Merge pull request #1085 from candy-lang/function-types-in-ast

Function types in AST; `loop(…)`, `repeat(…)`

compiler_v4/src/ast.rs

@@ -176,11 +176,30 @@ pub struct AstTypeParameter {
 // Types
 
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
-pub struct AstType {
+pub enum AstType {
+    Named(AstNamedType),
+    Function(AstFunctionType),
+}
+
+#[derive(Clone, Debug, Eq, Hash, PartialEq)]
+pub struct AstNamedType {
     pub name: AstResult<AstString>,
     pub type_arguments: Option<AstTypeArguments>,
 }
 
+#[derive(Clone, Debug, Eq, Hash, PartialEq)]
+pub struct AstFunctionType {
+    pub parameter_types: Vec<AstFunctionTypeParameterType>,
+    pub closing_parenthesis_error: Option<AstError>,
+    pub return_type: AstResult<Box<AstType>>,
+    pub span: Range<Offset>,
+}
+#[derive(Clone, Debug, Eq, Hash, PartialEq)]
+pub struct AstFunctionTypeParameterType {
+    pub type_: Box<AstType>,
+    pub comma_error: Option<AstError>,
+}
+
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
 pub struct AstTypeArguments {
     pub span: Range<Offset>,
@@ -496,11 +515,31 @@ impl CollectAstErrors for AstTypeParameter {
 }
 
 impl CollectAstErrors for AstType {
+    fn collect_errors_to(&self, errors: &mut Vec<CompilerError>) {
+        match &self {
+            Self::Named(named) => named.collect_errors_to(errors),
+            Self::Function(function) => function.collect_errors_to(errors),
+        }
+    }
+}
+impl CollectAstErrors for AstNamedType {
     fn collect_errors_to(&self, errors: &mut Vec<CompilerError>) {
         self.name.collect_errors_to(errors);
         self.type_arguments.collect_errors_to(errors);
     }
 }
+impl CollectAstErrors for AstFunctionType {
+    fn collect_errors_to(&self, errors: &mut Vec<CompilerError>) {
+        self.parameter_types.collect_errors_to(errors);
+        self.return_type.collect_errors_to(errors);
+    }
+}
+impl CollectAstErrors for AstFunctionTypeParameterType {
+    fn collect_errors_to(&self, errors: &mut Vec<CompilerError>) {
+        self.type_.collect_errors_to(errors);
+        self.comma_error.collect_errors_to(errors);
+    }
+}
 impl CollectAstErrors for AstTypeArguments {
     fn collect_errors_to(&self, errors: &mut Vec<CompilerError>) {
         self.arguments.collect_errors_to(errors);

compiler_v4/src/ast_to_hir.rs

@@ -654,6 +654,13 @@ impl<'a> Context<'a> {
             return hir::Err;
         };
 
+        let type_ = match type_ {
+            AstType::Named(type_) => type_,
+            AstType::Function(function_type) => {
+                self.add_error(function_type.span.clone(), "Function type is not a trait");
+                return hir::Err;
+            }
+        };
         let Some(name) = type_.name.value() else {
             return hir::Err;
         };
@@ -873,6 +880,23 @@ impl<'a> Context<'a> {
             return Type::Error;
         };
 
+        let type_ = match type_ {
+            AstType::Named(type_) => type_,
+            AstType::Function(type_) => {
+                return Type::Function(FunctionType {
+                    parameter_types: type_
+                        .parameter_types
+                        .iter()
+                        .map(|it| self.lower_type(type_parameters, self_base_type, &*it.type_))
+                        .collect(),
+                    return_type: Box::new(self.lower_type(
+                        type_parameters,
+                        self_base_type,
+                        type_.return_type.value().map(AsRef::as_ref),
+                    )),
+                })
+            }
+        };
         let Some(name) = type_.name.value() else {
             return Type::Error;
         };
@@ -1883,7 +1907,7 @@ impl<'c, 'a> BodyBuilder<'c, 'a> {
                 Ok(substitutions) => {
                     assert!(substitutions.is_empty());
                     self.push_lowered(
-                        name.string.clone(),
+                        None,
                         ExpressionKind::Call {
                             function: id,
                             substitutions,

compiler_v4/src/main.rs

@@ -104,13 +104,14 @@ fn debug(options: DebugOptions) -> ProgramResult {
         DebugOptions::Hir(options) => {
             let source = fs::read_to_string(&options.path).unwrap();
             let (hir, errors) = compile_hir(&options.path, &source);
+            println!("{}", hir.to_text(true));
+
             if !errors.is_empty() {
                 for error in errors {
                     error!("{}", error.to_string_with_location(&source));
                 }
                 return Err(Exit::CodeContainsErrors);
             }
-            println!("{}", hir.to_text(true));
         }
         DebugOptions::Mono(options) => {
             let source = fs::read_to_string(&options.path).unwrap();

compiler_v4/src/mono_to_c.rs

@@ -699,6 +699,9 @@ impl<'h> Context<'h> {
             }
 
             self.lower_expression(declaration_name, *id, expression);
+            if &*expression.type_ == "Never" {
+                self.push("// Returns `Never`\n");
+            }
             self.push("\n\n");
         }
     }
@@ -810,8 +813,11 @@ impl<'h> Context<'h> {
                     }
 
                     self.lower_body_expressions(declaration_name, &case.body);
-
-                    self.push(format!("{id} = {};\n", case.body.return_value_id()));
+                    if case.body.return_type() == "Never" {
+                        self.push("// Returns `Never`\n");
+                    } else {
+                        self.push(format!("{id} = {};\n", case.body.return_value_id()));
+                    }
 
                     self.push("break;");
                 }

compiler_v4/src/string_to_ast/type_.rs

@@ -1,25 +1,97 @@
 use super::{
-    literal::{closing_bracket, comma, opening_bracket},
+    literal::{closing_bracket, closing_parenthesis, comma, opening_bracket, opening_parenthesis},
     parser::{OptionOfParser, OptionOfParserWithValue, Parser},
     whitespace::{AndTrailingWhitespace, ValueAndTrailingWhitespace},
     word::raw_identifier,
 };
-use crate::ast::{AstError, AstString, AstType, AstTypeArgument, AstTypeArguments};
+use crate::ast::{
+    AstError, AstFunctionType, AstFunctionTypeParameterType, AstNamedType, AstString, AstType,
+    AstTypeArgument, AstTypeArguments,
+};
 use tracing::instrument;
 
 #[instrument(level = "trace")]
 pub fn type_(parser: Parser) -> Option<(Parser, AstType)> {
+    None.or_else(|| named_type(parser).map(|(parser, it)| (parser, AstType::Named(it))))
+        .or_else(|| function_type(parser).map(|(parser, it)| (parser, AstType::Function(it))))
+}
+
+#[instrument(level = "trace")]
+pub fn named_type(parser: Parser) -> Option<(Parser, AstNamedType)> {
     let (parser, name) = raw_identifier(parser)?.and_trailing_whitespace();
     let (parser, type_arguments) = type_arguments(parser).optional(parser);
     Some((
         parser,
-        AstType {
+        AstNamedType {
             name,
             type_arguments,
         },
     ))
 }
 
+#[instrument(level = "trace")]
+pub fn function_type(parser: Parser) -> Option<(Parser, AstFunctionType)> {
+    let start_offset = parser.offset();
+    let mut parser = opening_parenthesis(parser)?.and_trailing_whitespace();
+
+    // TODO: error on duplicate type parameter names
+    let mut parameter_types: Vec<AstFunctionTypeParameterType> = vec![];
+    let mut parser_for_missing_comma_error: Option<Parser> = None;
+    while let Some((new_parser, parameter_type, new_parser_for_missing_comma_error)) =
+        function_type_parameter_type(parser.and_trailing_whitespace())
+    {
+        if let Some(parser_for_missing_comma_error) = parser_for_missing_comma_error {
+            parameter_types.last_mut().unwrap().comma_error = Some(
+                parser_for_missing_comma_error
+                    .error_at_current_offset("This parameter type is missing a comma."),
+            );
+        }
+
+        parser = new_parser;
+        parameter_types.push(parameter_type);
+        parser_for_missing_comma_error = new_parser_for_missing_comma_error;
+    }
+    let parser = parser.and_trailing_whitespace();
+
+    let (parser, closing_parenthesis_error) = closing_parenthesis(parser)
+        .unwrap_or_ast_error(
+            parser,
+            "These parameter types are missing a closing parenthesis.",
+        )
+        .and_trailing_whitespace();
+
+    let (parser, return_type) =
+        type_(parser).unwrap_or_ast_error(parser, "This function type is missing a return type.");
+
+    Some((
+        parser,
+        AstFunctionType {
+            parameter_types,
+            closing_parenthesis_error,
+            return_type: return_type.map(Box::new),
+            span: start_offset..parser.offset(),
+        },
+    ))
+}
+#[instrument(level = "trace")]
+fn function_type_parameter_type<'a>(
+    parser: Parser,
+) -> Option<(Parser, AstFunctionTypeParameterType, Option<Parser>)> {
+    let (parser, type_) = type_(parser)?.and_trailing_whitespace();
+
+    let (parser, parser_for_missing_comma_error) =
+        comma(parser).map_or((parser, Some(parser)), |parser| (parser, None));
+
+    Some((
+        parser,
+        AstFunctionTypeParameterType {
+            type_: Box::new(type_),
+            comma_error: None,
+        },
+        parser_for_missing_comma_error,
+    ))
+}
+
 #[instrument(level = "trace")]
 pub fn type_arguments<'s>(parser: Parser<'s>) -> Option<(Parser, AstTypeArguments)> {
     let start_offset = parser.offset();

packages_v5/example.candy

@@ -288,6 +288,21 @@ fun needs(condition: Bool, message: Text) {
   }
 }
 
+fun loop(body: () Nothing) {
+  body()
+  loop(body)
+}
+fun repeat(times: Int, body: () Nothing) {
+  needs(times.isNonNegative())
+  switch times.isGreaterThan(0) {
+    false => {},
+    true => {
+      body()
+      repeat(times.subtract(1), body)
+    },
+  }
+}
+
 struct List[T] = builtin
 fun listFilled[T](length: Int, item: T) List[T] {
   builtinListFilled(length, item)
@@ -538,11 +553,14 @@ fun main() Int {
   print("Length: {list.length().toText()}")
   print("[{list.get(0).toText()}, {list.get(1).toText()}, {list.get(2).toText()}]")
 
+  print("orld!".endsWith("World!").toText().isEmpty())
+
   let foo = 123
   let addCaptured = (x: Int) { x.add(foo) }
   print("addCaptured(1) = {addCaptured(1).toText()}")
 
-  print("orld!".endsWith("World!").toText().isEmpty())
+  repeat(3, () { print("Hello, World!") })
+
   0
 }