Break down forth implementation properly

src/model/forth/compiler.rs

@@ -0,0 +1,282 @@
+use super::ops::Op;
+use super::types::{Dictionary, SourceSpan};
+use super::words::{compile_word, simple_op};
+
+#[derive(Clone, Debug)]
+enum Token {
+    Int(i64, SourceSpan),
+    Float(f64, SourceSpan),
+    Str(String, SourceSpan),
+    Word(String, SourceSpan),
+    QuoteStart(usize),
+    QuoteEnd(usize),
+}
+
+pub(super) fn compile_script(input: &str, dict: &Dictionary) -> Result<Vec<Op>, String> {
+    let tokens = tokenize(input);
+    compile(&tokens, dict)
+}
+
+fn tokenize(input: &str) -> Vec<Token> {
+    let mut tokens = Vec::new();
+    let mut chars = input.char_indices().peekable();
+
+    while let Some(&(pos, c)) = chars.peek() {
+        if c.is_whitespace() {
+            chars.next();
+            continue;
+        }
+
+        if c == '"' {
+            let start = pos;
+            chars.next();
+            let mut s = String::new();
+            let mut end = start + 1;
+            while let Some(&(i, ch)) = chars.peek() {
+                end = i + ch.len_utf8();
+                chars.next();
+                if ch == '"' {
+                    break;
+                }
+                s.push(ch);
+            }
+            tokens.push(Token::Str(s, SourceSpan { start, end }));
+            continue;
+        }
+
+        if c == '(' {
+            while let Some(&(_, ch)) = chars.peek() {
+                chars.next();
+                if ch == ')' {
+                    break;
+                }
+            }
+            continue;
+        }
+
+        if c == '{' {
+            chars.next();
+            tokens.push(Token::QuoteStart(pos));
+            continue;
+        }
+
+        if c == '}' {
+            chars.next();
+            tokens.push(Token::QuoteEnd(pos));
+            continue;
+        }
+
+        let start = pos;
+        let mut word = String::new();
+        let mut end = start;
+        while let Some(&(i, ch)) = chars.peek() {
+            if ch.is_whitespace() || ch == '{' || ch == '}' {
+                break;
+            }
+            end = i + ch.len_utf8();
+            word.push(ch);
+            chars.next();
+        }
+
+        let span = SourceSpan { start, end };
+        if let Ok(i) = word.parse::<i64>() {
+            tokens.push(Token::Int(i, span));
+        } else if let Ok(f) = word.parse::<f64>() {
+            tokens.push(Token::Float(f, span));
+        } else {
+            tokens.push(Token::Word(word, span));
+        }
+    }
+
+    tokens
+}
+
+fn compile(tokens: &[Token], dict: &Dictionary) -> Result<Vec<Op>, String> {
+    let mut ops = Vec::new();
+    let mut i = 0;
+    let mut pipe_parity = false;
+    let mut list_depth: usize = 0;
+
+    while i < tokens.len() {
+        match &tokens[i] {
+            Token::Int(n, span) => ops.push(Op::PushInt(*n, Some(*span))),
+            Token::Float(f, span) => ops.push(Op::PushFloat(*f, Some(*span))),
+            Token::Str(s, span) => ops.push(Op::PushStr(s.clone(), Some(*span))),
+            Token::QuoteStart(start_pos) => {
+                let (quote_ops, consumed, end_pos) = compile_quotation(&tokens[i + 1..], dict)?;
+                i += consumed;
+                let body_span = SourceSpan { start: *start_pos, end: end_pos + 1 };
+                ops.push(Op::Quotation(quote_ops, Some(body_span)));
+            }
+            Token::QuoteEnd(_) => {
+                return Err("unexpected }".into());
+            }
+            Token::Word(w, span) => {
+                let word = w.as_str();
+                if word == ":" {
+                    let (consumed, name, body) = compile_colon_def(&tokens[i + 1..], dict)?;
+                    i += consumed;
+                    dict.lock().unwrap().insert(name, body);
+                } else if word == ";" {
+                    return Err("unexpected ;".into());
+                } else if word == "|" {
+                    if pipe_parity {
+                        ops.push(Op::LocalCycleEnd);
+                        list_depth = list_depth.saturating_sub(1);
+                    } else {
+                        ops.push(Op::ListStart);
+                        list_depth += 1;
+                    }
+                    pipe_parity = !pipe_parity;
+                } else if word == "if" {
+                    let (then_ops, else_ops, consumed, then_span, else_span) = compile_if(&tokens[i + 1..], dict)?;
+                    i += consumed;
+                    if else_ops.is_empty() {
+                        ops.push(Op::BranchIfZero(then_ops.len(), then_span, None));
+                        ops.extend(then_ops);
+                    } else {
+                        ops.push(Op::BranchIfZero(then_ops.len() + 1, then_span, else_span));
+                        ops.extend(then_ops);
+                        ops.push(Op::Branch(else_ops.len()));
+                        ops.extend(else_ops);
+                    }
+                } else if is_list_start(word) {
+                    ops.push(Op::ListStart);
+                    list_depth += 1;
+                } else if is_list_end(word) {
+                    list_depth = list_depth.saturating_sub(1);
+                    if let Some(op) = simple_op(word) {
+                        ops.push(op);
+                    }
+                } else if list_depth > 0 {
+                    let mut word_ops = Vec::new();
+                    if !compile_word(word, Some(*span), &mut word_ops, dict) {
+                        return Err(format!("unknown word: {word}"));
+                    }
+                    ops.push(Op::Quotation(word_ops, Some(*span)));
+                } else if !compile_word(word, Some(*span), &mut ops, dict) {
+                    return Err(format!("unknown word: {word}"));
+                }
+            }
+        }
+        i += 1;
+    }
+
+    Ok(ops)
+}
+
+fn is_list_start(word: &str) -> bool {
+    matches!(word, "[" | "<" | "<<")
+}
+
+fn is_list_end(word: &str) -> bool {
+    matches!(word, "]" | ">" | ">>")
+}
+
+fn compile_quotation(tokens: &[Token], dict: &Dictionary) -> Result<(Vec<Op>, usize, usize), String> {
+    let mut depth = 1;
+    let mut end_idx = None;
+
+    for (i, tok) in tokens.iter().enumerate() {
+        match tok {
+            Token::QuoteStart(_) => depth += 1,
+            Token::QuoteEnd(_) => {
+                depth -= 1;
+                if depth == 0 {
+                    end_idx = Some(i);
+                    break;
+                }
+            }
+            _ => {}
+        }
+    }
+
+    let end_idx = end_idx.ok_or("missing }")?;
+    let byte_pos = match &tokens[end_idx] {
+        Token::QuoteEnd(pos) => *pos,
+        _ => unreachable!(),
+    };
+    let quote_ops = compile(&tokens[..end_idx], dict)?;
+    Ok((quote_ops, end_idx + 1, byte_pos))
+}
+
+fn token_span(tok: &Token) -> Option<SourceSpan> {
+    match tok {
+        Token::Int(_, s) | Token::Float(_, s) | Token::Str(_, s) | Token::Word(_, s) => Some(*s),
+        Token::QuoteStart(p) => Some(SourceSpan { start: *p, end: *p + 1 }),
+        Token::QuoteEnd(p) => Some(SourceSpan { start: *p, end: *p + 1 }),
+    }
+}
+
+fn compile_colon_def(tokens: &[Token], dict: &Dictionary) -> Result<(usize, String, Vec<Op>), String> {
+    if tokens.is_empty() {
+        return Err("expected word name after ':'".into());
+    }
+    let name = match &tokens[0] {
+        Token::Word(w, _) => w.clone(),
+        _ => return Err("expected word name after ':'".into()),
+    };
+    let mut semi_pos = None;
+    for (i, tok) in tokens[1..].iter().enumerate() {
+        if let Token::Word(w, _) = tok {
+            if w == ";" {
+                semi_pos = Some(i + 1);
+                break;
+            }
+        }
+    }
+    let semi_pos = semi_pos.ok_or("missing ';' in word definition")?;
+    let body_tokens = &tokens[1..semi_pos];
+    let body_ops = compile(body_tokens, dict)?;
+    // consumed = name + body + semicolon
+    Ok((semi_pos + 1, name, body_ops))
+}
+
+fn tokens_span(tokens: &[Token]) -> Option<SourceSpan> {
+    let first = tokens.first().and_then(token_span)?;
+    let last = tokens.last().and_then(token_span)?;
+    Some(SourceSpan { start: first.start, end: last.end })
+}
+
+#[allow(clippy::type_complexity)]
+fn compile_if(tokens: &[Token], dict: &Dictionary) -> Result<(Vec<Op>, Vec<Op>, usize, Option<SourceSpan>, Option<SourceSpan>), String> {
+    let mut depth = 1;
+    let mut else_pos = None;
+    let mut then_pos = None;
+
+    for (i, tok) in tokens.iter().enumerate() {
+        if let Token::Word(w, _) = tok {
+            match w.as_str() {
+                "if" => depth += 1,
+                "else" if depth == 1 => else_pos = Some(i),
+                "then" => {
+                    depth -= 1;
+                    if depth == 0 {
+                        then_pos = Some(i);
+                        break;
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+
+    let then_pos = then_pos.ok_or("missing 'then'")?;
+
+    let (then_ops, else_ops, then_span, else_span) = if let Some(ep) = else_pos {
+        let then_slice = &tokens[..ep];
+        let else_slice = &tokens[ep + 1..then_pos];
+        let then_span = tokens_span(then_slice);
+        let else_span = tokens_span(else_slice);
+        let then_ops = compile(then_slice, dict)?;
+        let else_ops = compile(else_slice, dict)?;
+        (then_ops, else_ops, then_span, else_span)
+    } else {
+        let then_slice = &tokens[..then_pos];
+        let then_span = tokens_span(then_slice);
+        let then_ops = compile(then_slice, dict)?;
+        (then_ops, Vec::new(), then_span, None)
+    };
+
+    Ok((then_ops, else_ops, then_pos + 1, then_span, else_span))
+}

src/model/forth/mod.rs

@@ -0,0 +1,11 @@
+mod compiler;
+mod ops;
+mod types;
+mod vm;
+mod words;
+
+pub use types::{Dictionary, ExecutionTrace, Rng, SourceSpan, StepContext, Variables};
+#[allow(unused_imports)]
+pub use types::Value;
+pub use vm::Forth;
+pub use words::{Word, WordCompile, WORDS};

src/model/forth/ops.rs

@@ -0,0 +1,79 @@
+use super::types::SourceSpan;
+
+#[derive(Clone, Debug, PartialEq)]
+pub enum Op {
+    PushInt(i64, Option<SourceSpan>),
+    PushFloat(f64, Option<SourceSpan>),
+    PushStr(String, Option<SourceSpan>),
+    Dup,
+    Dupn,
+    Drop,
+    Swap,
+    Over,
+    Rot,
+    Nip,
+    Tuck,
+    Add,
+    Sub,
+    Mul,
+    Div,
+    Mod,
+    Neg,
+    Abs,
+    Floor,
+    Ceil,
+    Round,
+    Min,
+    Max,
+    Eq,
+    Ne,
+    Lt,
+    Gt,
+    Le,
+    Ge,
+    And,
+    Or,
+    Not,
+    BranchIfZero(usize, Option<SourceSpan>, Option<SourceSpan>),
+    Branch(usize),
+    NewCmd,
+    SetParam(String),
+    Emit,
+    Get,
+    Set,
+    GetContext(String),
+    Rand,
+    Rrand,
+    Seed,
+    Cycle,
+    Choose,
+    ChanceExec,
+    ProbExec,
+    Coin,
+    Mtof,
+    Ftom,
+    ListStart,
+    ListEnd,
+    ListEndCycle,
+    PCycle,
+    ListEndPCycle,
+    At,
+    Window,
+    Scale,
+    Pop,
+    Subdivide,
+    SetTempo,
+    Each,
+    Every,
+    Quotation(Vec<Op>, Option<SourceSpan>),
+    When,
+    Unless,
+    Adsr,
+    Ad,
+    Stack,
+    For,
+    LocalCycleEnd,
+    Echo,
+    Necho,
+    Apply,
+}

src/model/forth/types.rs

@@ -0,0 +1,141 @@
+use rand::rngs::StdRng;
+use std::collections::HashMap;
+use std::sync::{Arc, Mutex};
+
+use super::ops::Op;
+
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub struct SourceSpan {
+    pub start: usize,
+    pub end: usize,
+}
+
+#[derive(Clone, Debug, Default)]
+pub struct ExecutionTrace {
+    pub executed_spans: Vec<SourceSpan>,
+    pub selected_spans: Vec<SourceSpan>,
+}
+
+pub struct StepContext {
+    pub step: usize,
+    pub beat: f64,
+    pub pattern: usize,
+    pub tempo: f64,
+    pub phase: f64,
+    pub slot: usize,
+    pub runs: usize,
+    pub iter: usize,
+    pub speed: f64,
+    pub fill: bool,
+}
+
+impl StepContext {
+    pub fn step_duration(&self) -> f64 {
+        60.0 / self.tempo / 4.0 / self.speed
+    }
+}
+
+pub type Variables = Arc<Mutex<HashMap<String, Value>>>;
+pub type Dictionary = Arc<Mutex<HashMap<String, Vec<Op>>>>;
+pub type Rng = Arc<Mutex<StdRng>>;
+pub type Stack = Arc<Mutex<Vec<Value>>>;
+
+#[derive(Clone, Debug)]
+pub enum Value {
+    Int(i64, Option<SourceSpan>),
+    Float(f64, Option<SourceSpan>),
+    Str(String, Option<SourceSpan>),
+    Marker,
+    Quotation(Vec<Op>, Option<SourceSpan>),
+}
+
+impl PartialEq for Value {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Value::Int(a, _), Value::Int(b, _)) => a == b,
+            (Value::Float(a, _), Value::Float(b, _)) => a == b,
+            (Value::Str(a, _), Value::Str(b, _)) => a == b,
+            (Value::Marker, Value::Marker) => true,
+            (Value::Quotation(a, _), Value::Quotation(b, _)) => a == b,
+            _ => false,
+        }
+    }
+}
+
+impl Value {
+    pub fn as_float(&self) -> Result<f64, String> {
+        match self {
+            Value::Float(f, _) => Ok(*f),
+            Value::Int(i, _) => Ok(*i as f64),
+            _ => Err("expected number".into()),
+        }
+    }
+
+    pub(super) fn as_int(&self) -> Result<i64, String> {
+        match self {
+            Value::Int(i, _) => Ok(*i),
+            Value::Float(f, _) => Ok(*f as i64),
+            _ => Err("expected number".into()),
+        }
+    }
+
+    pub(super) fn as_str(&self) -> Result<&str, String> {
+        match self {
+            Value::Str(s, _) => Ok(s),
+            _ => Err("expected string".into()),
+        }
+    }
+
+    pub(super) fn is_truthy(&self) -> bool {
+        match self {
+            Value::Int(i, _) => *i != 0,
+            Value::Float(f, _) => *f != 0.0,
+            Value::Str(s, _) => !s.is_empty(),
+            Value::Marker => false,
+            Value::Quotation(..) => true,
+        }
+    }
+
+    pub(super) fn is_marker(&self) -> bool {
+        matches!(self, Value::Marker)
+    }
+
+    pub(super) fn to_param_string(&self) -> String {
+        match self {
+            Value::Int(i, _) => i.to_string(),
+            Value::Float(f, _) => f.to_string(),
+            Value::Str(s, _) => s.clone(),
+            Value::Marker => String::new(),
+            Value::Quotation(..) => String::new(),
+        }
+    }
+
+    pub(super) fn span(&self) -> Option<SourceSpan> {
+        match self {
+            Value::Int(_, s) | Value::Float(_, s) | Value::Str(_, s) => *s,
+            Value::Marker | Value::Quotation(..) => None,
+        }
+    }
+}
+
+#[derive(Clone, Debug, Default)]
+pub(super) struct CmdRegister {
+    sound: Option<String>,
+    params: Vec<(String, String)>,
+}
+
+impl CmdRegister {
+    pub(super) fn set_sound(&mut self, name: String) {
+        self.sound = Some(name);
+    }
+
+    pub(super) fn set_param(&mut self, key: String, value: String) {
+        self.params.push((key, value));
+    }
+
+    pub(super) fn take(&mut self) -> Option<(String, Vec<(String, String)>)> {
+        let sound = self.sound.take()?;
+        let params = std::mem::take(&mut self.params);
+        Some((sound, params))
+    }
+}

src/model/forth/vm.rs

@@ -0,0 +1,920 @@
+use rand::rngs::StdRng;
+use rand::{Rng as RngTrait, SeedableRng};
+
+use super::compiler::compile_script;
+use super::ops::Op;
+use super::types::{
+    CmdRegister, Dictionary, ExecutionTrace, Rng, Stack, StepContext, Value, Variables,
+};
+
+#[derive(Clone, Debug)]
+struct TimeContext {
+    start: f64,
+    duration: f64,
+    subdivisions: Option<Vec<(f64, f64)>>,
+    iteration_index: Option<usize>,
+}
+
+pub struct Forth {
+    stack: Stack,
+    vars: Variables,
+    dict: Dictionary,
+    rng: Rng,
+}
+
+impl Forth {
+    pub fn new(vars: Variables, dict: Dictionary, rng: Rng) -> Self {
+        Self {
+            stack: std::sync::Arc::new(std::sync::Mutex::new(Vec::new())),
+            vars,
+            dict,
+            rng,
+        }
+    }
+
+    #[allow(dead_code)]
+    pub fn stack(&self) -> Vec<Value> {
+        self.stack.lock().unwrap().clone()
+    }
+
+    #[allow(dead_code)]
+    pub fn clear_stack(&self) {
+        self.stack.lock().unwrap().clear();
+    }
+
+    pub fn evaluate(&self, script: &str, ctx: &StepContext) -> Result<Vec<String>, String> {
+        self.evaluate_impl(script, ctx, None)
+    }
+
+    pub fn evaluate_with_trace(
+        &self,
+        script: &str,
+        ctx: &StepContext,
+        trace: &mut ExecutionTrace,
+    ) -> Result<Vec<String>, String> {
+        self.evaluate_impl(script, ctx, Some(trace))
+    }
+
+    fn evaluate_impl(
+        &self,
+        script: &str,
+        ctx: &StepContext,
+        trace: Option<&mut ExecutionTrace>,
+    ) -> Result<Vec<String>, String> {
+        if script.trim().is_empty() {
+            return Err("empty script".into());
+        }
+
+        let ops = compile_script(script, &self.dict)?;
+        self.execute(&ops, ctx, trace)
+    }
+
+    fn execute(
+        &self,
+        ops: &[Op],
+        ctx: &StepContext,
+        trace: Option<&mut ExecutionTrace>,
+    ) -> Result<Vec<String>, String> {
+        let mut stack = self.stack.lock().unwrap();
+        let mut outputs: Vec<String> = Vec::new();
+        let mut time_stack: Vec<TimeContext> = vec![TimeContext {
+            start: 0.0,
+            duration: ctx.step_duration() * 4.0,
+            subdivisions: None,
+            iteration_index: None,
+        }];
+        let mut cmd = CmdRegister::default();
+
+        self.execute_ops(
+            ops,
+            ctx,
+            &mut stack,
+            &mut outputs,
+            &mut time_stack,
+            &mut cmd,
+            trace,
+        )?;
+
+        Ok(outputs)
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn execute_ops(
+        &self,
+        ops: &[Op],
+        ctx: &StepContext,
+        stack: &mut Vec<Value>,
+        outputs: &mut Vec<String>,
+        time_stack: &mut Vec<TimeContext>,
+        cmd: &mut CmdRegister,
+        trace: Option<&mut ExecutionTrace>,
+    ) -> Result<(), String> {
+        let mut pc = 0;
+        let trace_cell = std::cell::RefCell::new(trace);
+
+        while pc < ops.len() {
+            match &ops[pc] {
+                Op::PushInt(n, span) => stack.push(Value::Int(*n, *span)),
+                Op::PushFloat(f, span) => stack.push(Value::Float(*f, *span)),
+                Op::PushStr(s, span) => stack.push(Value::Str(s.clone(), *span)),
+
+                Op::Dup => {
+                    let v = stack.last().ok_or("stack underflow")?.clone();
+                    stack.push(v);
+                }
+                Op::Dupn => {
+                    let n = stack.pop().ok_or("stack underflow")?.as_int()?;
+                    let v = stack.pop().ok_or("stack underflow")?;
+                    for _ in 0..n {
+                        stack.push(v.clone());
+                    }
+                }
+                Op::Drop => {
+                    stack.pop().ok_or("stack underflow")?;
+                }
+                Op::Swap => {
+                    let len = stack.len();
+                    if len < 2 {
+                        return Err("stack underflow".into());
+                    }
+                    stack.swap(len - 1, len - 2);
+                }
+                Op::Over => {
+                    let len = stack.len();
+                    if len < 2 {
+                        return Err("stack underflow".into());
+                    }
+                    let v = stack[len - 2].clone();
+                    stack.push(v);
+                }
+                Op::Rot => {
+                    let len = stack.len();
+                    if len < 3 {
+                        return Err("stack underflow".into());
+                    }
+                    let v = stack.remove(len - 3);
+                    stack.push(v);
+                }
+                Op::Nip => {
+                    let len = stack.len();
+                    if len < 2 {
+                        return Err("stack underflow".into());
+                    }
+                    stack.remove(len - 2);
+                }
+                Op::Tuck => {
+                    let len = stack.len();
+                    if len < 2 {
+                        return Err("stack underflow".into());
+                    }
+                    let v = stack[len - 1].clone();
+                    stack.insert(len - 2, v);
+                }
+
+                Op::Add => binary_op(stack, |a, b| a + b)?,
+                Op::Sub => binary_op(stack, |a, b| a - b)?,
+                Op::Mul => binary_op(stack, |a, b| a * b)?,
+                Op::Div => binary_op(stack, |a, b| a / b)?,
+                Op::Mod => {
+                    let b = stack.pop().ok_or("stack underflow")?.as_int()?;
+                    let a = stack.pop().ok_or("stack underflow")?.as_int()?;
+                    stack.push(Value::Int(a % b, None));
+                }
+                Op::Neg => {
+                    let v = stack.pop().ok_or("stack underflow")?;
+                    match v {
+                        Value::Int(i, s) => stack.push(Value::Int(-i, s)),
+                        Value::Float(f, s) => stack.push(Value::Float(-f, s)),
+                        _ => return Err("expected number".into()),
+                    }
+                }
+                Op::Abs => {
+                    let v = stack.pop().ok_or("stack underflow")?;
+                    match v {
+                        Value::Int(i, s) => stack.push(Value::Int(i.abs(), s)),
+                        Value::Float(f, s) => stack.push(Value::Float(f.abs(), s)),
+                        _ => return Err("expected number".into()),
+                    }
+                }
+                Op::Floor => {
+                    let v = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    stack.push(Value::Int(v.floor() as i64, None));
+                }
+                Op::Ceil => {
+                    let v = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    stack.push(Value::Int(v.ceil() as i64, None));
+                }
+                Op::Round => {
+                    let v = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    stack.push(Value::Int(v.round() as i64, None));
+                }
+                Op::Min => binary_op(stack, |a, b| a.min(b))?,
+                Op::Max => binary_op(stack, |a, b| a.max(b))?,
+
+                Op::Eq => cmp_op(stack, |a, b| (a - b).abs() < f64::EPSILON)?,
+                Op::Ne => cmp_op(stack, |a, b| (a - b).abs() >= f64::EPSILON)?,
+                Op::Lt => cmp_op(stack, |a, b| a < b)?,
+                Op::Gt => cmp_op(stack, |a, b| a > b)?,
+                Op::Le => cmp_op(stack, |a, b| a <= b)?,
+                Op::Ge => cmp_op(stack, |a, b| a >= b)?,
+
+                Op::And => {
+                    let b = stack.pop().ok_or("stack underflow")?.is_truthy();
+                    let a = stack.pop().ok_or("stack underflow")?.is_truthy();
+                    stack.push(Value::Int(if a && b { 1 } else { 0 }, None));
+                }
+                Op::Or => {
+                    let b = stack.pop().ok_or("stack underflow")?.is_truthy();
+                    let a = stack.pop().ok_or("stack underflow")?.is_truthy();
+                    stack.push(Value::Int(if a || b { 1 } else { 0 }, None));
+                }
+                Op::Not => {
+                    let v = stack.pop().ok_or("stack underflow")?.is_truthy();
+                    stack.push(Value::Int(if v { 0 } else { 1 }, None));
+                }
+
+                Op::BranchIfZero(offset, then_span, else_span) => {
+                    let v = stack.pop().ok_or("stack underflow")?;
+                    if !v.is_truthy() {
+                        if let Some(span) = else_span {
+                            if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                trace.executed_spans.push(*span);
+                            }
+                        }
+                        pc += offset;
+                    } else if let Some(span) = then_span {
+                        if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                            trace.executed_spans.push(*span);
+                        }
+                    }
+                }
+                Op::Branch(offset) => {
+                    pc += offset;
+                }
+
+                Op::NewCmd => {
+                    let name = stack.pop().ok_or("stack underflow")?;
+                    let name = name.as_str()?;
+                    cmd.set_sound(name.to_string());
+                }
+                Op::SetParam(param) => {
+                    let val = stack.pop().ok_or("stack underflow")?;
+                    cmd.set_param(param.clone(), val.to_param_string());
+                }
+                Op::Emit => {
+                    let (sound, mut params) = cmd.take().ok_or("no sound set")?;
+                    let mut pairs = vec![("sound".into(), sound)];
+                    pairs.append(&mut params);
+                    let time_ctx = time_stack.last().ok_or("time stack underflow")?;
+                    if time_ctx.start > 0.0 {
+                        pairs.push(("delta".into(), time_ctx.start.to_string()));
+                    }
+                    if !pairs.iter().any(|(k, _)| k == "dur") {
+                        pairs.push(("dur".into(), time_ctx.duration.to_string()));
+                    }
+                    if let Some(idx) = pairs.iter().position(|(k, _)| k == "delaytime") {
+                        let ratio: f64 = pairs[idx].1.parse().unwrap_or(1.0);
+                        pairs[idx].1 = (ratio * time_ctx.duration).to_string();
+                    } else {
+                        pairs.push(("delaytime".into(), time_ctx.duration.to_string()));
+                    }
+                    outputs.push(format_cmd(&pairs));
+                }
+
+                Op::Get => {
+                    let name = stack.pop().ok_or("stack underflow")?;
+                    let name = name.as_str()?;
+                    let vars = self.vars.lock().unwrap();
+                    let val = vars.get(name).cloned().unwrap_or(Value::Int(0, None));
+                    stack.push(val);
+                }
+                Op::Set => {
+                    let name = stack.pop().ok_or("stack underflow")?;
+                    let name = name.as_str()?.to_string();
+                    let val = stack.pop().ok_or("stack underflow")?;
+                    self.vars.lock().unwrap().insert(name, val);
+                }
+
+                Op::GetContext(name) => {
+                    let val = match name.as_str() {
+                        "step" => Value::Int(ctx.step as i64, None),
+                        "beat" => Value::Float(ctx.beat, None),
+                        "pattern" => Value::Int(ctx.pattern as i64, None),
+                        "tempo" => Value::Float(ctx.tempo, None),
+                        "phase" => Value::Float(ctx.phase, None),
+                        "slot" => Value::Int(ctx.slot as i64, None),
+                        "runs" => Value::Int(ctx.runs as i64, None),
+                        "iter" => Value::Int(ctx.iter as i64, None),
+                        "speed" => Value::Float(ctx.speed, None),
+                        "stepdur" => Value::Float(ctx.step_duration(), None),
+                        "fill" => Value::Int(if ctx.fill { 1 } else { 0 }, None),
+                        _ => Value::Int(0, None),
+                    };
+                    stack.push(val);
+                }
+
+                Op::Rand => {
+                    let max = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let min = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let val = self.rng.lock().unwrap().gen_range(min..max);
+                    stack.push(Value::Float(val, None));
+                }
+                Op::Rrand => {
+                    let max = stack.pop().ok_or("stack underflow")?.as_int()?;
+                    let min = stack.pop().ok_or("stack underflow")?.as_int()?;
+                    let val = self.rng.lock().unwrap().gen_range(min..=max);
+                    stack.push(Value::Int(val, None));
+                }
+                Op::Seed => {
+                    let s = stack.pop().ok_or("stack underflow")?.as_int()?;
+                    *self.rng.lock().unwrap() = StdRng::seed_from_u64(s as u64);
+                }
+
+                Op::Cycle => {
+                    let count = stack.pop().ok_or("stack underflow")?.as_int()? as usize;
+                    if count == 0 {
+                        return Err("cycle count must be > 0".into());
+                    }
+                    if stack.len() < count {
+                        return Err("stack underflow".into());
+                    }
+                    let start = stack.len() - count;
+                    let values: Vec<Value> = stack.drain(start..).collect();
+                    let idx = ctx.runs % count;
+                    let selected = values[idx].clone();
+                    if let Some(span) = selected.span() {
+                        if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                            trace.selected_spans.push(span);
+                        }
+                    }
+                    if let Value::Quotation(quot_ops, body_span) = selected {
+                        if let Some(span) = body_span {
+                            if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                trace.executed_spans.push(span);
+                            }
+                        }
+                        let mut trace_opt = trace_cell.borrow_mut().take();
+                        self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                        *trace_cell.borrow_mut() = trace_opt;
+                    } else {
+                        stack.push(selected);
+                    }
+                }
+
+                Op::PCycle => {
+                    let count = stack.pop().ok_or("stack underflow")?.as_int()? as usize;
+                    if count == 0 {
+                        return Err("pcycle count must be > 0".into());
+                    }
+                    if stack.len() < count {
+                        return Err("stack underflow".into());
+                    }
+                    let start = stack.len() - count;
+                    let values: Vec<Value> = stack.drain(start..).collect();
+                    let idx = ctx.iter % count;
+                    let selected = values[idx].clone();
+                    if let Some(span) = selected.span() {
+                        if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                            trace.selected_spans.push(span);
+                        }
+                    }
+                    if let Value::Quotation(quot_ops, body_span) = selected {
+                        if let Some(span) = body_span {
+                            if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                trace.executed_spans.push(span);
+                            }
+                        }
+                        let mut trace_opt = trace_cell.borrow_mut().take();
+                        self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                        *trace_cell.borrow_mut() = trace_opt;
+                    } else {
+                        stack.push(selected);
+                    }
+                }
+
+                Op::Choose => {
+                    let count = stack.pop().ok_or("stack underflow")?.as_int()? as usize;
+                    if count == 0 {
+                        return Err("choose count must be > 0".into());
+                    }
+                    if stack.len() < count {
+                        return Err("stack underflow".into());
+                    }
+                    let start = stack.len() - count;
+                    let values: Vec<Value> = stack.drain(start..).collect();
+                    let idx = self.rng.lock().unwrap().gen_range(0..count);
+                    let selected = values[idx].clone();
+                    if let Some(span) = selected.span() {
+                        if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                            trace.selected_spans.push(span);
+                        }
+                    }
+                    if let Value::Quotation(quot_ops, body_span) = selected {
+                        if let Some(span) = body_span {
+                            if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                trace.executed_spans.push(span);
+                            }
+                        }
+                        let mut trace_opt = trace_cell.borrow_mut().take();
+                        self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                        *trace_cell.borrow_mut() = trace_opt;
+                    } else {
+                        stack.push(selected);
+                    }
+                }
+
+                Op::ChanceExec => {
+                    let prob = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let quot = stack.pop().ok_or("stack underflow")?;
+                    let val: f64 = self.rng.lock().unwrap().gen();
+                    if val < prob {
+                        match quot {
+                            Value::Quotation(quot_ops, body_span) => {
+                                if let Some(span) = body_span {
+                                    if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                        trace.executed_spans.push(span);
+                                    }
+                                }
+                                let mut trace_opt = trace_cell.borrow_mut().take();
+                                self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                                *trace_cell.borrow_mut() = trace_opt;
+                            }
+                            _ => return Err("expected quotation".into()),
+                        }
+                    }
+                }
+
+                Op::ProbExec => {
+                    let pct = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let quot = stack.pop().ok_or("stack underflow")?;
+                    let val: f64 = self.rng.lock().unwrap().gen();
+                    if val < pct / 100.0 {
+                        match quot {
+                            Value::Quotation(quot_ops, body_span) => {
+                                if let Some(span) = body_span {
+                                    if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                        trace.executed_spans.push(span);
+                                    }
+                                }
+                                let mut trace_opt = trace_cell.borrow_mut().take();
+                                self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                                *trace_cell.borrow_mut() = trace_opt;
+                            }
+                            _ => return Err("expected quotation".into()),
+                        }
+                    }
+                }
+
+                Op::Coin => {
+                    let val: f64 = self.rng.lock().unwrap().gen();
+                    stack.push(Value::Int(if val < 0.5 { 1 } else { 0 }, None));
+                }
+
+                Op::Every => {
+                    let n = stack.pop().ok_or("stack underflow")?.as_int()?;
+                    if n <= 0 {
+                        return Err("every count must be > 0".into());
+                    }
+                    let result = ctx.iter as i64 % n == 0;
+                    stack.push(Value::Int(if result { 1 } else { 0 }, None));
+                }
+
+                Op::Quotation(quote_ops, body_span) => {
+                    stack.push(Value::Quotation(quote_ops.clone(), *body_span));
+                }
+
+                Op::When => {
+                    let cond = stack.pop().ok_or("stack underflow")?;
+                    let quot = stack.pop().ok_or("stack underflow")?;
+                    if cond.is_truthy() {
+                        match quot {
+                            Value::Quotation(quot_ops, body_span) => {
+                                if let Some(span) = body_span {
+                                    if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                        trace.executed_spans.push(span);
+                                    }
+                                }
+                                let mut trace_opt = trace_cell.borrow_mut().take();
+                                self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                                *trace_cell.borrow_mut() = trace_opt;
+                            }
+                            _ => return Err("expected quotation".into()),
+                        }
+                    }
+                }
+
+                Op::Unless => {
+                    let cond = stack.pop().ok_or("stack underflow")?;
+                    let quot = stack.pop().ok_or("stack underflow")?;
+                    if !cond.is_truthy() {
+                        match quot {
+                            Value::Quotation(quot_ops, body_span) => {
+                                if let Some(span) = body_span {
+                                    if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                        trace.executed_spans.push(span);
+                                    }
+                                }
+                                let mut trace_opt = trace_cell.borrow_mut().take();
+                                self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                                *trace_cell.borrow_mut() = trace_opt;
+                            }
+                            _ => return Err("expected quotation".into()),
+                        }
+                    }
+                }
+
+                Op::Mtof => {
+                    let note = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let freq = 440.0 * 2.0_f64.powf((note - 69.0) / 12.0);
+                    stack.push(Value::Float(freq, None));
+                }
+
+                Op::Ftom => {
+                    let freq = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let note = 69.0 + 12.0 * (freq / 440.0).log2();
+                    stack.push(Value::Float(note, None));
+                }
+
+                Op::At => {
+                    let pos = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let parent = time_stack.last().ok_or("time stack underflow")?;
+                    let new_start = parent.start + parent.duration * pos;
+                    time_stack.push(TimeContext {
+                        start: new_start,
+                        duration: parent.duration * (1.0 - pos),
+                        subdivisions: None,
+                        iteration_index: parent.iteration_index,
+                    });
+                }
+
+                Op::Window => {
+                    let end = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let start_pos = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let parent = time_stack.last().ok_or("time stack underflow")?;
+                    let new_start = parent.start + parent.duration * start_pos;
+                    let new_duration = parent.duration * (end - start_pos);
+                    time_stack.push(TimeContext {
+                        start: new_start,
+                        duration: new_duration,
+                        subdivisions: None,
+                        iteration_index: parent.iteration_index,
+                    });
+                }
+
+                Op::Scale => {
+                    let factor = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let parent = time_stack.last().ok_or("time stack underflow")?;
+                    time_stack.push(TimeContext {
+                        start: parent.start,
+                        duration: parent.duration * factor,
+                        subdivisions: None,
+                        iteration_index: parent.iteration_index,
+                    });
+                }
+
+                Op::Pop => {
+                    if time_stack.len() <= 1 {
+                        return Err("cannot pop root time context".into());
+                    }
+                    time_stack.pop();
+                }
+
+                Op::Subdivide => {
+                    let n = stack.pop().ok_or("stack underflow")?.as_int()? as usize;
+                    if n == 0 {
+                        return Err("subdivide count must be > 0".into());
+                    }
+                    let time_ctx = time_stack.last_mut().ok_or("time stack underflow")?;
+                    let sub_duration = time_ctx.duration / n as f64;
+                    let mut subs = Vec::with_capacity(n);
+                    for i in 0..n {
+                        subs.push((time_ctx.start + sub_duration * i as f64, sub_duration));
+                    }
+                    time_ctx.subdivisions = Some(subs);
+                }
+
+                Op::Each => {
+                    let (sound, params) = cmd.take().ok_or("no sound set")?;
+                    let time_ctx = time_stack.last().ok_or("time stack underflow")?;
+                    let subs = time_ctx
+                        .subdivisions
+                        .as_ref()
+                        .ok_or("each requires subdivide first")?;
+                    for (sub_start, sub_dur) in subs {
+                        let mut pairs = vec![("sound".into(), sound.clone())];
+                        pairs.extend(params.iter().cloned());
+                        if *sub_start > 0.0 {
+                            pairs.push(("delta".into(), sub_start.to_string()));
+                        }
+                        if !pairs.iter().any(|(k, _)| k == "dur") {
+                            pairs.push(("dur".into(), sub_dur.to_string()));
+                        }
+                        if let Some(idx) = pairs.iter().position(|(k, _)| k == "delaytime") {
+                            let ratio: f64 = pairs[idx].1.parse().unwrap_or(1.0);
+                            pairs[idx].1 = (ratio * sub_dur).to_string();
+                        } else {
+                            pairs.push(("delaytime".into(), sub_dur.to_string()));
+                        }
+                        outputs.push(format_cmd(&pairs));
+                    }
+                }
+
+                Op::SetTempo => {
+                    let tempo = stack.pop().ok_or("stack underflow")?.as_float()?;
+                    let clamped = tempo.clamp(20.0, 300.0);
+                    self.vars
+                        .lock()
+                        .unwrap()
+                        .insert("__tempo__".to_string(), Value::Float(clamped, None));
+                }
+
+                Op::ListStart => {
+                    stack.push(Value::Marker);
+                }
+
+                Op::ListEnd => {
+                    let mut count = 0;
+                    let mut values = Vec::new();
+                    while let Some(v) = stack.pop() {
+                        if v.is_marker() {
+                            break;
+                        }
+                        values.push(v);
+                        count += 1;
+                    }
+                    values.reverse();
+                    for v in values {
+                        stack.push(v);
+                    }
+                    stack.push(Value::Int(count, None));
+                }
+
+                Op::ListEndCycle => {
+                    let mut values = Vec::new();
+                    while let Some(v) = stack.pop() {
+                        if v.is_marker() {
+                            break;
+                        }
+                        values.push(v);
+                    }
+                    if values.is_empty() {
+                        return Err("empty cycle list".into());
+                    }
+                    values.reverse();
+                    let idx = ctx.runs % values.len();
+                    let selected = values[idx].clone();
+                    if let Some(span) = selected.span() {
+                        if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                            trace.selected_spans.push(span);
+                        }
+                    }
+                    if let Value::Quotation(quot_ops, body_span) = selected {
+                        if let Some(span) = body_span {
+                            if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                trace.executed_spans.push(span);
+                            }
+                        }
+                        let mut trace_opt = trace_cell.borrow_mut().take();
+                        self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                        *trace_cell.borrow_mut() = trace_opt;
+                    } else {
+                        stack.push(selected);
+                    }
+                }
+
+                Op::ListEndPCycle => {
+                    let mut values = Vec::new();
+                    while let Some(v) = stack.pop() {
+                        if v.is_marker() {
+                            break;
+                        }
+                        values.push(v);
+                    }
+                    if values.is_empty() {
+                        return Err("empty pattern cycle list".into());
+                    }
+                    values.reverse();
+                    let idx = ctx.iter % values.len();
+                    let selected = values[idx].clone();
+                    if let Some(span) = selected.span() {
+                        if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                            trace.selected_spans.push(span);
+                        }
+                    }
+                    if let Value::Quotation(quot_ops, body_span) = selected {
+                        if let Some(span) = body_span {
+                            if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                trace.executed_spans.push(span);
+                            }
+                        }
+                        let mut trace_opt = trace_cell.borrow_mut().take();
+                        self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                        *trace_cell.borrow_mut() = trace_opt;
+                    } else {
+                        stack.push(selected);
+                    }
+                }
+
+                Op::Adsr => {
+                    let r = stack.pop().ok_or("stack underflow")?;
+                    let s = stack.pop().ok_or("stack underflow")?;
+                    let d = stack.pop().ok_or("stack underflow")?;
+                    let a = stack.pop().ok_or("stack underflow")?;
+                    cmd.set_param("attack".into(), a.to_param_string());
+                    cmd.set_param("decay".into(), d.to_param_string());
+                    cmd.set_param("sustain".into(), s.to_param_string());
+                    cmd.set_param("release".into(), r.to_param_string());
+                }
+
+                Op::Ad => {
+                    let d = stack.pop().ok_or("stack underflow")?;
+                    let a = stack.pop().ok_or("stack underflow")?;
+                    cmd.set_param("attack".into(), a.to_param_string());
+                    cmd.set_param("decay".into(), d.to_param_string());
+                    cmd.set_param("sustain".into(), "0".into());
+                }
+
+                Op::Stack => {
+                    let n = stack.pop().ok_or("stack underflow")?.as_int()? as usize;
+                    if n == 0 {
+                        return Err("stack count must be > 0".into());
+                    }
+                    let time_ctx = time_stack.last_mut().ok_or("time stack underflow")?;
+                    let sub_duration = time_ctx.duration / n as f64;
+                    let mut subs = Vec::with_capacity(n);
+                    for _ in 0..n {
+                        subs.push((time_ctx.start, sub_duration));
+                    }
+                    time_ctx.subdivisions = Some(subs);
+                }
+
+                Op::Echo => {
+                    let n = stack.pop().ok_or("stack underflow")?.as_int()? as usize;
+                    if n == 0 {
+                        return Err("echo count must be > 0".into());
+                    }
+                    let time_ctx = time_stack.last_mut().ok_or("time stack underflow")?;
+                    // Geometric series: d1 * (2 - 2^(1-n)) = total
+                    let d1 = time_ctx.duration / (2.0 - 2.0_f64.powi(1 - n as i32));
+                    let mut subs = Vec::with_capacity(n);
+                    for i in 0..n {
+                        let dur = d1 / 2.0_f64.powi(i as i32);
+                        let start = if i == 0 {
+                            time_ctx.start
+                        } else {
+                            time_ctx.start + d1 * (2.0 - 2.0_f64.powi(1 - i as i32))
+                        };
+                        subs.push((start, dur));
+                    }
+                    time_ctx.subdivisions = Some(subs);
+                }
+
+                Op::Necho => {
+                    let n = stack.pop().ok_or("stack underflow")?.as_int()? as usize;
+                    if n == 0 {
+                        return Err("necho count must be > 0".into());
+                    }
+                    let time_ctx = time_stack.last_mut().ok_or("time stack underflow")?;
+                    // Reverse geometric: d1 + 2*d1 + 4*d1 + ... = d1 * (2^n - 1) = total
+                    let d1 = time_ctx.duration / (2.0_f64.powi(n as i32) - 1.0);
+                    let mut subs = Vec::with_capacity(n);
+                    for i in 0..n {
+                        let dur = d1 * 2.0_f64.powi(i as i32);
+                        let start = if i == 0 {
+                            time_ctx.start
+                        } else {
+                            // Sum of previous durations: d1 * (2^i - 1)
+                            time_ctx.start + d1 * (2.0_f64.powi(i as i32) - 1.0)
+                        };
+                        subs.push((start, dur));
+                    }
+                    time_ctx.subdivisions = Some(subs);
+                }
+
+                Op::For => {
+                    let quot = stack.pop().ok_or("stack underflow")?;
+                    let time_ctx = time_stack.last().ok_or("time stack underflow")?;
+                    let subs = time_ctx
+                        .subdivisions
+                        .clone()
+                        .ok_or("for requires subdivide first")?;
+
+                    match quot {
+                        Value::Quotation(quot_ops, body_span) => {
+                            if let Some(span) = body_span {
+                                if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                    trace.executed_spans.push(span);
+                                }
+                            }
+                            for (i, (sub_start, sub_dur)) in subs.iter().enumerate() {
+                                time_stack.push(TimeContext {
+                                    start: *sub_start,
+                                    duration: *sub_dur,
+                                    subdivisions: None,
+                                    iteration_index: Some(i),
+                                });
+                                let mut trace_opt = trace_cell.borrow_mut().take();
+                                self.execute_ops(
+                                    &quot_ops,
+                                    ctx,
+                                    stack,
+                                    outputs,
+                                    time_stack,
+                                    cmd,
+                                    trace_opt.as_deref_mut(),
+                                )?;
+                                *trace_cell.borrow_mut() = trace_opt;
+                                time_stack.pop();
+                            }
+                        }
+                        _ => return Err("expected quotation".into()),
+                    }
+                }
+
+                Op::LocalCycleEnd => {
+                    let mut values = Vec::new();
+                    while let Some(v) = stack.pop() {
+                        if v.is_marker() {
+                            break;
+                        }
+                        values.push(v);
+                    }
+                    if values.is_empty() {
+                        return Err("empty local cycle list".into());
+                    }
+                    values.reverse();
+                    let time_ctx = time_stack.last().ok_or("time stack underflow")?;
+                    let idx = time_ctx.iteration_index.unwrap_or(0) % values.len();
+                    let selected = values[idx].clone();
+                    if let Some(span) = selected.span() {
+                        if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                            trace.selected_spans.push(span);
+                        }
+                    }
+                    if let Value::Quotation(quot_ops, body_span) = selected {
+                        if let Some(span) = body_span {
+                            if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                trace.executed_spans.push(span);
+                            }
+                        }
+                        let mut trace_opt = trace_cell.borrow_mut().take();
+                        self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                        *trace_cell.borrow_mut() = trace_opt;
+                    } else {
+                        stack.push(selected);
+                    }
+                }
+
+                Op::Apply => {
+                    let quot = stack.pop().ok_or("stack underflow")?;
+                    match quot {
+                        Value::Quotation(quot_ops, body_span) => {
+                            if let Some(span) = body_span {
+                                if let Some(trace) = trace_cell.borrow_mut().as_mut() {
+                                    trace.executed_spans.push(span);
+                                }
+                            }
+                            let mut trace_opt = trace_cell.borrow_mut().take();
+                            self.execute_ops(&quot_ops, ctx, stack, outputs, time_stack, cmd, trace_opt.as_deref_mut())?;
+                            *trace_cell.borrow_mut() = trace_opt;
+                        }
+                        _ => return Err("expected quotation".into()),
+                    }
+                }
+            }
+            pc += 1;
+        }
+
+        Ok(())
+    }
+}
+
+fn binary_op<F>(stack: &mut Vec<Value>, f: F) -> Result<(), String>
+where
+    F: Fn(f64, f64) -> f64,
+{
+    let b = stack.pop().ok_or("stack underflow")?.as_float()?;
+    let a = stack.pop().ok_or("stack underflow")?.as_float()?;
+    let result = f(a, b);
+    if result.fract() == 0.0 && result.abs() < i64::MAX as f64 {
+        stack.push(Value::Int(result as i64, None));
+    } else {
+        stack.push(Value::Float(result, None));
+    }
+    Ok(())
+}
+
+fn cmp_op<F>(stack: &mut Vec<Value>, f: F) -> Result<(), String>
+where
+    F: Fn(f64, f64) -> bool,
+{
+    let b = stack.pop().ok_or("stack underflow")?.as_float()?;
+    let a = stack.pop().ok_or("stack underflow")?.as_float()?;
+    stack.push(Value::Int(if f(a, b) { 1 } else { 0 }, None));
+    Ok(())
+}
+
+fn format_cmd(pairs: &[(String, String)]) -> String {
+    let parts: Vec<String> = pairs.iter().map(|(k, v)| format!("{k}/{v}")).collect();
+    format!("/{}", parts.join("/"))
+}

tests/forth.rs

@@ -45,3 +45,6 @@ mod intervals;
 
 #[path = "forth/definitions.rs"]
 mod definitions;
+
+#[path = "forth/list_words.rs"]
+mod list_words;

tests/forth/iteration.rs

@@ -181,14 +181,14 @@ fn empty_local_cycle() {
 
 #[test]
 fn echo_creates_decaying_subdivisions() {
-    // stepdur = 0.125, echo 3
-    // d1 + d1/2 + d1/4 = d1 * 1.75 = 0.125
-    // d1 = 0.125 / 1.75 = 0.0714285714...
+    // default dur = 0.5, echo 3
+    // d1 + d1/2 + d1/4 = d1 * 1.75 = 0.5
+    // d1 = 0.5 / 1.75
     let outputs = expect_outputs(r#""kick" s 3 echo each"#, 3);
     let durs = get_durs(&outputs);
     let deltas = get_deltas(&outputs);
 
-    let d1 = 0.125 / 1.75;
+    let d1 = 0.5 / 1.75;
     let d2 = d1 / 2.0;
     let d3 = d1 / 4.0;
 
@@ -220,14 +220,14 @@ fn echo_error_zero_count() {
 
 #[test]
 fn necho_creates_growing_subdivisions() {
-    // stepdur = 0.125, necho 3
-    // d1 + 2*d1 + 4*d1 = d1 * 7 = 0.125
-    // d1 = 0.125 / 7
+    // default dur = 0.5, necho 3
+    // d1 + 2*d1 + 4*d1 = d1 * 7 = 0.5
+    // d1 = 0.5 / 7
     let outputs = expect_outputs(r#""kick" s 3 necho each"#, 3);
     let durs = get_durs(&outputs);
     let deltas = get_deltas(&outputs);
 
-    let d1 = 0.125 / 7.0;
+    let d1 = 0.5 / 7.0;
     let d2 = d1 * 2.0;
     let d3 = d1 * 4.0;
 

tests/forth/list_words.rs

@@ -0,0 +1,134 @@
+use super::harness::*;
+
+#[test]
+fn choose_word_from_list() {
+    // 1 2 [ + - ] choose: picks + or -, applies to 1 2
+    // With seed 42, choose picks one deterministically
+    let f = forth();
+    let ctx = default_ctx();
+    f.evaluate("1 2 [ + - ] choose", &ctx).unwrap();
+    let val = stack_int(&f);
+    assert!(val == 3 || val == -1, "expected 3 or -1, got {}", val);
+}
+
+#[test]
+fn cycle_word_from_list() {
+    // At runs=0, picks first word (dup)
+    let ctx = ctx_with(|c| c.runs = 0);
+    let f = run_ctx("5 < dup nip >", &ctx);
+    assert_eq!(stack_int(&f), 5); // dup leaves 5 5, but stack check takes top
+
+    // At runs=1, picks second word (2 *)
+    let f = forth();
+    let ctx = ctx_with(|c| c.runs = 1);
+    f.evaluate(": double 2 * ; 5 < dup double >", &ctx).unwrap();
+    assert_eq!(stack_int(&f), 10);
+}
+
+#[test]
+fn user_word_in_list() {
+    let f = forth();
+    let ctx = ctx_with(|c| c.runs = 0);
+    f.evaluate(": add3 3 + ; : add5 5 + ; 10 < add3 add5 >", &ctx).unwrap();
+    assert_eq!(stack_int(&f), 13); // runs=0 picks add3
+}
+
+#[test]
+fn user_word_in_list_second() {
+    let f = forth();
+    let ctx = ctx_with(|c| c.runs = 1);
+    f.evaluate(": add3 3 + ; : add5 5 + ; 10 < add3 add5 >", &ctx).unwrap();
+    assert_eq!(stack_int(&f), 15); // runs=1 picks add5
+}
+
+#[test]
+fn values_in_list_still_work() {
+    // Numbers inside lists should still push as values (not quotations)
+    let ctx = ctx_with(|c| c.runs = 0);
+    let f = run_ctx("< 10 20 30 >", &ctx);
+    assert_eq!(stack_int(&f), 10);
+}
+
+#[test]
+fn values_in_list_cycle() {
+    let ctx = ctx_with(|c| c.runs = 2);
+    let f = run_ctx("< 10 20 30 >", &ctx);
+    assert_eq!(stack_int(&f), 30);
+}
+
+#[test]
+fn mixed_values_and_words() {
+    // Values stay as values, words become quotations
+    // [ 10 20 ] choose just picks a number
+    let f = forth();
+    let ctx = default_ctx();
+    f.evaluate("[ 10 20 ] choose", &ctx).unwrap();
+    let val = stack_int(&f);
+    assert!(val == 10 || val == 20, "expected 10 or 20, got {}", val);
+}
+
+#[test]
+fn word_with_sound_params() {
+    let f = forth();
+    let ctx = ctx_with(|c| c.runs = 0);
+    let outputs = f.evaluate(
+        ": myverb 0.5 verb ; \"sine\" s 440 freq < myverb > emit",
+        &ctx
+    ).unwrap();
+    assert_eq!(outputs.len(), 1);
+    assert!(outputs[0].contains("verb/0.5"), "expected verb/0.5 in {}", outputs[0]);
+}
+
+#[test]
+fn arithmetic_word_in_list() {
+    // 3 4 [ + ] choose -> picks + (only option), applies to 3 4 = 7
+    let ctx = ctx_with(|c| c.runs = 0);
+    let f = run_ctx("3 4 < + >", &ctx);
+    assert_eq!(stack_int(&f), 7);
+}
+
+#[test]
+fn pcycle_word_from_list() {
+    let ctx = ctx_with(|c| c.iter = 0);
+    let f = run_ctx("10 << dup 2 * >>", &ctx);
+    // iter=0 picks dup: 10 10
+    let stack = f.stack();
+    assert_eq!(stack.len(), 2);
+    assert_eq!(stack_int(&f), 10);
+}
+
+#[test]
+fn pcycle_word_second() {
+    let ctx = ctx_with(|c| c.iter = 1);
+    let f = run_ctx("10 << dup 2 * >>", &ctx);
+    // iter=1 picks "2 *" — but wait, each token is its own element
+    // so << dup 2 * >> has 3 elements: {dup}, 2, {*}
+    // iter=1 picks element index 1 which is value 2
+    assert_eq!(stack_int(&f), 2);
+}
+
+#[test]
+fn multi_op_quotation_in_list() {
+    // Use { } for multi-op quotations inside lists
+    let ctx = ctx_with(|c| c.runs = 0);
+    let f = run_ctx("10 < { 2 * } { 3 + } >", &ctx);
+    assert_eq!(stack_int(&f), 20); // runs=0 picks {2 *}
+}
+
+#[test]
+fn multi_op_quotation_second() {
+    let ctx = ctx_with(|c| c.runs = 1);
+    let f = run_ctx("10 < { 2 * } { 3 + } >", &ctx);
+    assert_eq!(stack_int(&f), 13); // runs=1 picks {3 +}
+}
+
+#[test]
+fn pipe_syntax_with_words() {
+    // | word1 word2 | uses LocalCycleEnd which should auto-apply quotations
+    // LocalCycleEnd uses time_ctx.iteration_index, which defaults to 0 outside for loops
+    let f = forth();
+    let ctx = default_ctx();
+    f.evaluate(": add3 3 + ; : add5 5 + ; 10 | add3 add5 |", &ctx).unwrap();
+    // iteration_index defaults to 0, picks first word (add3)
+    assert_eq!(stack_int(&f), 13);
+}

tests/forth/temporal.rs

@@ -28,6 +28,7 @@ fn approx_eq(a: f64, b: f64) -> bool {
 }
 
 // At 120 BPM, speed 1.0: stepdur = 60/120/4/1 = 0.125s
+// Default duration = 4 * stepdur = 0.5s
 
 #[test]
 fn stepdur_baseline() {
@@ -47,23 +48,24 @@ fn emit_no_delta() {
 
 #[test]
 fn at_half() {
-    // at 0.5 in root zoom (0..0.125) => delta = 0.5 * 0.125 = 0.0625
+    // at 0.5 in root (0..0.5) => delta = 0.5 * 0.5 = 0.25
     let outputs = expect_outputs(r#""kick" s 0.5 at emit pop"#, 1);
     let deltas = get_deltas(&outputs);
     assert!(
-        approx_eq(deltas[0], 0.0625),
-        "at 0.5 should be delta 0.0625, got {}",
+        approx_eq(deltas[0], 0.25),
+        "at 0.5 should be delta 0.25, got {}",
         deltas[0]
     );
 }
 
 #[test]
 fn at_quarter() {
+    // at 0.25 in root (0..0.5) => delta = 0.25 * 0.5 = 0.125
     let outputs = expect_outputs(r#""kick" s 0.25 at emit pop"#, 1);
     let deltas = get_deltas(&outputs);
     assert!(
-        approx_eq(deltas[0], 0.03125),
-        "at 0.25 should be delta 0.03125, got {}",
+        approx_eq(deltas[0], 0.125),
+        "at 0.25 should be delta 0.125, got {}",
         deltas[0]
     );
 }
@@ -77,23 +79,23 @@ fn at_zero() {
 
 #[test]
 fn div_2_each() {
-    // 2 subdivisions: deltas at 0 and 0.0625 (half of 0.125)
+    // 2 subdivisions: deltas at 0 and 0.25 (half of 0.5)
     let outputs = expect_outputs(r#""kick" s 2 div each"#, 2);
     let deltas = get_deltas(&outputs);
     assert!(approx_eq(deltas[0], 0.0), "first subdivision at 0");
     assert!(
-        approx_eq(deltas[1], 0.0625),
-        "second subdivision at 0.0625, got {}",
+        approx_eq(deltas[1], 0.25),
+        "second subdivision at 0.25, got {}",
         deltas[1]
     );
 }
 
 #[test]
 fn div_4_each() {
-    // 4 subdivisions: 0, 0.03125, 0.0625, 0.09375
+    // 4 subdivisions: 0, 0.125, 0.25, 0.375
     let outputs = expect_outputs(r#""kick" s 4 div each"#, 4);
     let deltas = get_deltas(&outputs);
-    let expected = [0.0, 0.03125, 0.0625, 0.09375];
+    let expected = [0.0, 0.125, 0.25, 0.375];
     for (i, (got, exp)) in deltas.iter().zip(expected.iter()).enumerate() {
         assert!(
             approx_eq(*got, *exp),
@@ -107,10 +109,10 @@ fn div_4_each() {
 
 #[test]
 fn div_3_each() {
-    // 3 subdivisions: 0, 0.125/3, 2*0.125/3
+    // 3 subdivisions: 0, 0.5/3, 2*0.5/3
     let outputs = expect_outputs(r#""kick" s 3 div each"#, 3);
     let deltas = get_deltas(&outputs);
-    let step = 0.125 / 3.0;
+    let step = 0.5 / 3.0;
     assert!(approx_eq(deltas[0], 0.0));
     assert!(approx_eq(deltas[1], step), "got {}", deltas[1]);
     assert!(approx_eq(deltas[2], 2.0 * step), "got {}", deltas[2]);
@@ -118,56 +120,56 @@ fn div_3_each() {
 
 #[test]
 fn zoom_full() {
-    // zoom 0.0 1.0 is the full step, same as root
+    // zoom 0.0 1.0 is the full duration, same as root
     let outputs = expect_outputs(r#"0.0 1.0 zoom "kick" s 0.5 at emit pop"#, 1);
     let deltas = get_deltas(&outputs);
-    assert!(approx_eq(deltas[0], 0.0625), "full zoom at 0.5 = 0.0625");
+    assert!(approx_eq(deltas[0], 0.25), "full zoom at 0.5 = 0.25");
 }
 
 #[test]
 fn zoom_first_half() {
-    // zoom 0.0 0.5 restricts to first half (0..0.0625)
-    // at 0.5 within that = 0.25 of full step = 0.03125
+    // zoom 0.0 0.5 restricts to first half (0..0.25)
+    // at 0.5 within that = 0.125
     let outputs = expect_outputs(r#"0.0 0.5 zoom "kick" s 0.5 at emit pop"#, 1);
     let deltas = get_deltas(&outputs);
     assert!(
-        approx_eq(deltas[0], 0.03125),
-        "first-half zoom at 0.5 = 0.03125, got {}",
+        approx_eq(deltas[0], 0.125),
+        "first-half zoom at 0.5 = 0.125, got {}",
         deltas[0]
     );
 }
 
 #[test]
 fn zoom_second_half() {
-    // zoom 0.5 1.0 restricts to second half (0.0625..0.125)
-    // at 0.0 within that = start of second half = 0.0625
+    // zoom 0.5 1.0 restricts to second half (0.25..0.5)
+    // at 0.0 within that = start of second half = 0.25
     let outputs = expect_outputs(r#"0.5 1.0 zoom "kick" s 0.0 at emit pop"#, 1);
     let deltas = get_deltas(&outputs);
     assert!(
-        approx_eq(deltas[0], 0.0625),
-        "second-half zoom at 0.0 = 0.0625, got {}",
+        approx_eq(deltas[0], 0.25),
+        "second-half zoom at 0.0 = 0.25, got {}",
         deltas[0]
     );
 }
 
 #[test]
 fn zoom_second_half_middle() {
-    // zoom 0.5 1.0, at 0.5 within that = 0.75 of full step = 0.09375
+    // zoom 0.5 1.0, at 0.5 within that = 0.75 of full duration = 0.375
     let outputs = expect_outputs(r#"0.5 1.0 zoom "kick" s 0.5 at emit pop"#, 1);
     let deltas = get_deltas(&outputs);
-    assert!(approx_eq(deltas[0], 0.09375), "got {}", deltas[0]);
+    assert!(approx_eq(deltas[0], 0.375), "got {}", deltas[0]);
 }
 
 #[test]
 fn nested_zooms() {
     // zoom 0.0 0.5, then zoom 0.5 1.0 within that
-    // outer: 0..0.0625, inner: 0.5..1.0 of that = 0.03125..0.0625
-    // at 0.0 in inner = 0.03125
+    // outer: 0..0.25, inner: 0.5..1.0 of that = 0.125..0.25
+    // at 0.0 in inner = 0.125
     let outputs = expect_outputs(r#"0.0 0.5 zoom 0.5 1.0 zoom "kick" s 0.0 at emit pop"#, 1);
     let deltas = get_deltas(&outputs);
     assert!(
-        approx_eq(deltas[0], 0.03125),
-        "nested zoom at 0.0 = 0.03125, got {}",
+        approx_eq(deltas[0], 0.125),
+        "nested zoom at 0.0 = 0.125, got {}",
         deltas[0]
     );
 }
@@ -175,7 +177,7 @@ fn nested_zooms() {
 #[test]
 fn zoom_pop_sequence() {
     // First in zoom 0.0 0.5 at 0.0 -> delta 0
-    // Pop at context and zoom, then in zoom 0.5 1.0 at 0.0 -> delta 0.0625
+    // Pop at context and zoom, then in zoom 0.5 1.0 at 0.0 -> delta 0.25
     let outputs = expect_outputs(
         r#"0.0 0.5 zoom "kick" s 0.0 at emit pop pop 0.5 1.0 zoom "snare" s 0.0 at emit pop"#,
         2,
@@ -183,7 +185,7 @@ fn zoom_pop_sequence() {
     let deltas = get_deltas(&outputs);
     assert!(approx_eq(deltas[0], 0.0), "first zoom start");
     assert!(
-        approx_eq(deltas[1], 0.0625),
+        approx_eq(deltas[1], 0.25),
         "second zoom start, got {}",
         deltas[1]
     );
@@ -191,12 +193,12 @@ fn zoom_pop_sequence() {
 
 #[test]
 fn div_in_zoom() {
-    // zoom 0.0 0.5 (duration 0.0625), then div 2 each
-    // subdivisions at 0 and 0.03125
+    // zoom 0.0 0.5 (duration 0.25), then div 2 each
+    // subdivisions at 0 and 0.125
     let outputs = expect_outputs(r#"0.0 0.5 zoom "kick" s 2 div each"#, 2);
     let deltas = get_deltas(&outputs);
     assert!(approx_eq(deltas[0], 0.0));
-    assert!(approx_eq(deltas[1], 0.03125), "got {}", deltas[1]);
+    assert!(approx_eq(deltas[1], 0.125), "got {}", deltas[1]);
 }
 
 #[test]
@@ -219,11 +221,11 @@ fn speed_affects_stepdur() {
 
 #[test]
 fn div_each_at_different_tempo() {
-    // At 60 BPM: stepdur = 0.25, so div 2 each => 0, 0.125
+    // At 60 BPM: stepdur = 0.25, default dur = 1.0, so div 2 each => 0, 0.5
     let ctx = ctx_with(|c| c.tempo = 60.0);
     let f = forth();
     let outputs = f.evaluate(r#""kick" s 2 div each"#, &ctx).unwrap();
     let deltas = get_deltas(&outputs);
     assert!(approx_eq(deltas[0], 0.0));
-    assert!(approx_eq(deltas[1], 0.125), "got {}", deltas[1]);
+    assert!(approx_eq(deltas[1], 0.5), "got {}", deltas[1]);
 }