25 files changed, 275 insertions, 195 deletions

diff --git a/cli/src/main.rs b/cli/src/main.rs
index 65b21e22..b7cac1ee 100644
--- a/cli/src/main.rs
+++ b/cli/src/main.rs
@@ -229,12 +229,11 @@ fn compile(command: CompileCommand) -> StrResult<()> {
 /// Compile a single time.
 fn compile_once(world: &mut SystemWorld, command: &CompileCommand) -> StrResult<()> {
     status(command, Status::Compiling).unwrap();
-    world.reset();
 
-    let main = world.resolve(&command.input).map_err(|err| err.to_string())?;
-    let source = world.source(main);
+    world.reset();
+    world.main = world.resolve(&command.input).map_err(|err| err.to_string())?;
 
-    match typst::compile(world, source) {
+    match typst::compile(world) {
         // Export the PDF.
         Ok(document) => {
             let buffer = typst::export::pdf(&document);
@@ -372,6 +371,7 @@ struct SystemWorld {
     hashes: RefCell<HashMap<PathBuf, FileResult<PathHash>>>,
     paths: RefCell<HashMap<PathHash, PathSlot>>,
     sources: FrozenVec<Box<Source>>,
+    main: SourceId,
 }
 
 /// Holds details about the location of a font and lazily the font itself.
@@ -401,6 +401,7 @@ impl SystemWorld {
             hashes: RefCell::default(),
             paths: RefCell::default(),
             sources: FrozenVec::new(),
+            main: SourceId::detached(),
         }
     }
 }
@@ -414,6 +415,25 @@ impl World for SystemWorld {
         &self.library
     }
 
+    fn main(&self) -> &Source {
+        self.source(self.main)
+    }
+
+    fn resolve(&self, path: &Path) -> FileResult<SourceId> {
+        self.slot(path)?
+            .source
+            .get_or_init(|| {
+                let buf = read(path)?;
+                let text = String::from_utf8(buf)?;
+                Ok(self.insert(path, text))
+            })
+            .clone()
+    }
+
+    fn source(&self, id: SourceId) -> &Source {
+        &self.sources[id.into_u16() as usize]
+    }
+
     fn book(&self) -> &Prehashed<FontBook> {
         &self.book
     }
@@ -434,21 +454,6 @@ impl World for SystemWorld {
             .get_or_init(|| read(path).map(Buffer::from))
             .clone()
     }
-
-    fn resolve(&self, path: &Path) -> FileResult<SourceId> {
-        self.slot(path)?
-            .source
-            .get_or_init(|| {
-                let buf = read(path)?;
-                let text = String::from_utf8(buf)?;
-                Ok(self.insert(path, text))
-            })
-            .clone()
-    }
-
-    fn source(&self, id: SourceId) -> &Source {
-        &self.sources[id.into_u16() as usize]
-    }
 }
 
 impl SystemWorld {
diff --git a/docs/src/html.rs b/docs/src/html.rs
index fc9d7d9e..206dee00 100644
--- a/docs/src/html.rs
+++ b/docs/src/html.rs
@@ -307,7 +307,7 @@ fn code_block(resolver: &dyn Resolver, lang: &str, text: &str) -> Html {
 
     let source = Source::new(SourceId::from_u16(0), Path::new("main.typ"), compile);
     let world = DocWorld(source);
-    let mut frames = match typst::compile(&world, &world.0) {
+    let mut frames = match typst::compile(&world) {
         Ok(doc) => doc.pages,
         Err(err) => {
             let msg = &err[0].message;
@@ -335,6 +335,19 @@ impl World for DocWorld {
         &LIBRARY
     }
 
+    fn main(&self) -> &Source {
+        &self.0
+    }
+
+    fn resolve(&self, _: &Path) -> FileResult<SourceId> {
+        unimplemented!()
+    }
+
+    fn source(&self, id: SourceId) -> &Source {
+        assert_eq!(id.into_u16(), 0, "invalid source id");
+        &self.0
+    }
+
     fn book(&self) -> &Prehashed<FontBook> {
         &FONTS.0
     }
@@ -350,13 +363,4 @@ impl World for DocWorld {
             .contents()
             .into())
     }
-
-    fn resolve(&self, _: &Path) -> FileResult<SourceId> {
-        unimplemented!()
-    }
-
-    fn source(&self, id: SourceId) -> &Source {
-        assert_eq!(id.into_u16(), 0, "invalid source id");
-        &self.0
-    }
 }
diff --git a/library/src/layout/enum.rs b/library/src/layout/enum.rs
index 1c08cd5f..05b42bd8 100644
--- a/library/src/layout/enum.rs
+++ b/library/src/layout/enum.rs
@@ -180,7 +180,7 @@ impl Layout for EnumNode {
 
             let resolved = if full {
                 parents.push(number);
-                let content = numbering.apply(vt.world, &parents)?.display();
+                let content = numbering.apply_vt(vt, &parents)?.display();
                 parents.pop();
                 content
             } else {
@@ -188,7 +188,7 @@ impl Layout for EnumNode {
                     Numbering::Pattern(pattern) => {
                         TextNode::packed(pattern.apply_kth(parents.len(), number))
                     }
-                    other => other.apply(vt.world, &[number])?.display(),
+                    other => other.apply_vt(vt, &[number])?.display(),
                 }
             };
 
diff --git a/library/src/layout/list.rs b/library/src/layout/list.rs
index c954ab67..fe78131d 100644
--- a/library/src/layout/list.rs
+++ b/library/src/layout/list.rs
@@ -128,7 +128,7 @@ impl Layout for ListNode {
         };
 
         let depth = self.depth(styles);
-        let marker = self.marker(styles).resolve(vt.world, depth)?;
+        let marker = self.marker(styles).resolve(vt, depth)?;
 
         let mut cells = vec![];
         for item in self.children() {
@@ -181,17 +181,14 @@ pub enum ListMarker {
 
 impl ListMarker {
     /// Resolve the marker for the given depth.
-    fn resolve(&self, world: Tracked<dyn World>, depth: usize) -> SourceResult<Content> {
+    fn resolve(&self, vt: &mut Vt, depth: usize) -> SourceResult<Content> {
         Ok(match self {
             Self::Content(list) => list
                 .get(depth)
                 .or(list.last())
                 .cloned()
                 .unwrap_or_else(|| TextNode::packed('•')),
-            Self::Func(func) => {
-                let args = Args::new(func.span(), [Value::Int(depth as i64)]);
-                func.call_detached(world, args)?.display()
-            }
+            Self::Func(func) => func.call_vt(vt, [Value::Int(depth as i64)])?.display(),
         })
     }
 }
diff --git a/library/src/layout/mod.rs b/library/src/layout/mod.rs
index fc0279eb..b29da700 100644
--- a/library/src/layout/mod.rs
+++ b/library/src/layout/mod.rs
@@ -47,6 +47,7 @@ use std::mem;
 
 use typed_arena::Arena;
 use typst::diag::SourceResult;
+use typst::eval::Tracer;
 use typst::model::{applicable, realize, SequenceNode, StyleVecBuilder, StyledNode};
 
 use crate::math::{FormulaNode, LayoutMath};
@@ -68,11 +69,12 @@ impl LayoutRoot for Content {
         fn cached(
             node: &Content,
             world: Tracked<dyn World>,
+            tracer: TrackedMut<Tracer>,
             provider: TrackedMut<StabilityProvider>,
             introspector: Tracked<Introspector>,
             styles: StyleChain,
         ) -> SourceResult<Document> {
-            let mut vt = Vt { world, provider, introspector };
+            let mut vt = Vt { world, tracer, provider, introspector };
             let scratch = Scratch::default();
             let (realized, styles) = realize_root(&mut vt, &scratch, node, styles)?;
             realized
@@ -84,6 +86,7 @@ impl LayoutRoot for Content {
         cached(
             self,
             vt.world,
+            TrackedMut::reborrow_mut(&mut vt.tracer),
             TrackedMut::reborrow_mut(&mut vt.provider),
             vt.introspector,
             styles,
@@ -129,12 +132,13 @@ impl Layout for Content {
         fn cached(
             node: &Content,
             world: Tracked<dyn World>,
+            tracer: TrackedMut<Tracer>,
             provider: TrackedMut<StabilityProvider>,
             introspector: Tracked<Introspector>,
             styles: StyleChain,
             regions: Regions,
         ) -> SourceResult<Fragment> {
-            let mut vt = Vt { world, provider, introspector };
+            let mut vt = Vt { world, tracer, provider, introspector };
             let scratch = Scratch::default();
             let (realized, styles) = realize_block(&mut vt, &scratch, node, styles)?;
             realized
@@ -146,6 +150,7 @@ impl Layout for Content {
         cached(
             self,
             vt.world,
+            TrackedMut::reborrow_mut(&mut vt.tracer),
             TrackedMut::reborrow_mut(&mut vt.provider),
             vt.introspector,
             styles,
diff --git a/library/src/layout/page.rs b/library/src/layout/page.rs
index 962e8a16..eeb74a55 100644
--- a/library/src/layout/page.rs
+++ b/library/src/layout/page.rs
@@ -403,13 +403,10 @@ pub enum Marginal {
 
 impl Marginal {
     /// Resolve the marginal based on the page number.
-    pub fn resolve(&self, vt: &Vt, page: usize) -> SourceResult<Content> {
+    pub fn resolve(&self, vt: &mut Vt, page: usize) -> SourceResult<Content> {
         Ok(match self {
             Self::Content(content) => content.clone(),
-            Self::Func(func) => {
-                let args = Args::new(func.span(), [Value::Int(page as i64)]);
-                func.call_detached(vt.world, args)?.display()
-            }
+            Self::Func(func) => func.call_vt(vt, [Value::Int(page as i64)])?.display(),
         })
     }
 }
diff --git a/library/src/layout/par.rs b/library/src/layout/par.rs
index 1906dd7c..8657d7fb 100644
--- a/library/src/layout/par.rs
+++ b/library/src/layout/par.rs
@@ -1,3 +1,4 @@
+use typst::eval::Tracer;
 use unicode_bidi::{BidiInfo, Level as BidiLevel};
 use unicode_script::{Script, UnicodeScript};
 use xi_unicode::LineBreakIterator;
@@ -138,6 +139,7 @@ impl ParNode {
         fn cached(
             par: &ParNode,
             world: Tracked<dyn World>,
+            tracer: TrackedMut<Tracer>,
             provider: TrackedMut<StabilityProvider>,
             introspector: Tracked<Introspector>,
             styles: StyleChain,
@@ -145,7 +147,7 @@ impl ParNode {
             region: Size,
             expand: bool,
         ) -> SourceResult<Fragment> {
-            let mut vt = Vt { world, provider, introspector };
+            let mut vt = Vt { world, tracer, provider, introspector };
             let children = par.children();
 
             // Collect all text into one string for BiDi analysis.
@@ -166,6 +168,7 @@ impl ParNode {
         cached(
             self,
             vt.world,
+            TrackedMut::reborrow_mut(&mut vt.tracer),
             TrackedMut::reborrow_mut(&mut vt.provider),
             vt.introspector,
             styles,
diff --git a/library/src/layout/table.rs b/library/src/layout/table.rs
index 024bb0d6..d4b6e7d7 100644
--- a/library/src/layout/table.rs
+++ b/library/src/layout/table.rs
@@ -227,14 +227,13 @@ pub enum Celled<T> {
 
 impl<T: Cast + Clone> Celled<T> {
     /// Resolve the value based on the cell position.
-    pub fn resolve(&self, vt: &Vt, x: usize, y: usize) -> SourceResult<T> {
+    pub fn resolve(&self, vt: &mut Vt, x: usize, y: usize) -> SourceResult<T> {
         Ok(match self {
             Self::Value(value) => value.clone(),
-            Self::Func(func) => {
-                let args =
-                    Args::new(func.span(), [Value::Int(x as i64), Value::Int(y as i64)]);
-                func.call_detached(vt.world, args)?.cast().at(func.span())?
-            }
+            Self::Func(func) => func
+                .call_vt(vt, [Value::Int(x as i64), Value::Int(y as i64)])?
+                .cast()
+                .at(func.span())?,
         })
     }
 }
diff --git a/library/src/meta/counter.rs b/library/src/meta/counter.rs
index b8f719ac..b61e8913 100644
--- a/library/src/meta/counter.rs
+++ b/library/src/meta/counter.rs
@@ -3,6 +3,7 @@ use std::str::FromStr;
 
 use ecow::{eco_vec, EcoVec};
 use smallvec::{smallvec, SmallVec};
+use typst::eval::Tracer;
 
 use super::{Numbering, NumberingPattern};
 use crate::layout::PageNode;
@@ -125,10 +126,16 @@ impl Show for CounterNode {
                     return counter.resolve(vt, id, &numbering);
                 }
 
-                let sequence = counter.sequence(vt.world, vt.introspector)?;
+                let sequence = counter.sequence(
+                    vt.world,
+                    TrackedMut::reborrow_mut(&mut vt.tracer),
+                    TrackedMut::reborrow_mut(&mut vt.provider),
+                    vt.introspector,
+                )?;
+
                 Ok(match (sequence.single(id), sequence.single(None)) {
                     (Some(current), Some(total)) => {
-                        numbering.apply(vt.world, &[current, total])?.display()
+                        numbering.apply_vt(vt, &[current, total])?.display()
                     }
                     _ => Content::empty(),
                 })
@@ -213,7 +220,7 @@ impl Counter {
     /// id.
     pub fn resolve(
         &self,
-        vt: &Vt,
+        vt: &mut Vt,
         stop: Option<StableId>,
         numbering: &Numbering,
     ) -> SourceResult<Content> {
@@ -221,9 +228,15 @@ impl Counter {
             return Ok(Content::empty());
         }
 
-        let sequence = self.sequence(vt.world, vt.introspector)?;
+        let sequence = self.sequence(
+            vt.world,
+            TrackedMut::reborrow_mut(&mut vt.tracer),
+            TrackedMut::reborrow_mut(&mut vt.provider),
+            vt.introspector,
+        )?;
+
         Ok(match sequence.at(stop) {
-            Some(state) => numbering.apply(vt.world, &state.0)?.display(),
+            Some(state) => numbering.apply_vt(vt, &state.0)?.display(),
             None => Content::empty(),
         })
     }
@@ -236,8 +249,11 @@ impl Counter {
     fn sequence(
         &self,
         world: Tracked<dyn World>,
+        tracer: TrackedMut<Tracer>,
+        provider: TrackedMut<StabilityProvider>,
         introspector: Tracked<Introspector>,
     ) -> SourceResult<CounterSequence> {
+        let mut vt = Vt { world, tracer, provider, introspector };
         let mut search = Selector::Node(
             NodeId::of::<CounterNode>(),
             Some(dict! { "counter" => self.clone() }),
@@ -277,7 +293,7 @@ impl Counter {
                     None => Some(CounterUpdate::Step(NonZeroUsize::ONE)),
                 },
             } {
-                state.update(world, update)?;
+                state.update(&mut vt, update)?;
             }
 
             stops.push((id, state.clone()));
@@ -335,17 +351,15 @@ pub struct CounterState(pub SmallVec<[NonZeroUsize; 3]>);
 
 impl CounterState {
     /// Advance the counter and return the numbers for the given heading.
-    pub fn update(
-        &mut self,
-        world: Tracked<dyn World>,
-        update: CounterUpdate,
-    ) -> SourceResult<()> {
+    pub fn update(&mut self, vt: &mut Vt, update: CounterUpdate) -> SourceResult<()> {
         match update {
             CounterUpdate::Set(state) => *self = state,
             CounterUpdate::Step(level) => self.step(level),
             CounterUpdate::Func(func) => {
-                let args = Args::new(func.span(), self.0.iter().copied().map(Into::into));
-                *self = func.call_detached(world, args)?.cast().at(func.span())?
+                *self = func
+                    .call_vt(vt, self.0.iter().copied().map(Into::into))?
+                    .cast()
+                    .at(func.span())?
             }
         }
         Ok(())
diff --git a/library/src/meta/numbering.rs b/library/src/meta/numbering.rs
index 6febc408..6facb833 100644
--- a/library/src/meta/numbering.rs
+++ b/library/src/meta/numbering.rs
@@ -64,7 +64,7 @@ pub fn numbering(
     #[variadic]
     numbers: Vec<NonZeroUsize>,
 ) -> Value {
-    numbering.apply(vm.world(), &numbers)?
+    numbering.apply_vm(vm, &numbers)?
 }
 
 /// How to number a sequence of things.
@@ -78,11 +78,7 @@ pub enum Numbering {
 
 impl Numbering {
     /// Apply the pattern to the given numbers.
-    pub fn apply(
-        &self,
-        world: Tracked<dyn World>,
-        numbers: &[NonZeroUsize],
-    ) -> SourceResult<Value> {
+    pub fn apply_vm(&self, vm: &mut Vm, numbers: &[NonZeroUsize]) -> SourceResult<Value> {
         Ok(match self {
             Self::Pattern(pattern) => Value::Str(pattern.apply(numbers).into()),
             Self::Func(func) => {
@@ -90,7 +86,17 @@ impl Numbering {
                     func.span(),
                     numbers.iter().map(|n| Value::Int(n.get() as i64)),
                 );
-                func.call_detached(world, args)?
+                func.call_vm(vm, args)?
+            }
+        })
+    }
+
+    /// Apply the pattern to the given numbers.
+    pub fn apply_vt(&self, vt: &mut Vt, numbers: &[NonZeroUsize]) -> SourceResult<Value> {
+        Ok(match self {
+            Self::Pattern(pattern) => Value::Str(pattern.apply(numbers).into()),
+            Self::Func(func) => {
+                func.call_vt(vt, numbers.iter().map(|n| Value::Int(n.get() as i64)))?
             }
         })
     }
diff --git a/library/src/meta/outline.rs b/library/src/meta/outline.rs
index 97611036..7cd26eba 100644
--- a/library/src/meta/outline.rs
+++ b/library/src/meta/outline.rs
@@ -91,10 +91,12 @@ impl Show for OutlineNode {
         let depth = self.depth(styles);
 
         let mut ancestors: Vec<&HeadingNode> = vec![];
-        for node in vt.introspector.query(Selector::Node(
+        let nodes = vt.introspector.query(Selector::Node(
             NodeId::of::<HeadingNode>(),
             Some(dict! { "outlined" => true }),
-        )) {
+        ));
+
+        for node in &nodes {
             let heading = node.to::<HeadingNode>().unwrap();
             let stable_id = heading.0.stable_id().unwrap();
             if !heading.outlined(StyleChain::default()) {
diff --git a/library/src/meta/query.rs b/library/src/meta/query.rs
index c91f0d1a..bab8ed7c 100644
--- a/library/src/meta/query.rs
+++ b/library/src/meta/query.rs
@@ -59,11 +59,6 @@ impl Show for QueryNode {
         let target = self.target();
         let (before, after) = vt.introspector.query_split(target, id);
         let func = self.format();
-        let args = Args::new(func.span(), [encode(before), encode(after)]);
-        Ok(func.call_detached(vt.world, args)?.display())
+        Ok(func.call_vt(vt, [before.into(), after.into()])?.display())
     }
 }
-
-fn encode(list: Vec<&Content>) -> Value {
-    Value::Array(list.into_iter().cloned().map(Value::Content).collect())
-}
diff --git a/library/src/meta/reference.rs b/library/src/meta/reference.rs
index f05692dd..0603ee4e 100644
--- a/library/src/meta/reference.rs
+++ b/library/src/meta/reference.rs
@@ -80,7 +80,7 @@ impl Show for RefNode {
             return self.to_citation(styles).show(vt, styles);
         }
 
-        let &[node] = matches.as_slice() else {
+        let [node] = matches.as_slice() else {
             bail!(self.span(), if matches.is_empty() {
                 "label does not exist in the document"
             } else {
@@ -102,8 +102,7 @@ impl Show for RefNode {
             Smart::Custom(None) => Content::empty(),
             Smart::Custom(Some(Supplement::Content(content))) => content.clone(),
             Smart::Custom(Some(Supplement::Func(func))) => {
-                let args = Args::new(func.span(), [node.clone().into()]);
-                func.call_detached(vt.world, args)?.display()
+                func.call_vt(vt, [node.clone().into()])?.display()
             }
         };
 
diff --git a/library/src/meta/state.rs b/library/src/meta/state.rs
index 8b0a0aa6..6b521301 100644
--- a/library/src/meta/state.rs
+++ b/library/src/meta/state.rs
@@ -1,6 +1,7 @@
 use std::fmt::{self, Debug, Formatter, Write};
 
 use ecow::EcoVec;
+use typst::eval::Tracer;
 
 use crate::prelude::*;
 
@@ -118,7 +119,7 @@ impl State {
     /// Display the state at the postition of the given stable id.
     fn resolve(
         &self,
-        vt: &Vt,
+        vt: &mut Vt,
         stop: Option<StableId>,
         func: Option<Func>,
     ) -> SourceResult<Content> {
@@ -126,12 +127,17 @@ impl State {
             return Ok(Content::empty());
         }
 
-        let sequence = self.sequence(vt.world, vt.introspector)?;
+        let sequence = self.sequence(
+            vt.world,
+            TrackedMut::reborrow_mut(&mut vt.tracer),
+            TrackedMut::reborrow_mut(&mut vt.provider),
+            vt.introspector,
+        )?;
+
         Ok(match sequence.at(stop) {
             Some(value) => {
                 if let Some(func) = func {
-                    let args = Args::new(func.span(), [value]);
-                    func.call_detached(vt.world, args)?.display()
+                    func.call_vt(vt, [value])?.display()
                 } else {
                     value.display()
                 }
@@ -148,8 +154,11 @@ impl State {
     fn sequence(
         &self,
         world: Tracked<dyn World>,
+        tracer: TrackedMut<Tracer>,
+        provider: TrackedMut<StabilityProvider>,
         introspector: Tracked<Introspector>,
     ) -> SourceResult<StateSequence> {
+        let mut vt = Vt { world, tracer, provider, introspector };
         let search = Selector::Node(
             NodeId::of::<StateNode>(),
             Some(dict! { "state" => self.clone() }),
@@ -165,10 +174,7 @@ impl State {
             if let StateAction::Update(update) = node.action() {
                 match update {
                     StateUpdate::Set(value) => state = value,
-                    StateUpdate::Func(func) => {
-                        let args = Args::new(func.span(), [state]);
-                        state = func.call_detached(world, args)?;
-                    }
+                    StateUpdate::Func(func) => state = func.call_vt(&mut vt, [state])?,
                 }
             }
 
diff --git a/src/eval/array.rs b/src/eval/array.rs
index 979f15d4..e42fd28d 100644
--- a/src/eval/array.rs
+++ b/src/eval/array.rs
@@ -144,7 +144,7 @@ impl Array {
         }
         for item in self.iter() {
             let args = Args::new(func.span(), [item.clone()]);
-            if func.call(vm, args)?.cast::<bool>().at(func.span())? {
+            if func.call_vm(vm, args)?.cast::<bool>().at(func.span())? {
                 return Ok(Some(item.clone()));
             }
         }
@@ -158,7 +158,7 @@ impl Array {
         }
         for (i, item) in self.iter().enumerate() {
             let args = Args::new(func.span(), [item.clone()]);
-            if func.call(vm, args)?.cast::<bool>().at(func.span())? {
+            if func.call_vm(vm, args)?.cast::<bool>().at(func.span())? {
                 return Ok(Some(i as i64));
             }
         }
@@ -175,7 +175,7 @@ impl Array {
         let mut kept = EcoVec::new();
         for item in self.iter() {
             let args = Args::new(func.span(), [item.clone()]);
-            if func.call(vm, args)?.cast::<bool>().at(func.span())? {
+            if func.call_vm(vm, args)?.cast::<bool>().at(func.span())? {
                 kept.push(item.clone())
             }
         }
@@ -196,7 +196,7 @@ impl Array {
                     args.push(func.span(), Value::Int(i as i64));
                 }
                 args.push(func.span(), item.clone());
-                func.call(vm, args)
+                func.call_vm(vm, args)
             })
             .collect()
     }
@@ -209,7 +209,7 @@ impl Array {
         let mut acc = init;
         for item in self.iter() {
             let args = Args::new(func.span(), [acc, item.clone()]);
-            acc = func.call(vm, args)?;
+            acc = func.call_vm(vm, args)?;
         }
         Ok(acc)
     }
@@ -221,7 +221,7 @@ impl Array {
         }
         for item in self.iter() {
             let args = Args::new(func.span(), [item.clone()]);
-            if func.call(vm, args)?.cast::<bool>().at(func.span())? {
+            if func.call_vm(vm, args)?.cast::<bool>().at(func.span())? {
                 return Ok(true);
             }
         }
@@ -236,7 +236,7 @@ impl Array {
         }
         for item in self.iter() {
             let args = Args::new(func.span(), [item.clone()]);
-            if !func.call(vm, args)?.cast::<bool>().at(func.span())? {
+            if !func.call_vm(vm, args)?.cast::<bool>().at(func.span())? {
                 return Ok(false);
             }
         }
diff --git a/src/eval/func.rs b/src/eval/func.rs
index a5fa6fa1..c3ec4233 100644
--- a/src/eval/func.rs
+++ b/src/eval/func.rs
@@ -13,7 +13,7 @@ use super::{
     Vm,
 };
 use crate::diag::{bail, SourceResult, StrResult};
-use crate::model::{NodeId, Selector, StyleMap};
+use crate::model::{NodeId, Selector, StyleMap, Vt};
 use crate::syntax::ast::{self, AstNode, Expr};
 use crate::syntax::{SourceId, Span, SyntaxNode};
 use crate::util::hash128;
@@ -82,7 +82,7 @@ impl Func {
     }
 
     /// Call the function with the given arguments.
-    pub fn call(&self, vm: &mut Vm, mut args: Args) -> SourceResult<Value> {
+    pub fn call_vm(&self, vm: &mut Vm, mut args: Args) -> SourceResult<Value> {
         match &**self.0 {
             Repr::Native(native) => {
                 let value = (native.func)(vm, &mut args)?;
@@ -111,23 +111,29 @@ impl Func {
             }
             Repr::With(wrapped, applied) => {
                 args.items = applied.items.iter().cloned().chain(args.items).collect();
-                return wrapped.call(vm, args);
+                return wrapped.call_vm(vm, args);
             }
         }
     }
 
-    /// Call the function without an existing virtual machine.
-    pub fn call_detached(
+    /// Call the function with a Vt.
+    pub fn call_vt(
         &self,
-        world: Tracked<dyn World>,
-        args: Args,
+        vt: &mut Vt,
+        args: impl IntoIterator<Item = Value>,
     ) -> SourceResult<Value> {
         let route = Route::default();
         let id = SourceId::detached();
         let scopes = Scopes::new(None);
-        let mut tracer = Tracer::default();
-        let mut vm = Vm::new(world, route.track(), tracer.track_mut(), id, scopes, 0);
-        self.call(&mut vm, args)
+        let mut vm = Vm::new(
+            vt.world,
+            route.track(),
+            TrackedMut::reborrow_mut(&mut vt.tracer),
+            id,
+            scopes,
+        );
+        let args = Args::new(self.span(), args);
+        self.call_vm(&mut vm, args)
     }
 
     /// Apply the given arguments to the function.
@@ -208,7 +214,7 @@ impl From<NodeId> for Func {
 /// A native Rust function.
 pub struct NativeFunc {
     /// The function's implementation.
-    pub func: fn(&Vm, &mut Args) -> SourceResult<Value>,
+    pub func: fn(&mut Vm, &mut Args) -> SourceResult<Value>,
     /// Details about the function.
     pub info: Lazy<FuncInfo>,
 }
@@ -352,10 +358,11 @@ impl Closure {
         args.finish()?;
 
         // Evaluate the body.
-        let mut sub = Vm::new(world, route, tracer, closure.location, scopes, depth);
-        let result = closure.body.eval(&mut sub);
+        let mut sub = Vm::new(world, route, tracer, closure.location, scopes);
+        sub.depth = depth;
 
         // Handle control flow.
+        let result = closure.body.eval(&mut sub);
         match sub.flow {
             Some(Flow::Return(_, Some(explicit))) => return Ok(explicit),
             Some(Flow::Return(_, None)) => {}
diff --git a/src/eval/mod.rs b/src/eval/mod.rs
index 127c930f..1c002c49 100644
--- a/src/eval/mod.rs
+++ b/src/eval/mod.rs
@@ -81,7 +81,7 @@ pub fn eval(
     // Evaluate the module.
     let route = unsafe { Route::insert(route, id) };
     let scopes = Scopes::new(Some(library));
-    let mut vm = Vm::new(world, route.track(), tracer, id, scopes, 0);
+    let mut vm = Vm::new(world, route.track(), tracer, id, scopes);
     let root = match source.root().cast::<ast::Markup>() {
         Some(markup) if vm.traced.is_some() => markup,
         _ => source.ast()?,
@@ -121,7 +121,7 @@ pub fn eval_code_str(
     let scopes = Scopes::new(Some(library));
     let route = Route::default();
     let mut tracer = Tracer::default();
-    let mut vm = Vm::new(world, route.track(), tracer.track_mut(), id, scopes, 0);
+    let mut vm = Vm::new(world, route.track(), tracer.track_mut(), id, scopes);
     let code = root.cast::<ast::Code>().unwrap();
     let result = code.eval(&mut vm);
 
@@ -139,34 +139,33 @@ pub fn eval_code_str(
 /// virtual machine is created for each module evaluation and function call.
 pub struct Vm<'a> {
     /// The compilation environment.
-    pub(super) world: Tracked<'a, dyn World>,
+    world: Tracked<'a, dyn World>,
     /// The language items.
-    pub(super) items: LangItems,
+    items: LangItems,
     /// The route of source ids the VM took to reach its current location.
-    pub(super) route: Tracked<'a, Route>,
+    route: Tracked<'a, Route>,
     /// The tracer for inspection of the values an expression produces.
-    pub(super) tracer: TrackedMut<'a, Tracer>,
+    tracer: TrackedMut<'a, Tracer>,
     /// The current location.
-    pub(super) location: SourceId,
+    location: SourceId,
     /// A control flow event that is currently happening.
-    pub(super) flow: Option<Flow>,
+    flow: Option<Flow>,
     /// The stack of scopes.
-    pub(super) scopes: Scopes<'a>,
+    scopes: Scopes<'a>,
     /// The current call depth.
-    pub(super) depth: usize,
+    depth: usize,
     /// A span that is currently traced.
-    pub(super) traced: Option<Span>,
+    traced: Option<Span>,
 }
 
 impl<'a> Vm<'a> {
     /// Create a new virtual machine.
-    pub(super) fn new(
+    fn new(
         world: Tracked<'a, dyn World>,
         route: Tracked<'a, Route>,
         tracer: TrackedMut<'a, Tracer>,
         location: SourceId,
         scopes: Scopes<'a>,
-        depth: usize,
     ) -> Self {
         let traced = tracer.span(location);
         Self {
@@ -177,7 +176,7 @@ impl<'a> Vm<'a> {
             location,
             flow: None,
             scopes,
-            depth,
+            depth: 0,
             traced,
         }
     }
@@ -358,7 +357,7 @@ fn eval_markup(
                 }
 
                 let tail = eval_markup(vm, exprs)?;
-                seq.push(tail.styled_with_recipe(vm.world, recipe)?)
+                seq.push(tail.styled_with_recipe(vm, recipe)?)
             }
             expr => match expr.eval(vm)? {
                 Value::Label(label) => {
@@ -791,7 +790,7 @@ fn eval_code(
                 }
 
                 let tail = eval_code(vm, exprs)?.display();
-                Value::Content(tail.styled_with_recipe(vm.world, recipe)?)
+                Value::Content(tail.styled_with_recipe(vm, recipe)?)
             }
             _ => expr.eval(vm)?,
         };
@@ -1053,7 +1052,7 @@ impl Eval for ast::FuncCall {
 
         let callee = callee.cast::<Func>().at(callee_span)?;
         let point = || Tracepoint::Call(callee.name().map(Into::into));
-        callee.call(vm, args).trace(vm.world, point, span)
+        callee.call_vm(vm, args).trace(vm.world, point, span)
     }
 }
 
diff --git a/src/ide/analyze.rs b/src/ide/analyze.rs
index ccb89a9c..68b82b05 100644
--- a/src/ide/analyze.rs
+++ b/src/ide/analyze.rs
@@ -36,11 +36,23 @@ pub fn analyze_expr(world: &(dyn World + 'static), node: &LinkedNode) -> Vec<Val
                 }
             }
 
-            let span = node.span();
-            let source = world.source(span.source());
             let route = Route::default();
-            let mut tracer = Tracer::new(Some(span));
-            eval(world.track(), route.track(), tracer.track_mut(), source).ok();
+            let mut tracer = Tracer::new(Some(node.span()));
+            typst::eval::eval(
+                world.track(),
+                route.track(),
+                tracer.track_mut(),
+                world.main(),
+            )
+            .and_then(|module| {
+                typst::model::typeset(
+                    world.track(),
+                    tracer.track_mut(),
+                    &module.content(),
+                )
+            })
+            .ok();
+
             tracer.finish()
         }
 
diff --git a/src/lib.rs b/src/lib.rs
index 7cfed897..9dbaf721 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -63,14 +63,15 @@ use crate::syntax::{Source, SourceId};
 use crate::util::Buffer;
 
 /// Compile a source file into a fully layouted document.
-pub fn compile(world: &(dyn World + 'static), source: &Source) -> SourceResult<Document> {
+pub fn compile(world: &(dyn World + 'static)) -> SourceResult<Document> {
     // Evaluate the source file into a module.
     let route = Route::default();
     let mut tracer = Tracer::default();
-    let module = eval::eval(world.track(), route.track(), tracer.track_mut(), source)?;
+    let module =
+        eval::eval(world.track(), route.track(), tracer.track_mut(), world.main())?;
 
     // Typeset the module's contents.
-    model::typeset(world.track(), &module.content())
+    model::typeset(world.track(), tracer.track_mut(), &module.content())
 }
 
 /// The environment in which typesetting occurs.
@@ -86,6 +87,15 @@ pub trait World {
     /// The standard library.
     fn library(&self) -> &Prehashed<Library>;
 
+    /// The main source file.
+    fn main(&self) -> &Source;
+
+    /// Try to resolve the unique id of a source file.
+    fn resolve(&self, path: &Path) -> FileResult<SourceId>;
+
+    /// Access a source file by id.
+    fn source(&self, id: SourceId) -> &Source;
+
     /// Metadata about all known fonts.
     fn book(&self) -> &Prehashed<FontBook>;
 
@@ -94,10 +104,4 @@ pub trait World {
 
     /// Try to access a file at a path.
     fn file(&self, path: &Path) -> FileResult<Buffer>;
-
-    /// Try to resolve the unique id of a source file.
-    fn resolve(&self, path: &Path) -> FileResult<SourceId>;
-
-    /// Access a source file by id.
-    fn source(&self, id: SourceId) -> &Source;
 }
diff --git a/src/model/content.rs b/src/model/content.rs
index bd24829d..5317236e 100644
--- a/src/model/content.rs
+++ b/src/model/content.rs
@@ -4,7 +4,6 @@ use std::hash::{Hash, Hasher};
 use std::iter::{self, Sum};
 use std::ops::{Add, AddAssign, Deref};
 
-use comemo::Tracked;
 use ecow::{eco_format, EcoString, EcoVec};
 use once_cell::sync::Lazy;
 
@@ -19,7 +18,6 @@ use crate::eval::{
 };
 use crate::syntax::Span;
 use crate::util::pretty_array_like;
-use crate::World;
 
 /// Composable representation of styled content.
 #[derive(Clone, Hash)]
@@ -219,13 +217,9 @@ impl Content {
     }
 
     /// Style this content with a recipe, eagerly applying it if possible.
-    pub fn styled_with_recipe(
-        self,
-        world: Tracked<dyn World>,
-        recipe: Recipe,
-    ) -> SourceResult<Self> {
+    pub fn styled_with_recipe(self, vm: &mut Vm, recipe: Recipe) -> SourceResult<Self> {
         if recipe.selector.is_none() {
-            recipe.apply(world, self)
+            recipe.apply_vm(vm, self)
         } else {
             Ok(self.styled(Style::Recipe(recipe)))
         }
diff --git a/src/model/realize.rs b/src/model/realize.rs
index 70c75644..634a31fd 100644
--- a/src/model/realize.rs
+++ b/src/model/realize.rs
@@ -97,7 +97,7 @@ pub fn realize(
 
 /// Try to apply a recipe to the target.
 fn try_apply(
-    vt: &Vt,
+    vt: &mut Vt,
     target: &Content,
     recipe: &Recipe,
     guard: Guard,
@@ -108,7 +108,7 @@ fn try_apply(
                 return Ok(None);
             }
 
-            recipe.apply(vt.world, target.clone().guarded(guard)).map(Some)
+            recipe.apply_vt(vt, target.clone().guarded(guard)).map(Some)
         }
 
         Some(Selector::Label(label)) => {
@@ -116,7 +116,7 @@ fn try_apply(
                 return Ok(None);
             }
 
-            recipe.apply(vt.world, target.clone().guarded(guard)).map(Some)
+            recipe.apply_vt(vt, target.clone().guarded(guard)).map(Some)
         }
 
         Some(Selector::Regex(regex)) => {
@@ -140,7 +140,7 @@ fn try_apply(
                 }
 
                 let piece = make(m.as_str().into()).guarded(guard);
-                let transformed = recipe.apply(vt.world, piece)?;
+                let transformed = recipe.apply_vt(vt, piece)?;
                 result.push(transformed);
                 cursor = m.end();
             }
diff --git a/src/model/styles.rs b/src/model/styles.rs
index 359f1461..8cccb5f6 100644
--- a/src/model/styles.rs
+++ b/src/model/styles.rs
@@ -1,15 +1,13 @@
 use std::fmt::{self, Debug, Formatter, Write};
 use std::iter;
 
-use comemo::Tracked;
 use ecow::{eco_format, EcoString, EcoVec};
 
-use super::{Content, Label, Node, NodeId};
+use super::{Content, Label, Node, NodeId, Vt};
 use crate::diag::{SourceResult, Trace, Tracepoint};
-use crate::eval::{cast_from_value, Args, Cast, Dict, Func, Regex, Value};
+use crate::eval::{cast_from_value, Args, Cast, Dict, Func, Regex, Value, Vm};
 use crate::syntax::Span;
 use crate::util::pretty_array_like;
-use crate::World;
 
 /// A map of style properties.
 #[derive(Default, Clone, Hash)]
@@ -197,20 +195,32 @@ impl Recipe {
     }
 
     /// Apply the recipe to the given content.
-    pub fn apply(
-        &self,
-        world: Tracked<dyn World>,
-        content: Content,
-    ) -> SourceResult<Content> {
+    pub fn apply_vm(&self, vm: &mut Vm, content: Content) -> SourceResult<Content> {
         match &self.transform {
             Transform::Content(content) => Ok(content.clone()),
             Transform::Func(func) => {
                 let args = Args::new(self.span, [Value::Content(content.clone())]);
-                let mut result = func.call_detached(world, args);
+                let mut result = func.call_vm(vm, args);
                 // For selector-less show rules, a tracepoint makes no sense.
                 if self.selector.is_some() {
                     let point = || Tracepoint::Show(content.id().name.into());
-                    result = result.trace(world, point, content.span());
+                    result = result.trace(vm.world(), point, content.span());
+                }
+                Ok(result?.display())
+            }
+            Transform::Style(styles) => Ok(content.styled_with_map(styles.clone())),
+        }
+    }
+
+    /// Apply the recipe to the given content.
+    pub fn apply_vt(&self, vt: &mut Vt, content: Content) -> SourceResult<Content> {
+        match &self.transform {
+            Transform::Content(content) => Ok(content.clone()),
+            Transform::Func(func) => {
+                let mut result = func.call_vt(vt, [Value::Content(content.clone())]);
+                if self.selector.is_some() {
+                    let point = || Tracepoint::Show(content.id().name.into());
+                    result = result.trace(vt.world, point, content.span());
                 }
                 Ok(result?.display())
             }
diff --git a/src/model/typeset.rs b/src/model/typeset.rs
index e9cb3d2c..683f2846 100644
--- a/src/model/typeset.rs
+++ b/src/model/typeset.rs
@@ -6,13 +6,18 @@ use comemo::{Constraint, Track, Tracked, TrackedMut};
 use super::{Content, Selector, StyleChain};
 use crate::diag::SourceResult;
 use crate::doc::{Document, Element, Frame, Location, Meta};
+use crate::eval::Tracer;
 use crate::geom::{Point, Transform};
 use crate::util::NonZeroExt;
 use crate::World;
 
 /// Typeset content into a fully layouted document.
 #[comemo::memoize]
-pub fn typeset(world: Tracked<dyn World>, content: &Content) -> SourceResult<Document> {
+pub fn typeset(
+    world: Tracked<dyn World>,
+    mut tracer: TrackedMut<Tracer>,
+    content: &Content,
+) -> SourceResult<Document> {
     let library = world.library();
     let styles = StyleChain::new(&library.styles);
 
@@ -27,6 +32,7 @@ pub fn typeset(world: Tracked<dyn World>, content: &Content) -> SourceResult<Doc
         let mut provider = StabilityProvider::new();
         let mut vt = Vt {
             world,
+            tracer: TrackedMut::reborrow_mut(&mut tracer),
             provider: provider.track_mut(),
             introspector: introspector.track_with(&constraint),
         };
@@ -52,6 +58,8 @@ pub fn typeset(world: Tracked<dyn World>, content: &Content) -> SourceResult<Doc
 pub struct Vt<'a> {
     /// The compilation environment.
     pub world: Tracked<'a, dyn World>,
+    /// The tracer for inspection of the values an expression produces.
+    pub tracer: TrackedMut<'a, Tracer>,
     /// Provides stable identities to nodes.
     pub provider: TrackedMut<'a, StabilityProvider>,
     /// Provides access to information about the document.
@@ -162,8 +170,8 @@ impl Introspector {
     }
 
     /// Query for all metadata matches for the given selector.
-    pub fn query(&self, selector: Selector) -> Vec<&Content> {
-        self.all().filter(|node| selector.matches(node)).collect()
+    pub fn query(&self, selector: Selector) -> Vec<Content> {
+        self.all().filter(|node| selector.matches(node)).cloned().collect()
     }
 
     /// Query for all metadata matches before the given id.
@@ -171,14 +179,15 @@ impl Introspector {
         &self,
         selector: Selector,
         id: StableId,
-    ) -> (Vec<&Content>, Vec<&Content>) {
+    ) -> (Vec<Content>, Vec<Content>) {
         let mut iter = self.all();
         let before = iter
             .by_ref()
             .take_while(|node| node.stable_id() != Some(id))
             .filter(|node| selector.matches(node))
+            .cloned()
             .collect();
-        let after = iter.filter(|node| selector.matches(node)).collect();
+        let after = iter.filter(|node| selector.matches(node)).cloned().collect();
         (before, after)
     }
 
diff --git a/tests/src/benches.rs b/tests/src/benches.rs
index 21fdbc7a..b1e77692 100644
--- a/tests/src/benches.rs
+++ b/tests/src/benches.rs
@@ -80,17 +80,17 @@ fn bench_typeset(iai: &mut Iai) {
     )
     .unwrap();
     let content = module.content();
-    iai.run(|| typst::model::typeset(world.track(), &content));
+    iai.run(|| typst::model::typeset(world.track(), tracer.track_mut(), &content));
 }
 
 fn bench_compile(iai: &mut Iai) {
     let world = BenchWorld::new();
-    iai.run(|| typst::compile(&world, &world.source));
+    iai.run(|| typst::compile(&world));
 }
 
 fn bench_render(iai: &mut Iai) {
     let world = BenchWorld::new();
-    let document = typst::compile(&world, &world.source).unwrap();
+    let document = typst::compile(&world).unwrap();
     iai.run(|| typst::export::render(&document.pages[0], 1.0, Color::WHITE))
 }
 
@@ -124,6 +124,18 @@ impl World for BenchWorld {
         &self.library
     }
 
+    fn main(&self) -> &Source {
+        &self.source
+    }
+
+    fn resolve(&self, path: &Path) -> FileResult<SourceId> {
+        Err(FileError::NotFound(path.into()))
+    }
+
+    fn source(&self, _: SourceId) -> &Source {
+        &self.source
+    }
+
     fn book(&self) -> &Prehashed<FontBook> {
         &self.book
     }
@@ -135,12 +147,4 @@ impl World for BenchWorld {
     fn file(&self, path: &Path) -> FileResult<Buffer> {
         Err(FileError::NotFound(path.into()))
     }
-
-    fn resolve(&self, path: &Path) -> FileResult<SourceId> {
-        Err(FileError::NotFound(path.into()))
-    }
-
-    fn source(&self, _: SourceId) -> &Source {
-        unimplemented!()
-    }
 }
diff --git a/tests/src/tests.rs b/tests/src/tests.rs
index 1fb40204..9e6d94a3 100644
--- a/tests/src/tests.rs
+++ b/tests/src/tests.rs
@@ -207,6 +207,7 @@ struct TestWorld {
     fonts: Vec<Font>,
     paths: RefCell<HashMap<PathBuf, PathSlot>>,
     sources: FrozenVec<Box<Source>>,
+    main: SourceId,
 }
 
 #[derive(Default)]
@@ -236,6 +237,7 @@ impl TestWorld {
             fonts,
             paths: RefCell::default(),
             sources: FrozenVec::new(),
+            main: SourceId::detached(),
         }
     }
 }
@@ -249,19 +251,8 @@ impl World for TestWorld {
         &self.library
     }
 
-    fn book(&self) -> &Prehashed<FontBook> {
-        &self.book
-    }
-
-    fn font(&self, id: usize) -> Option<Font> {
-        Some(self.fonts[id].clone())
-    }
-
-    fn file(&self, path: &Path) -> FileResult<Buffer> {
-        self.slot(path)
-            .buffer
-            .get_or_init(|| read(path).map(Buffer::from))
-            .clone()
+    fn main(&self) -> &Source {
+        self.source(self.main)
     }
 
     fn resolve(&self, path: &Path) -> FileResult<SourceId> {
@@ -278,20 +269,38 @@ impl World for TestWorld {
     fn source(&self, id: SourceId) -> &Source {
         &self.sources[id.into_u16() as usize]
     }
+
+    fn book(&self) -> &Prehashed<FontBook> {
+        &self.book
+    }
+
+    fn font(&self, id: usize) -> Option<Font> {
+        Some(self.fonts[id].clone())
+    }
+
+    fn file(&self, path: &Path) -> FileResult<Buffer> {
+        self.slot(path)
+            .buffer
+            .get_or_init(|| read(path).map(Buffer::from))
+            .clone()
+    }
 }
 
 impl TestWorld {
     fn set(&mut self, path: &Path, text: String) -> SourceId {
         let slot = self.slot(path);
-        if let Some(&Ok(id)) = slot.source.get() {
+        let id = if let Some(&Ok(id)) = slot.source.get() {
             drop(slot);
             self.sources.as_mut()[id.into_u16() as usize].replace(text);
             id
         } else {
             let id = self.insert(path, text);
             slot.source.set(Ok(id)).unwrap();
+            drop(slot);
             id
-        }
+        };
+        self.main = id;
+        id
     }
 
     fn slot(&self, path: &Path) -> RefMut<PathSlot> {
@@ -448,7 +457,7 @@ fn test_part(
         println!("Model:\n{:#?}\n", module.content());
     }
 
-    let (mut frames, errors) = match typst::compile(world, source) {
+    let (mut frames, errors) = match typst::compile(world) {
         Ok(document) => (document.pages, vec![]),
         Err(errors) => (vec![], *errors),
     };