Implement named constructor (#188)

* Implement named constructor

* Fix llvm backend trying to use relative paths

After #186 all module paths should be absolute, and as such it's not necessary to prefix them with ./

ante-ls/src/main.rs

@@ -239,8 +239,12 @@ fn walk_ast<'a>(ast: &'a Ast<'a>, idx: usize) -> &'a Ast<'a> {
                 }
             },
             Ast::NamedConstructor(n) => {
-                if let Some((_, arg)) = n.args.iter().find(|(_, arg)| arg.locate().contains_index(&idx)) {
-                    ast = arg;
+                let statements = match n.sequence.as_ref() {
+                    Ast::Sequence(s) => &s.statements,
+                    _ => unreachable!(),
+                };
+                if let Some(stmt) = statements.iter().find(|stmt| stmt.locate().contains_index(&idx)) {
+                    ast = stmt;
                 } else if n.constructor.locate().contains_index(&idx) {
                     ast = &n.constructor;
                 } else {

examples/nameresolution/named_constructor.an

@@ -0,0 +1,23 @@
+type T a b =
+  x: a
+  y: b
+
+x = 4
+
+t1 = T with x = 3, z = 5
+t2 = T with y = 3.2, x
+
+// Declarations should not leak from the named constructor
+z = y * 2.0
+
+// args: --check
+// expected stderr:
+// named_constructor.an:7:6	error: Missing fields: y
+// t1 = T with x = 3, z = 5
+// 
+// named_constructor.an:7:20	error: z is not a struct field
+// t1 = T with x = 3, z = 5
+// 
+// named_constructor.an:11:5	error: No declaration for `y` was found in scope
+// z = y * 2.0
+

examples/typechecking/named_constructor.an

@@ -0,0 +1,16 @@
+type Foo a b=
+  x: a
+  y: b
+
+x = "Hello World"
+
+hello_foo y = Foo with x, y
+
+foo = hello_foo 42
+
+// args: --check --show-types
+// expected stdout:
+// Foo : (forall a b c. (a - b -> (Foo a b) can c))
+// foo : (Foo String (Int a))
+// hello_foo : (forall a b. (a -> (Foo String a) can b))
+// x : String

src/error/mod.rs

@@ -60,6 +60,9 @@ pub enum DiagnosticKind {
     HandlerMissingCases(/*missing effect cases*/ Vec<String>),
     ImportShadowsPreviousDefinition(/*item name*/ String),
     Unused(/*item name*/ String),
+    NotAStruct(/*struct name*/ String),
+    MissingFields(/*missing struct fields*/ Vec<String>),
+    NotAStructField(/*field name*/ String),
 
     //
     //                  Type Checking
@@ -206,6 +209,15 @@ impl Display for DiagnosticKind {
             DiagnosticKind::Unused(item) => {
                 write!(f, "{item} is unused (prefix name with _ to silence this warning)")
             },
+            DiagnosticKind::NotAStruct(name) => {
+                write!(f, "{} is not a struct", name)
+            },
+            DiagnosticKind::NotAStructField(name) => {
+                write!(f, "{} is not a struct field", name)
+            },
+            DiagnosticKind::MissingFields(fields) => {
+                write!(f, "Missing fields: {}", fields.join(", "))
+            },
             DiagnosticKind::TypeLengthMismatch(left, right) => {
                 write!(
                     f,
@@ -366,7 +378,10 @@ impl DiagnosticKind {
             | MultipleMatchingImpls(_, _)
             | NoMatchingImpls(_)
             | MissingCase(_)
-            | InternalError(_) => Error,
+            | InternalError(_)
+            | NotAStruct(_)
+            | MissingFields(_)
+            | NotAStructField(_) => Error,
         }
     }
 }

src/hir/monomorphisation.rs

@@ -125,7 +125,7 @@ impl<'c> Context<'c> {
             Assignment(assignment) => self.monomorphise_assignment(assignment),
             EffectDefinition(_) => todo!(),
             Handle(_) => todo!(),
-            NamedConstructor(_) => todo!(),
+            NamedConstructor(constructor) => self.monomorphise_named_constructor(constructor),
         }
     }
 
@@ -1586,6 +1586,13 @@ impl<'c> Context<'c> {
         hir::Ast::Assignment(hir::Assignment { lhs: Box::new(lhs), rhs: Box::new(self.monomorphise(&assignment.rhs)) })
     }
 
+    fn monomorphise_named_constructor(&mut self, constructor: &ast::NamedConstructor<'c>) -> hir::Ast {
+        match constructor.sequence.as_ref() {
+            ast::Ast::Sequence(sequence) => self.monomorphise_sequence(sequence),
+            _ => unreachable!(),
+        }
+    }
+
     pub fn extract(ast: hir::Ast, member_index: u32, result_type: Type) -> hir::Ast {
         use hir::{
             Ast,

src/llvm/mod.rs

@@ -112,7 +112,7 @@ pub fn run(path: &Path, ast: hir::Ast, args: &Cli) {
 
     // Run the program by default if --build was not passed
     if !args.build {
-        let program_command = PathBuf::from("./".to_string() + &binary_name);
+        let program_command = PathBuf::from(&binary_name);
         Command::new(program_command).spawn().unwrap().wait().unwrap();
     }
 

src/nameresolution/mod.rs

@@ -1627,7 +1627,102 @@ impl<'c> Resolvable<'c> for ast::Handle<'c> {
 impl<'c> Resolvable<'c> for ast::NamedConstructor<'c> {
     fn declare(&mut self, _resolver: &mut NameResolver, _cache: &mut ModuleCache<'c>) {}
 
-    fn define(&mut self, _resolver: &mut NameResolver, _cache: &mut ModuleCache<'c>) {
-        todo!()
+    fn define(&mut self, resolver: &mut NameResolver, cache: &mut ModuleCache<'c>) {
+        let type_name = match self.constructor.as_ref() {
+            Ast::Variable(ast::Variable { kind, .. }) => kind.name(),
+            _ => {
+                // This should never happen since constructor is parsed with the `variant` parser
+                cache.push_diagnostic(
+                    self.constructor.locate(),
+                    D::InternalError("Expected consturctor field to be a Variable"),
+                );
+                return;
+            },
+        };
+        // This will increment the use count for that type.
+        // It will result in it being one higher than it needs to,
+        // as the define pass on the sequence will do it again,
+        // since it ends with a FunctionCall. Is that a problem?
+        let type_info = match resolver.lookup_type(type_name.as_ref(), cache) {
+            Some(id) => &cache.type_infos[id.0],
+            None => {
+                cache.push_diagnostic(self.location, D::NotInScope("Type", type_name.as_ref().clone()));
+                return;
+            },
+        };
+
+        // Field names in the order they appear in the type definition
+        let struct_fields = match &type_info.body {
+            TypeInfoBody::Struct(fields) => fields.iter().map(|field| &field.name),
+            _ => {
+                cache.push_diagnostic(self.constructor.locate(), D::NotAStruct(type_name.as_ref().clone()));
+                return;
+            },
+        };
+        let statements = match self.sequence.as_mut() {
+            Ast::Sequence(ast::Sequence { statements, .. }) => statements,
+            _ => {
+                // This should never happen again, but it's better to emit an error than panic
+                cache.push_diagnostic(self.location, D::InternalError("Expected statements field to be a Variable"));
+                return;
+            },
+        };
+
+        // Fields referenced in the constructor
+        let mut defined_fields = statements
+            .iter()
+            .map(|stmt| {
+                let (variable, location) = match stmt {
+                    Ast::Definition(ast::Definition { pattern, location, .. }) => (pattern.as_ref(), location),
+                    Ast::Variable(v) => (stmt, &v.location),
+                    _ => unreachable!(),
+                };
+
+                let name = match variable {
+                    Ast::Variable(ast::Variable { kind: ast::VariableKind::Identifier(name), .. }) => name,
+                    _ => unreachable!(),
+                };
+
+                (name, (variable, location))
+            })
+            .collect::<HashMap<_, _>>();
+
+        let (missing_fields, args) =
+            struct_fields.fold((Vec::new(), Vec::new()), |(mut missing_fields, mut args), field| {
+                if let Some((variable, _)) = defined_fields.remove(field) {
+                    args.push(variable.clone());
+                } else {
+                    missing_fields.push(field);
+                }
+                (missing_fields, args)
+            });
+
+        let has_missing_fields = !missing_fields.is_empty();
+        let has_unknown_fields = !defined_fields.is_empty();
+
+        if has_missing_fields {
+            cache.push_diagnostic(
+                self.constructor.locate(),
+                D::MissingFields(missing_fields.into_iter().cloned().collect()),
+            );
+        }
+
+        for (name, (_, location)) in defined_fields {
+            cache.push_diagnostic(*location, D::NotAStructField(name.clone()));
+        }
+
+        if has_missing_fields || has_unknown_fields {
+            return;
+        }
+
+        let call = ast::Ast::function_call(self.constructor.as_ref().clone(), args, self.location);
+
+        // We only want to keep definitions in the sequence to keep the Hir simpler
+        statements.retain(|stmt| matches!(stmt, Ast::Definition(_)));
+        statements.push(call);
+
+        resolver.push_scope(cache);
+        self.sequence.define(resolver, cache);
+        resolver.pop_scope(cache, false, None);
     }
 }

src/parser/ast.rs

@@ -400,8 +400,7 @@ pub struct Handle<'a> {
 #[derive(Debug, Clone)]
 pub struct NamedConstructor<'a> {
     pub constructor: Box<Ast<'a>>,
-    pub args: Vec<(String, Ast<'a>)>,
-
+    pub sequence: Box<Ast<'a>>,
     pub location: Location<'a>,
     pub typ: Option<types::Type>,
 }
@@ -709,8 +708,13 @@ impl<'a> Ast<'a> {
         Ast::Handle(Handle { expression: Box::new(expression), branches, location, resumes: vec![], typ: None })
     }
 
-    pub fn named_constructor(constructor: Ast<'a>, args: Vec<(String, Ast<'a>)>, location: Location<'a>) -> Ast<'a> {
-        Ast::NamedConstructor(NamedConstructor { constructor: Box::new(constructor), args, location, typ: None })
+    pub fn named_constructor(constructor: Ast<'a>, sequence: Ast<'a>, location: Location<'a>) -> Ast<'a> {
+        Ast::NamedConstructor(NamedConstructor {
+            constructor: Box::new(constructor),
+            sequence: Box::new(sequence),
+            location,
+            typ: None,
+        })
     }
 
     /// This is a bit of a hack.

src/parser/mod.rs

@@ -458,36 +458,39 @@ parser!(function_call loc =
 parser!(named_constructor_expr loc =
     constructor <- variant;
     _ <- expect(Token::With);
-    args !<- named_constructor_args;
-    Ast::named_constructor(constructor, args, loc)
+    sequence !<- named_constructor_args;
+    Ast::named_constructor(constructor, sequence, loc)
 );
 
-fn named_constructor_args<'a, 'b>(input: Input<'a, 'b>) -> ParseResult<'a, 'b, Vec<(String, Ast<'b>)>> {
+fn named_constructor_args<'a, 'b>(input: Input<'a, 'b>) -> ParseResult<'a, 'b, Ast<'b>> {
     if let Token::Indent = input[0].0 {
         named_constructor_block_args(input)
     } else {
         named_constructor_inline_args(input)
     }
 }
 
-parser!(named_constructor_block_args loc -> 'b Vec<(String, Ast<'b>)> =
+parser!(named_constructor_block_args loc -> 'b Ast<'b> =
     _ <- expect(Token::Indent);
-    args <- delimited_trailing(named_constructor_arg, expect(Token::Newline), false);
+    statements <- delimited_trailing(named_constructor_arg, expect(Token::Newline), false);
     _ !<- expect(Token::Unindent);
-    args
+    Ast::sequence(statements, loc)
 );
 
-parser!(named_constructor_inline_args loc -> 'b Vec<(String, Ast<'b>)> =
-    args <- delimited(named_constructor_arg, expect(Token::Comma));
-    args
+parser!(named_constructor_inline_args loc -> 'b Ast<'b> =
+    statements <- delimited(named_constructor_arg, expect(Token::Comma));
+    Ast::sequence(statements, loc)
 );
 
-fn named_constructor_arg<'a, 'b>(input: Input<'a, 'b>) -> ParseResult<'a, 'b, (String, Ast<'b>)> {
+fn named_constructor_arg<'a, 'b>(input: Input<'a, 'b>) -> ParseResult<'a, 'b, Ast<'b>> {
     let (input, ident, start) = identifier(input)?;
+    let field_name = Ast::variable(vec![], ident, start);
     let (input, maybe_expr, end) = maybe(pair(expect(Token::Equal), function_argument))(input)?;
-    // Desugar bar, baz into bar = bar, baz = baz
-    let expr = maybe_expr.map_or_else(|| Ast::variable(vec![], ident.clone(), start), |(_, expr)| expr);
-    Ok((input, (ident, expr), start.union(end)))
+    let expr = match maybe_expr {
+        Some((_, expr)) => Ast::definition(field_name, expr, start.union(end)),
+        None => field_name,
+    };
+    Ok((input, expr, start.union(end)))
 }
 
 parser!(pattern_function_call loc =

src/parser/pretty_printer.rs

@@ -275,7 +275,16 @@ impl<'a> Display for ast::Handle<'a> {
 
 impl<'a> Display for ast::NamedConstructor<'a> {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        let args = fmap(self.args.iter(), |(name, expr)| format!("{name} = {expr}"));
+        let statements = match self.sequence.as_ref() {
+            Ast::Sequence(ast::Sequence { statements, .. }) => statements,
+            _ => unreachable!(),
+        };
+        let args = fmap(statements, |stmt| match stmt {
+            Ast::Definition(ast::Definition { pattern, expr, .. }) => format!("{pattern} = {expr}"),
+            Ast::Variable(v) => format!("{v} = {v}"),
+            _ => unreachable!(),
+        });
+
         write!(f, "({} with {})", self.constructor, args.join(", "))
     }
 }

src/types/typechecker.rs

@@ -2060,7 +2060,7 @@ impl<'a> Inferable<'a> for ast::Handle<'a> {
 }
 
 impl<'a> Inferable<'a> for ast::NamedConstructor<'a> {
-    fn infer_impl(&mut self, _checker: &mut ModuleCache<'a>) -> TypeResult {
-        todo!()
+    fn infer_impl(&mut self, cache: &mut ModuleCache<'a>) -> TypeResult {
+        self.sequence.infer_impl(cache)
     }
 }