ast: struct

src/ast.rs

@@ -32,6 +32,10 @@ pub enum Pat {
     MetId(String),
     /// Matches anything, and binds it to a name
     Name(String),
+    /// Matches a Struct Expression `Ident { Pat }`
+    Struct(String, Box<Pat>),
+    /// Matches a Tuple Struct Expression `Ident ( Pat )`
+    TupStruct(String, Box<Pat>),
     /// Matches a partial decomposition (`..rest`) or upper-bounded range (`..100`).
     Rest(Option<Box<Pat>>),
     /// Matches a literal value by equality comparison
@@ -119,6 +123,11 @@ pub struct MakeArm<A: Annotation = Span>(pub String, pub Option<Anno<Expr<A>, A>
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Mod<A: Annotation = Span>(pub Ty, pub Anno<Expr<A>, A>);
 
+/// A record-type definition
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Struct(pub Pat);
+
+
 /// Expressions: The beating heart of Dough
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum Expr<A: Annotation = Span> {
@@ -132,6 +141,8 @@ pub enum Expr<A: Annotation = Span> {
     Let(Box<Let<A>>),
     /// `const Pat<NoTopAlt> (= Expr)?` (Basically let rec)
     Const(Box<Const<A>>),
+    /// struct Pat<NoTopAlt>
+    Struct(Box<Struct>),
     /// `| Pat<Tuple> | Expr` | `|| Expr` | `fn Ident? (Pat,*) Expr`
     Fn(Box<Fn<A>>),
     /// Expr { (Ident (: Expr)?),* }
@@ -298,6 +309,13 @@ impl<A: Annotation> Display for Mod<A> {
     }
 }
 
+impl Display for Struct {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self(pat) = self;
+        write!(f, "struct {pat}")
+    }
+}
+
 impl<A: Annotation> Display for Expr<A> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
@@ -306,6 +324,7 @@ impl<A: Annotation> Display for Expr<A> {
             Self::Lit(literal) => literal.fmt(f),
             Self::Let(v) => v.fmt(f),
             Self::Const(v) => v.fmt(f),
+            Self::Struct(v) => v.fmt(f),
             Self::Make(v) => v.fmt(f),
             Self::Match(v) => v.fmt(f),
             Self::Mod(v) => v.fmt(f),
@@ -419,6 +438,8 @@ impl Display for Pat {
             Self::Lit(literal) => literal.fmt(f),
             Self::MetId(name) => write!(f, "`{name}"),
             Self::Name(name) => name.fmt(f),
+            Self::Struct(name, bind) => write!(f, "{name} {{{bind}}}"),
+            Self::TupStruct(name, bind) => write!(f, "{name} {bind}"),
             Self::Rest(Some(rest)) => write!(f, "..{rest}"),
             Self::Rest(None) => write!(f, ".."),
             Self::Tuple(pats) => f.delimit("(", ")").list(pats, ", "),