Refresh parser 🌊

src/parse/collection.rs

@@ -4,7 +4,7 @@ use super::*;
 pub fn args(p: &mut Parser) -> ExprArgs {
     let start = p.start();
     let items = collection(p, vec![]);
-    ExprArgs { span: p.span_from(start), items }
+    ExprArgs { span: p.span(start), items }
 }
 
 /// Parse a parenthesized group, which can be either of:

src/parse/mod.rs

@@ -70,8 +70,8 @@ fn node(p: &mut Parser, at_start: &mut bool) -> Option<Node> {
         Token::Raw(t) => raw(p, t),
         Token::UnicodeEscape(t) => Node::Text(unicode_escape(p, t)),
 
-        // Keywords.
+        // Hashtag + keyword / identifier.
-        Token::Let | Token::If | Token::For => {
+        Token::Ident(_) | Token::Let | Token::If | Token::For => {
             *at_start = false;
             let stmt = token == Token::Let;
             let group = if stmt { Group::Stmt } else { Group::Expr };
@@ -100,12 +100,6 @@ fn node(p: &mut Parser, at_start: &mut bool) -> Option<Node> {
             return Some(Node::Expr(template(p)));
         }
 
-        // Bracket function.
-        Token::HashBracket => {
-            *at_start = false;
-            return Some(Node::Expr(bracket_call(p)?));
-        }
-
         // Comments.
         Token::LineComment(_) | Token::BlockComment(_) => {
             p.eat();
@@ -125,7 +119,7 @@ fn node(p: &mut Parser, at_start: &mut bool) -> Option<Node> {
 /// Parse a heading.
 fn heading(p: &mut Parser) -> Node {
     let start = p.start();
-    p.assert(&[Token::Eq]);
+    p.assert(Token::Eq);
 
     // Count depth.
     let mut level: usize = 0;
@@ -174,62 +168,94 @@ fn unicode_escape(p: &mut Parser, token: TokenUnicodeEscape) -> String {
     text
 }
 
-/// Parse a bracketed function call.
+/// Parse a primary expression.
-fn bracket_call(p: &mut Parser) -> Option<Expr> {
+fn primary(p: &mut Parser) -> Option<Expr> {
-    p.start_group(Group::Bracket, TokenMode::Code);
+    if let Some(expr) = literal(p) {
-
+        return Some(expr);
-    // One header is guaranteed, but there may be more (through chaining).
-    let mut outer = vec![];
-    let mut inner = bracket_subheader(p);
-    while p.eat_if(Token::Pipe) {
-        if let Some(new) = bracket_subheader(p) {
-            outer.extend(inner);
-            inner = Some(new);
-        }
     }
 
-    p.end_group();
+    match p.peek() {
-
+        // Function or identifier.
-    let body = match p.peek() {
+        Some(Token::Ident(string)) => {
-        Some(Token::LeftBracket) => Some(bracket_body(p)),
+            let ident = Ident {
-        _ => None,
+                span: p.eat_span(),
+                string: string.into(),
             };
 
-    let mut inner = inner?;
+            match p.peek_direct() {
-    if let Some(body) = body {
+                Some(Token::LeftParen) | Some(Token::LeftBracket) => Some(call(p, ident)),
-        inner.span.expand(body.span());
+                _ => Some(Expr::Ident(ident)),
-        inner.args.items.push(ExprArg::Pos(body));
+            }
         }
 
-    while let Some(mut top) = outer.pop() {
+        // Keywords.
-        top.args.items.push(ExprArg::Pos(Expr::Call(inner)));
+        Some(Token::Let) => expr_let(p),
-        inner = top;
+        Some(Token::If) => expr_if(p),
+        Some(Token::For) => expr_for(p),
+
+        // Structures.
+        Some(Token::LeftBrace) => block(p, true),
+        Some(Token::LeftBracket) => Some(template(p)),
+        Some(Token::LeftParen) => Some(parenthesized(p)),
+
+        // Nothing.
+        _ => {
+            p.expected("expression");
+            None
+        }
+    }
 }
 
-    Some(Expr::Call(inner))
+/// Parse a literal.
+fn literal(p: &mut Parser) -> Option<Expr> {
+    let kind = match p.peek()? {
+        // Basic values.
+        Token::None => LitKind::None,
+        Token::Bool(b) => LitKind::Bool(b),
+        Token::Int(i) => LitKind::Int(i),
+        Token::Float(f) => LitKind::Float(f),
+        Token::Length(val, unit) => LitKind::Length(val, unit),
+        Token::Angle(val, unit) => LitKind::Angle(val, unit),
+        Token::Percent(p) => LitKind::Percent(p),
+        Token::Color(color) => LitKind::Color(color),
+        Token::Str(token) => LitKind::Str({
+            if !token.terminated {
+                p.expected_at("quote", p.peek_span().end);
+            }
+            resolve::resolve_string(token.string)
+        }),
+        _ => return None,
+    };
+    Some(Expr::Lit(Lit { span: p.eat_span(), kind }))
 }
 
-/// Parse one subheader of a bracketed function call.
+// Parse a template value: `[...]`.
-fn bracket_subheader(p: &mut Parser) -> Option<ExprCall> {
+fn template(p: &mut Parser) -> Expr {
-    p.start_group(Group::Subheader, TokenMode::Code);
-    let name = ident(p);
-    let args = args(p);
-    let span = p.end_group();
-    Some(ExprCall {
-        span,
-        callee: Box::new(Expr::Ident(name?)),
-        args,
-    })
-}
-
-/// Parse the body of a bracketed function call.
-fn bracket_body(p: &mut Parser) -> Expr {
     p.start_group(Group::Bracket, TokenMode::Markup);
     let tree = Rc::new(tree(p));
     let span = p.end_group();
     Expr::Template(ExprTemplate { span, tree })
 }
 
+/// Parse a block expression: `{...}`.
+fn block(p: &mut Parser, scopes: bool) -> Option<Expr> {
+    p.start_group(Group::Brace, TokenMode::Code);
+    let mut exprs = vec![];
+    while !p.eof() {
+        p.start_group(Group::Stmt, TokenMode::Code);
+        if let Some(expr) = expr(p) {
+            exprs.push(expr);
+            if !p.eof() {
+                p.expected_at("semicolon or line break", p.end());
+            }
+        }
+        p.end_group();
+        p.skip_white();
+    }
+    let span = p.end_group();
+    Some(Expr::Block(ExprBlock { span, exprs, scoping: scopes }))
+}
+
 /// Parse an expression.
 fn expr(p: &mut Parser) -> Option<Expr> {
     expr_with(p, 0)
@@ -242,7 +268,7 @@ fn expr_with(p: &mut Parser, min_prec: usize) -> Option<Expr> {
         Some(op) => {
             let prec = op.precedence();
             let expr = Box::new(expr_with(p, prec)?);
-            Expr::Unary(ExprUnary { span: p.span_from(start), op, expr })
+            Expr::Unary(ExprUnary { span: p.span(start), op, expr })
         }
         None => primary(p)?,
     };
@@ -276,114 +302,37 @@ fn expr_with(p: &mut Parser, min_prec: usize) -> Option<Expr> {
     Some(lhs)
 }
 
-/// Parse a primary expression.
+/// Parse a function call.
-fn primary(p: &mut Parser) -> Option<Expr> {
+fn call(p: &mut Parser, name: Ident) -> Expr {
-    if let Some(expr) = literal(p) {
+    let mut args = match p.peek_direct() {
-        return Some(expr);
+        Some(Token::LeftParen) => {
-    }
-
-    match p.peek() {
-        // Function or identifier.
-        Some(Token::Ident(string)) => {
-            let ident = Ident {
-                span: p.eat_span(),
-                string: string.into(),
-            };
-            if p.peek() == Some(Token::LeftParen) {
-                Some(paren_call(p, ident))
-            } else {
-                Some(Expr::Ident(ident))
-            }
-        }
-
-        // Keywords.
-        Some(Token::Let) => expr_let(p),
-        Some(Token::If) => expr_if(p),
-        Some(Token::For) => expr_for(p),
-
-        // Structures.
-        Some(Token::LeftBrace) => block(p, true),
-        Some(Token::LeftBracket) => Some(template(p)),
-        Some(Token::HashBracket) => bracket_call(p),
-        Some(Token::LeftParen) => Some(parenthesized(p)),
-
-        // Nothing.
-        _ => {
-            p.expected("expression");
-            None
-        }
-    }
-}
-
-/// Parse a literal.
-fn literal(p: &mut Parser) -> Option<Expr> {
-    let kind = match p.peek()? {
-        // Basic values.
-        Token::None => LitKind::None,
-        Token::Bool(b) => LitKind::Bool(b),
-        Token::Int(i) => LitKind::Int(i),
-        Token::Float(f) => LitKind::Float(f),
-        Token::Length(val, unit) => LitKind::Length(val, unit),
-        Token::Angle(val, unit) => LitKind::Angle(val, unit),
-        Token::Percent(p) => LitKind::Percent(p),
-        Token::Color(color) => LitKind::Color(color),
-        Token::Str(token) => LitKind::Str(string(p, token)),
-        _ => return None,
-    };
-    Some(Expr::Lit(Lit { span: p.eat_span(), kind }))
-}
-
-// Parse a template value: `[...]`.
-fn template(p: &mut Parser) -> Expr {
-    p.start_group(Group::Bracket, TokenMode::Markup);
-    let tree = Rc::new(tree(p));
-    let span = p.end_group();
-    Expr::Template(ExprTemplate { span, tree })
-}
-
-/// Parse a block expression: `{...}`.
-fn block(p: &mut Parser, scopes: bool) -> Option<Expr> {
-    p.start_group(Group::Brace, TokenMode::Code);
-    let mut exprs = vec![];
-    while !p.eof() {
-        p.start_group(Group::Stmt, TokenMode::Code);
-        if let Some(expr) = expr(p) {
-            exprs.push(expr);
-            if !p.eof() {
-                p.expected_at("semicolon or line break", p.end());
-            }
-        }
-        p.end_group();
-        p.skip_white();
-    }
-    let span = p.end_group();
-    Some(Expr::Block(ExprBlock { span, exprs, scoping: scopes }))
-}
-
-/// Parse a parenthesized function call.
-fn paren_call(p: &mut Parser, name: Ident) -> Expr {
             p.start_group(Group::Paren, TokenMode::Code);
             let args = args(p);
             p.end_group();
+            args
+        }
+        _ => ExprArgs {
+            span: Span::at(name.span.end),
+            items: vec![],
+        },
+    };
+
+    if p.peek_direct() == Some(Token::LeftBracket) {
+        let body = template(p);
+        args.items.push(ExprArg::Pos(body));
+    }
+
     Expr::Call(ExprCall {
-        span: p.span_from(name.span.start),
+        span: p.span(name.span.start),
         callee: Box::new(Expr::Ident(name)),
         args,
     })
 }
 
-/// Parse a string.
-fn string(p: &mut Parser, token: TokenStr) -> String {
-    if !token.terminated {
-        p.expected_at("quote", p.peek_span().end);
-    }
-    resolve::resolve_string(token.string)
-}
-
 /// Parse a let expression.
 fn expr_let(p: &mut Parser) -> Option<Expr> {
     let start = p.start();
-    p.assert(&[Token::Let]);
+    p.assert(Token::Let);
 
     let mut expr_let = None;
     if let Some(binding) = ident(p) {
@@ -393,7 +342,7 @@ fn expr_let(p: &mut Parser) -> Option<Expr> {
         }
 
         expr_let = Some(Expr::Let(ExprLet {
-            span: p.span_from(start),
+            span: p.span(start),
             binding,
             init: init.map(Box::new),
         }))
@@ -405,18 +354,24 @@ fn expr_let(p: &mut Parser) -> Option<Expr> {
 /// Parse an if expresion.
 fn expr_if(p: &mut Parser) -> Option<Expr> {
     let start = p.start();
-    p.assert(&[Token::If]);
+    p.assert(Token::If);
 
     let mut expr_if = None;
     if let Some(condition) = expr(p) {
         if let Some(if_body) = body(p) {
             let mut else_body = None;
-            if p.eat_if(Token::Else) {
+
+            // We are in code mode but still want to react to `#else` if the
+            // outer mode is markup.
+            if match p.outer_mode() {
+                TokenMode::Markup => p.eat_if(Token::Invalid("#else")),
+                TokenMode::Code => p.eat_if(Token::Else),
+            } {
                 else_body = body(p);
             }
 
             expr_if = Some(Expr::If(ExprIf {
-                span: p.span_from(start),
+                span: p.span(start),
                 condition: Box::new(condition),
                 if_body: Box::new(if_body),
                 else_body: else_body.map(Box::new),
@@ -430,7 +385,7 @@ fn expr_if(p: &mut Parser) -> Option<Expr> {
 /// Parse a for expression.
 fn expr_for(p: &mut Parser) -> Option<Expr> {
     let start = p.start();
-    p.assert(&[Token::For]);
+    p.assert(Token::For);
 
     let mut expr_for = None;
     if let Some(pattern) = for_pattern(p) {
@@ -438,7 +393,7 @@ fn expr_for(p: &mut Parser) -> Option<Expr> {
             if let Some(iter) = expr(p) {
                 if let Some(body) = body(p) {
                     expr_for = Some(Expr::For(ExprFor {
-                        span: p.span_from(start),
+                        span: p.span(start),
                         pattern,
                         iter: Box::new(iter),
                         body: Box::new(body),

src/parse/parser.rs

@@ -10,6 +10,8 @@ pub struct Parser<'s> {
     pub diags: DiagSet,
     /// An iterator over the source tokens.
     tokens: Tokens<'s>,
+    /// The stack of open groups.
+    groups: Vec<GroupEntry>,
     /// The next token.
     next: Option<Token<'s>>,
     /// The peeked token.
@@ -19,21 +21,20 @@ pub struct Parser<'s> {
     next_start: Pos,
     /// The end position of the last (non-whitespace if in code mode) token.
     last_end: Pos,
-    /// The stack of open groups.
-    groups: Vec<GroupEntry>,
 }
 
 /// A logical group of tokens, e.g. `[...]`.
+#[derive(Debug, Copy, Clone)]
 struct GroupEntry {
     /// The start position of the group. Used by `Parser::end_group` to return
     /// The group's full span.
-    start: Pos,
+    pub start: Pos,
     /// The kind of group this is. This decides which tokens will end the group.
-    /// For example, a [`GroupKind::Paren`] will be ended by
+    /// For example, a [`Group::Paren`] will be ended by
     /// [`Token::RightParen`].
-    kind: Group,
+    pub kind: Group,
     /// The mode the parser was in _before_ the group started.
-    prev_mode: TokenMode,
+    pub outer_mode: TokenMode,
 }
 
 /// A group, confined by optional start and end delimiters.
@@ -60,13 +61,13 @@ impl<'s> Parser<'s> {
         let mut tokens = Tokens::new(src, TokenMode::Markup);
         let next = tokens.next();
         Self {
-            tokens,
+            diags: DiagSet::new(),
             next,
+            tokens,
+            last_end: Pos::ZERO,
             peeked: next,
             next_start: Pos::ZERO,
-            last_end: Pos::ZERO,
             groups: vec![],
-            diags: DiagSet::new(),
         }
     }
 
@@ -118,16 +119,16 @@ impl<'s> Parser<'s> {
         self.groups.push(GroupEntry {
             start: self.next_start,
             kind,
-            prev_mode: self.tokens.mode(),
+            outer_mode: self.tokens.mode(),
         });
 
         self.tokens.set_mode(mode);
         self.repeek();
 
         match kind {
-            Group::Paren => self.assert(&[Token::LeftParen]),
+            Group::Paren => self.assert(Token::LeftParen),
-            Group::Bracket => self.assert(&[Token::HashBracket, Token::LeftBracket]),
+            Group::Bracket => self.assert(Token::LeftBracket),
-            Group::Brace => self.assert(&[Token::LeftBrace]),
+            Group::Brace => self.assert(Token::LeftBrace),
             Group::Subheader => {}
             Group::Stmt => {}
             Group::Expr => {}
@@ -141,7 +142,7 @@ impl<'s> Parser<'s> {
     pub fn end_group(&mut self) -> Span {
         let prev_mode = self.tokens.mode();
         let group = self.groups.pop().expect("no started group");
-        self.tokens.set_mode(group.prev_mode);
+        self.tokens.set_mode(group.outer_mode);
         self.repeek();
 
         let mut rescan = self.tokens.mode() != prev_mode;
@@ -173,6 +174,62 @@ impl<'s> Parser<'s> {
         Span::new(group.start, self.last_end)
     }
 
+    /// The tokenization mode outside of the current group.
+    ///
+    /// For example, this would be [`Markup`] if we are in a [`Code`] group that
+    /// is embedded in a [`Markup`] group.
+    ///
+    /// [`Markup`]: TokenMode::Markup
+    /// [`Code`]: TokenMode::Code
+    pub fn outer_mode(&mut self) -> TokenMode {
+        self.groups.last().map_or(TokenMode::Markup, |group| group.outer_mode)
+    }
+
+    /// Whether the end of the source string or group is reached.
+    pub fn eof(&self) -> bool {
+        self.peek().is_none()
+    }
+
+    /// Peek at the next token without consuming it.
+    pub fn peek(&self) -> Option<Token<'s>> {
+        self.peeked
+    }
+
+    /// Peek at the next token if it follows immediately after the last one
+    /// without any whitespace in between.
+    pub fn peek_direct(&self) -> Option<Token<'s>> {
+        if self.next_start == self.last_end {
+            self.peeked
+        } else {
+            None
+        }
+    }
+
+    /// Peek at the span of the next token.
+    ///
+    /// Has length zero if `peek()` returns `None`.
+    pub fn peek_span(&self) -> Span {
+        Span::new(
+            self.next_start,
+            if self.eof() { self.next_start } else { self.tokens.pos() },
+        )
+    }
+
+    /// Peek at the source of the next token.
+    pub fn peek_src(&self) -> &'s str {
+        self.get(self.peek_span())
+    }
+
+    /// Checks whether the next token fulfills a condition.
+    ///
+    /// Returns `false` if there is no next token.
+    pub fn check<F>(&self, f: F) -> bool
+    where
+        F: FnOnce(Token<'s>) -> bool,
+    {
+        self.peek().map_or(false, f)
+    }
+
     /// Consume the next token.
     pub fn eat(&mut self) -> Option<Token<'s>> {
         let token = self.peek()?;
@@ -210,8 +267,8 @@ impl<'s> Parser<'s> {
         Span::new(start, self.last_end)
     }
 
-    /// Consume the next token if it is the given one and produce an error if
+    /// Consume the next token if it is the given one and produce a diagnostic
-    /// not.
+    /// if not.
     pub fn expect(&mut self, t: Token) -> bool {
         let eaten = self.eat_if(t);
         if !eaten {
@@ -221,9 +278,9 @@ impl<'s> Parser<'s> {
     }
 
     /// Consume the next token, debug-asserting that it is one of the given ones.
-    pub fn assert(&mut self, ts: &[Token]) {
+    pub fn assert(&mut self, t: Token) {
         let next = self.eat();
-        debug_assert!(next.map_or(false, |n| ts.contains(&n)));
+        debug_assert_eq!(next, Some(t));
     }
 
     /// Skip whitespace and comment tokens.
@@ -238,41 +295,6 @@ impl<'s> Parser<'s> {
         }
     }
 
-    /// Peek at the next token without consuming it.
-    pub fn peek(&self) -> Option<Token<'s>> {
-        self.peeked
-    }
-
-    /// Peek at the span of the next token.
-    ///
-    /// Has length zero if `peek()` returns `None`.
-    pub fn peek_span(&self) -> Span {
-        Span::new(
-            self.next_start,
-            if self.eof() { self.next_start } else { self.tokens.pos() },
-        )
-    }
-
-    /// Peek at the source of the next token.
-    pub fn peek_src(&self) -> &'s str {
-        self.get(self.peek_span())
-    }
-
-    /// Checks whether the next token fulfills a condition.
-    ///
-    /// Returns `false` if there is no next token.
-    pub fn check<F>(&self, f: F) -> bool
-    where
-        F: FnOnce(Token<'s>) -> bool,
-    {
-        self.peek().map_or(false, f)
-    }
-
-    /// Whether the end of the source string or group is reached.
-    pub fn eof(&self) -> bool {
-        self.peek().is_none()
-    }
-
     /// The position at which the next token starts.
     pub fn start(&self) -> Pos {
         self.next_start
@@ -285,8 +307,8 @@ impl<'s> Parser<'s> {
         self.last_end
     }
 
-    /// The span from
+    /// The span from `start` to the end of the last token.
-    pub fn span_from(&self, start: Pos) -> Span {
+    pub fn span(&self, start: Pos) -> Span {
         Span::new(start, self.last_end)
     }
 

src/pretty.rs

@@ -127,10 +127,10 @@ impl PrettyWithMap for Node {
                 if let Some(map) = map {
                     let value = &map[&(expr as *const _)];
                     value.pretty(p);
-                } else if let Expr::Call(call) = expr {
-                    // Format bracket functions appropriately.
-                    pretty_bracketed(call, p, false)
                 } else {
+                    if expr.has_short_form() {
+                        p.push('#');
+                    }
                     expr.pretty(p);
                 }
             }
@@ -287,15 +287,11 @@ impl Pretty for Named {
 
 impl Pretty for ExprTemplate {
     fn pretty(&self, p: &mut Printer) {
-        if let [Node::Expr(Expr::Call(call))] = self.tree.as_slice() {
-            pretty_bracketed(call, p, false);
-        } else {
         p.push('[');
         self.tree.pretty_with_map(p, None);
         p.push(']');
     }
 }
-}
 
 impl Pretty for ExprGroup {
     fn pretty(&self, p: &mut Printer) {
@@ -354,51 +350,25 @@ impl Pretty for BinOp {
 impl Pretty for ExprCall {
     fn pretty(&self, p: &mut Printer) {
         self.callee.pretty(p);
-        p.push('(');
-        self.args.pretty(p);
-        p.push(')');
-    }
-}
-
-/// Pretty print a bracket function, with body or chaining when possible.
-pub fn pretty_bracketed(call: &ExprCall, p: &mut Printer, chained: bool) {
-    if chained {
-        p.push_str(" | ");
-    } else {
-        p.push_str("#[");
-    }
-
-    // Function name.
-    call.callee.pretty(p);
 
         let mut write_args = |items: &[ExprArg]| {
-        if !items.is_empty() {
+            p.push('(');
-            p.push(' ');
             p.join(items, ", ", |item, p| item.pretty(p));
-        }
+            p.push(')');
         };
 
-    match call.args.items.as_slice() {
+        match self.args.items.as_slice() {
-        // This can written as a chain.
+            // This can be moved behind the arguments.
             //
-        // Example: Transforms "#[v][[f]]" => "#[v | f]".
+            // Example: Transforms "#v(a, [b])" => "#v(a)[b]".
-        [head @ .., ExprArg::Pos(Expr::Call(call))] => {
-            write_args(head);
-            pretty_bracketed(call, p, true);
-        }
-
-        // This can be written with a body.
-        //
-        // Example: Transforms "#[v [Hi]]" => "#[v][Hi]".
             [head @ .., ExprArg::Pos(Expr::Template(template))] => {
+                if !head.is_empty() {
                     write_args(head);
-            p.push(']');
+                }
                 template.pretty(p);
             }
 
-        items => {
+            items => write_args(items),
-            write_args(items);
-            p.push(']');
         }
     }
 }
@@ -420,7 +390,7 @@ impl Pretty for ExprArg {
 
 impl Pretty for ExprLet {
     fn pretty(&self, p: &mut Printer) {
-        p.push_str("#let ");
+        p.push_str("let ");
         self.binding.pretty(p);
         if let Some(init) = &self.init {
             p.push_str(" = ");
@@ -431,12 +401,13 @@ impl Pretty for ExprLet {
 
 impl Pretty for ExprIf {
     fn pretty(&self, p: &mut Printer) {
-        p.push_str("#if ");
+        p.push_str("if ");
         self.condition.pretty(p);
         p.push(' ');
         self.if_body.pretty(p);
         if let Some(expr) = &self.else_body {
-            p.push_str(" #else ");
+            // FIXME: Hashtag in markup.
+            p.push_str(" else ");
             expr.pretty(p);
         }
     }
@@ -444,9 +415,9 @@ impl Pretty for ExprIf {
 
 impl Pretty for ExprFor {
     fn pretty(&self, p: &mut Printer) {
-        p.push_str("#for ");
+        p.push_str("for ");
         self.pattern.pretty(p);
-        p.push_str(" #in ");
+        p.push_str(" in ");
         self.iter.pretty(p);
         p.push(' ');
         self.body.pretty(p);
@@ -728,7 +699,7 @@ mod tests {
         // Blocks.
         roundtrip("{}");
         roundtrip("{1}");
-        roundtrip("{ #let x = 1; x += 2; x + 1 }");
+        roundtrip("{ let x = 1; x += 2; x + 1 }");
         roundtrip("[{}]");
 
         // Operators.
@@ -736,24 +707,20 @@ mod tests {
         roundtrip("{not true}");
         roundtrip("{1 + 3}");
 
-        // Parenthesized calls.
+        // Function calls.
         roundtrip("{v()}");
         roundtrip("{v(1)}");
         roundtrip("{v(a: 1, b)}");
-
+        roundtrip("#v()");
-        // Bracket functions.
+        roundtrip("#v(1)");
-        roundtrip("#[v]");
+        roundtrip("#v(1, 2)[*Ok*]");
-        roundtrip("#[v 1]");
+        roundtrip("#v(1, f[2])");
-        roundtrip("#[v 1, 2][*Ok*]");
-        roundtrip("#[v 1 | f 2]");
-        test_parse("{#[v]}", "{v()}");
-        test_parse("#[v 1, #[f 2]]", "#[v 1 | f 2]");
 
         // Keywords.
         roundtrip("#let x = 1 + 2");
-        roundtrip("#if x [y] #else [z]");
+        roundtrip("#for x in y {z}");
-        roundtrip("#for x #in y {z}");
+        roundtrip("#for k, x in y {z}");
-        roundtrip("#for k, x #in y {z}");
+        test_parse("#if x [y] #else [z]", "#if x [y] else [z]");
     }
 
     #[test]

src/syntax/expr.rs

@@ -54,6 +54,17 @@ impl Expr {
             Self::For(v) => v.span,
         }
     }
+
+    /// Whether the expression can be shorten in markup with a hashtag.
+    pub fn has_short_form(&self) -> bool {
+        matches!(self,
+            Expr::Ident(_)
+            | Expr::Call(_)
+            | Expr::Let(_)
+            | Expr::If(_)
+            | Expr::For(_)
+        )
+    }
 }
 
 /// A literal.

src/syntax/token.rs

@@ -6,8 +6,6 @@ use crate::geom::{AngularUnit, LengthUnit};
 pub enum Token<'s> {
     /// A left square bracket: `[`.
     LeftBracket,
-    /// A hashtag followed by a left square bracket: `#[`.
-    HashBracket,
     /// A right square bracket: `]`.
     RightBracket,
     /// A left curly brace: `{`.
@@ -191,7 +189,6 @@ impl<'s> Token<'s> {
     pub fn name(self) -> &'static str {
         match self {
             Self::LeftBracket => "opening bracket",
-            Self::HashBracket => "start of bracket function",
             Self::RightBracket => "closing bracket",
             Self::LeftBrace => "opening brace",
             Self::RightBrace => "closing brace",

tests/lang/typ/block-invalid.typ

@@ -20,7 +20,7 @@
     // Error: 9-12 expected identifier, found string
     for "v"
 
-    // Error: 10 expected keyword `#in`
+    // Error: 10 expected keyword `in`
     for v let z = 1 + 2
 
     z

tests/lang/typ/call-invalid.typ

@@ -7,7 +7,7 @@
 ---
 #let x = "string"
 
-// Error: 2-3 expected function, found string
+// Error: 1-3 expected function, found string
 #x()
 
 ---
@@ -20,5 +20,5 @@
 
 ---
 // Error: 3:1 expected quote
-// Error: 2:1 expected closing bracket
+// Error: 2:1 expected closing paren
 #f("]

tests/lang/typ/call-value.typ

@@ -2,7 +2,7 @@
 // Ref: false
 
 ---
-// Whitespace is insignificant.
+// Whitespace is significant.
 #test(type(1), "integer")
 #test (type (1), "integer")
 

tests/lang/typ/comment.typ

@@ -11,7 +11,7 @@ C/*
 */D
 
 // Works in code.
-#test(type /*1*/ (1) //
+#test(type(/*1*/ 1) //
 , "integer")
 
 ---

tests/lang/typ/emph.typ

@@ -8,7 +8,7 @@ _Emphasized!_
 Partly em_phas_ized.
 
 // Scoped to body.
-#[box][_Scoped] to body.
+#box[_Scoped] to body.
 
 // Unterminated is fine.
 _The End

tests/lang/typ/expr-invalid.typ

@@ -35,22 +35,22 @@
 // Error: 1:31-1:39 cannot divide integer by length
 {(1 + "2", 40% - 1, 2 * true, 3 / 12pt)}
 
-// Error: 15-23 cannot apply '+=' to integer and string
+// Error: 14-22 cannot apply '+=' to integer and string
 { let x = 1; x += "2" }
 
 ---
 // Bad left-hand sides of assignment.
 
-// Error: 1:3-1:6 cannot assign to this expression
+// Error: 3-6 cannot assign to this expression
 { (x) = "" }
 
-// Error: 1:3-1:8 cannot assign to this expression
+// Error: 3-8 cannot assign to this expression
 { 1 + 2 += 3 }
 
-// Error: 1:3-1:4 unknown variable
+// Error: 3-4 unknown variable
 { z = 1 }
 
-// Error: 1:3-1:6 cannot assign to a constant
+// Error: 3-6 cannot assign to a constant
 { box = "hi" }
 
 // Works if we define box beforehand

tests/lang/typ/expr-prec.typ

@@ -21,7 +21,7 @@
 #test((1), 1)
 #test((1+2)*-3, -9)
 
-// Error: 15 expected closing paren
+// Error: 14 expected closing paren
 #test({(1 + 1}, 2)
 
 ---

tests/lang/typ/for-invalid.typ

@@ -4,7 +4,7 @@
 // Error: 5-5 expected identifier
 #for
 
-// Error: 7-7 expected keyword `#in`
+// Error: 7-7 expected keyword `in`
 #for v
 
 // Error: 10-10 expected expression
@@ -28,5 +28,5 @@ A#for "v" thing.
 #for "v" in iter {}
 
 // Should output `+ b in iter`.
-// Error: 7 expected keyword `#in`
+// Error: 7 expected keyword `in`
 #for a + b in iter {}

tests/lang/typ/if-invalid.typ

@@ -10,7 +10,7 @@
 // Error: 6 expected body
 #if x
 
-// Error: 1-6 unexpected keyword `#else`
+// Error: 1-6 unexpected keyword `else`
 #else {}
 
 ---

tests/library/typ/image.typ

@@ -7,10 +7,10 @@
 // Load an RGB JPEG image.
 #image("res/tiger.jpg")
 
-// Error: 9-30 failed to load image
+// Error: 8-29 failed to load image
 #image("path/does/not/exist")
 
-// Error: 9-30 failed to load image
+// Error: 8-29 failed to load image
 #image("typ/image-error.typ")
 
 ---