Improve built-in values and errors

src/abstract_tree/index.rs

@@ -34,7 +34,10 @@ impl AbstractTree for Index {
 
             expression.node.expected_type(_context)
         } else {
-            Err(ValidationError::CannotIndex(left_type))
+            Err(ValidationError::CannotIndex {
+                r#type: left_type,
+                position: self.left.position,
+            })
         }
     }
 
@@ -53,7 +56,10 @@ impl AbstractTree for Index {
                     Err(ValidationError::CannotIndexWith(left_type, right_type))
                 }
             }
-            _ => Err(ValidationError::CannotIndex(left_type)),
+            _ => Err(ValidationError::CannotIndex {
+                r#type: left_type,
+                position: self.left.position,
+            }),
         }
     }
 

src/context.rs

@@ -6,7 +6,7 @@ use std::{
 use crate::{
     abstract_tree::{Identifier, Type},
     error::RwLockPoisonError,
-    value::BuiltInFunction,
+    value::{BuiltInFunction, BuiltInValue},
     Value,
 };
 
@@ -53,7 +53,14 @@ impl Context {
     }
 
     pub fn contains(&self, identifier: &Identifier) -> Result<bool, RwLockPoisonError> {
-        Ok(self.inner.read()?.contains_key(identifier))
+        if self.inner.read()?.contains_key(identifier) {
+            Ok(true)
+        } else {
+            match identifier.as_str() {
+                "io" | "output" => Ok(true),
+                _ => Ok(false),
+            }
+        }
     }
 
     pub fn get_type(&self, identifier: &Identifier) -> Result<Option<Type>, RwLockPoisonError> {
@@ -67,6 +74,7 @@ impl Context {
         }
 
         let r#type = match identifier.as_str() {
+            "io" => BuiltInValue::Io.r#type(),
             "output" => BuiltInFunction::Output.r#type(),
             _ => return Ok(None),
         };
@@ -79,6 +87,7 @@ impl Context {
             Ok(Some(value.clone()))
         } else {
             let value = match identifier.as_str() {
+                "io" => BuiltInValue::Io.value(),
                 "output" => Value::built_in_function(BuiltInFunction::Output),
                 _ => return Ok(None),
             };

src/error.rs

@@ -1,6 +1,6 @@
 use std::{io, ops::Range, sync::PoisonError};
 
-use ariadne::{Label, ReportBuilder};
+use ariadne::{Color, Fmt, Label, ReportBuilder};
 use chumsky::{prelude::Rich, span::Span};
 
 use crate::{
@@ -33,6 +33,8 @@ impl Error {
         self,
         mut builder: ReportBuilder<'_, Range<usize>>,
     ) -> ReportBuilder<'_, Range<usize>> {
+        let type_color = Color::Green;
+
         match self {
             Error::Parse { expected, span } => {
                 let message = match expected.as_str() {
@@ -66,16 +68,18 @@ impl Error {
             },
             Error::Validation { error, position } => match error {
                 ValidationError::ExpectedBoolean { actual, position } => {
-                    builder.add_label(
-                        Label::new(position.0..position.1)
-                            .with_message(format!("Expected boolean but got {actual}.")),
-                    );
+                    builder.add_label(Label::new(position.0..position.1).with_message(format!(
+                        "Expected {} but got {}.",
+                        "boolean".fg(type_color),
+                        actual.fg(type_color)
+                    )));
                 }
                 ValidationError::ExpectedIntegerOrFloat => {
-                    builder.add_label(
-                        Label::new(position.0..position.1)
-                            .with_message("Expected integer or float."),
-                    );
+                    builder.add_label(Label::new(position.0..position.1).with_message(format!(
+                        "Expected {} or {}.",
+                        "integer".fg(type_color),
+                        "float".fg(type_color)
+                    )));
                 }
                 ValidationError::RwLockPoison(_) => todo!(),
                 ValidationError::TypeCheck {
@@ -86,10 +90,12 @@ impl Error {
                     let TypeConflict { actual, expected } = conflict;
 
                     builder.add_labels([
-                        Label::new(expected_postion.0..expected_postion.1)
-                            .with_message(format!("Type {expected} established here.")),
+                        Label::new(expected_postion.0..expected_postion.1).with_message(format!(
+                            "Type {} established here.",
+                            expected.fg(type_color)
+                        )),
                         Label::new(actual_position.0..actual_position.1)
-                            .with_message(format!("Got type {actual} here.")),
+                            .with_message(format!("Got type {} here.", actual.fg(type_color))),
                     ]);
                 }
                 ValidationError::VariableNotFound(identifier) => {
@@ -99,7 +105,10 @@ impl Error {
                             .with_priority(1),
                     );
                 }
-                ValidationError::CannotIndex(_) => todo!(),
+                ValidationError::CannotIndex { r#type, position } => builder.add_label(
+                    Label::new(position.0..position.1)
+                        .with_message(format!("Cannot index into a {}.", r#type.fg(type_color))),
+                ),
                 ValidationError::CannotIndexWith(_, _) => todo!(),
                 ValidationError::InterpreterExpectedReturn => todo!(),
                 ValidationError::ExpectedFunction { .. } => todo!(),
@@ -169,7 +178,10 @@ impl PartialEq for RuntimeError {
 
 #[derive(Debug, PartialEq)]
 pub enum ValidationError {
-    CannotIndex(Type),
+    CannotIndex {
+        r#type: Type,
+        position: SourcePosition,
+    },
     CannotIndexWith(Type, Type),
     ExpectedBoolean {
         actual: Type,

src/value.rs

@@ -377,24 +377,34 @@ impl BuiltInFunction {
 impl Display for BuiltInFunction {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         match self {
-            BuiltInFunction::Output => write!(f, "(to_output : any) : none rust_magic();"),
-            BuiltInFunction::ReadLine => todo!(),
+            BuiltInFunction::Output => write!(f, "(to_output : any) : none {{ *MAGIC* }}"),
+            BuiltInFunction::ReadLine => write!(f, "() : str {{ *MAGIC* }}"),
         }
     }
 }
 
+static IO: OnceLock<Value> = OnceLock::new();
+
 pub enum BuiltInValue {
     Io,
 }
 
 impl BuiltInValue {
-    pub fn io() -> Value {
-        static IO: OnceLock<Value> = OnceLock::new();
+    pub fn value(self) -> Value {
+        match self {
+            BuiltInValue::Io => {
+                let mut properties = BTreeMap::new();
 
-        let mut properties = BTreeMap::new();
+                properties.insert(Identifier::new("read_line"), BuiltInFunction::read_line());
 
-        properties.insert(Identifier::new("read_line"), BuiltInFunction::read_line());
+                IO.get_or_init(|| Value::map(properties)).clone()
+            }
+        }
+    }
 
-        IO.get_or_init(|| Value::map(properties)).clone()
+    pub fn r#type(self) -> Type {
+        match self {
+            BuiltInValue::Io => Type::Map,
+        }
     }
 }