diff --git a/Cargo.lock b/Cargo.lock
index 1d5ecb602..a5f06a239 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2408,6 +2408,7 @@ dependencies = [
  "tracing",
  "ttf-parser",
  "typst-macros",
+ "typst-syntax",
  "unicode-general-category",
  "unicode-ident",
  "unicode-math-class",
@@ -2516,6 +2517,21 @@ dependencies = [
  "syn 2.0.16",
 ]
 
+[[package]]
+name = "typst-syntax"
+version = "0.6.0"
+dependencies = [
+ "comemo",
+ "ecow",
+ "once_cell",
+ "serde",
+ "tracing",
+ "unicode-ident",
+ "unicode-math-class",
+ "unicode-segmentation",
+ "unscanny",
+]
+
 [[package]]
 name = "typst-tests"
 version = "0.6.0"
diff --git a/crates/typst-cli/src/compile.rs b/crates/typst-cli/src/compile.rs
index 3250202b2..9dfa4d41a 100644
--- a/crates/typst-cli/src/compile.rs
+++ b/crates/typst-cli/src/compile.rs
@@ -7,9 +7,8 @@ use termcolor::{ColorChoice, StandardStream};
 use typst::diag::{bail, SourceError, StrResult};
 use typst::doc::Document;
 use typst::eval::eco_format;
-use typst::file::FileId;
 use typst::geom::Color;
-use typst::syntax::Source;
+use typst::syntax::{FileId, Source};
 use typst::World;
 
 use crate::args::{CompileCommand, DiagnosticFormat};
@@ -168,7 +167,7 @@ fn print_diagnostics(
                     .map(|e| (eco_format!("hint: {e}")).into())
                     .collect(),
             )
-            .with_labels(vec![Label::primary(error.span.id(), error.span.range(world))]);
+            .with_labels(vec![Label::primary(error.span.id(), world.range(error.span))]);
 
         term::emit(&mut w, &config, world, &diag)?;
 
@@ -176,7 +175,7 @@ fn print_diagnostics(
         for point in error.trace {
             let message = point.v.to_string();
             let help = Diagnostic::help().with_message(message).with_labels(vec![
-                Label::primary(point.span.id(), point.span.range(world)),
+                Label::primary(point.span.id(), world.range(point.span)),
             ]);
 
             term::emit(&mut w, &config, world, &help)?;
diff --git a/crates/typst-cli/src/package.rs b/crates/typst-cli/src/package.rs
index 6853796b3..4bde65244 100644
--- a/crates/typst-cli/src/package.rs
+++ b/crates/typst-cli/src/package.rs
@@ -5,7 +5,7 @@ use std::path::{Path, PathBuf};
 use codespan_reporting::term::{self, termcolor};
 use termcolor::WriteColor;
 use typst::diag::{PackageError, PackageResult};
-use typst::file::PackageSpec;
+use typst::syntax::PackageSpec;
 
 use super::color_stream;
 
diff --git a/crates/typst-cli/src/world.rs b/crates/typst-cli/src/world.rs
index f09a3f6c7..cfa96d363 100644
--- a/crates/typst-cli/src/world.rs
+++ b/crates/typst-cli/src/world.rs
@@ -10,9 +10,8 @@ use same_file::Handle;
 use siphasher::sip128::{Hasher128, SipHasher13};
 use typst::diag::{FileError, FileResult, StrResult};
 use typst::eval::{eco_format, Datetime, Library};
-use typst::file::FileId;
 use typst::font::{Font, FontBook};
-use typst::syntax::Source;
+use typst::syntax::{FileId, Source};
 use typst::util::{Bytes, PathExt};
 use typst::World;
 
diff --git a/crates/typst-docs/src/html.rs b/crates/typst-docs/src/html.rs
index 4cbf5661f..ed49f9fef 100644
--- a/crates/typst-docs/src/html.rs
+++ b/crates/typst-docs/src/html.rs
@@ -5,10 +5,9 @@ use pulldown_cmark as md;
 use typed_arena::Arena;
 use typst::diag::FileResult;
 use typst::eval::Datetime;
-use typst::file::FileId;
 use typst::font::{Font, FontBook};
 use typst::geom::{Point, Size};
-use typst::syntax::Source;
+use typst::syntax::{FileId, Source};
 use typst::util::Bytes;
 use typst::World;
 use yaml_front_matter::YamlFrontMatter;
diff --git a/crates/typst-library/src/prelude.rs b/crates/typst-library/src/prelude.rs
index c720e770d..b4acbea0c 100644
--- a/crates/typst-library/src/prelude.rs
+++ b/crates/typst-library/src/prelude.rs
@@ -19,8 +19,6 @@ pub use typst::eval::{
     Func, IntoValue, Never, NoneValue, Scope, Str, Symbol, Type, Value, Vm,
 };
 #[doc(no_inline)]
-pub use typst::file::FileId;
-#[doc(no_inline)]
 pub use typst::geom::*;
 #[doc(no_inline)]
 pub use typst::model::{
@@ -30,7 +28,7 @@ pub use typst::model::{
     Unlabellable, Vt,
 };
 #[doc(no_inline)]
-pub use typst::syntax::{Span, Spanned};
+pub use typst::syntax::{FileId, Span, Spanned};
 #[doc(no_inline)]
 pub use typst::util::NonZeroExt;
 #[doc(no_inline)]
diff --git a/crates/typst-syntax/Cargo.toml b/crates/typst-syntax/Cargo.toml
new file mode 100644
index 000000000..928635c4c
--- /dev/null
+++ b/crates/typst-syntax/Cargo.toml
@@ -0,0 +1,27 @@
+[package]
+name = "typst-syntax"
+description = "Parser and syntax tree for Typst."
+categories = ["compilers", "science"]
+keywords = ["typst"]
+version.workspace = true
+rust-version.workspace = true
+authors.workspace = true
+edition.workspace = true
+homepage.workspace = true
+repository.workspace = true
+license.workspace = true
+
+[lib]
+doctest = false
+bench = false
+
+[dependencies]
+comemo = "0.3"
+ecow = "0.1.1"
+once_cell = "1"
+serde = { version = "1", features = ["derive"] }
+tracing = "0.1.37"
+unicode-ident = "1.0"
+unicode-math-class = "0.1"
+unicode-segmentation = "1"
+unscanny = "0.1"
diff --git a/crates/typst/src/syntax/ast.rs b/crates/typst-syntax/src/ast.rs
similarity index 99%
rename from crates/typst/src/syntax/ast.rs
rename to crates/typst-syntax/src/ast.rs
index 48be1b07f..c2755d0c6 100644
--- a/crates/typst/src/syntax/ast.rs
+++ b/crates/typst-syntax/src/ast.rs
@@ -11,8 +11,6 @@ use unscanny::Scanner;
 use super::{
     is_id_continue, is_id_start, is_newline, split_newlines, Span, SyntaxKind, SyntaxNode,
 };
-use crate::geom::{AbsUnit, AngleUnit};
-use crate::util::NonZeroExt;
 
 /// A typed AST node.
 pub trait AstNode: Sized {
@@ -680,7 +678,7 @@ impl Heading {
             .children()
             .find(|node| node.kind() == SyntaxKind::HeadingMarker)
             .and_then(|node| node.len().try_into().ok())
-            .unwrap_or(NonZeroUsize::ONE)
+            .unwrap_or(NonZeroUsize::new(1).unwrap())
     }
 }
 
@@ -1012,12 +1010,12 @@ impl Numeric {
         let split = text.len() - count;
         let value = text[..split].parse().unwrap_or_default();
         let unit = match &text[split..] {
-            "pt" => Unit::Length(AbsUnit::Pt),
-            "mm" => Unit::Length(AbsUnit::Mm),
-            "cm" => Unit::Length(AbsUnit::Cm),
-            "in" => Unit::Length(AbsUnit::In),
-            "deg" => Unit::Angle(AngleUnit::Deg),
-            "rad" => Unit::Angle(AngleUnit::Rad),
+            "pt" => Unit::Pt,
+            "mm" => Unit::Mm,
+            "cm" => Unit::Cm,
+            "in" => Unit::In,
+            "deg" => Unit::Deg,
+            "rad" => Unit::Rad,
             "em" => Unit::Em,
             "fr" => Unit::Fr,
             "%" => Unit::Percent,
@@ -1031,10 +1029,18 @@ impl Numeric {
 /// Unit of a numeric value.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
 pub enum Unit {
-    /// An absolute length unit.
-    Length(AbsUnit),
-    /// An angular unit.
-    Angle(AngleUnit),
+    /// Points.
+    Pt,
+    /// Millimeters.
+    Mm,
+    /// Centimeters.
+    Cm,
+    /// Inches.
+    In,
+    /// Radians.
+    Rad,
+    /// Degrees.
+    Deg,
     /// Font-relative: `1em` is the same as the font size.
     Em,
     /// Fractions: `fr`.
diff --git a/crates/typst/src/file.rs b/crates/typst-syntax/src/file.rs
similarity index 71%
rename from crates/typst/src/file.rs
rename to crates/typst-syntax/src/file.rs
index 8aaa746be..fc1bed212 100644
--- a/crates/typst/src/file.rs
+++ b/crates/typst-syntax/src/file.rs
@@ -2,7 +2,7 @@
 
 use std::collections::HashMap;
 use std::fmt::{self, Debug, Display, Formatter};
-use std::path::{Path, PathBuf};
+use std::path::{Component, Path, PathBuf};
 use std::str::FromStr;
 use std::sync::RwLock;
 
@@ -10,9 +10,7 @@ use ecow::{eco_format, EcoString};
 use once_cell::sync::Lazy;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
-use crate::diag::{bail, FileError, StrResult};
-use crate::syntax::is_ident;
-use crate::util::PathExt;
+use super::is_ident;
 
 /// The global package-path interner.
 static INTERNER: Lazy<RwLock<Interner>> =
@@ -27,7 +25,7 @@ struct Interner {
 /// An interned pair of a package specification and a path.
 type Pair = &'static (Option<PackageSpec>, PathBuf);
 
-/// Identifies a file.
+/// Identifies a file in a project or package.
 ///
 /// This type is globally interned and thus cheap to copy, compare, and hash.
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
@@ -48,7 +46,7 @@ impl FileId {
         );
 
         // Try to find an existing entry that we can reuse.
-        let pair = (package, path.normalize());
+        let pair = (package, normalize_path(path));
         if let Some(&id) = INTERNER.read().unwrap().to_id.get(&pair) {
             return id;
         }
@@ -99,9 +97,9 @@ impl FileId {
     }
 
     /// Resolve a file location relative to this file.
-    pub fn join(self, path: &str) -> StrResult<Self> {
+    pub fn join(self, path: &str) -> Result<Self, EcoString> {
         if self.is_detached() {
-            bail!("cannot access file system from here");
+            Err("cannot access file system from here")?;
         }
 
         let package = self.package().cloned();
@@ -145,6 +143,29 @@ impl Debug for FileId {
     }
 }
 
+/// Lexically normalize a path.
+fn normalize_path(path: &Path) -> PathBuf {
+    let mut out = PathBuf::new();
+    for component in path.components() {
+        match component {
+            Component::CurDir => {}
+            Component::ParentDir => match out.components().next_back() {
+                Some(Component::Normal(_)) => {
+                    out.pop();
+                }
+                _ => out.push(component),
+            },
+            Component::Prefix(_) | Component::RootDir | Component::Normal(_) => {
+                out.push(component)
+            }
+        }
+    }
+    if out.as_os_str().is_empty() {
+        out.push(Component::CurDir);
+    }
+    out
+}
+
 /// Identifies a package.
 #[derive(Debug, Clone, Eq, PartialEq, Hash)]
 pub struct PackageSpec {
@@ -153,7 +174,7 @@ pub struct PackageSpec {
     /// The name of the package within its namespace.
     pub name: EcoString,
     /// The package's version.
-    pub version: Version,
+    pub version: PackageVersion,
 }
 
 impl FromStr for PackageSpec {
@@ -162,30 +183,30 @@ impl FromStr for PackageSpec {
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let mut s = unscanny::Scanner::new(s);
         if !s.eat_if('@') {
-            bail!("package specification must start with '@'");
+            Err("package specification must start with '@'")?;
         }
 
         let namespace = s.eat_until('/');
         if namespace.is_empty() {
-            bail!("package specification is missing namespace");
+            Err("package specification is missing namespace")?;
         } else if !is_ident(namespace) {
-            bail!("`{namespace}` is not a valid package namespace");
+            Err(eco_format!("`{namespace}` is not a valid package namespace"))?;
         }
 
         s.eat_if('/');
 
         let name = s.eat_until(':');
         if name.is_empty() {
-            bail!("package specification is missing name");
+            Err("package specification is missing name")?;
         } else if !is_ident(name) {
-            bail!("`{name}` is not a valid package name");
+            Err(eco_format!("`{name}` is not a valid package name"))?;
         }
 
         s.eat_if(':');
 
         let version = s.after();
         if version.is_empty() {
-            bail!("package specification is missing version");
+            Err("package specification is missing version")?;
         }
 
         Ok(Self {
@@ -204,7 +225,7 @@ impl Display for PackageSpec {
 
 /// A package's version.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
-pub struct Version {
+pub struct PackageVersion {
     /// The package's major version.
     pub major: u32,
     /// The package's minor version.
@@ -213,15 +234,16 @@ pub struct Version {
     pub patch: u32,
 }
 
-impl FromStr for Version {
+impl FromStr for PackageVersion {
     type Err = EcoString;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let mut parts = s.split('.');
         let mut next = |kind| {
-            let Some(part) = parts.next().filter(|s| !s.is_empty()) else {
-                bail!("version number is missing {kind} version");
-            };
+            let part = parts
+                .next()
+                .filter(|s| !s.is_empty())
+                .ok_or_else(|| eco_format!("version number is missing {kind} version"))?;
             part.parse::<u32>()
                 .map_err(|_| eco_format!("`{part}` is not a valid {kind} version"))
         };
@@ -230,74 +252,28 @@ impl FromStr for Version {
         let minor = next("minor")?;
         let patch = next("patch")?;
         if let Some(rest) = parts.next() {
-            bail!("version number has unexpected fourth component: `{rest}`");
+            Err(eco_format!("version number has unexpected fourth component: `{rest}`"))?;
         }
 
         Ok(Self { major, minor, patch })
     }
 }
 
-impl Display for Version {
+impl Display for PackageVersion {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         write!(f, "{}.{}.{}", self.major, self.minor, self.patch)
     }
 }
 
-impl Serialize for Version {
+impl Serialize for PackageVersion {
     fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
         s.collect_str(self)
     }
 }
 
-impl<'de> Deserialize<'de> for Version {
+impl<'de> Deserialize<'de> for PackageVersion {
     fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
         let string = EcoString::deserialize(d)?;
         string.parse().map_err(serde::de::Error::custom)
     }
 }
-
-/// A parsed package manifest.
-#[derive(Debug, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
-pub struct PackageManifest {
-    /// Details about the package itself.
-    pub package: PackageInfo,
-}
-
-impl PackageManifest {
-    /// Parse the manifest from raw bytes.
-    pub fn parse(bytes: &[u8]) -> StrResult<Self> {
-        let string = std::str::from_utf8(bytes).map_err(FileError::from)?;
-        toml::from_str(string).map_err(|err| {
-            eco_format!("package manifest is malformed: {}", err.message())
-        })
-    }
-
-    /// Ensure that this manifest is indeed for the specified package.
-    pub fn validate(&self, spec: &PackageSpec) -> StrResult<()> {
-        if self.package.name != spec.name {
-            bail!("package manifest contains mismatched name `{}`", self.package.name);
-        }
-
-        if self.package.version != spec.version {
-            bail!(
-                "package manifest contains mismatched version {}",
-                self.package.version
-            );
-        }
-
-        Ok(())
-    }
-}
-
-/// The `package` key in the manifest.
-///
-/// More fields are specified, but they are not relevant to the compiler.
-#[derive(Debug, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
-pub struct PackageInfo {
-    /// The name of the package within its namespace.
-    pub name: EcoString,
-    /// The package's version.
-    pub version: Version,
-    /// The path of the entrypoint into the package.
-    pub entrypoint: EcoString,
-}
diff --git a/crates/typst/src/syntax/kind.rs b/crates/typst-syntax/src/kind.rs
similarity index 100%
rename from crates/typst/src/syntax/kind.rs
rename to crates/typst-syntax/src/kind.rs
diff --git a/crates/typst/src/syntax/lexer.rs b/crates/typst-syntax/src/lexer.rs
similarity index 99%
rename from crates/typst/src/syntax/lexer.rs
rename to crates/typst-syntax/src/lexer.rs
index 8fe08f4cc..b96b3c073 100644
--- a/crates/typst/src/syntax/lexer.rs
+++ b/crates/typst-syntax/src/lexer.rs
@@ -649,7 +649,7 @@ fn keyword(ident: &str) -> Option<SyntaxKind> {
     })
 }
 
-/// Whether this character denotes a newline.
+/// Whether a character is interpreted as a newline by Typst.
 #[inline]
 pub fn is_newline(character: char) -> bool {
     matches!(
@@ -716,13 +716,13 @@ pub fn is_ident(string: &str) -> bool {
 
 /// Whether a character can start an identifier.
 #[inline]
-pub(crate) fn is_id_start(c: char) -> bool {
+pub fn is_id_start(c: char) -> bool {
     is_xid_start(c) || c == '_'
 }
 
 /// Whether a character can continue an identifier.
 #[inline]
-pub(crate) fn is_id_continue(c: char) -> bool {
+pub fn is_id_continue(c: char) -> bool {
     is_xid_continue(c) || c == '_' || c == '-'
 }
 
diff --git a/crates/typst-syntax/src/lib.rs b/crates/typst-syntax/src/lib.rs
new file mode 100644
index 000000000..8562bb19b
--- /dev/null
+++ b/crates/typst-syntax/src/lib.rs
@@ -0,0 +1,23 @@
+//! Parser and syntax tree for Typst.
+
+pub mod ast;
+
+mod file;
+mod kind;
+mod lexer;
+mod node;
+mod parser;
+mod reparser;
+mod source;
+mod span;
+
+pub use self::file::{FileId, PackageSpec, PackageVersion};
+pub use self::kind::SyntaxKind;
+pub use self::lexer::{is_id_continue, is_id_start, is_ident, is_newline};
+pub use self::node::{LinkedChildren, LinkedNode, SyntaxError, SyntaxNode};
+pub use self::parser::{parse, parse_code, parse_math};
+pub use self::source::Source;
+pub use self::span::{Span, Spanned};
+
+use self::lexer::{split_newlines, LexMode, Lexer};
+use self::parser::{reparse_block, reparse_markup};
diff --git a/crates/typst/src/syntax/node.rs b/crates/typst-syntax/src/node.rs
similarity index 94%
rename from crates/typst/src/syntax/node.rs
rename to crates/typst-syntax/src/node.rs
index 3bbecb6cb..f949b4ddc 100644
--- a/crates/typst/src/syntax/node.rs
+++ b/crates/typst-syntax/src/node.rs
@@ -6,9 +6,7 @@ use std::sync::Arc;
 use ecow::EcoString;
 
 use super::ast::AstNode;
-use super::{Span, SyntaxKind};
-use crate::diag::SourceError;
-use crate::file::FileId;
+use super::{FileId, Span, SyntaxKind};
 
 /// A node in the untyped syntax tree.
 #[derive(Clone, Eq, PartialEq, Hash)]
@@ -60,7 +58,7 @@ impl SyntaxNode {
         match &self.0 {
             Repr::Leaf(leaf) => leaf.len(),
             Repr::Inner(inner) => inner.len,
-            Repr::Error(error) => error.len(),
+            Repr::Error(node) => node.len(),
         }
     }
 
@@ -69,19 +67,19 @@ impl SyntaxNode {
         match &self.0 {
             Repr::Leaf(leaf) => leaf.span,
             Repr::Inner(inner) => inner.span,
-            Repr::Error(error) => error.span,
+            Repr::Error(node) => node.error.span,
         }
     }
 
-    /// The text of the node if it is a leaf node.
+    /// The text of the node if it is a leaf or error node.
     ///
     /// Returns the empty string if this is an inner node.
     pub fn text(&self) -> &EcoString {
         static EMPTY: EcoString = EcoString::new();
         match &self.0 {
             Repr::Leaf(leaf) => &leaf.text,
-            Repr::Error(error) => &error.text,
             Repr::Inner(_) => &EMPTY,
+            Repr::Error(node) => &node.text,
         }
     }
 
@@ -91,10 +89,10 @@ impl SyntaxNode {
     pub fn into_text(self) -> EcoString {
         match self.0 {
             Repr::Leaf(leaf) => leaf.text,
-            Repr::Error(error) => error.text.clone(),
-            Repr::Inner(node) => {
-                node.children.iter().cloned().map(Self::into_text).collect()
+            Repr::Inner(inner) => {
+                inner.children.iter().cloned().map(Self::into_text).collect()
             }
+            Repr::Error(node) => node.text.clone(),
         }
     }
 
@@ -130,27 +128,19 @@ impl SyntaxNode {
     pub fn erroneous(&self) -> bool {
         match &self.0 {
             Repr::Leaf(_) => false,
-            Repr::Inner(node) => node.erroneous,
+            Repr::Inner(inner) => inner.erroneous,
             Repr::Error(_) => true,
         }
     }
 
-    /// Adds a user-presentable hint if this is an error node.
-    pub fn hint(&mut self, hint: impl Into<EcoString>) {
-        if let Repr::Error(error) = &mut self.0 {
-            Arc::make_mut(error).hint(hint);
-        }
-    }
-
     /// The error messages for this node and its descendants.
-    pub fn errors(&self) -> Vec<SourceError> {
+    pub fn errors(&self) -> Vec<SyntaxError> {
         if !self.erroneous() {
             return vec![];
         }
 
-        if let Repr::Error(error) = &self.0 {
-            vec![SourceError::new(error.span, error.message.clone())
-                .with_hints(error.hints.to_owned())]
+        if let Repr::Error(node) = &self.0 {
+            vec![node.error.clone()]
         } else {
             self.children()
                 .filter(|node| node.erroneous())
@@ -159,12 +149,19 @@ impl SyntaxNode {
         }
     }
 
+    /// Add a user-presentable hint if this is an error node.
+    pub fn hint(&mut self, hint: impl Into<EcoString>) {
+        if let Repr::Error(node) = &mut self.0 {
+            Arc::make_mut(node).hint(hint);
+        }
+    }
+
     /// Set a synthetic span for the node and all its descendants.
     pub fn synthesize(&mut self, span: Span) {
         match &mut self.0 {
             Repr::Leaf(leaf) => leaf.span = span,
             Repr::Inner(inner) => Arc::make_mut(inner).synthesize(span),
-            Repr::Error(error) => Arc::make_mut(error).span = span,
+            Repr::Error(node) => Arc::make_mut(node).error.span = span,
         }
     }
 }
@@ -209,7 +206,7 @@ impl SyntaxNode {
         match &mut self.0 {
             Repr::Leaf(leaf) => leaf.span = mid,
             Repr::Inner(inner) => Arc::make_mut(inner).numberize(id, None, within)?,
-            Repr::Error(error) => Arc::make_mut(error).span = mid,
+            Repr::Error(node) => Arc::make_mut(node).error.span = mid,
         }
 
         Ok(())
@@ -271,9 +268,9 @@ impl SyntaxNode {
     /// The upper bound of assigned numbers in this subtree.
     pub(super) fn upper(&self) -> u64 {
         match &self.0 {
-            Repr::Inner(inner) => inner.upper,
             Repr::Leaf(leaf) => leaf.span.number() + 1,
-            Repr::Error(error) => error.span.number() + 1,
+            Repr::Inner(inner) => inner.upper,
+            Repr::Error(node) => node.error.span.number() + 1,
         }
     }
 }
@@ -281,8 +278,8 @@ impl SyntaxNode {
 impl Debug for SyntaxNode {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         match &self.0 {
-            Repr::Inner(node) => node.fmt(f),
-            Repr::Leaf(node) => node.fmt(f),
+            Repr::Leaf(leaf) => leaf.fmt(f),
+            Repr::Inner(inner) => inner.fmt(f),
             Repr::Error(node) => node.fmt(f),
         }
     }
@@ -541,25 +538,22 @@ impl Debug for InnerNode {
 /// An error node in the untyped syntax tree.
 #[derive(Clone, Eq, PartialEq, Hash)]
 struct ErrorNode {
-    /// The error message.
-    message: EcoString,
     /// The source text of the node.
     text: EcoString,
-    /// The node's span.
-    span: Span,
-    /// Additonal hints to the user, indicating how this error could be avoided
-    /// or worked around.
-    hints: Vec<EcoString>,
+    /// The syntax error.
+    error: SyntaxError,
 }
 
 impl ErrorNode {
     /// Create new error node.
     fn new(message: impl Into<EcoString>, text: impl Into<EcoString>) -> Self {
         Self {
-            message: message.into(),
             text: text.into(),
-            span: Span::detached(),
-            hints: vec![],
+            error: SyntaxError {
+                span: Span::detached(),
+                message: message.into(),
+                hints: vec![],
+            },
         }
     }
 
@@ -570,16 +564,28 @@ impl ErrorNode {
 
     /// Add a user-presentable hint to this error node.
     fn hint(&mut self, hint: impl Into<EcoString>) {
-        self.hints.push(hint.into());
+        self.error.hints.push(hint.into());
     }
 }
 
 impl Debug for ErrorNode {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "Error: {:?} ({})", self.text, self.message)
+        write!(f, "Error: {:?} ({})", self.text, self.error.message)
     }
 }
 
+/// A syntactical error.
+#[derive(Debug, Clone, Eq, PartialEq, Hash)]
+pub struct SyntaxError {
+    /// The node's span.
+    pub span: Span,
+    /// The error message.
+    pub message: EcoString,
+    /// Additonal hints to the user, indicating how this error could be avoided
+    /// or worked around.
+    pub hints: Vec<EcoString>,
+}
+
 /// A syntax node in a context.
 ///
 /// Knows its exact offset in the file and provides access to its
@@ -870,7 +876,7 @@ impl std::error::Error for Unnumberable {}
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::syntax::Source;
+    use crate::Source;
 
     #[test]
     fn test_linked_node() {
diff --git a/crates/typst/src/syntax/parser.rs b/crates/typst-syntax/src/parser.rs
similarity index 99%
rename from crates/typst/src/syntax/parser.rs
rename to crates/typst-syntax/src/parser.rs
index a6a4d4b38..24cf71164 100644
--- a/crates/typst/src/syntax/parser.rs
+++ b/crates/typst-syntax/src/parser.rs
@@ -7,15 +7,15 @@ use unicode_math_class::MathClass;
 use super::{ast, is_newline, LexMode, Lexer, SyntaxKind, SyntaxNode};
 
 /// Parse a source file.
+#[tracing::instrument(skip_all)]
 pub fn parse(text: &str) -> SyntaxNode {
     let mut p = Parser::new(text, 0, LexMode::Markup);
     markup(&mut p, true, 0, |_| false);
     p.finish().into_iter().next().unwrap()
 }
 
-/// Parse code directly.
-///
-/// This is only used for syntax highlighting.
+/// Parse top-level code.
+#[tracing::instrument(skip_all)]
 pub fn parse_code(text: &str) -> SyntaxNode {
     let mut p = Parser::new(text, 0, LexMode::Code);
     let m = p.marker();
@@ -25,6 +25,14 @@ pub fn parse_code(text: &str) -> SyntaxNode {
     p.finish().into_iter().next().unwrap()
 }
 
+/// Parse top-level math.
+#[tracing::instrument(skip_all)]
+pub fn parse_math(text: &str) -> SyntaxNode {
+    let mut p = Parser::new(text, 0, LexMode::Math);
+    math(&mut p, |_| false);
+    p.finish().into_iter().next().unwrap()
+}
+
 fn markup(
     p: &mut Parser,
     mut at_start: bool,
diff --git a/crates/typst/src/syntax/reparser.rs b/crates/typst-syntax/src/reparser.rs
similarity index 100%
rename from crates/typst/src/syntax/reparser.rs
rename to crates/typst-syntax/src/reparser.rs
diff --git a/crates/typst/src/syntax/source.rs b/crates/typst-syntax/src/source.rs
similarity index 94%
rename from crates/typst/src/syntax/source.rs
rename to crates/typst-syntax/src/source.rs
index 2f3e41446..25b3b86c6 100644
--- a/crates/typst/src/syntax/source.rs
+++ b/crates/typst-syntax/src/source.rs
@@ -7,12 +7,8 @@ use std::sync::Arc;
 
 use comemo::Prehashed;
 
-use super::ast::Markup;
 use super::reparser::reparse;
-use super::{is_newline, parse, LinkedNode, Span, SyntaxNode};
-use crate::diag::SourceResult;
-use crate::file::FileId;
-use crate::util::StrExt;
+use super::{is_newline, parse, FileId, LinkedNode, Span, SyntaxNode};
 
 /// A source file.
 ///
@@ -68,16 +64,6 @@ impl Source {
         &self.0.root
     }
 
-    /// The root node of the file's typed abstract syntax tree.
-    pub fn ast(&self) -> SourceResult<Markup> {
-        let errors = self.root().errors();
-        if errors.is_empty() {
-            Ok(self.root().cast().expect("root node must be markup"))
-        } else {
-            Err(Box::new(errors))
-        }
-    }
-
     /// The id of the source file.
     pub fn id(&self) -> FileId {
         self.0.id
@@ -148,7 +134,7 @@ impl Source {
     /// Get the length of the file in UTF-16 code units.
     pub fn len_utf16(&self) -> usize {
         let last = self.0.lines.last().unwrap();
-        last.utf16_idx + self.0.text[last.byte_idx..].len_utf16()
+        last.utf16_idx + len_utf16(&self.0.text[last.byte_idx..])
     }
 
     /// Get the length of the file in lines.
@@ -163,12 +149,22 @@ impl Source {
         LinkedNode::new(self.root()).find(span)
     }
 
+    /// Get the byte range for the given span in this file.
+    ///
+    /// Panics if the span does not point into this source file.
+    #[track_caller]
+    pub fn range(&self, span: Span) -> Range<usize> {
+        self.find(span)
+            .expect("span does not point into this source file")
+            .range()
+    }
+
     /// Return the index of the UTF-16 code unit at the byte index.
     pub fn byte_to_utf16(&self, byte_idx: usize) -> Option<usize> {
         let line_idx = self.byte_to_line(byte_idx)?;
         let line = self.0.lines.get(line_idx)?;
         let head = self.0.text.get(line.byte_idx..byte_idx)?;
-        Some(line.utf16_idx + head.len_utf16())
+        Some(line.utf16_idx + len_utf16(head))
     }
 
     /// Return the index of the line that contains the given byte index.
@@ -306,6 +302,12 @@ fn lines_from(
     })
 }
 
+/// The number of code units this string would use if it was encoded in
+/// UTF16. This runs in linear time.
+fn len_utf16(string: &str) -> usize {
+    string.chars().map(char::len_utf16).sum()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/crates/typst/src/syntax/span.rs b/crates/typst-syntax/src/span.rs
similarity index 83%
rename from crates/typst/src/syntax/span.rs
rename to crates/typst-syntax/src/span.rs
index 5c2202525..8715e476b 100644
--- a/crates/typst/src/syntax/span.rs
+++ b/crates/typst-syntax/src/span.rs
@@ -2,15 +2,13 @@ use std::fmt::{self, Debug, Formatter};
 use std::num::NonZeroU64;
 use std::ops::Range;
 
-use super::Source;
-use crate::file::FileId;
-use crate::World;
+use super::FileId;
 
 /// A unique identifier for a syntax node.
 ///
 /// This is used throughout the compiler to track which source section an error
-/// or element stems from. Can be [mapped back](Self::range) to a byte range for
-/// user facing display.
+/// or element stems from. Can be [mapped back](super::Source::range) to a byte
+/// range for user facing display.
 ///
 /// During editing, the span values stay mostly stable, even for nodes behind an
 /// insertion. This is not true for simple ranges as they would shift. Spans can
@@ -79,24 +77,6 @@ impl Span {
     pub const fn is_detached(self) -> bool {
         self.id().is_detached()
     }
-
-    /// Get the byte range for this span.
-    #[track_caller]
-    pub fn range(self, world: &dyn World) -> Range<usize> {
-        let source = world
-            .source(self.id())
-            .expect("span does not point into any source file");
-        self.range_in(&source)
-    }
-
-    /// Get the byte range for this span in the given source file.
-    #[track_caller]
-    pub fn range_in(self, source: &Source) -> Range<usize> {
-        source
-            .find(self)
-            .expect("span does not point into this source file")
-            .range()
-    }
 }
 
 /// A value with a span locating it in the source code.
diff --git a/crates/typst/Cargo.toml b/crates/typst/Cargo.toml
index 06c135627..2e2f83f89 100644
--- a/crates/typst/Cargo.toml
+++ b/crates/typst/Cargo.toml
@@ -17,6 +17,7 @@ bench = false
 
 [dependencies]
 typst-macros = { path = "../typst-macros" }
+typst-syntax = { path = "../typst-syntax" }
 bitflags = { version = "2", features = ["serde"] }
 bytemuck = "1"
 comemo = "0.3"
diff --git a/crates/typst/src/diag.rs b/crates/typst/src/diag.rs
index 08d3d5281..85fb10a20 100644
--- a/crates/typst/src/diag.rs
+++ b/crates/typst/src/diag.rs
@@ -8,8 +8,7 @@ use std::string::FromUtf8Error;
 
 use comemo::Tracked;
 
-use crate::file::PackageSpec;
-use crate::syntax::{Span, Spanned};
+use crate::syntax::{PackageSpec, Span, Spanned, SyntaxError};
 use crate::World;
 
 /// Early-return with a [`StrResult`] or [`SourceResult`].
@@ -103,6 +102,17 @@ impl SourceError {
     }
 }
 
+impl From<SyntaxError> for SourceError {
+    fn from(error: SyntaxError) -> Self {
+        Self {
+            span: error.span,
+            message: error.message,
+            trace: vec![],
+            hints: error.hints,
+        }
+    }
+}
+
 /// A part of an error's [trace](SourceError::trace).
 #[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub enum Tracepoint {
@@ -151,11 +161,11 @@ impl<T> Trace<T> for SourceResult<T> {
                 return errors;
             }
 
-            let trace_range = span.range(&*world);
+            let trace_range = world.range(span);
             for error in errors.iter_mut().filter(|e| !e.span.is_detached()) {
                 // Skip traces that surround the error.
                 if error.span.id() == span.id() {
-                    let error_range = error.span.range(&*world);
+                    let error_range = world.range(error.span);
                     if trace_range.start <= error_range.start
                         && trace_range.end >= error_range.end
                     {
diff --git a/crates/typst/src/eval/func.rs b/crates/typst/src/eval/func.rs
index 22f948ce3..372e3042f 100644
--- a/crates/typst/src/eval/func.rs
+++ b/crates/typst/src/eval/func.rs
@@ -11,10 +11,9 @@ use super::{
     Value, Vm,
 };
 use crate::diag::{bail, SourceResult, StrResult};
-use crate::file::FileId;
 use crate::model::{DelayedErrors, ElemFunc, Introspector, Locator, Vt};
 use crate::syntax::ast::{self, AstNode, Expr, Ident};
-use crate::syntax::{Span, SyntaxNode};
+use crate::syntax::{FileId, Span, SyntaxNode};
 use crate::World;
 
 /// An evaluatable function.
@@ -380,8 +379,9 @@ impl Closure {
                     }
                     ast::Pattern::Normal(_) => unreachable!(),
                     _ => {
-                        pattern.define(
+                        super::define_pattern(
                             &mut vm,
+                            pattern,
                             args.expect::<Value>("pattern parameter")?,
                         )?;
                     }
diff --git a/crates/typst/src/eval/mod.rs b/crates/typst/src/eval/mod.rs
index 06f931aa0..33c5f1a2f 100644
--- a/crates/typst/src/eval/mod.rs
+++ b/crates/typst/src/eval/mod.rs
@@ -61,19 +61,22 @@ use std::path::Path;
 
 use comemo::{Track, Tracked, TrackedMut, Validate};
 use ecow::{EcoString, EcoVec};
+use serde::{Deserialize, Serialize};
 use unicode_segmentation::UnicodeSegmentation;
 
 use self::func::{CapturesVisitor, Closure};
 use crate::diag::{
-    bail, error, At, SourceError, SourceResult, StrResult, Trace, Tracepoint,
+    bail, error, At, FileError, SourceError, SourceResult, StrResult, Trace, Tracepoint,
 };
-use crate::file::{FileId, PackageManifest, PackageSpec};
 use crate::model::{
     Content, DelayedErrors, Introspector, Label, Locator, Recipe, ShowableSelector,
     Styles, Transform, Unlabellable, Vt,
 };
 use crate::syntax::ast::{self, AstNode};
-use crate::syntax::{parse_code, Source, Span, Spanned, SyntaxKind, SyntaxNode};
+use crate::syntax::{
+    parse_code, FileId, PackageSpec, PackageVersion, Source, Span, Spanned, SyntaxKind,
+    SyntaxNode,
+};
 use crate::World;
 
 const MAX_ITERATIONS: usize = 10_000;
@@ -114,13 +117,16 @@ pub fn eval(
     let route = Route::insert(route, id);
     let scopes = Scopes::new(Some(library));
     let mut vm = Vm::new(vt, route.track(), id, scopes);
-    let root = match source.root().cast::<ast::Markup>() {
-        Some(markup) if vm.traced.is_some() => markup,
-        _ => source.ast()?,
-    };
+
+    let root = source.root();
+    let errors = root.errors();
+    if !errors.is_empty() && vm.traced.is_none() {
+        return Err(Box::new(errors.into_iter().map(Into::into).collect()));
+    }
 
     // Evaluate the module.
-    let result = root.eval(&mut vm);
+    let markup = root.cast::<ast::Markup>().unwrap();
+    let result = markup.eval(&mut vm);
 
     // Handle control flow.
     if let Some(flow) = vm.flow {
@@ -146,7 +152,7 @@ pub fn eval_string(
 
     let errors = root.errors();
     if !errors.is_empty() {
-        return Err(Box::new(errors));
+        return Err(Box::new(errors.into_iter().map(Into::into).collect()));
     }
 
     // Prepare VT.
@@ -506,7 +512,11 @@ impl Eval for ast::Expr {
     }
 }
 
-impl ast::Expr {
+trait ExprExt {
+    fn eval_display(&self, vm: &mut Vm) -> SourceResult<Content>;
+}
+
+impl ExprExt for ast::Expr {
     fn eval_display(&self, vm: &mut Vm) -> SourceResult<Content> {
         Ok(self.eval(vm)?.display().spanned(self.span()))
     }
@@ -1013,73 +1023,71 @@ impl Eval for ast::Binary {
     #[tracing::instrument(name = "Binary::eval", skip_all)]
     fn eval(&self, vm: &mut Vm) -> SourceResult<Self::Output> {
         match self.op() {
-            ast::BinOp::Add => self.apply(vm, ops::add),
-            ast::BinOp::Sub => self.apply(vm, ops::sub),
-            ast::BinOp::Mul => self.apply(vm, ops::mul),
-            ast::BinOp::Div => self.apply(vm, ops::div),
-            ast::BinOp::And => self.apply(vm, ops::and),
-            ast::BinOp::Or => self.apply(vm, ops::or),
-            ast::BinOp::Eq => self.apply(vm, ops::eq),
-            ast::BinOp::Neq => self.apply(vm, ops::neq),
-            ast::BinOp::Lt => self.apply(vm, ops::lt),
-            ast::BinOp::Leq => self.apply(vm, ops::leq),
-            ast::BinOp::Gt => self.apply(vm, ops::gt),
-            ast::BinOp::Geq => self.apply(vm, ops::geq),
-            ast::BinOp::In => self.apply(vm, ops::in_),
-            ast::BinOp::NotIn => self.apply(vm, ops::not_in),
-            ast::BinOp::Assign => self.assign(vm, |_, b| Ok(b)),
-            ast::BinOp::AddAssign => self.assign(vm, ops::add),
-            ast::BinOp::SubAssign => self.assign(vm, ops::sub),
-            ast::BinOp::MulAssign => self.assign(vm, ops::mul),
-            ast::BinOp::DivAssign => self.assign(vm, ops::div),
+            ast::BinOp::Add => apply_binary_expr(self, vm, ops::add),
+            ast::BinOp::Sub => apply_binary_expr(self, vm, ops::sub),
+            ast::BinOp::Mul => apply_binary_expr(self, vm, ops::mul),
+            ast::BinOp::Div => apply_binary_expr(self, vm, ops::div),
+            ast::BinOp::And => apply_binary_expr(self, vm, ops::and),
+            ast::BinOp::Or => apply_binary_expr(self, vm, ops::or),
+            ast::BinOp::Eq => apply_binary_expr(self, vm, ops::eq),
+            ast::BinOp::Neq => apply_binary_expr(self, vm, ops::neq),
+            ast::BinOp::Lt => apply_binary_expr(self, vm, ops::lt),
+            ast::BinOp::Leq => apply_binary_expr(self, vm, ops::leq),
+            ast::BinOp::Gt => apply_binary_expr(self, vm, ops::gt),
+            ast::BinOp::Geq => apply_binary_expr(self, vm, ops::geq),
+            ast::BinOp::In => apply_binary_expr(self, vm, ops::in_),
+            ast::BinOp::NotIn => apply_binary_expr(self, vm, ops::not_in),
+            ast::BinOp::Assign => apply_assignment(self, vm, |_, b| Ok(b)),
+            ast::BinOp::AddAssign => apply_assignment(self, vm, ops::add),
+            ast::BinOp::SubAssign => apply_assignment(self, vm, ops::sub),
+            ast::BinOp::MulAssign => apply_assignment(self, vm, ops::mul),
+            ast::BinOp::DivAssign => apply_assignment(self, vm, ops::div),
         }
     }
 }
 
-impl ast::Binary {
-    /// Apply a basic binary operation.
-    fn apply(
-        &self,
-        vm: &mut Vm,
-        op: fn(Value, Value) -> StrResult<Value>,
-    ) -> SourceResult<Value> {
-        let lhs = self.lhs().eval(vm)?;
+/// Apply a basic binary operation.
+fn apply_binary_expr(
+    binary: &ast::Binary,
+    vm: &mut Vm,
+    op: fn(Value, Value) -> StrResult<Value>,
+) -> SourceResult<Value> {
+    let lhs = binary.lhs().eval(vm)?;
 
-        // Short-circuit boolean operations.
-        if (self.op() == ast::BinOp::And && lhs == Value::Bool(false))
-            || (self.op() == ast::BinOp::Or && lhs == Value::Bool(true))
-        {
-            return Ok(lhs);
-        }
-
-        let rhs = self.rhs().eval(vm)?;
-        op(lhs, rhs).at(self.span())
+    // Short-circuit boolean operations.
+    if (binary.op() == ast::BinOp::And && lhs == Value::Bool(false))
+        || (binary.op() == ast::BinOp::Or && lhs == Value::Bool(true))
+    {
+        return Ok(lhs);
     }
 
-    /// Apply an assignment operation.
-    fn assign(
-        &self,
-        vm: &mut Vm,
-        op: fn(Value, Value) -> StrResult<Value>,
-    ) -> SourceResult<Value> {
-        let rhs = self.rhs().eval(vm)?;
-        let lhs = self.lhs();
+    let rhs = binary.rhs().eval(vm)?;
+    op(lhs, rhs).at(binary.span())
+}
 
-        // An assignment to a dictionary field is different from a normal access
-        // since it can create the field instead of just modifying it.
-        if self.op() == ast::BinOp::Assign {
-            if let ast::Expr::FieldAccess(access) = &lhs {
-                let dict = access.access_dict(vm)?;
-                dict.insert(access.field().take().into(), rhs);
-                return Ok(Value::None);
-            }
+/// Apply an assignment operation.
+fn apply_assignment(
+    binary: &ast::Binary,
+    vm: &mut Vm,
+    op: fn(Value, Value) -> StrResult<Value>,
+) -> SourceResult<Value> {
+    let rhs = binary.rhs().eval(vm)?;
+    let lhs = binary.lhs();
+
+    // An assignment to a dictionary field is different from a normal access
+    // since it can create the field instead of just modifying it.
+    if binary.op() == ast::BinOp::Assign {
+        if let ast::Expr::FieldAccess(access) = &lhs {
+            let dict = access_dict(vm, access)?;
+            dict.insert(access.field().take().into(), rhs);
+            return Ok(Value::None);
         }
-
-        let location = self.lhs().access(vm)?;
-        let lhs = std::mem::take(&mut *location);
-        *location = op(lhs, rhs).at(self.span())?;
-        Ok(Value::None)
     }
+
+    let location = binary.lhs().access(vm)?;
+    let lhs = std::mem::take(&mut *location);
+    *location = op(lhs, rhs).at(binary.span())?;
+    Ok(Value::None)
 }
 
 impl Eval for ast::FieldAccess {
@@ -1293,150 +1301,160 @@ impl Eval for ast::Closure {
     }
 }
 
-impl ast::Pattern {
-    fn destruct_array<F>(
-        &self,
-        vm: &mut Vm,
-        value: Array,
-        f: F,
-        destruct: &ast::Destructuring,
-    ) -> SourceResult<Value>
-    where
-        F: Fn(&mut Vm, ast::Expr, Value) -> SourceResult<Value>,
-    {
-        let mut i = 0;
-        let len = value.as_slice().len();
-        for p in destruct.bindings() {
-            match p {
-                ast::DestructuringKind::Normal(expr) => {
-                    let Ok(v) = value.at(i as i64, None) else {
+/// Destruct the value into the pattern by binding.
+fn define_pattern(
+    vm: &mut Vm,
+    pattern: &ast::Pattern,
+    value: Value,
+) -> SourceResult<Value> {
+    destructure(vm, pattern, value, |vm, expr, value| match expr {
+        ast::Expr::Ident(ident) => {
+            vm.define(ident, value);
+            Ok(Value::None)
+        }
+        _ => bail!(expr.span(), "nested patterns are currently not supported"),
+    })
+}
+
+/// Destruct the value into the pattern by assignment.
+fn assign_pattern(
+    vm: &mut Vm,
+    pattern: &ast::Pattern,
+    value: Value,
+) -> SourceResult<Value> {
+    destructure(vm, pattern, value, |vm, expr, value| {
+        let location = expr.access(vm)?;
+        *location = value;
+        Ok(Value::None)
+    })
+}
+
+/// Destruct the given value into the pattern and apply the function to each binding.
+#[tracing::instrument(skip_all)]
+fn destructure<T>(
+    vm: &mut Vm,
+    pattern: &ast::Pattern,
+    value: Value,
+    f: T,
+) -> SourceResult<Value>
+where
+    T: Fn(&mut Vm, ast::Expr, Value) -> SourceResult<Value>,
+{
+    match pattern {
+        ast::Pattern::Normal(expr) => {
+            f(vm, expr.clone(), value)?;
+            Ok(Value::None)
+        }
+        ast::Pattern::Placeholder(_) => Ok(Value::None),
+        ast::Pattern::Destructuring(destruct) => match value {
+            Value::Array(value) => destructure_array(vm, pattern, value, f, destruct),
+            Value::Dict(value) => destructure_dict(vm, value, f, destruct),
+            _ => bail!(pattern.span(), "cannot destructure {}", value.type_name()),
+        },
+    }
+}
+
+fn destructure_array<F>(
+    vm: &mut Vm,
+    pattern: &ast::Pattern,
+    value: Array,
+    f: F,
+    destruct: &ast::Destructuring,
+) -> SourceResult<Value>
+where
+    F: Fn(&mut Vm, ast::Expr, Value) -> SourceResult<Value>,
+{
+    let mut i = 0;
+    let len = value.as_slice().len();
+    for p in destruct.bindings() {
+        match p {
+            ast::DestructuringKind::Normal(expr) => {
+                let Ok(v) = value.at(i as i64, None) else {
                         bail!(expr.span(), "not enough elements to destructure");
                     };
-                    f(vm, expr, v.clone())?;
-                    i += 1;
-                }
-                ast::DestructuringKind::Sink(spread) => {
-                    let sink_size = (1 + len).checked_sub(destruct.bindings().count());
-                    let sink = sink_size.and_then(|s| value.as_slice().get(i..i + s));
-                    if let (Some(sink_size), Some(sink)) = (sink_size, sink) {
-                        if let Some(expr) = spread.expr() {
-                            f(vm, expr, Value::Array(sink.into()))?;
-                        }
-                        i += sink_size;
-                    } else {
-                        bail!(self.span(), "not enough elements to destructure")
+                f(vm, expr, v.clone())?;
+                i += 1;
+            }
+            ast::DestructuringKind::Sink(spread) => {
+                let sink_size = (1 + len).checked_sub(destruct.bindings().count());
+                let sink = sink_size.and_then(|s| value.as_slice().get(i..i + s));
+                if let (Some(sink_size), Some(sink)) = (sink_size, sink) {
+                    if let Some(expr) = spread.expr() {
+                        f(vm, expr, Value::Array(sink.into()))?;
                     }
+                    i += sink_size;
+                } else {
+                    bail!(pattern.span(), "not enough elements to destructure")
                 }
-                ast::DestructuringKind::Named(named) => {
-                    bail!(named.span(), "cannot destructure named elements from an array")
-                }
-                ast::DestructuringKind::Placeholder(underscore) => {
-                    if i < len {
-                        i += 1
-                    } else {
-                        bail!(underscore.span(), "not enough elements to destructure")
-                    }
+            }
+            ast::DestructuringKind::Named(named) => {
+                bail!(named.span(), "cannot destructure named elements from an array")
+            }
+            ast::DestructuringKind::Placeholder(underscore) => {
+                if i < len {
+                    i += 1
+                } else {
+                    bail!(underscore.span(), "not enough elements to destructure")
                 }
             }
         }
-        if i < len {
-            bail!(self.span(), "too many elements to destructure");
-        }
-
-        Ok(Value::None)
+    }
+    if i < len {
+        bail!(pattern.span(), "too many elements to destructure");
     }
 
-    fn destruct_dict<F>(
-        &self,
-        vm: &mut Vm,
-        dict: Dict,
-        f: F,
-        destruct: &ast::Destructuring,
-    ) -> SourceResult<Value>
-    where
-        F: Fn(&mut Vm, ast::Expr, Value) -> SourceResult<Value>,
-    {
-        let mut sink = None;
-        let mut used = HashSet::new();
-        for p in destruct.bindings() {
-            match p {
-                ast::DestructuringKind::Normal(ast::Expr::Ident(ident)) => {
-                    let v = dict
-                        .at(&ident, None)
-                        .map_err(|_| "destructuring key not found in dictionary")
-                        .at(ident.span())?;
-                    f(vm, ast::Expr::Ident(ident.clone()), v.clone())?;
-                    used.insert(ident.take());
-                }
-                ast::DestructuringKind::Sink(spread) => sink = spread.expr(),
-                ast::DestructuringKind::Named(named) => {
-                    let name = named.name();
-                    let v = dict
-                        .at(&name, None)
-                        .map_err(|_| "destructuring key not found in dictionary")
-                        .at(name.span())?;
-                    f(vm, named.expr(), v.clone())?;
-                    used.insert(name.take());
-                }
-                ast::DestructuringKind::Placeholder(_) => {}
-                ast::DestructuringKind::Normal(expr) => {
-                    bail!(expr.span(), "expected key, found expression");
-                }
+    Ok(Value::None)
+}
+
+fn destructure_dict<F>(
+    vm: &mut Vm,
+    dict: Dict,
+    f: F,
+    destruct: &ast::Destructuring,
+) -> SourceResult<Value>
+where
+    F: Fn(&mut Vm, ast::Expr, Value) -> SourceResult<Value>,
+{
+    let mut sink = None;
+    let mut used = HashSet::new();
+    for p in destruct.bindings() {
+        match p {
+            ast::DestructuringKind::Normal(ast::Expr::Ident(ident)) => {
+                let v = dict
+                    .at(&ident, None)
+                    .map_err(|_| "destructuring key not found in dictionary")
+                    .at(ident.span())?;
+                f(vm, ast::Expr::Ident(ident.clone()), v.clone())?;
+                used.insert(ident.take());
+            }
+            ast::DestructuringKind::Sink(spread) => sink = spread.expr(),
+            ast::DestructuringKind::Named(named) => {
+                let name = named.name();
+                let v = dict
+                    .at(&name, None)
+                    .map_err(|_| "destructuring key not found in dictionary")
+                    .at(name.span())?;
+                f(vm, named.expr(), v.clone())?;
+                used.insert(name.take());
+            }
+            ast::DestructuringKind::Placeholder(_) => {}
+            ast::DestructuringKind::Normal(expr) => {
+                bail!(expr.span(), "expected key, found expression");
             }
         }
+    }
 
-        if let Some(expr) = sink {
-            let mut sink = Dict::new();
-            for (key, value) in dict {
-                if !used.contains(key.as_str()) {
-                    sink.insert(key, value);
-                }
+    if let Some(expr) = sink {
+        let mut sink = Dict::new();
+        for (key, value) in dict {
+            if !used.contains(key.as_str()) {
+                sink.insert(key, value);
             }
-            f(vm, expr, Value::Dict(sink))?;
         }
-
-        Ok(Value::None)
+        f(vm, expr, Value::Dict(sink))?;
     }
 
-    /// Destruct the given value into the pattern and apply the function to each binding.
-    #[tracing::instrument(skip_all)]
-    fn apply<T>(&self, vm: &mut Vm, value: Value, f: T) -> SourceResult<Value>
-    where
-        T: Fn(&mut Vm, ast::Expr, Value) -> SourceResult<Value>,
-    {
-        match self {
-            ast::Pattern::Normal(expr) => {
-                f(vm, expr.clone(), value)?;
-                Ok(Value::None)
-            }
-            ast::Pattern::Placeholder(_) => Ok(Value::None),
-            ast::Pattern::Destructuring(destruct) => match value {
-                Value::Array(value) => self.destruct_array(vm, value, f, destruct),
-                Value::Dict(value) => self.destruct_dict(vm, value, f, destruct),
-                _ => bail!(self.span(), "cannot destructure {}", value.type_name()),
-            },
-        }
-    }
-
-    /// Destruct the value into the pattern by binding.
-    pub fn define(&self, vm: &mut Vm, value: Value) -> SourceResult<Value> {
-        self.apply(vm, value, |vm, expr, value| match expr {
-            ast::Expr::Ident(ident) => {
-                vm.define(ident, value);
-                Ok(Value::None)
-            }
-            _ => bail!(expr.span(), "nested patterns are currently not supported"),
-        })
-    }
-
-    /// Destruct the value into the pattern by assignment.
-    pub fn assign(&self, vm: &mut Vm, value: Value) -> SourceResult<Value> {
-        self.apply(vm, value, |vm, expr, value| {
-            let location = expr.access(vm)?;
-            *location = value;
-            Ok(Value::None)
-        })
-    }
+    Ok(Value::None)
 }
 
 impl Eval for ast::LetBinding {
@@ -1450,7 +1468,7 @@ impl Eval for ast::LetBinding {
         };
 
         match self.kind() {
-            ast::LetBindingKind::Normal(pattern) => pattern.define(vm, value),
+            ast::LetBindingKind::Normal(pattern) => define_pattern(vm, &pattern, value),
             ast::LetBindingKind::Closure(ident) => {
                 vm.define(ident, value);
                 Ok(Value::None)
@@ -1464,7 +1482,7 @@ impl Eval for ast::DestructAssignment {
 
     fn eval(&self, vm: &mut Vm) -> SourceResult<Self::Output> {
         let value = self.value().eval(vm)?;
-        self.pattern().assign(vm, value)?;
+        assign_pattern(vm, &self.pattern(), value)?;
         Ok(Value::None)
     }
 }
@@ -1614,7 +1632,7 @@ impl Eval for ast::ForLoop {
 
                 #[allow(unused_parens)]
                 for value in $iter {
-                    $pat.define(vm, value.into_value())?;
+                    define_pattern(vm, &$pat, value.into_value())?;
 
                     let body = self.body();
                     let value = body.eval(vm)?;
@@ -1812,6 +1830,52 @@ fn import_file(vm: &mut Vm, path: &str, span: Span) -> SourceResult<Module> {
         .trace(world, point, span)
 }
 
+/// A parsed package manifest.
+#[derive(Debug, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
+struct PackageManifest {
+    /// Details about the package itself.
+    package: PackageInfo,
+}
+
+impl PackageManifest {
+    /// Parse the manifest from raw bytes.
+    fn parse(bytes: &[u8]) -> StrResult<Self> {
+        let string = std::str::from_utf8(bytes).map_err(FileError::from)?;
+        toml::from_str(string).map_err(|err| {
+            eco_format!("package manifest is malformed: {}", err.message())
+        })
+    }
+
+    /// Ensure that this manifest is indeed for the specified package.
+    fn validate(&self, spec: &PackageSpec) -> StrResult<()> {
+        if self.package.name != spec.name {
+            bail!("package manifest contains mismatched name `{}`", self.package.name);
+        }
+
+        if self.package.version != spec.version {
+            bail!(
+                "package manifest contains mismatched version {}",
+                self.package.version
+            );
+        }
+
+        Ok(())
+    }
+}
+
+/// The `package` key in the manifest.
+///
+/// More fields are specified, but they are not relevant to the compiler.
+#[derive(Debug, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
+struct PackageInfo {
+    /// The name of the package within its namespace.
+    name: EcoString,
+    /// The package's version.
+    version: PackageVersion,
+    /// The path of the entrypoint into the package.
+    entrypoint: EcoString,
+}
+
 impl Eval for ast::LoopBreak {
     type Output = Value;
 
@@ -1889,20 +1953,21 @@ impl Access for ast::Parenthesized {
 
 impl Access for ast::FieldAccess {
     fn access<'a>(&self, vm: &'a mut Vm) -> SourceResult<&'a mut Value> {
-        self.access_dict(vm)?.at_mut(&self.field().take()).at(self.span())
+        access_dict(vm, self)?.at_mut(&self.field().take()).at(self.span())
     }
 }
 
-impl ast::FieldAccess {
-    fn access_dict<'a>(&self, vm: &'a mut Vm) -> SourceResult<&'a mut Dict> {
-        match self.target().access(vm)? {
-            Value::Dict(dict) => Ok(dict),
-            value => bail!(
-                self.target().span(),
-                "expected dictionary, found {}",
-                value.type_name(),
-            ),
-        }
+fn access_dict<'a>(
+    vm: &'a mut Vm,
+    access: &ast::FieldAccess,
+) -> SourceResult<&'a mut Dict> {
+    match access.target().access(vm)? {
+        Value::Dict(dict) => Ok(dict),
+        value => bail!(
+            access.target().span(),
+            "expected dictionary, found {}",
+            value.type_name(),
+        ),
     }
 }
 
diff --git a/crates/typst/src/eval/value.rs b/crates/typst/src/eval/value.rs
index cf866baae..d324c891f 100644
--- a/crates/typst/src/eval/value.rs
+++ b/crates/typst/src/eval/value.rs
@@ -82,8 +82,12 @@ impl Value {
     pub fn numeric(pair: (f64, ast::Unit)) -> Self {
         let (v, unit) = pair;
         match unit {
-            ast::Unit::Length(unit) => Abs::with_unit(v, unit).into_value(),
-            ast::Unit::Angle(unit) => Angle::with_unit(v, unit).into_value(),
+            ast::Unit::Pt => Abs::pt(v).into_value(),
+            ast::Unit::Mm => Abs::mm(v).into_value(),
+            ast::Unit::Cm => Abs::cm(v).into_value(),
+            ast::Unit::In => Abs::inches(v).into_value(),
+            ast::Unit::Rad => Angle::rad(v).into_value(),
+            ast::Unit::Deg => Angle::deg(v).into_value(),
             ast::Unit::Em => Em::new(v).into_value(),
             ast::Unit::Fr => Fr::new(v).into_value(),
             ast::Unit::Percent => Ratio::new(v / 100.0).into_value(),
diff --git a/crates/typst/src/ide/jump.rs b/crates/typst/src/ide/jump.rs
index 14a82e267..b2aeab9d9 100644
--- a/crates/typst/src/ide/jump.rs
+++ b/crates/typst/src/ide/jump.rs
@@ -3,10 +3,9 @@ use std::num::NonZeroUsize;
 use ecow::EcoString;
 
 use crate::doc::{Destination, Frame, FrameItem, Meta, Position};
-use crate::file::FileId;
 use crate::geom::{Geometry, Point, Size};
 use crate::model::Introspector;
-use crate::syntax::{LinkedNode, Source, Span, SyntaxKind};
+use crate::syntax::{FileId, LinkedNode, Source, Span, SyntaxKind};
 use crate::World;
 
 /// Where to [jump](jump_from_click) to.
diff --git a/crates/typst/src/lib.rs b/crates/typst/src/lib.rs
index 8b3d1d3d5..861cb853f 100644
--- a/crates/typst/src/lib.rs
+++ b/crates/typst/src/lib.rs
@@ -40,18 +40,20 @@ extern crate self as typst;
 #[macro_use]
 pub mod util;
 #[macro_use]
-pub mod diag;
-#[macro_use]
 pub mod eval;
+pub mod diag;
 pub mod doc;
 pub mod export;
-pub mod file;
 pub mod font;
 pub mod geom;
 pub mod ide;
 pub mod image;
 pub mod model;
-pub mod syntax;
+
+#[doc(inline)]
+pub use typst_syntax as syntax;
+
+use std::ops::Range;
 
 use comemo::{Prehashed, Track, TrackedMut};
 use ecow::EcoString;
@@ -59,9 +61,8 @@ use ecow::EcoString;
 use crate::diag::{FileResult, SourceResult};
 use crate::doc::Document;
 use crate::eval::{Datetime, Library, Route, Tracer};
-use crate::file::{FileId, PackageSpec};
 use crate::font::{Font, FontBook};
-use crate::syntax::Source;
+use crate::syntax::{FileId, PackageSpec, Source, Span};
 use crate::util::Bytes;
 
 /// Compile a source file into a fully layouted document.
@@ -75,7 +76,6 @@ pub fn compile(world: &dyn World) -> SourceResult<Document> {
     let mut tracer = tracer.track_mut();
 
     // Evaluate the source file into a module.
-    tracing::info!("Starting evaluation");
     let module = eval::eval(
         world,
         route.track(),
@@ -144,4 +144,12 @@ pub trait World {
     fn packages(&self) -> &[(PackageSpec, Option<EcoString>)] {
         &[]
     }
+
+    /// Get the byte range for a span.
+    #[track_caller]
+    fn range(&self, span: Span) -> Range<usize> {
+        self.source(span.id())
+            .expect("span does not point into any source file")
+            .range(span)
+    }
 }
diff --git a/crates/typst/src/syntax/mod.rs b/crates/typst/src/syntax/mod.rs
deleted file mode 100644
index 1ce1e4c09..000000000
--- a/crates/typst/src/syntax/mod.rs
+++ /dev/null
@@ -1,23 +0,0 @@
-//! Syntax definition, parsing, and highlighting.
-
-pub mod ast;
-
-mod kind;
-mod lexer;
-mod node;
-mod parser;
-mod reparser;
-mod source;
-mod span;
-
-pub use self::kind::SyntaxKind;
-pub use self::lexer::{is_ident, is_newline};
-pub use self::node::{LinkedChildren, LinkedNode, SyntaxNode};
-pub use self::parser::{parse, parse_code};
-pub use self::source::Source;
-pub use self::span::{Span, Spanned};
-
-pub(crate) use self::lexer::{is_id_continue, is_id_start};
-
-use self::lexer::{split_newlines, LexMode, Lexer};
-use self::parser::{reparse_block, reparse_markup};
diff --git a/crates/typst/src/util/mod.rs b/crates/typst/src/util/mod.rs
index 05914b042..39c62a93e 100644
--- a/crates/typst/src/util/mod.rs
+++ b/crates/typst/src/util/mod.rs
@@ -53,19 +53,6 @@ impl NonZeroExt for NonZeroUsize {
     };
 }
 
-/// Extra methods for [`str`].
-pub trait StrExt {
-    /// The number of code units this string would use if it was encoded in
-    /// UTF16. This runs in linear time.
-    fn len_utf16(&self) -> usize;
-}
-
-impl StrExt for str {
-    fn len_utf16(&self) -> usize {
-        self.chars().map(char::len_utf16).sum()
-    }
-}
-
 /// Extra methods for [`Arc`].
 pub trait ArcExt<T> {
     /// Takes the inner value if there is exactly one strong reference and
@@ -123,9 +110,6 @@ where
 
 /// Extra methods for [`Path`].
 pub trait PathExt {
-    /// Lexically normalize a path.
-    fn normalize(&self) -> PathBuf;
-
     /// Treat `self` as a virtual root relative to which the `path` is resolved.
     ///
     /// Returns `None` if the path lexically escapes the root. The path
@@ -134,28 +118,6 @@ pub trait PathExt {
 }
 
 impl PathExt for Path {
-    fn normalize(&self) -> PathBuf {
-        let mut out = PathBuf::new();
-        for component in self.components() {
-            match component {
-                Component::CurDir => {}
-                Component::ParentDir => match out.components().next_back() {
-                    Some(Component::Normal(_)) => {
-                        out.pop();
-                    }
-                    _ => out.push(component),
-                },
-                Component::Prefix(_) | Component::RootDir | Component::Normal(_) => {
-                    out.push(component)
-                }
-            }
-        }
-        if out.as_os_str().is_empty() {
-            out.push(Component::CurDir);
-        }
-        out
-    }
-
     fn join_rooted(&self, path: &Path) -> Option<PathBuf> {
         let mut parts: Vec<_> = self.components().collect();
         let root = parts.len();
diff --git a/docs/dev/architecture.md b/docs/dev/architecture.md
index 83ff40c85..3dd27a419 100644
--- a/docs/dev/architecture.md
+++ b/docs/dev/architecture.md
@@ -41,7 +41,7 @@ them.
 
 
 ## Parsing
-The syntax tree and parser are located in `crates/typst/src/syntax`. Parsing is
+The syntax tree and parser are located in `crates/typst-syntax`. Parsing is
 a pure function `&str -> SyntaxNode` without any further dependencies. The
 result is a concrete syntax tree reflecting the whole file structure, including
 whitespace and comments. Parsing cannot fail. If there are syntactic errors, the
diff --git a/tests/src/benches.rs b/tests/src/benches.rs
index 9ee7a2f3d..8e70ffd73 100644
--- a/tests/src/benches.rs
+++ b/tests/src/benches.rs
@@ -2,10 +2,9 @@ use comemo::{Prehashed, Track, Tracked};
 use iai::{black_box, main, Iai};
 use typst::diag::FileResult;
 use typst::eval::{Datetime, Library};
-use typst::file::FileId;
 use typst::font::{Font, FontBook};
 use typst::geom::Color;
-use typst::syntax::Source;
+use typst::syntax::{FileId, Source};
 use typst::util::Bytes;
 use typst::World;
 use unscanny::Scanner;
diff --git a/tests/src/tests.rs b/tests/src/tests.rs
index b2a87a5cc..ee9ae9f95 100644
--- a/tests/src/tests.rs
+++ b/tests/src/tests.rs
@@ -17,7 +17,6 @@ use oxipng::{InFile, Options, OutFile};
 use rayon::iter::{ParallelBridge, ParallelIterator};
 use std::cell::OnceCell;
 use tiny_skia as sk;
-use typst::file::FileId;
 use unscanny::Scanner;
 use walkdir::WalkDir;
 
@@ -26,7 +25,7 @@ use typst::doc::{Document, Frame, FrameItem, Meta};
 use typst::eval::{eco_format, func, Datetime, Library, NoneValue, Value};
 use typst::font::{Font, FontBook};
 use typst::geom::{Abs, Color, RgbaColor, Smart};
-use typst::syntax::{Source, Span, SyntaxNode};
+use typst::syntax::{FileId, Source, Span, SyntaxNode};
 use typst::util::{Bytes, PathExt};
 use typst::World;
 use typst_library::layout::{Margin, PageElem};
@@ -541,7 +540,7 @@ fn test_part(
         .inspect(|error| assert!(!error.span.is_detached()))
         .filter(|error| error.span.id() == source.id())
         .flat_map(|error| {
-            let range = error.span.range(world);
+            let range = world.range(error.span);
             let output_error =
                 UserOutput::Error(range.clone(), error.message.replace('\\', "/"));
             let hints = error