615 lines
23 KiB
Rust
615 lines
23 KiB
Rust
use std::rc::Rc;
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use std::collections::BTreeMap;
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use std::fmt;
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use std::cell::RefCell;
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use anyhow::{anyhow,bail,Result};
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// This first Simple Lisp really is
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//
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// No fexprs, no mutation, no continuations, no macros, no strings.
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// Int/Bool/Nil/Pair/Symbol/Closure/Prim.
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//
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// Figuring out GC between a JIT and Rust will be tricky.
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// Can start with a like tracing-JIT-into-bytecode
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// Replcing Env with pairs or somesuch would make JIT interop easier I think, because we wouldn't
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// have to deal with refcell, but then we would again for mutation.
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// Maybe doing all allocation on the Rust side with #[no_mangle] functions would make things easier
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// mmmm no let's make our own Box, Rc, maybe Arc
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// rustonomicon
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// What if we're cute and use the ID
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// like we will eventually use value tagging
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// like, use the same encoding
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// interned symbols and all
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#[derive(Debug, Eq, PartialEq, Ord, PartialOrd, Clone, Copy)]
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pub struct ID {
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id: i64
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}
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impl fmt::Display for ID {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "{}", self.id)
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}
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}
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#[derive(Debug)]
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pub enum Form {
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Nil,
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Int(i32),
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Bool(bool),
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Symbol(String, RefCell<Option<ID>>),
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Pair(Rc<Form>, Rc<Form>, RefCell<Option<ID>>),
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Closure(Vec<String>, Rc<RefCell<Env>>, Rc<Form>, ID),
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Prim(Prim),
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}
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#[derive(Debug, Eq, PartialEq, Clone, Copy)]
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pub enum Prim {
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Add,
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Sub,
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Mul,
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Div,
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Mod,
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Eq,
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Cons,
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Car,
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Cdr,
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}
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impl Form {
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fn my_eq(&self, o: &Rc<Form>) -> bool {
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match self {
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Form::Nil => o.is_nil(),
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Form::Int(i) => if let Ok(oi) = o.int() { *i == oi } else { false },
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Form::Bool(b) => if let Ok(ob) = o.bool() { *b == ob } else { false },
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Form::Symbol(s, _id) => if let Ok(os) = o.sym() { s == os } else { false },
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Form::Pair(a,b,_id) => if let Ok((oa,ob)) = o.pair() { a.my_eq(&oa) && b.my_eq(&ob) } else { false },
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Form::Closure(_, _, _, _) => false,
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Form::Prim(p) => match &**o { Form::Prim(op) => p == op, _ => false },
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}
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}
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fn new_pair(car: Rc<Form>, cdr: Rc<Form>) -> Rc<Form> {
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Rc::new(Form::Pair(car, cdr, RefCell::new(None)))
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}
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fn new_nil() -> Rc<Form> {
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Rc::new(Form::Nil)
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}
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fn new_int(i: i32) -> Rc<Form> {
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Rc::new(Form::Int(i))
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}
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fn new_bool(b: bool) -> Rc<Form> {
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Rc::new(Form::Bool(b))
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}
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fn new_closure(params: Vec<String>, env: Rc<RefCell<Env>>, body: Rc<Form>, ctx: &mut Ctx) -> Rc<Form> {
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Rc::new(Form::Closure(params, env, body, ctx.alloc_id()))
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}
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fn truthy(&self) -> bool {
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match self {
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Form::Bool(b) => *b,
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Form::Nil => false,
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_ => true,
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}
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}
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fn bool(&self) -> Result<bool> {
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match self {
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Form::Bool(b) => Ok(*b),
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_ => Err(anyhow!("bool on not a bool")),
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}
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}
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fn int(&self) -> Result<i32> {
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match self {
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Form::Int(i) => Ok(*i),
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_ => Err(anyhow!("int on not a int")),
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}
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}
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fn prim(&self) -> Result<Prim> {
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match self {
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Form::Prim(p) => Ok(*p),
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_ => Err(anyhow!("prim on not a prim")),
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}
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}
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fn sym(&self) -> Result<&str> {
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match self {
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Form::Symbol(s, _id) => Ok(s),
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_ => Err(anyhow!("sym on not a sym")),
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}
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}
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fn pair(&self) -> Result<(Rc<Form>,Rc<Form>)> {
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match self {
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Form::Pair(car, cdr, _id) => Ok((Rc::clone(car),Rc::clone(cdr))),
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_ => Err(anyhow!("pair on not a pair")),
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}
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}
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fn car(&self) -> Result<Rc<Form>> {
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match self {
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Form::Pair(car, _cdr, _id) => Ok(Rc::clone(car)),
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_ => Err(anyhow!("car on not a pair")),
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}
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}
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fn cdr(&self) -> Result<Rc<Form>> {
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match self {
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Form::Pair(_car, cdr, _id) => Ok(Rc::clone(cdr)),
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_ => Err(anyhow!("cdr on not a pair")),
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}
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}
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fn is_nil(&self) -> bool {
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match self {
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Form::Nil => true,
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_ => false,
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}
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}
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pub fn append(&self, x: Rc<Form>) -> Result<Rc<Form>> {
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match self {
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Form::Pair(car, cdr, _id) => cdr.append(x).map(|x| Rc::new(Form::Pair(Rc::clone(car), x, RefCell::new(None)))),
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Form::Nil => Ok(Rc::new(Form::Pair(x, Rc::new(Form::Nil), RefCell::new(None)))),
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_ => Err(anyhow!("append to not a pair")),
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}
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}
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}
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#[derive(Debug)]
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pub struct Env {
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u: Option<Rc<RefCell<Env>>>,
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// split this into
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// BTreeMap<String, usize>
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// Vec<usize> so that traced code can refer by index
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m: BTreeMap<String, Rc<Form>>
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}
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impl Env {
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pub fn root_env() -> Rc<RefCell<Env>> {
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Rc::new(RefCell::new(Env {
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u: None,
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m: [
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("+", Rc::new(Form::Prim(Prim::Add))),
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("-", Rc::new(Form::Prim(Prim::Sub))),
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("*", Rc::new(Form::Prim(Prim::Mul))),
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("/", Rc::new(Form::Prim(Prim::Div))),
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("%", Rc::new(Form::Prim(Prim::Mod))),
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("cons", Rc::new(Form::Prim(Prim::Cons))),
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("cdr", Rc::new(Form::Prim(Prim::Cdr))),
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("car", Rc::new(Form::Prim(Prim::Car))),
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("=", Rc::new(Form::Prim(Prim::Eq))),
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("nil", Form::new_nil()),
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].into_iter().map(|(s,p)| (s.to_owned(), p)).collect()
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}))
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}
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pub fn chain(o: &Rc<RefCell<Env>>) -> Rc<RefCell<Env>> {
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Rc::new(RefCell::new(Env {
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u: Some(Rc::clone(o)),
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m: BTreeMap::new(),
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}))
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}
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pub fn lookup(&self, s: &str) -> Result<Rc<Form>> {
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if let Some(r) = self.m.get(s) {
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Ok(Rc::clone(r))
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} else if let Some(u) = &self.u {
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u.borrow().lookup(s)
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} else {
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bail!("lookup of {s} failed")
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}
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}
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pub fn define(&mut self, s: String, v: Rc<Form>) {
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// no mutation, shadowing in inner scope ok
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assert!(!self.m.contains_key(&s));
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self.m.insert(s, v);
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}
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}
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#[derive(Debug)]
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enum Op {
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Guard { const_value: Rc<Form>, side: (Option<Rc<Form>>, Rc<Cont>) },
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Debug,
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Define { sym: String },
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}
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impl fmt::Display for Op {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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match self {
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Op::Guard { const_value, side } => write!(f, "Guard"),
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Op::Debug => write!(f, "Debug"),
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Op::Define { sym } => write!(f, "Define {sym}"),
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}
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}
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}
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#[derive(Debug)]
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struct Trace {
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id: ID,
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// needs to track which are constants
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ops: Vec<Op>,
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}
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impl Trace {
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fn new(id: ID) -> Self {
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Trace { id, ops: vec![] }
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}
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}
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impl fmt::Display for Trace {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "Trace for {} [", self.id)?;
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for op in &self.ops {
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write!(f, " {}", op)?;
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}
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write!(f, " ]")?;
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Ok(())
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}
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}
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#[derive(Debug)]
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struct Ctx {
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id_counter: i64,
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func_calls: BTreeMap<ID, i64>,
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tracing: Option<Trace>,
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traces: BTreeMap<ID, Trace>,
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}
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impl fmt::Display for Ctx {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "Ctx")
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}
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}
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impl Ctx {
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fn new() -> Ctx {
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Ctx {
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id_counter: 0,
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func_calls: BTreeMap::new(),
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tracing: None,
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traces: BTreeMap::new(),
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}
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}
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fn alloc_id(&mut self) -> ID {
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self.id_counter += 1;
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ID { id: self.id_counter }
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}
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fn trace_running(&self) -> bool { self.tracing.is_some() }
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fn trace_call_start(&mut self, id: ID) {
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// Needs to take and use parameters for mid-trace
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// needs to guard on function called if non-constant
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let entry = self.func_calls.entry(id).or_insert(0);
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println!("tracing call start for {id}, has been called {} times so far", *entry);
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*entry += 1;
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if let Some(trace) = &self.tracing {
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if trace.id == id {
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println!("Ending trace at recursive call!");
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println!("\t{}", trace);
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self.traces.insert(id, self.tracing.take().unwrap());
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}
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} else if *entry > 1 && self.traces.get(&id).is_none() {
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self.tracing = Some(Trace::new(id));
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}
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}
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fn trace_call_end(&mut self, id: ID) {
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// associate with it or something
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println!("tracing call end for {id}");
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if let Some(trace) = &self.tracing {
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if trace.id == id {
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println!("Ending trace at end of call!");
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println!("\t{}", trace);
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self.traces.insert(id, self.tracing.take().unwrap());
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}
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}
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}
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fn trace_guard<T: Into<Form> + std::fmt::Debug >(&mut self, value: T, other: impl Fn()->(Option<Rc<Form>>,Rc<Cont>)) {
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println!("Tracing guard {value:?}");
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if let Some(trace) = &mut self.tracing {
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trace.ops.push(Op::Guard { const_value: Rc::new(value.into()), side: other() });
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}
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}
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fn trace_debug(&mut self) {
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if let Some(trace) = &mut self.tracing {
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trace.ops.push(Op::Debug);
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}
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}
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fn trace_define(&mut self, sym: &str) {
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if let Some(trace) = &mut self.tracing {
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trace.ops.push(Op::Define { sym: sym.to_owned() });
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}
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}
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fn trace_call_bit(&mut self) {
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if let Some(trace) = &mut self.tracing {
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// TODO
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}
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}
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// Trace call start, of course, handles the other side!
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// Though I guess that means call start should recieve the parameters
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// also, for like variables, it should guard on what function
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// if dynamic, interacts with the constant tracking
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fn trace_prim(&mut self, p: &Prim) {
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if let Some(trace) = &mut self.tracing {
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// TODO
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}
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}
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fn trace_lookup(&mut self, s: &str) {
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if let Some(trace) = &mut self.tracing {
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// TODO
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}
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}
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fn trace_constant(&mut self, c: &Rc<Form>) {
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if let Some(trace) = &mut self.tracing {
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// TODO
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}
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}
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fn trace_lambda(&mut self, params: &[String], e: &Rc<RefCell<Env>>, body: &Rc<Form>) {
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if let Some(trace) = &mut self.tracing {
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// TODO
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}
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}
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}
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#[derive(Clone,Debug)]
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enum Cont {
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MetaRet,
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Ret { e: Rc<RefCell<Env>>, id: ID, c: Rc<Cont> },
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Eval { c: Rc<Cont> },
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Prim { s: &'static str, to_go: Rc<Form>, c: Rc<Cont> },
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Call { evaled: Vec<Rc<Form>>, to_go: Rc<Form>, c: Rc<Cont> },
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}
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pub fn eval(f: Rc<Form>) -> Result<Rc<Form>> {
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let mut ctx = Ctx::new();
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let mut f = f;
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let mut e = Env::root_env();
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let mut c = Cont::Eval { c: Rc::new(Cont::MetaRet) };
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loop {
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match c {
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Cont::MetaRet => {
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println!("Ctx was {ctx}");
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assert!(!ctx.trace_running());
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return Ok(f);
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}
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Cont::Ret { e: ne, id, c: nc } => {
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ctx.trace_call_end(id);
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e = ne;
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c = (*nc).clone();
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},
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Cont::Prim { s, to_go, c: nc } => {
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match s {
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"if" => {
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let thn = to_go.car()?;
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let els = to_go.cdr()?.car()?;
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if f.truthy() {
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ctx.trace_guard(true, || (Some(Rc::clone(&els)), Rc::new(Cont::Eval { c: Rc::clone(&nc) })));
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f = thn;
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} else {
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ctx.trace_guard(false, ||(Some(Rc::clone(&thn)), Rc::new(Cont::Eval { c: Rc::clone(&nc) })));
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f = els;
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}
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c = Cont::Eval { c: nc };
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},
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"or" => {
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let other = to_go.car()?;
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if !f.truthy() {
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ctx.trace_guard(false, || (None, nc.clone()));
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f = other;
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c = Cont::Eval { c: nc };
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} else {
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ctx.trace_guard(true, || (Some(Rc::clone(&other)), Rc::new(Cont::Eval { c: Rc::clone(&nc) })));
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c = (*nc).clone();
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}
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},
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"and" => {
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let other = to_go.car()?;
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if f.truthy() {
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ctx.trace_guard(true, || (None, nc.clone()));
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f = other;
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c = Cont::Eval { c: nc };
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} else {
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ctx.trace_guard(false, || (Some(Rc::clone(&other)), Rc::new(Cont::Eval { c: Rc::clone(&nc) })));
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c = (*nc).clone();
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}
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},
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"begin" => {
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if to_go.is_nil() {
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c = (*nc).clone();
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} else {
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f = to_go.car()?;
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c = Cont::Eval { c: Rc::new(Cont::Prim { s: "begin", to_go: to_go.cdr()?, c: nc }) };
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}
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},
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"debug" => {
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println!("Debug: {f}");
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ctx.trace_debug();
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c = (*nc).clone();
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},
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"define" => {
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let sym = to_go.sym()?.to_string();
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ctx.trace_define(&sym);
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e.borrow_mut().define(sym, Rc::clone(&f));
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c = (*nc).clone();
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},
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_ => {
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panic!("bad prim {s}");
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}
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}
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},
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Cont::Call { mut evaled, to_go, c: nc } => {
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ctx.trace_call_bit();
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evaled.push(f);
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if to_go.is_nil() {
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// do call
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let arg_len = evaled.len() - 1;
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let mut evaled_iter = evaled.into_iter();
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let comb = evaled_iter.next().unwrap();
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match &*comb {
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Form::Closure(ps, ie, b, id) => {
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if ps.len() != arg_len {
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bail!("arguments length doesn't match");
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}
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let new_env = Env::chain(&ie);
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for (name, value) in ps.iter().zip(evaled_iter) {
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new_env.borrow_mut().define(name.to_string(), value);
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}
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ctx.trace_call_start(*id);
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c = Cont::Eval { c: Rc::new(Cont::Ret { e: Rc::clone(&e), id: *id, c: nc }) };
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f = Rc::clone(&b);
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e = new_env;
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},
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Form::Prim(p) => {
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ctx.trace_prim(p);
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let a = evaled_iter.next().unwrap();
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f = match comb.prim().unwrap() {
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Prim::Car => a.car()?,
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Prim::Cdr => a.cdr()?,
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_ => {
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let b = evaled_iter.next().unwrap();
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match comb.prim().unwrap() {
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Prim::Add => Form::new_int(a.int()? + b.int()?),
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Prim::Sub => Form::new_int(a.int()? - b.int()?),
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Prim::Mul => Form::new_int(a.int()? * b.int()?),
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Prim::Div => Form::new_int(a.int()? / b.int()?),
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Prim::Mod => Form::new_int(a.int()? % b.int()?),
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Prim::Cons => Form::new_pair(a, b),
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Prim::Eq => Form::new_bool(a.my_eq(&b)),
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_ => unreachable!(),
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}
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}
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};
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c = (*nc).clone();
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},
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_ => {
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bail!("tried to call a non-comb {}", comb)
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},
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}
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} else {
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f = to_go.car()?;
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c = Cont::Eval { c: Rc::new(Cont::Call { evaled, to_go: to_go.cdr()?, c: nc }) };
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}
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}
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Cont::Eval { c: nc } => {
|
|
let tmp = f;
|
|
match &*tmp {
|
|
Form::Symbol(s, _id) => {
|
|
ctx.trace_lookup(s);
|
|
f = e.borrow().lookup(s)?;
|
|
c = (*nc).clone();
|
|
},
|
|
Form::Pair(car, cdr, _id) => {
|
|
match &**car {
|
|
Form::Symbol(s, _id) if s == "if" => {
|
|
f = cdr.car()?;
|
|
c = Cont::Eval { c: Rc::new(Cont::Prim { s: "if", to_go: cdr.cdr()?, c: nc }) };
|
|
}
|
|
// and/or has to short-circut, so special form
|
|
// just like Scheme (bad ;) )
|
|
Form::Symbol(s, _id) if s == "or" => {
|
|
f = cdr.car()?;
|
|
c = Cont::Eval { c: Rc::new(Cont::Prim { s: "or", to_go: cdr.cdr()?, c: nc }) };
|
|
}
|
|
Form::Symbol(s, _id) if s == "and" => {
|
|
f = cdr.car()?;
|
|
c = Cont::Eval { c: Rc::new(Cont::Prim { s: "and", to_go: cdr.cdr()?, c: nc }) };
|
|
}
|
|
Form::Symbol(s, _id) if s == "begin" => {
|
|
f = cdr.car()?;
|
|
c = Cont::Eval { c: Rc::new(Cont::Prim { s: "begin", to_go: cdr.cdr()?, c: nc }) };
|
|
}
|
|
Form::Symbol(s, _id) if s == "debug" => {
|
|
f = cdr.car()?;
|
|
c = Cont::Eval { c: Rc::new(Cont::Prim { s: "debug", to_go: cdr.cdr()?, c: nc }) };
|
|
}
|
|
// This is a fast and loose ~simple lisp~, so just go for it
|
|
// and can have convention that this is always top levelish
|
|
Form::Symbol(s, _id) if s == "define" => {
|
|
// note the swap, evaluating the second not the first (define a value..)
|
|
f = cdr.cdr()?.car()?;
|
|
c = Cont::Eval { c: Rc::new(Cont::Prim { s: "define", to_go: cdr.car()?, c: nc }) };
|
|
}
|
|
Form::Symbol(s, _id) if s == "quote" => {
|
|
f = cdr.car()?;
|
|
ctx.trace_constant(&f);
|
|
c = (*nc).clone();
|
|
}
|
|
// (lambda (a b) body)
|
|
Form::Symbol(s, _id) if s == "lambda" => {
|
|
let mut params_vec = vec![];
|
|
let mut params = cdr.car()?;
|
|
while let Ok((ncar, ncdr)) = params.pair() {
|
|
params_vec.push(ncar.sym()?.to_string());
|
|
params = ncdr;
|
|
}
|
|
let body = cdr.cdr()?.car()?;
|
|
// Later on, the id of the closure should maybe be augmented
|
|
// or replaced with the id of the code it was made out of?
|
|
ctx.trace_lambda(¶ms_vec, &e, &body);
|
|
f = Form::new_closure(params_vec, Rc::clone(&e), body, &mut ctx);
|
|
c = (*nc).clone();
|
|
}
|
|
_ => {
|
|
f = Rc::clone(car);
|
|
c = Cont::Eval { c: Rc::new(Cont::Call { evaled: vec![], to_go: Rc::clone(cdr), c: nc }) };
|
|
}
|
|
}
|
|
},
|
|
_ => {
|
|
// value, no eval
|
|
f = tmp;
|
|
ctx.trace_constant(&f);
|
|
c = (*nc).clone();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// optimized as a function based off side table of id keyed -> opt
|
|
// that id might be nice for debugging too
|
|
// Symbol ID's could actually be used for environment lookups
|
|
// this is just interning
|
|
// todo, strings not symbols?
|
|
impl From<String> for Form { fn from(item: String) -> Self { Form::Symbol(item, RefCell::new(None)) } }
|
|
impl From<&str> for Form { fn from(item: &str) -> Self { Form::Symbol(item.to_owned(), RefCell::new(None)) } }
|
|
impl From<i32> for Form { fn from(item: i32) -> Self { Form::Int(item) } }
|
|
impl From<bool> for Form { fn from(item: bool) -> Self { Form::Bool(item) } }
|
|
impl<A: Into<Form>, B: Into<Form>> From<(A, B)> for Form {
|
|
fn from(item: (A, B)) -> Self {
|
|
Form::Pair(Rc::new(item.0.into()), Rc::new(item.1.into()), RefCell::new(None))
|
|
}
|
|
}
|
|
|
|
impl fmt::Display for Form {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
match self {
|
|
Form::Nil => write!(f, "nil"),
|
|
Form::Int(i) => write!(f, "{i}"),
|
|
Form::Bool(b) => write!(f, "{b}"),
|
|
Form::Symbol(s, _id) => write!(f, "'{s}"),
|
|
Form::Pair(car, cdr, _id) => {
|
|
write!(f, "({}", car)?;
|
|
let mut traverse: Rc<Form> = Rc::clone(cdr);
|
|
loop {
|
|
match &*traverse {
|
|
Form::Pair(ref carp, ref cdrp, ref _id) => {
|
|
write!(f, " {}", carp)?;
|
|
traverse = Rc::clone(cdrp);
|
|
},
|
|
Form::Nil => {
|
|
write!(f, ")")?;
|
|
return Ok(());
|
|
},
|
|
x => {
|
|
write!(f, ". {x})")?;
|
|
return Ok(());
|
|
},
|
|
}
|
|
}
|
|
},
|
|
Form::Closure(params, inner_env, code, id) => {
|
|
write!(f, "<closure{} {:?}>", id, params)
|
|
}
|
|
Form::Prim(p) => {
|
|
match p {
|
|
Prim::Add => write!(f, "+"),
|
|
Prim::Sub => write!(f, "-"),
|
|
Prim::Mul => write!(f, "*"),
|
|
Prim::Div => write!(f, "/"),
|
|
Prim::Mod => write!(f, "%"),
|
|
Prim::Cons => write!(f, "cons"),
|
|
Prim::Car => write!(f, "car"),
|
|
Prim::Cdr => write!(f, "cdr"),
|
|
Prim::Eq => write!(f, "="),
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|