Math shorthands

src/model/eval.rs

@@ -424,6 +424,7 @@ impl Eval for ast::MathNode {
             Self::Space(_) => (vm.items.space)(),
             Self::Linebreak(v) => v.eval(vm)?,
             Self::Escape(v) => (vm.items.math_atom)(v.get().into()),
+            Self::Shorthand(v) => (vm.items.math_atom)(v.get().into()),
             Self::Atom(v) => v.eval(vm)?,
             Self::Symbol(v) => (vm.items.symbol)(v.get().clone()),
             Self::Script(v) => v.eval(vm)?,

src/syntax/ast.rs

@@ -441,6 +441,9 @@ pub enum MathNode {
     Linebreak(Linebreak),
     /// An escape sequence: `\#`, `\u{1F5FA}`.
     Escape(Escape),
+    /// A shorthand for a unicode codepoint. For example, `->` for a right
+    /// arrow.
+    Shorthand(Shorthand),
     /// An atom: `x`, `+`, `12`.
     Atom(Atom),
     /// Symbol notation: `:arrow:l:` or `arrow:l`. Notations without any colons
@@ -464,6 +467,7 @@ impl AstNode for MathNode {
             SyntaxKind::Space { .. } => node.cast().map(Self::Space),
             SyntaxKind::Linebreak => node.cast().map(Self::Linebreak),
             SyntaxKind::Escape(_) => node.cast().map(Self::Escape),
+            SyntaxKind::Shorthand(_) => node.cast().map(Self::Shorthand),
             SyntaxKind::Atom(_) => node.cast().map(Self::Atom),
             SyntaxKind::Symbol(_) => node.cast().map(Self::Symbol),
             SyntaxKind::Script => node.cast().map(Self::Script),
@@ -479,6 +483,7 @@ impl AstNode for MathNode {
             Self::Space(v) => v.as_untyped(),
             Self::Linebreak(v) => v.as_untyped(),
             Self::Escape(v) => v.as_untyped(),
+            Self::Shorthand(v) => v.as_untyped(),
             Self::Atom(v) => v.as_untyped(),
             Self::Symbol(v) => v.as_untyped(),
             Self::Script(v) => v.as_untyped(),

src/syntax/parsing.rs

@@ -442,6 +442,7 @@ fn math_primary(p: &mut Parser) {
         | SyntaxKind::Linebreak
         | SyntaxKind::Escape(_)
         | SyntaxKind::Str(_)
+        | SyntaxKind::Shorthand(_)
         | SyntaxKind::Symbol(_) => p.eat(),
 
         // Atoms.

src/syntax/tokens.rs

@@ -439,6 +439,18 @@ impl Tokens<'_> {
 impl Tokens<'_> {
     fn math(&mut self, start: usize, c: char) -> SyntaxKind {
         match c {
+            // Symbol shorthands.
+            '|' if self.s.eat_if("->") => SyntaxKind::Shorthand('\u{21A6}'),
+            '<' if self.s.eat_if("->") => SyntaxKind::Shorthand('\u{2194}'),
+            '<' if self.s.eat_if("=>") => SyntaxKind::Shorthand('\u{21D4}'),
+            '!' if self.s.eat_if('=') => SyntaxKind::Shorthand('\u{2260}'),
+            '<' if self.s.eat_if('=') => SyntaxKind::Shorthand('\u{2264}'),
+            '>' if self.s.eat_if('=') => SyntaxKind::Shorthand('\u{2265}'),
+            '<' if self.s.eat_if('-') => SyntaxKind::Shorthand('\u{2190}'),
+            '-' if self.s.eat_if('>') => SyntaxKind::Shorthand('\u{2192}'),
+            '=' if self.s.eat_if('>') => SyntaxKind::Shorthand('\u{21D2}'),
+            ':' if self.s.eat_if('=') => SyntaxKind::Shorthand('\u{2254}'),
+
             // Multi-char things.
             '#' => self.hash(start),
 

tests/typ/math/shorthand.typ

@@ -0,0 +1,4 @@
+// Test math shorthands.
+
+---
+$ f : NN <=> RR, n |-> sqrt(n) $