Use rust-style turbofish

dust-lang/src/abstract_tree/function_call.rs

@@ -152,15 +152,15 @@ impl AbstractNode for FunctionCall {
 
         let function_context = Context::new(Some(context.clone()));
 
-        if let Some(type_parameters) = function.type_parameters() {
-            for identifier in type_parameters {
-                function_context.set_type(
-                    identifier.clone(),
-                    Type::Generic {
-                        identifier: identifier.clone(),
-                        concrete_type: None,
-                    },
-                )?;
+        if let (Some(type_parameters), Some(type_arguments)) =
+            (function.type_parameters(), self.type_arguments)
+        {
+            for (identifier, constructor) in
+                type_parameters.into_iter().zip(type_arguments.into_iter())
+            {
+                let r#type = constructor.construct(context)?;
+
+                function_context.set_type(identifier.clone(), r#type)?;
             }
         }
 

dust-lang/src/lib.rs

@@ -299,10 +299,7 @@ impl InterpreterError {
                                 self.source_id.clone(),
                                 position.1,
                             )
-                            .with_message("An error occured that forced the program to exit.")
-                            .with_help(
-                                "There may be unexpected side-effects because the program could not finish.",
-                            )
+                            .with_message("An error occured that forced the program to exit. There may be unexpected side-effects because the program could not finish.")
                             .with_note(note)
                             .with_label(
                                 Label::new((self.source_id.clone(), position.0..position.1)).with_message("Error occured here.")
@@ -359,11 +356,17 @@ impl InterpreterError {
                     ),
                     ValidationError::RwLockPoison(_) => todo!(),
                     ValidationError::TypeCheck {
-                        conflict,
+                        conflict: TypeConflict { actual, expected },
                         actual_position,
                         expected_position,
                     } => {
-                        let TypeConflict { actual, expected } = conflict;
+                        if let Type::Generic {
+                            concrete_type: None,
+                            ..
+                        } = actual
+                        {
+                            builder = builder.with_help("Try specifying the type using turbofish.");
+                        }
 
                         if let Some(position) = expected_position {
                             builder.add_label(

dust-lang/src/parser/mod.rs

@@ -414,19 +414,17 @@ pub fn parser<'src>(
                 expression
             });
 
-            let turbofish = type_constructor
-                .clone()
-                .separated_by(just(Token::Symbol(Symbol::Comma)))
-                .at_least(1)
-                .collect()
-                .delimited_by(
-                    just(Token::Symbol(Symbol::ParenOpen)),
-                    just(Token::Symbol(Symbol::ParenClose)),
-                )
-                .delimited_by(
-                    just(Token::Symbol(Symbol::DoubleColon)),
-                    just(Token::Symbol(Symbol::DoubleColon)),
-                );
+            let turbofish = just(Token::Symbol(Symbol::DoubleColon)).ignore_then(
+                type_constructor
+                    .clone()
+                    .separated_by(just(Token::Symbol(Symbol::Comma)))
+                    .at_least(1)
+                    .collect()
+                    .delimited_by(
+                        just(Token::Symbol(Symbol::Less)),
+                        just(Token::Symbol(Symbol::Greater)),
+                    ),
+            );
 
             let atom = choice((
                 built_in_function.clone(),

dust-lang/src/parser/tests.rs

@@ -539,7 +539,7 @@ fn function_call() {
 #[test]
 fn function_call_with_type_arguments() {
     assert_eq!(
-        parse(&lex("foobar::(str)::('hi')").unwrap()).unwrap()[0],
+        parse(&lex("foobar::<str>('hi')").unwrap()).unwrap()[0],
         Statement::Expression(Expression::FunctionCall(
             FunctionCall::new(
                 Expression::Identifier(Identifier::new("foobar").with_position((0, 6))),
@@ -547,10 +547,10 @@ fn function_call_with_type_arguments() {
                     RawTypeConstructor::String.with_position((9, 12))
                 )]),
                 Some(vec![Expression::Value(
-                    ValueNode::String("hi".to_string()).with_position((16, 20))
+                    ValueNode::String("hi".to_string()).with_position((14, 18))
                 )]),
             )
-            .with_position((0, 21))
+            .with_position((0, 19))
         ))
     )
 }

dust-lang/tests/functions.rs

@@ -7,7 +7,7 @@ fn function_call_with_type_argument() {
             "test",
             "
             foobar = fn |T| (x: T) -> T { x }
-            foobar::(int)::(42)
+            foobar::<int>(42)
             ",
         ),
         Ok(Some(Value::integer(42)))

std/json.ds

@@ -1,5 +1,5 @@
 json = {
 	parse = fn |T| (input: str) -> T {
-		__JSON_PARSE__::(T)::(input)
+		__JSON_PARSE__::<T>(input)
 	}
 }