr {
                         kind: ExprKind::Cart(vec![(
                             Expr {
-                                kind: ExprKind::Literal(Value::Str("able".to_string())),
+                                kind: ExprKind::Literal(Value::Str("able".to_owned())),
                                 span: 1..7,
                             },
                             Expr {
-                                kind: ExprKind::Literal(Value::Str("ablecorp".to_string())),
+                                kind: ExprKind::Literal(Value::Str("ablecorp".to_owned())),
                                 span: 11..21,
                             },
                         )]),

ablescript/src/variables.rs

@@ -1,13 +1,13 @@
 use std::{
-    cell::RefCell, collections::HashMap, convert::TryFrom, fmt::Display, hash::Hash, io::Write,
+    cell::RefCell, collections::HashMap, fmt::Display, hash::Hash, io::Write, mem::discriminant,
-    mem::discriminant, rc::Rc,
+    ops, rc::Rc, vec,
 };
 
 use rand::Rng;
 
-use crate::{ast::Stmt, consts};
+use crate::{ast::Stmt, brian::INSTRUCTION_MAPPINGS, consts};
 
-#[derive(Debug, Clone, Copy, PartialEq)]
+#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
 pub enum Abool {
     Never = -1,
     Sometimes = 0,
@@ -36,16 +36,43 @@ impl From<Abool> for bool {
 
 #[derive(Debug, PartialEq, Clone, Hash)]
 pub enum Functio {
-    BfFunctio {
+    Bf {
         instructions: Vec<u8>,
         tape_len: usize,
     },
-    AbleFunctio {
+    Able {
         params: Vec<String>,
         body: Vec<Stmt>,
     },
+    Chain {
+        functios: Box<(Functio, Functio)>,
+        kind: FunctioChainKind,
+    },
+    Eval(String),
 }
 
+impl Functio {
+    pub fn arity(&self) -> usize {
+        match self {
+            Functio::Bf {
+                instructions: _,
+                tape_len: _,
+            } => 0,
+            Functio::Able { params, body: _ } => params.len(),
+            Functio::Chain { functios, kind: _ } => functios.0.arity() + functios.1.arity(),
+            Functio::Eval(_) => 0,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Copy, Clone, Hash)]
+pub enum FunctioChainKind {
+    Equal,
+    ByArity,
+}
+
+pub type Cart = HashMap<Value, Rc<RefCell<Value>>>;
+
 #[derive(Debug, Clone)]
 pub enum Value {
     Nul,
@@ -54,7 +81,13 @@ pub enum Value {
     Bool(bool),
     Abool(Abool),
     Functio(Functio),
-    Cart(HashMap<Value, Rc<RefCell<Value>>>),
+    Cart(Cart),
+}
+
+impl Default for Value {
+    fn default() -> Self {
+        Self::Nul
+    }
 }
 
 impl Hash for Value {
@@ -72,24 +105,6 @@ impl Hash for Value {
     }
 }
 
-impl PartialEq for Value {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Value::Nul, Value::Nul) => true,
-            (Value::Str(left), Value::Str(right)) => left == right,
-            (Value::Int(left), Value::Int(right)) => left == right,
-            (Value::Bool(left), Value::Bool(right)) => left == right,
-            (Value::Abool(left), Value::Abool(right)) => left == right,
-            (Value::Functio(left), Value::Functio(right)) => left == right,
-            (Value::Cart(_), Value::Cart(_)) => self.to_string() == other.to_string(),
-            (_, _) => false,
-            // TODO: do more coercions!
-        }
-    }
-}
-
-impl Eq for Value {}
-
 impl Value {
     /// Write an AbleScript value to a Brainfuck input stream by
     /// coercing the value to an integer, then truncating that integer
@@ -98,73 +113,668 @@ impl Value {
     /// any IO errors will cause a panic.
     pub fn bf_write(&self, stream: &mut impl Write) {
         stream
-            .write_all(&[self.clone().to_i32() as u8])
+            .write_all(&[self.clone().into_i32() as u8])
             .expect("Failed to write to Brainfuck input");
     }
 
     /// Coerce a value to an integer.
-    pub fn to_i32(&self) -> i32 {
+    pub fn into_i32(self) -> i32 {
         match self {
-            Value::Abool(a) => *a as _,
+            Value::Abool(a) => a as _,
-            Value::Bool(b) => *b as _,
+            Value::Bool(b) => b as _,
             Value::Functio(func) => match func {
-                Functio::BfFunctio {
+                // Compares lengths of functions:
+                // BfFunctio - Sum of lengths of instructions and length of tape
+                // AbleFunctio - Sum of argument count and body length
+                // Eval - Length of input code
+                Functio::Bf {
                     instructions,
                     tape_len,
                 } => (instructions.len() + tape_len) as _,
-                Functio::AbleFunctio { params, body } => (params.len() + body.len()) as _,
+                Functio::Able { params, body } => (params.len() + format!("{:?}", body).len()) as _,
+                Functio::Chain { functios, kind } => {
+                    let (lhs, rhs) = *functios;
+                    match kind {
+                        FunctioChainKind::Equal => {
+                            Value::Int(Value::Functio(lhs).into_i32())
+                                + Value::Int(Value::Functio(rhs).into_i32())
+                        }
+                        FunctioChainKind::ByArity => {
+                            Value::Int(Value::Functio(lhs).into_i32())
+                                * Value::Int(Value::Functio(rhs).into_i32())
+                        }
+                    }
+                    .into_i32()
+                }
+                Functio::Eval(s) => s.len() as _,
             },
-            Value::Int(i) => *i,
+            Value::Int(i) => i,
             Value::Nul => consts::ANSWER,
             Value::Str(text) => text.parse().unwrap_or(consts::ANSWER),
             Value::Cart(c) => c.len() as _,
         }
     }
 
-    /// Coerce a Value to a boolean. The conversion cannot fail.
+    /// Coerce a value to a boolean.
-    pub fn to_bool(&self) -> bool {
+    pub fn into_bool(self) -> bool {
         match self {
-            Value::Abool(b) => (*b).into(),
+            Value::Abool(b) => b.into(),
-            Value::Bool(b) => *b,
+            Value::Bool(b) => b,
             Value::Functio(_) => true,
-            Value::Int(x) => *x != 0,
+            Value::Int(x) => x != 0,
-            Value::Nul => true,
+            Value::Nul => false,
-            Value::Str(s) => !s.is_empty(),
+            Value::Str(s) => match s.to_lowercase().as_str() {
+                "false" | "no" | "🇳🇴" => false,
+                "true" | "yes" => true,
+                s => !s.is_empty(),
+            },
             Value::Cart(c) => !c.is_empty(),
         }
     }
 
-    /// Index a value with another value, as in the "a[b]" syntax.
+    /// Coerce a value to an aboolean.
-    pub fn index(&self, index: &Value) -> Rc<RefCell<Value>> {
+    pub fn into_abool(self) -> Abool {
-        Rc::new(RefCell::new(match self {
+        match self {
-            Value::Nul => Value::Nul,
+            Value::Nul => Abool::Never,
-            Value::Str(s) => Value::Int(
+            Value::Str(s) => match s.to_lowercase().as_str() {
-                usize::try_from(index.to_i32() - 1)
+                "never" => Abool::Never,
-                    .ok()
+                "sometimes" => Abool::Sometimes,
-                    .and_then(|idx| s.as_bytes().get(idx).cloned())
+                "always" => Abool::Always,
-                    .map(|value| value as i32)
+                s => {
-                    .unwrap_or(0),
+                    if s.is_empty() {
-            ),
+                        Abool::Never
-            Value::Int(i) => Value::Int(
+                    } else {
-                usize::try_from(index.to_i32() - 1)
+                        Abool::Always
-                    .ok()
+                    }
-                    .and_then(|idx| format!("{}", i).as_bytes().get(idx).cloned())
+                }
-                    .map(|value| value as i32)
+            },
-                    .unwrap_or(0),
+            Value::Int(x) => match x.cmp(&0) {
-            ),
+                std::cmp::Ordering::Less => Abool::Never,
-            Value::Bool(b) => Value::Int(
+                std::cmp::Ordering::Equal => Abool::Sometimes,
-                usize::try_from(index.to_i32() - 1)
+                std::cmp::Ordering::Greater => Abool::Always,
-                    .ok()
+            },
-                    .and_then(|idx| format!("{}", b).as_bytes().get(idx).cloned())
+            Value::Bool(b) => {
-                    .map(|value| value as i32)
+                if b {
-                    .unwrap_or(0),
+                    Abool::Always
-            ),
+                } else {
-            Value::Abool(b) => Value::Int(*b as i32),
+                    Abool::Never
-            Value::Functio(_) => Value::Int(42),
+                }
-            Value::Cart(c) => {
-                return (c.get(index).cloned()).unwrap_or_else(|| Rc::new(RefCell::new(Value::Nul)))
             }
-        }))
+            Value::Abool(a) => a,
+            Value::Functio(f) => match f {
+                Functio::Bf {
+                    instructions,
+                    tape_len,
+                } => Value::Int(
+                    (instructions.iter().map(|x| *x as usize).sum::<usize>() * tape_len) as _,
+                )
+                .into_abool(),
+                Functio::Able { params, body } => {
+                    let str_to_i32 =
+                        |x: String| -> i32 { x.as_bytes().into_iter().map(|x| *x as i32).sum() };
+
+                    let params: i32 = params.into_iter().map(str_to_i32).sum();
+                    let body: i32 = body
+                        .into_iter()
+                        .map(|x| format!("{:?}", x))
+                        .map(str_to_i32)
+                        .sum();
+
+                    Value::Int((params + body) % 3 - 1).into_abool()
+                }
+                Functio::Chain { functios, kind } => {
+                    let (lhs, rhs) = *functios;
+                    match kind {
+                        FunctioChainKind::Equal => {
+                            Value::Abool(Value::Functio(lhs).into_abool())
+                                + Value::Abool(Value::Functio(rhs).into_abool())
+                        }
+                        FunctioChainKind::ByArity => {
+                            Value::Abool(Value::Functio(lhs).into_abool())
+                                * Value::Abool(Value::Functio(rhs).into_abool())
+                        }
+                    }
+                    .into_abool()
+                }
+                Functio::Eval(code) => Value::Str(code).into_abool(),
+            },
+            Value::Cart(c) => {
+                if c.is_empty() {
+                    Abool::Never
+                } else {
+                    Abool::Always
+                }
+            }
+        }
+    }
+
+    /// Coerce a value to a functio.
+    pub fn into_functio(self) -> Functio {
+        match self {
+            Value::Nul => Functio::Able {
+                body: vec![],
+                params: vec![],
+            },
+            Value::Str(s) => Functio::Eval(s),
+            Value::Int(i) => Functio::Bf {
+                instructions: {
+                    std::iter::successors(Some(i as usize), |i| {
+                        Some(i / INSTRUCTION_MAPPINGS.len())
+                    })
+                    .take_while(|&i| i != 0)
+                    .map(|i| INSTRUCTION_MAPPINGS[i % INSTRUCTION_MAPPINGS.len()])
+                    .collect()
+                },
+                tape_len: crate::brian::DEFAULT_TAPE_SIZE_LIMIT,
+            },
+            Value::Bool(b) => Functio::Eval(
+                if b {
+                    r#"loop{"Buy Able products!"print;}"#
+                } else {
+                    ""
+                }
+                .to_owned(),
+            ),
+            Value::Abool(a) => Functio::Eval(match a {
+                Abool::Never => "".to_owned(),
+                Abool::Sometimes => {
+                    use rand::seq::SliceRandom;
+                    let mut str_chars: Vec<_> = "Buy Able Products!".chars().collect();
+                    str_chars.shuffle(&mut rand::thread_rng());
+
+                    format!(r#""{}"print;"#, str_chars.iter().collect::<String>())
+                }
+                Abool::Always => r#"loop{"Buy Able products!"print;}"#.to_owned(),
+            }),
+            Value::Functio(f) => f,
+            Value::Cart(c) => {
+                let kind = if let Some(114514) = c
+                    .get(&Value::Str("1452251871514141792252515212116".to_owned()))
+                    .map(|x| x.borrow().to_owned().into_i32())
+                {
+                    FunctioChainKind::Equal
+                } else {
+                    FunctioChainKind::ByArity
+                };
+
+                let mut cart_vec = c.iter().collect::<Vec<_>>();
+                cart_vec.sort_by(|x, y| x.0.partial_cmp(y.0).unwrap_or(std::cmp::Ordering::Less));
+
+                cart_vec
+                    .into_iter()
+                    .map(|(_, x)| x.borrow().to_owned().into_functio())
+                    .reduce(|acc, x| Functio::Chain {
+                        functios: Box::new((acc, x)),
+                        kind,
+                    })
+                    .unwrap_or_else(|| Functio::Eval(r#""Buy Able Products!"print;"#.to_owned()))
+            }
+        }
+    }
+
+    /// Coerce a value into a cart.
+    pub fn into_cart(self) -> Cart {
+        match self {
+            Value::Nul => HashMap::new(),
+            Value::Str(s) => s
+                .chars()
+                .enumerate()
+                .map(|(i, x)| {
+                    (
+                        Value::Int(i as i32 + 1),
+                        Rc::new(RefCell::new(Value::Str(x.to_string()))),
+                    )
+                })
+                .collect(),
+            Value::Int(i) => Value::Str(i.to_string()).into_cart(),
+            Value::Bool(b) => Value::Str(b.to_string()).into_cart(),
+            Value::Abool(a) => Value::Str(a.to_string()).into_cart(),
+            Value::Functio(f) => match f {
+                Functio::Able { params, body } => {
+                    let params: Cart = params
+                        .into_iter()
+                        .enumerate()
+                        .map(|(i, x)| {
+                            (
+                                Value::Int(i as i32 + 1),
+                                Rc::new(RefCell::new(Value::Str(x))),
+                            )
+                        })
+                        .collect();
+
+                    let body: Cart = body
+                        .into_iter()
+                        .enumerate()
+                        .map(|(i, x)| {
+                            (
+                                Value::Int(i as i32 + 1),
+                                Rc::new(RefCell::new(Value::Str(format!("{:?}", x)))),
+                            )
+                        })
+                        .collect();
+
+                    let mut cart = HashMap::new();
+                    cart.insert(
+                        Value::Str("params".to_owned()),
+                        Rc::new(RefCell::new(Value::Cart(params))),
+                    );
+
+                    cart.insert(
+                        Value::Str("body".to_owned()),
+                        Rc::new(RefCell::new(Value::Cart(body))),
+                    );
+
+                    cart
+                }
+                Functio::Bf {
+                    instructions,
+                    tape_len,
+                } => {
+                    let mut cart: Cart = instructions
+                        .into_iter()
+                        .enumerate()
+                        .map(|(i, x)| {
+                            (
+                                Value::Int(i as i32 + 1),
+                                Rc::new(RefCell::new(
+                                    char::from_u32(x as u32)
+                                        .map(|x| Value::Str(x.to_string()))
+                                        .unwrap_or(Value::Nul),
+                                )),
+                            )
+                        })
+                        .collect();
+
+                    cart.insert(
+                        Value::Str("tapelen".to_owned()),
+                        Rc::new(RefCell::new(Value::Int(tape_len as _))),
+                    );
+                    cart
+                }
+                Functio::Chain { functios, kind } => {
+                    let (lhs, rhs) = *functios;
+                    match kind {
+                        FunctioChainKind::Equal => {
+                            Value::Cart(Value::Functio(lhs).into_cart())
+                                + Value::Cart(Value::Functio(rhs).into_cart())
+                        }
+                        FunctioChainKind::ByArity => {
+                            Value::Cart(Value::Functio(lhs).into_cart())
+                                * Value::Cart(Value::Functio(rhs).into_cart())
+                        }
+                    }
+                    .into_cart()
+                }
+                Functio::Eval(s) => Value::Str(s).into_cart(),
+            },
+            Value::Cart(c) => c,
+        }
+    }
+}
+
+impl ops::Add for Value {
+    type Output = Value;
+
+    fn add(self, rhs: Self) -> Self::Output {
+        match self {
+            Value::Nul => match rhs {
+                Value::Nul => Value::Nul,
+                Value::Str(_) => Value::Str(self.to_string()) + rhs,
+                Value::Int(_) => Value::Int(self.into_i32()) + rhs,
+                Value::Bool(_) => Value::Bool(self.into_bool()) + rhs,
+                Value::Abool(_) => Value::Abool(self.into_abool()) + rhs,
+                Value::Functio(_) => Value::Functio(self.into_functio()) + rhs,
+                Value::Cart(_) => Value::Cart(self.into_cart()) + rhs,
+            },
+            Value::Str(s) => Value::Str(format!("{}{}", s, rhs.to_string())),
+            Value::Int(i) => Value::Int(i.wrapping_add(rhs.into_i32())),
+            Value::Bool(b) => Value::Bool(b || rhs.into_bool()),
+            Value::Abool(_) => {
+                Value::Abool(Value::Int(self.into_i32().max(rhs.into_i32())).into_abool())
+            }
+            Value::Functio(f) => Value::Functio(Functio::Chain {
+                functios: Box::new((f, rhs.into_functio())),
+                kind: FunctioChainKind::Equal,
+            }),
+            Value::Cart(c) => {
+                Value::Cart(c.into_iter().chain(rhs.into_cart().into_iter()).collect())
+            }
+        }
+    }
+}
+
+impl ops::Sub for Value {
+    type Output = Value;
+
+    fn sub(self, rhs: Self) -> Self::Output {
+        match self {
+            Value::Nul => match rhs {
+                Value::Nul => Value::Nul,
+                Value::Str(_) => Value::Str(self.to_string()) - rhs,
+                Value::Int(_) => Value::Int(self.into_i32()) - rhs,
+                Value::Bool(_) => Value::Bool(self.into_bool()) - rhs,
+                Value::Abool(_) => Value::Abool(self.into_abool()) - rhs,
+                Value::Functio(_) => Value::Functio(self.into_functio()) - rhs,
+                Value::Cart(_) => Value::Cart(self.into_cart()) - rhs,
+            },
+            Value::Str(s) => Value::Str(s.replace(&rhs.to_string(), "")),
+            Value::Int(i) => Value::Int(i.wrapping_sub(rhs.into_i32())),
+            Value::Bool(b) => Value::Bool(b ^ rhs.into_bool()),
+            Value::Abool(_) => (self.clone() + rhs.clone()) * !(self * rhs),
+            Value::Functio(f) => Value::Functio(match f {
+                Functio::Bf {
+                    instructions: lhs_ins,
+                    tape_len: lhs_tl,
+                } => match rhs.into_functio() {
+                    Functio::Bf {
+                        instructions: rhs_ins,
+                        tape_len: rhs_tl,
+                    } => Functio::Bf {
+                        instructions: lhs_ins
+                            .into_iter()
+                            .zip(rhs_ins.into_iter())
+                            .filter_map(|(l, r)| if l != r { Some(l) } else { None })
+                            .collect(),
+                        tape_len: lhs_tl - rhs_tl,
+                    },
+                    rhs => Functio::Bf {
+                        instructions: lhs_ins
+                            .into_iter()
+                            .zip(Value::Functio(rhs).to_string().bytes())
+                            .filter_map(|(l, r)| if l != r { Some(l) } else { None })
+                            .collect(),
+                        tape_len: lhs_tl,
+                    },
+                },
+                Functio::Able {
+                    params: lhs_params,
+                    body: lhs_body,
+                } => match rhs.into_functio() {
+                    Functio::Able {
+                        params: rhs_params,
+                        body: rhs_body,
+                    } => Functio::Able {
+                        params: lhs_params
+                            .into_iter()
+                            .zip(rhs_params.into_iter())
+                            .filter_map(|(l, r)| if l != r { Some(l) } else { None })
+                            .collect(),
+                        body: lhs_body
+                            .into_iter()
+                            .zip(rhs_body.into_iter())
+                            .filter_map(|(l, r)| if l != r { Some(l) } else { None })
+                            .collect(),
+                    },
+                    rhs => Value::Int(
+                        Value::Functio(Functio::Able {
+                            params: lhs_params,
+                            body: lhs_body,
+                        })
+                        .into_i32()
+                            - Value::Functio(rhs).into_i32(),
+                    )
+                    .into_functio(),
+                },
+                Functio::Chain { functios, .. } => {
+                    let rhs = rhs.into_functio();
+                    let (a, b) = *functios;
+
+                    match (a == rhs, b == rhs) {
+                        (_, true) => a,
+                        (true, _) => b,
+                        (_, _) => (Value::Functio(a) - Value::Functio(rhs)).into_functio(),
+                    }
+                }
+                Functio::Eval(lhs_code) => Functio::Eval(lhs_code.replace(
+                    &match rhs.into_functio() {
+                        Functio::Eval(code) => code,
+                        rhs => Value::Functio(rhs).to_string(),
+                    },
+                    "",
+                )),
+            }),
+            Value::Cart(c) => Value::Cart({
+                let rhs_cart = rhs.into_cart();
+                c.into_iter()
+                    .filter(|(k, v)| rhs_cart.get(k) != Some(v))
+                    .collect()
+            }),
+        }
+    }
+}
+
+impl ops::Mul for Value {
+    type Output = Value;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        match self {
+            Value::Nul => match rhs {
+                Value::Nul => Value::Nul,
+                Value::Str(_) => Value::Str(self.to_string()) * rhs,
+                Value::Int(_) => Value::Int(self.into_i32()) * rhs,
+                Value::Bool(_) => Value::Bool(self.into_bool()) * rhs,
+                Value::Abool(_) => Value::Abool(self.into_abool()) * rhs,
+                Value::Functio(_) => Value::Functio(self.into_functio()) * rhs,
+                Value::Cart(_) => Value::Cart(self.into_cart()) * rhs,
+            },
+            Value::Str(s) => Value::Str(s.repeat(rhs.into_i32() as usize)),
+            Value::Int(i) => Value::Int(i.wrapping_mul(rhs.into_i32())),
+            Value::Bool(b) => Value::Bool(b && rhs.into_bool()),
+            Value::Abool(_) => {
+                Value::Abool(Value::Int(self.into_i32().min(rhs.into_i32())).into_abool())
+            }
+            Value::Functio(f) => Value::Functio(Functio::Chain {
+                functios: Box::new((f, rhs.into_functio())),
+                kind: FunctioChainKind::ByArity,
+            }),
+            Value::Cart(c) => {
+                let rhsc = rhs.into_cart();
+
+                Value::Cart(
+                    c.into_iter()
+                        .map(|(k, v)| {
+                            if let Some(k) = rhsc.get(&k) {
+                                (k.borrow().clone(), v)
+                            } else {
+                                (k, v)
+                            }
+                        })
+                        .collect(),
+                )
+            }
+        }
+    }
+}
+
+impl ops::Div for Value {
+    type Output = Value;
+
+    fn div(self, rhs: Self) -> Self::Output {
+        match self {
+            Value::Nul => match rhs {
+                Value::Nul => Value::Nul,
+                Value::Str(_) => Value::Str(self.to_string()) / rhs,
+                Value::Int(_) => Value::Int(self.into_i32()) / rhs,
+                Value::Bool(_) => Value::Bool(self.into_bool()) / rhs,
+                Value::Abool(_) => Value::Abool(self.into_abool()) / rhs,
+                Value::Functio(_) => Value::Functio(self.into_functio()) / rhs,
+                Value::Cart(_) => Value::Cart(self.into_cart()) / rhs,
+            },
+            Value::Str(s) => Value::Cart(
+                s.split(&rhs.to_string())
+                    .enumerate()
+                    .map(|(i, x)| {
+                        (
+                            Value::Int(i as i32 + 1),
+                            Rc::new(RefCell::new(Value::Str(x.to_owned()))),
+                        )
+                    })
+                    .collect(),
+            ),
+            Value::Int(i) => Value::Int(i.wrapping_div(match rhs.into_i32() {
+                0 => consts::ANSWER,
+                x => x,
+            })),
+            Value::Bool(b) => Value::Bool(!b || rhs.into_bool()),
+            Value::Abool(_) => !self + rhs,
+            Value::Functio(f) => Value::Functio(match f {
+                Functio::Bf {
+                    instructions,
+                    tape_len,
+                } => {
+                    let fraction = 1.0 / rhs.into_i32() as f64;
+                    let len = instructions.len();
+                    Functio::Bf {
+                        instructions: instructions
+                            .into_iter()
+                            .take((len as f64 * fraction) as usize)
+                            .collect(),
+                        tape_len,
+                    }
+                }
+                Functio::Able { params, body } => {
+                    let fraction = 1.0 / rhs.into_i32() as f64;
+                    let len = body.len();
+                    Functio::Able {
+                        params,
+                        body: body
+                            .into_iter()
+                            .take((len as f64 * fraction) as usize)
+                            .collect(),
+                    }
+                }
+                Functio::Chain { functios, kind } => {
+                    let functios = *functios;
+                    Functio::Chain {
+                        functios: Box::new((
+                            (Value::Functio(functios.0) / rhs.clone()).into_functio(),
+                            (Value::Functio(functios.1) / rhs).into_functio(),
+                        )),
+                        kind,
+                    }
+                }
+                Functio::Eval(s) => {
+                    let fraction = 1.0 / rhs.into_i32() as f64;
+                    let len = s.len();
+                    Functio::Eval(s.chars().take((len as f64 * fraction) as usize).collect())
+                }
+            }),
+            Value::Cart(c) => {
+                let cart_len = c.len();
+                let chunk_len = rhs.into_i32() as usize;
+
+                Value::Cart(
+                    c.into_iter()
+                        .collect::<Vec<_>>()
+                        .chunks(cart_len / chunk_len + (cart_len % chunk_len != 0) as usize)
+                        .enumerate()
+                        .map(|(k, v)| {
+                            (
+                                Value::Int(k as i32 + 1),
+                                Rc::new(RefCell::new(Value::Cart(v.iter().cloned().collect()))),
+                            )
+                        })
+                        .collect(),
+                )
+            }
+        }
+    }
+}
+
+impl ops::Not for Value {
+    type Output = Value;
+
+    fn not(self) -> Self::Output {
+        match self {
+            Value::Nul => Value::Nul,
+            Value::Str(s) => Value::Str(s.chars().rev().collect()),
+            Value::Int(i) => Value::Int(i.swap_bytes()),
+            Value::Bool(b) => Value::Bool(!b),
+            Value::Abool(a) => Value::Abool(match a {
+                Abool::Never => Abool::Always,
+                Abool::Sometimes => Abool::Sometimes,
+                Abool::Always => Abool::Never,
+            }),
+            Value::Functio(f) => Value::Functio(match f {
+                Functio::Bf {
+                    mut instructions,
+                    tape_len,
+                } => {
+                    instructions.reverse();
+
+                    Functio::Bf {
+                        instructions,
+                        tape_len,
+                    }
+                }
+                Functio::Able {
+                    mut params,
+                    mut body,
+                } => {
+                    params.reverse();
+                    body.reverse();
+
+                    Functio::Able { params, body }
+                }
+                Functio::Chain { functios, kind } => {
+                    let (a, b) = *functios;
+                    Functio::Chain {
+                        functios: Box::new((
+                            (!Value::Functio(b)).into_functio(),
+                            (!Value::Functio(a)).into_functio(),
+                        )),
+                        kind,
+                    }
+                }
+                Functio::Eval(code) => Functio::Eval(code.chars().rev().collect()),
+            }),
+            Value::Cart(c) => Value::Cart(
+                c.into_iter()
+                    .map(|(k, v)| (v.borrow().clone(), Rc::new(RefCell::new(k))))
+                    .collect(),
+            ),
+        }
+    }
+}
+
+impl PartialEq for Value {
+    fn eq(&self, other: &Self) -> bool {
+        let other = other.clone();
+
+        match self {
+            Value::Nul => matches!(other, Value::Nul),
+            Value::Str(s) => *s == other.to_string(),
+            Value::Int(i) => *i == other.into_i32(),
+            Value::Bool(b) => *b == other.into_bool(),
+            Value::Abool(a) => *a == other.into_abool(),
+            Value::Functio(f) => *f == other.into_functio(),
+            Value::Cart(c) => *c == other.into_cart(),
+        }
+    }
+}
+
+impl Eq for Value {}
+
+impl PartialOrd for Value {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        use std::cmp::Ordering::*;
+        let other = other.clone();
+
+        match self {
+            Value::Nul => {
+                if other == Value::Nul {
+                    Some(Equal)
+                } else {
+                    None
+                }
+            }
+            Value::Str(s) => Some(s.cmp(&other.to_string())),
+            Value::Int(i) => Some(i.cmp(&other.into_i32())),
+            Value::Bool(b) => Some(b.cmp(&other.into_bool())),
+            Value::Abool(a) => a.partial_cmp(&other.into_abool()),
+            Value::Functio(_) => self.clone().into_i32().partial_cmp(&other.into_i32()),
+            Value::Cart(c) => Some(c.len().cmp(&other.into_cart().len())),
+        }
     }
 }
 
@@ -177,7 +787,7 @@ impl Display for Value {
             Value::Bool(v) => write!(f, "{}", v),
             Value::Abool(v) => write!(f, "{}", v),
             Value::Functio(v) => match v {
-                Functio::BfFunctio {
+                Functio::Bf {
                     instructions,
                     tape_len,
                 } => {
@@ -189,7 +799,7 @@ impl Display for Value {
                             .expect("Brainfuck functio source should be UTF-8")
                     )
                 }
-                Functio::AbleFunctio { params, body } => {
+                Functio::Able { params, body } => {
                     write!(
                         f,
                         "({}) -> {:?}",
@@ -199,12 +809,34 @@ impl Display for Value {
                         body,
                     )
                 }
+                Functio::Chain { functios, kind } => {
+                    let (a, b) = *functios.clone();
+                    write!(
+                        f,
+                        "{} {} {} ",
+                        Value::Functio(a),
+                        match kind {
+                            FunctioChainKind::Equal => '+',
+                            FunctioChainKind::ByArity => '*',
+                        },
+                        Value::Functio(b)
+                    )
+                }
+                Functio::Eval(s) => write!(f, "{}", s),
             },
             Value::Cart(c) => {
                 write!(f, "[")?;
+                let mut cart_vec = c.iter().collect::<Vec<_>>();
+                cart_vec.sort_by(|x, y| x.0.partial_cmp(y.0).unwrap_or(std::cmp::Ordering::Less));
 
-                for (key, value) in c {
+                for (idx, (key, value)) in cart_vec.into_iter().enumerate() {
-                    write!(f, "{} <= {},", value.borrow(), key)?;
+                    write!(
+                        f,
+                        "{}{} <= {}",
+                        if idx != 0 { ", " } else { "" },
+                        value.borrow(),
+                        key
+                    )?;
                 }
 
                 write!(f, "]")