var decls

crates/lexer/src/complex_tokens.rs

@@ -380,21 +380,14 @@ pub(crate) fn parse_comment<'a>(source: &'a mut Source) -> Result<bool> {
     }
 
     let doc = source.next_if_eq(&'/').is_some();
-    eprintln!("doc comment: {doc}");
     loop {
         // take until new line
-        source
-            .take_while_inclusive(|&c| c != '\n')
-            .inspect(|c| eprintln!("skipping comment char: {c}"))
-            .for_each(drop);
+        source.take_while_inclusive(|&c| c != '\n').for_each(drop);
 
         let mut copy = source.clone();
         // skip whitespaces after new line to find continuation of comment
         (&mut copy)
-            .take_while_ref(|&c| {
-                eprintln!("Skipping whitespace: {c}");
-                is_things::is_whitespace(c) && c != '\n'
-            })
+            .take_while_ref(|&c| is_things::is_whitespace(c) && c != '\n')
             .for_each(drop);
 
         if (copy.next() == Some('/')) && (copy.next() == Some('/')) {

crates/lexer/src/lib.rs

@@ -496,8 +496,6 @@ impl<'a> TokenIterator<'a> {
             Some('/') if self.follows("//") => {
                 let doc = complex_tokens::parse_comment(&mut source).ok()?;
                 self.offset += source.offset();
-                eprintln!("next: {:?}", source.next());
-                eprintln!("rest: {:?}", &self.source[self.offset..]);
 
                 let lexeme = &self.source[start..self.offset];
                 if doc {

crates/parser/src/lib.rs

@@ -1,4 +1,4 @@
-use std::{hash::Hash, ops::Range, sync::Arc};
+use std::{fmt::Display, hash::Hash, ops::Range, sync::Arc};
 
 use chumsky::{
     IterParser, Parser,
@@ -6,8 +6,8 @@ use chumsky::{
     extra::{self, SimpleState},
     input::{IterInput, MapExtra},
     pratt::{infix, left, postfix, prefix, right},
-    prelude::{Recursive, choice, just, recursive},
-    recursive::Direct,
+    prelude::{Recursive, choice, just, none_of, recursive, via_parser},
+    recursive::{Direct, Indirect},
     select, text,
 };
 use internment::Intern;
@@ -63,6 +63,86 @@ pub enum InnerType {
 
 type Type = internment::Intern<InnerType>;
 
+impl Display for InnerType {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let name = match self {
+            InnerType::Top => "⊤",
+            InnerType::Bottom => "⊥",
+            InnerType::Unit => "()",
+            InnerType::Bool => "bool",
+            InnerType::AnyInt => "comptime_int",
+            InnerType::AnyUInt => "comptime_uint",
+            InnerType::Str => "str",
+            InnerType::Int { signed, size } => {
+                return write!(
+                    f,
+                    "{}{}",
+                    if *signed { "i" } else { "u" },
+                    match size {
+                        IntSize::Bits(bits) => bits.to_string(),
+                        IntSize::Pointer => "size".to_string(),
+                    }
+                );
+            }
+            InnerType::Float { float_type } => match float_type {
+                FloatType::F32 => "f32",
+                FloatType::F64 => "f64",
+            },
+            InnerType::Pointer { pointee } => {
+                return write!(f, "*{}", pointee);
+            }
+            InnerType::Array { element, size } => {
+                return write!(f, "[{}; {}]", element, size);
+            }
+            InnerType::Function {
+                return_type,
+                parameter_types,
+            } => {
+                write!(f, "fn(")?;
+
+                if let Some((last, rest)) = parameter_types.split_last() {
+                    for param in rest {
+                        write!(f, "{}, ", param)?;
+                    }
+                    write!(f, "{}", last)?;
+                }
+                return write!(f, ") -> {}", return_type);
+            }
+            InnerType::Tuple { elements } => {
+                write!(f, "(")?;
+
+                if let Some((last, rest)) = elements.split_last() {
+                    for elem in rest {
+                        write!(f, "{}, ", elem)?;
+                    }
+                    write!(f, "{}", last)?;
+                }
+                return write!(f, ")");
+            }
+            InnerType::TypeUnion { types } => {
+                if let Some((last, rest)) = types.split_last() {
+                    for ty in rest {
+                        write!(f, "{} | ", ty)?;
+                    }
+                    write!(f, "{}", last)?;
+                }
+                return Ok(());
+            }
+            InnerType::TypeIntersection { types } => {
+                if let Some((last, rest)) = types.split_last() {
+                    for ty in rest {
+                        write!(f, "{} ^ ", ty)?;
+                    }
+                    write!(f, "{}", last)?;
+                }
+                return Ok(());
+            }
+        };
+
+        write!(f, "{name}")
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum FloatType {
     F32,
@@ -108,8 +188,18 @@ pub enum ControlFlowKind {
     Continue,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct Index(u32);
+impl ControlFlowKind {
+    fn as_str(&self) -> &'static str {
+        match self {
+            ControlFlowKind::Return => "RETURN",
+            ControlFlowKind::Break => "BREAK",
+            ControlFlowKind::Continue => "CONTINUE",
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Index(pub u32);
 
 impl Index {
     pub fn as_value(self) -> PlaceOrValue {
@@ -128,14 +218,7 @@ pub enum AstNode {
     File {
         decls: Vec<Index>,
     },
-    FunctionProto {
-        name: String,
-        return_type: Type,
-        parameter_list: Index,
-    },
-    ParameterList {
-        parameters: Vec<Index>,
-    },
+    ParameterList(ParameterList),
     Parameter(Parameter),
     FunctionDecl(FunctionDecl),
     Block {
@@ -157,7 +240,7 @@ pub enum AstNode {
     VarDecl {
         mutable: bool,
         name: String,
-        var_type: Type,
+        var_type: Option<Type>,
     },
     Assignment {
         dest: Index,
@@ -166,7 +249,7 @@ pub enum AstNode {
     GlobalDecl {
         name: String,
         var_type: Type,
-        value: Index,
+        expr: Index,
     },
     StructDecl {
         name: String,
@@ -325,6 +408,20 @@ impl PlaceOrValue {
             PlaceOrValue::Value(i) => i,
         }
     }
+    pub fn with_index(self, index: Index) -> Self {
+        match self {
+            PlaceOrValue::Place(_) => PlaceOrValue::Place(index),
+            PlaceOrValue::Value(_) => PlaceOrValue::Value(index),
+        }
+    }
+
+    pub fn eq_placeness(&self, other: &Self) -> bool {
+        match (self, other) {
+            (PlaceOrValue::Place(_), PlaceOrValue::Place(_))
+            | (PlaceOrValue::Value(_), PlaceOrValue::Value(_)) => true,
+            _ => false,
+        }
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
@@ -335,13 +432,9 @@ pub enum Visibility {
 }
 
 #[derive(Debug, Error)]
-pub enum ParseError<'a> {
-    #[error("End of file.")]
-    EOF,
-    #[error("Unexpected token: {0:?}")]
-    UnexpectedToken(Token<'a>),
-    #[error("Not a type.")]
-    NotAType,
+pub enum ParseError {
+    #[error("expected a valid if condition expression")]
+    IfCondition,
 }
 
 #[derive(Default, Debug)]
@@ -349,6 +442,14 @@ pub struct Ast {
     nodes: Vec<AstNode>,
 }
 
+impl core::ops::Index<Index> for Ast {
+    type Output = AstNode;
+
+    fn index(&self, index: Index) -> &Self::Output {
+        self.nodes.get(index.0 as usize).expect("Invalid AST index")
+    }
+}
+
 impl Ast {
     pub fn new() -> Self {
         Self::default()
@@ -366,7 +467,7 @@ pub struct FunctionDecl {
     name: String,
     visibility: Visibility,
     return_type: Type,
-    parameter_list: ParameterList,
+    parameter_list: Index,
     body: Index,
 }
 
@@ -413,7 +514,7 @@ fn new_token_input<'a>(input: &'a str) -> TokenInput<'a> {
     IterInput::new(spanned_input, num_bytes..num_bytes)
 }
 
-fn type_parser<'a, E>() -> impl Parser<'a, TokenInput<'a>, Type, E>
+fn type_parser<'a, E>() -> impl Parser<'a, TokenInput<'a>, Type, E> + Clone
 where
     E: chumsky::extra::ParserExtra<'a, TokenInput<'a>, Error = EmptyErr> + 'a,
 {
@@ -466,17 +567,153 @@ where
     })
 }
 
-fn visibility<'a>() -> impl Parser<'a, TokenInput<'a>, Visibility, ParserExtra> {
+fn visibility<'a>() -> impl Parser<'a, TokenInput<'a>, Visibility, ParserExtra> + Clone {
     choice((just(Token::Pub).to(Visibility::Public),))
         .or_not()
         .map(|v| v.unwrap_or(Visibility::Private))
 }
 
-fn func_parser<'a>() -> impl Parser<'a, TokenInput<'a>, Index, ParserExtra> {
+type ParserExtra = chumsky::extra::Full<EmptyErr, SimpleState<Ast>, ()>;
+
+struct ParserCtx<'src, 'b> {
+    expr: Recursive<Indirect<'src, 'b, TokenInput<'src>, PlaceOrValue, ParserExtra>>,
+    function: Recursive<Indirect<'src, 'b, TokenInput<'src>, Index, ParserExtra>>,
+}
+
+impl<'src, 'b> ParserCtx<'src, 'b>
+where
+    'src: 'b,
+{
+    fn new() -> Self {
+        let mut this = Self {
+            expr: Recursive::declare(),
+            function: Recursive::declare(),
+        };
+
+        let function = this.create_function_decl();
+        this.function.define(function);
+        let expr = this.create_expr();
+        this.expr.define(expr);
+
+        this
+    }
+
+    pub fn expr(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, PlaceOrValue, ParserExtra> + Clone + use<'src, 'b>
+    {
+        self.expr.clone()
+    }
+
+    pub fn function(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, Index, ParserExtra> + Clone + use<'src, 'b> {
+        self.function.clone()
+    }
+
+    fn var_decl(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, Index, ParserExtra> + Clone + use<'src, 'b> {
+        let ident = select! {Token::Ident(ident) => ident};
+        just(Token::Let)
+            .ignored()
+            .then(select! {Token::Mutable => ()}.or_not())
+            .then(ident)
+            .then(
+                just(Token::Colon)
+                    .ignore_then(type_parser::<ParserExtra>())
+                    .or_not(),
+            )
+            .then(
+                just(Token::Equal)
+                    .ignore_then(self.expr().map_with(Self::into_value))
+                    .or_not(),
+            )
+            .then_ignore(just(Token::Semi))
+            .map_with(|((((_, mutable), ident), var_type), val), e: &mut E| {
+                let decl = e.state().push(AstNode::VarDecl {
+                    mutable: mutable.is_some(),
+                    name: ident.to_string(),
+                    var_type,
+                });
+                if let Some(expr) = val {
+                    e.state().push(AstNode::Assignment {
+                        dest: decl,
+                        expr: expr.index(),
+                    })
+                } else {
+                    decl
+                }
+            })
+    }
+
+    fn stmt(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, Index, ParserExtra> + Clone + use<'src, 'b> {
+        choice((
+            self.function.clone(),
+            self.var_decl(),
+            self.expr
+                .clone()
+                .then_ignore(just(Token::Semi))
+                .map(PlaceOrValue::index),
+        ))
+    }
+
+    fn simple_expr(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, PlaceOrValue, ParserExtra> + Clone + use<'src, 'b>
+    {
+        let ident = select! {Token::Ident(ident) => ident}.map_with(
+            |ident, e: &mut MapExtra<TokenInput<'src>, ParserExtra>| {
+                e.state()
+                    .push(AstNode::UnresolvedDeclRef {
+                        name: ident.to_string(),
+                    })
+                    .as_place()
+            },
+        );
+
+        let constant = select! {
+            Token::True => (Intern::new(Value::Bool(true)), Intern::new(InnerType::Bool)),
+            Token::False => (Intern::new(Value::Bool(false)), Intern::new(InnerType::Bool)),
+            Token::FloatingConstant(lexeme)|
+            Token::DotFloatingConstant(lexeme)|
+            Token::FloatingExpConstant(lexeme)|
+            Token::DotFloatingExpConstant(lexeme) => {
+                constants::parse_floating_constant(lexeme)
+            },
+            Token::IntegerConstant(lexeme) => {
+                constants::parse_integer_constant(lexeme, Radix::Dec)
+            },
+            tok @ Token::IntegerHexConstant(lexeme)|
+            tok @ Token::IntegerOctConstant(lexeme)|
+            tok @ Token::IntegerBinConstant(lexeme) => {
+                let radix = Radix::from_token(tok).unwrap();
+                constants::parse_integer_constant(&lexeme[2..], radix)
+            },
+        }
+        .map_with(|(value, ty), e: &mut E| {
+            e.state().push(AstNode::Constant { ty, value }).as_value()
+        });
+
+        choice((
+            unit().map(PlaceOrValue::Value),
+            ident,
+            constant,
+            self.expr
+                .clone()
+                .delimited_by(just(Token::OpenParens), just(Token::CloseParens)),
+            self.block(),
+        ))
+    }
+
+    fn create_function_decl(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, Index, ParserExtra> + Clone + use<'src, 'b> {
         let ident = select! {Token::Ident(ident) => ident};
 
-    let param = just(Token::Mutable)
-        .to(())
+        let param = select! {Token::Mutable => ()}
             .or_not()
             .then(ident)
             .then_ignore(just(Token::Colon))
@@ -495,22 +732,26 @@ fn func_parser<'a>() -> impl Parser<'a, TokenInput<'a>, Index, ParserExtra> {
             .collect::<Vec<_>>()
             .delimited_by(just(Token::OpenParens), just(Token::CloseParens))
             .labelled("function parameters")
-        .map(|params| ParameterList { parameters: params });
+            .map_with(|params, e: &mut E| {
+                e.state()
+                    .push(AstNode::ParameterList(ParameterList { parameters: params }))
+            });
 
-    visibility()
+        let ret_type = just(Token::MinusGreater)
+            .ignore_then(type_parser::<ParserExtra>())
+            .or_not();
+
+        attrs()
+            .or_not()
+            .then(visibility())
             .then_ignore(just(Token::Fn))
             .then(ident)
             .then(params)
-        // optional return type
-        .then(
-            just(Token::MinusGreater)
-                .ignore_then(type_parser())
-                .or_not(),
-        )
-        .then(block())
-        .map_with(|((((vis, ident), params), ret), body), e| {
+            .then(ret_type)
+            .then(self.block())
+            .map_with(|(((((attrs, vis), ident), params), ret), body), e| {
                 e.state().push(AstNode::FunctionDecl(FunctionDecl {
-                attrs: None,
+                    attrs,
                     name: ident.to_string(),
                     visibility: vis,
                     return_type: ret.unwrap_or_else(|| Intern::new(InnerType::Unit)),
@@ -520,79 +761,44 @@ fn func_parser<'a>() -> impl Parser<'a, TokenInput<'a>, Index, ParserExtra> {
             })
     }
 
-type ParserExtra = chumsky::extra::Full<EmptyErr, SimpleState<Ast>, ()>;
-
-fn block<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> + Clone {
-    just(Token::OpenBrace)
-        .ignored()
-        .then_ignore(just(Token::CloseBrace))
-        .map_with(|_, e: &mut MapExtra<'_, '_, _, ParserExtra>| {
-            e.state()
-                .push(AstNode::Block {
-                    statements: vec![],
-                    expr: None,
+    fn block(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, PlaceOrValue, ParserExtra> + Clone + use<'src, 'b>
+    {
+        self.stmt()
+            .repeated()
+            .collect::<Vec<_>>()
+            .then(self.expr.clone().or_not())
+            .delimited_by(just(Token::OpenBrace), just(Token::CloseBrace))
+            .map_with(|(statements, expr), e: &mut E| {
+                expr.unwrap_or(PlaceOrValue::Value(Index(u32::MAX)))
+                    .with_index(e.state().push(AstNode::Block {
+                        statements,
+                        expr: expr.map(PlaceOrValue::index),
+                    }))
             })
+    }
+
+    fn into_value(idx: PlaceOrValue, e: &mut E) -> PlaceOrValue {
+        match idx {
+            PlaceOrValue::Place(index) => e.state().push(AstNode::PlaceToValue { expr: index }),
+            PlaceOrValue::Value(index) => index,
+        }
         .as_value()
-            // TODO: add statements and expr and map placeness by expr
-        })
     }
 
-fn unit<'a>() -> impl Parser<'a, TokenInput<'a>, Index, ParserExtra> + Clone {
-    just(Token::OpenParens)
-        .ignored()
-        .ignore_then(just(Token::CloseParens))
-        .map_with(|_, e: &mut MapExtra<TokenInput<'a>, ParserExtra>| {
-            e.state().push(AstNode::Constant {
-                ty: Intern::new(InnerType::Unit),
-                value: Intern::new(Value::Unit),
-            })
-        })
+    fn into_place(idx: PlaceOrValue, e: &mut E) -> PlaceOrValue {
+        match idx {
+            PlaceOrValue::Value(index) => e.state().push(AstNode::ValueToPlace { expr: index }),
+            PlaceOrValue::Place(index) => index,
         }
-
-type E<'a, 'b> = MapExtra<'a, 'b, TokenInput<'a>, ParserExtra>;
-
-fn simple_expr<'a, 'b>(
-    expr: Recursive<Direct<'a, 'b, TokenInput<'a>, PlaceOrValue, ParserExtra>>,
-) -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> + Clone {
-    let ident = select! {Token::Ident(ident) => ident}.map_with(
-        |ident, e: &mut MapExtra<TokenInput<'a>, ParserExtra>| {
-            e.state()
-                .push(AstNode::UnresolvedDeclRef {
-                    name: ident.to_string(),
-                })
         .as_place()
-        },
-    );
-
-    let constant = select! {
-        Token::FloatingConstant(lexeme)|
-        Token::DotFloatingConstant(lexeme)|
-        Token::FloatingExpConstant(lexeme)|
-        Token::DotFloatingExpConstant(lexeme) => {
-            constants::parse_floating_constant(lexeme)
-        },
-        Token::IntegerConstant(lexeme) => {
-            constants::parse_integer_constant(lexeme, Radix::Dec)
-        },
-        tok @ Token::IntegerHexConstant(lexeme)|
-        tok @ Token::IntegerOctConstant(lexeme)|
-        tok @ Token::IntegerBinConstant(lexeme) => {
-            let radix = Radix::from_token(tok).unwrap();
-            constants::parse_integer_constant(&lexeme[2..], radix)
-        },
-    }
-    .map_with(|(value, ty), e: &mut E| e.state().push(AstNode::Constant { ty, value }).as_value());
-
-    choice((
-        unit().map(PlaceOrValue::Value),
-        ident,
-        constant,
-        expr.delimited_by(just(Token::OpenParens), just(Token::CloseParens)),
-        block(),
-    ))
     }
 
-fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
+    fn create_expr(
+        &'_ self,
+    ) -> impl Parser<'src, TokenInput<'src>, PlaceOrValue, ParserExtra> + Clone + use<'src, 'b>
+    {
         let assignment = choice((
             just(Token::Equal),
             just(Token::PlusEqual),
@@ -637,25 +843,8 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
 
         let r#as = just(Token::As).ignore_then(type_parser::<ParserExtra>());
 
-    fn into_value(idx: PlaceOrValue, e: &mut E) -> PlaceOrValue {
-        match idx {
-            PlaceOrValue::Place(index) => e.state().push(AstNode::PlaceToValue { expr: index }),
-            PlaceOrValue::Value(index) => index,
-        }
-        .as_value()
-    }
-
-    fn into_place(idx: PlaceOrValue, e: &mut E) -> PlaceOrValue {
-        match idx {
-            PlaceOrValue::Value(index) => e.state().push(AstNode::ValueToPlace { expr: index }),
-            PlaceOrValue::Place(index) => index,
-        }
-        .as_place()
-    }
-
         // TODO: postfix: function call, field access, array subscript
-    recursive(move |_expr| {
-        let simple = simple_expr(_expr.clone());
+        let _expr = self.expr.clone();
 
         let subscript = _expr
             .clone()
@@ -664,12 +853,12 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
                 just(Token::CloseSquareBracket),
             )
             // subscript takes a value as the index
-            .map_with(into_value);
+            .map_with(Self::into_value);
 
         let arguments = _expr
             .clone()
             // arguments take values
-            .map_with(into_value)
+            .map_with(Self::into_value)
             .map(PlaceOrValue::index)
             .separated_by(just(Token::Comma))
             .allow_trailing()
@@ -678,10 +867,10 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
 
         let field = just(Token::Dot).ignore_then(select! {Token::Ident(ident) => ident});
 
-        let assignment_expr = simple.pratt((
+        let assignment_expr = self.simple_expr().pratt((
             postfix(100, subscript, |expr, index: PlaceOrValue, e: &mut E| {
                 let node = AstNode::Subscript {
-                    expr: into_value(expr, e).index(),
+                    expr: Self::into_value(expr, e).index(),
                     index: index.index(),
                 };
                 // subscript yields a place
@@ -689,7 +878,7 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
             }),
             postfix(100, arguments, |callee, arguments, e: &mut E| {
                 let node = AstNode::CallExpr {
-                    callee: into_value(callee, e).index(),
+                    callee: Self::into_value(callee, e).index(),
                     arguments,
                 };
                 // function call yields a value
@@ -697,7 +886,7 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
             }),
             postfix(100, field, |expr, field: &str, e: &mut E| {
                 let node = AstNode::FieldAccess {
-                    expr: into_place(expr, e).index(),
+                    expr: Self::into_place(expr, e).index(),
                     field: field.to_string(),
                 };
                 // field access yields a place
@@ -705,15 +894,15 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
             }),
             postfix(99, r#as, |expr, ty, e: &mut E| {
                 let node = AstNode::ExplicitCast {
-                    expr: into_value(expr, e).index(),
+                    expr: Self::into_value(expr, e).index(),
                     ty,
                 };
                 e.state().push(node).as_value()
             }),
             prefix(95, prefixes, |op, expr, e: &mut E| {
                 let node = match op {
-                    Token::Bang => AstNode::Not(into_value(expr, e).index()),
-                    Token::Minus => AstNode::Negate(into_value(expr, e).index()),
+                    Token::Bang => AstNode::Not(Self::into_value(expr, e).index()),
+                    Token::Minus => AstNode::Negate(Self::into_value(expr, e).index()),
                     Token::Star => {
                         return e
                             .state()
@@ -721,15 +910,15 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
                             .as_place();
                     }
                     Token::Ampersand => AstNode::AddressOf {
-                        expr: into_place(expr, e).index(),
+                        expr: Self::into_place(expr, e).index(),
                     },
                     _ => unreachable!(),
                 };
                 e.state().push(node).as_value()
             }),
             infix(left(90), multiplicative, |left, op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = match op {
                     Token::Star => AstNode::Multiply { left, right },
                     Token::Slash => AstNode::Divide { left, right },
@@ -739,8 +928,8 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
                 e.state().push(node).as_value()
             }),
             infix(left(80), additive, |left, op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = match op {
                     Token::Plus => AstNode::Add { left, right },
                     Token::Minus => AstNode::Subtract { left, right },
@@ -749,8 +938,8 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
                 e.state().push(node).as_value()
             }),
             infix(left(70), shift, |left, op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = match op {
                     Token::LessLess => AstNode::ShiftLeft { left, right },
                     Token::GreaterGreater => AstNode::ShiftRight { left, right },
@@ -759,8 +948,8 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
                 e.state().push(node).as_value()
             }),
             infix(left(60), relational, |left, op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = match op {
                     Token::Less => AstNode::Less { left, right },
                     Token::LessEqual => AstNode::LessEq { left, right },
@@ -771,8 +960,8 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
                 e.state().push(node).as_value()
             }),
             infix(left(50), equality, |left, op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = match op {
                     Token::EqualEqual => AstNode::Eq { left, right },
                     Token::BangEqual => AstNode::NotEq { left, right },
@@ -781,42 +970,42 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
                 e.state().push(node).as_value()
             }),
             infix(left(40), and, |left, _op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = AstNode::BitAnd { left, right };
                 e.state().push(node).as_value()
             }),
             infix(left(30), xor, |left, _op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = AstNode::BitXor { left, right };
                 e.state().push(node).as_value()
             }),
             infix(left(20), or, |left, _op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = AstNode::BitOr { left, right };
                 e.state().push(node).as_value()
             }),
             infix(left(10), logical_and, |left, _op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = AstNode::LogicalAnd { left, right };
                 e.state().push(node).as_value()
             }),
             infix(left(5), logical_or, |left, _op, right, e: &mut E| {
-                let left = into_value(left, e).index();
-                let right = into_value(right, e).index();
+                let left = Self::into_value(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = AstNode::LogicalOr { left, right };
                 e.state().push(node).as_value()
             }),
             infix(right(1), assignment, |left, op, right, e: &mut E| {
-                let dest = into_place(left, e).index();
-                let right = into_value(right, e).index();
+                let dest = Self::into_place(left, e).index();
+                let right = Self::into_value(right, e).index();
                 let node = if op == Token::Equal {
                     AstNode::Assignment { dest, expr: right }
                 } else {
-                    let left = into_value(left, e).index();
+                    let left = Self::into_value(left, e).index();
                     let right = match op {
                         Token::PlusEqual => e.state().push(AstNode::Add { left, right }),
                         Token::MinusEqual => e.state().push(AstNode::Subtract { left, right }),
@@ -838,41 +1027,128 @@ fn expr<'a>() -> impl Parser<'a, TokenInput<'a>, PlaceOrValue, ParserExtra> {
             }),
         ));
 
-        let else_expr = just(Token::Else).ignore_then(_expr.clone());
+        let expr = choice((self.if_else_expr(), assignment_expr)).labelled("expression");
 
-        let if_expr = just(Token::If)
+        expr
+    }
+
+    fn if_else_expr(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, PlaceOrValue, ParserExtra> + Clone + use<'src, 'b>
+    {
+        let else_expr = just(Token::Else).ignore_then(self.expr());
+
+        just(Token::If)
             .ignore_then(
-                _expr
-                    .clone()
-                    .map_with(into_value)
+                self.expr()
+                    .map_with(Self::into_value)
                     .map(PlaceOrValue::index)
-                    .delimited_by(just(Token::OpenParens), just(Token::CloseParens)),
+                    .delimited_by(just(Token::OpenParens), just(Token::CloseParens))
+                    .recover_with(via_parser({
+                        // parenthised recovery:
+                        recursive(|recovery| {
+                            just(Token::OpenParens)
+                                .ignored()
+                                .ignore_then(choice((
+                                    none_of([Token::CloseParens, Token::OpenParens]).map(|_| ()),
+                                    recovery.map(|_| ()),
+                                )))
+                                .repeated()
+                                .then_ignore(just(Token::CloseParens))
+                        })
+                        .map_with(|_, e: &mut E| {
+                            e.state().push(AstNode::Error {
+                                err: Box::new(ParseError::IfCondition),
+                            })
+                        })
+                    })),
             )
-            .then(_expr.clone())
+            .then(self.expr())
             .then(else_expr.or_not())
             .map_with(|((condition, then), or), e: &mut E| {
-                // TODO: determine placeness from branches
+                use PlaceOrValue::*;
+                let (then, or) = match (then, or) {
+                    (Place(then), Some(Place(or))) => (Place(then), Some(Place(or))),
+                    _ => (
+                        Self::into_value(then, e),
+                        or.map(|or| Self::into_value(or, e)),
+                    ),
+                };
                 let node = AstNode::If {
                     condition,
                     then: then.index(),
                     r#else: or.map(PlaceOrValue::index),
                 };
-                e.state().push(node).as_value()
-            });
-
-        let expr = choice((if_expr, assignment_expr)).labelled("expression");
-
-        Arc::new(expr)
+                then.with_index(e.state().push(node))
             })
     }
 
+    fn global_decl(&self) -> impl Parser<'src, TokenInput<'src>, Index, ParserExtra> + Clone {
+        let ident = select! {Token::Ident(ident) => ident};
+
+        attrs()
+            .or_not()
+            .then(visibility())
+            .then_ignore(just(Token::Let))
+            .then(ident)
+            .then_ignore(just(Token::Colon))
+            .then(type_parser::<ParserExtra>())
+            .then_ignore(just(Token::Equal))
+            .then(self.expr.clone())
+            .then_ignore(just(Token::Semi))
+            .map_with(|((((_attrs, _vis), name), var_type), value), e| {
+                e.state().push(AstNode::GlobalDecl {
+                    name: name.to_string(),
+                    var_type,
+                    expr: value.index(),
+                })
+            })
+    }
+
+    fn file(&self) -> impl Parser<'src, TokenInput<'src>, Index, ParserExtra> + Clone {
+        choice((self.function.clone(), self.global_decl()))
+            .repeated()
+            .collect::<Vec<_>>()
+            .map_with(|decls, e: &mut E| e.state().push(AstNode::File { decls }))
+    }
+}
+
+fn unit<'a>() -> impl Parser<'a, TokenInput<'a>, Index, ParserExtra> + Clone {
+    just(Token::OpenParens)
+        .ignored()
+        .ignore_then(just(Token::CloseParens))
+        .map_with(|_, e: &mut MapExtra<TokenInput<'a>, ParserExtra>| {
+            e.state().push(AstNode::Constant {
+                ty: Intern::new(InnerType::Unit),
+                value: Intern::new(Value::Unit),
+            })
+        })
+}
+
+type E<'a, 'b> = MapExtra<'a, 'b, TokenInput<'a>, ParserExtra>;
+
+fn attrs<'a>() -> impl Parser<'a, TokenInput<'a>, Index, ParserExtra> + Clone {
+    let docs = select! { Token::DocComment(doc) => doc }.map_with(|doc, e: &mut E| {
+        e.state().push(AstNode::Doc {
+            text: doc.to_string(),
+        })
+    });
+
+    docs.repeated()
+        .at_least(1)
+        .collect::<Vec<_>>()
+        .map_with(|attrs, e: &mut E| e.state().push(AstNode::Attributes { attrs }))
+}
+
 mod constants;
+mod pretty;
+mod symbols;
 
 #[cfg(test)]
 mod tests {
-    use chumsky::{Parser, extra::SimpleState};
+    use chumsky::{ParseResult, Parser, extra::SimpleState};
 
-    use crate::{Ast, AstNode, new_token_input, type_parser};
+    use crate::{Ast, AstNode, ParserCtx, ParserExtra, new_token_input, pretty, type_parser};
 
     #[test]
     fn print_ast_node_size() {
@@ -932,16 +1208,91 @@ mod tests {
         );
     }
 
+    fn print_ast<'src, T>(
+        tokens: crate::TokenInput<'src>,
+        parser: impl Parser<'src, crate::TokenInput<'src>, T, ParserExtra>,
+    ) {
+        let mut state = SimpleState(Ast::new());
+        let out = parser.parse_with_state(tokens, &mut state);
+        for e in out.errors() {
+            eprintln!("Error: {}", e);
+            panic!("errors occured while parsing.")
+        }
+        let ast = state.0;
+        let mut pretty = pretty::PrettyPrint::new();
+        pretty.print(&ast);
+    }
+
     #[test]
     fn parse_exprs() {
-        let print_ast = |tokens| {
-            let mut state = SimpleState(Ast::new());
-            let out = crate::expr().parse_with_state(tokens, &mut state).unwrap();
-            eprintln!("{:?}", state.0);
-        };
+        let ctx = crate::ParserCtx::new();
 
-        print_ast(new_token_input("()"));
-        print_ast(new_token_input("!() as i32"));
-        print_ast(new_token_input("1 << 2 & 3"));
+        print_ast(new_token_input("true"), ctx.expr());
+    }
+
+    #[test]
+    fn parse_fns() {
+        let ctx = crate::ParserCtx::new();
+
+        print_ast(
+            new_token_input(
+                r#"
+/// docs!
+fn my_function(a: i32, b: *const u8) -> i32 {
+    let mut x: i32;
+    x = a + 1;
+    x
+}
+"#,
+            ),
+            ctx.function(),
+        );
+    }
+
+    #[test]
+    fn parse_var_decl() {
+        let ctx = crate::ParserCtx::new();
+        print_ast(
+            new_token_input(
+                r#"
+let mut x: i32 = 10;
+"#,
+            ),
+            ctx.var_decl(),
+        );
+    }
+
+    #[test]
+    fn parse_stmts() {
+        let ctx = crate::ParserCtx::new();
+        print_ast(
+            new_token_input(
+                r#"
+let mut x: i32 = 10;
+"#,
+            ),
+            ctx.stmt(),
+        );
+        print_ast(
+            new_token_input(
+                r#"
+(if (true) {x} else {y}) = x + x;
+"#,
+            ),
+            ctx.stmt(),
+        );
+    }
+
+    #[test]
+    fn parse_if_expr() {
+        let ctx = crate::ParserCtx::new();
+        print_ast(
+            new_token_input(
+                r#"
+if (true) 1 / 2 else true
+"#,
+            ),
+            ctx.if_else_expr(),
+        );
     }
 }

crates/parser/src/pretty.rs

@@ -0,0 +1,398 @@
+use crate::{Ast, AstNode, Index};
+
+pub struct PrettyPrint {
+    lines: Vec<String>,
+    indents: Vec<Indent>,
+}
+
+const VERTICAL: &str = "│";
+const HORIZONTAL: &str = "─";
+const CONNECTOR: &str = "├";
+const END_CONNECTOR: &str = "└";
+const EMPTY: &str = " ";
+
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+enum Indent {
+    Vertical,
+    End,
+    Empty,
+}
+
+impl PrettyPrint {
+    pub fn new() -> Self {
+        Self {
+            lines: Vec::new(),
+            indents: Vec::new(),
+        }
+    }
+
+    fn push_line(&mut self, line: String) {
+        let (last, rest) = self
+            .indents
+            .split_last_mut()
+            .map_or::<(Option<&mut Indent>, &mut [Indent]), _>((None, &mut []), |(last, rest)| {
+                (Some(last), rest)
+            });
+        let rest = rest.iter_mut().map(|indent| match *indent {
+            Indent::Vertical => VERTICAL,
+            Indent::End => {
+                *indent = Indent::Empty;
+                END_CONNECTOR
+            }
+            Indent::Empty => EMPTY,
+        });
+        let last = if let Some(last) = last {
+            match last {
+                Indent::Vertical => CONNECTOR,
+                Indent::End => {
+                    *last = Indent::Empty;
+                    END_CONNECTOR
+                }
+                Indent::Empty => CONNECTOR,
+            }
+        } else {
+            ""
+        };
+
+        self.lines.push(
+            rest.chain(std::iter::once(last))
+                .chain(std::iter::once(line.as_str()))
+                .collect::<String>(),
+        );
+    }
+
+    pub fn print(mut self, ast: &Ast) {
+        let root = ast.nodes.len().checked_sub(1).unwrap();
+        self.stuff(ast, Index(root as u32));
+        for line in self.lines {
+            println!("{}", line);
+        }
+    }
+
+    fn with_indent<I>(
+        &mut self,
+        mut items: impl DoubleEndedIterator<Item = I>,
+        mut f: impl FnMut(&mut Self, I),
+    ) {
+        if let Some(last) = (&mut items).next_back() {
+            self.indents.push(Indent::Vertical);
+            for item in items {
+                f(self, item);
+            }
+            *self.indents.last_mut().unwrap() = Indent::End;
+            f(self, last);
+            self.indents.pop();
+        }
+    }
+
+    fn stuff(&mut self, ast: &Ast, node: Index) {
+        let mut node = ast.nodes.get(node.0 as usize).unwrap();
+
+        match node {
+            AstNode::Root { files } => {
+                self.push_line(format!(
+                    "{} {{num_files: {}}}",
+                    node_name(node),
+                    files.len()
+                ));
+
+                self.with_indent(files.iter(), |this, idx| {
+                    this.stuff(ast, *idx);
+                });
+            }
+            AstNode::File { decls } => {
+                self.push_line(format!(
+                    "{} {{num_decls: {}}}",
+                    node_name(node),
+                    decls.len()
+                ));
+
+                self.with_indent(decls.iter(), |this, idx| {
+                    this.stuff(ast, *idx);
+                });
+            }
+            AstNode::ParameterList(parameters) => {
+                self.push_line(format!(
+                    "{}[{}]",
+                    node_name(node),
+                    parameters.parameters.len()
+                ));
+
+                self.with_indent(parameters.parameters.iter(), |this, idx| {
+                    this.stuff(ast, *idx);
+                });
+            }
+            AstNode::Parameter(parameter) => {
+                self.push_line(format!(
+                    "{} [{}: {}]",
+                    node_name(node),
+                    parameter.name,
+                    parameter.param_type
+                ));
+            }
+            AstNode::FunctionDecl(function_decl) => {
+                self.push_line(format!("{} {}", node_name(node), function_decl.name,));
+                self.indents.push(Indent::Vertical);
+                self.push_line(format!("VISIBILITY: {:?}", function_decl.visibility));
+                self.stuff(ast, function_decl.parameter_list);
+                self.push_line(format!("RETURN_TYPE: {}", function_decl.return_type));
+                *self.indents.last_mut().unwrap() = Indent::End;
+                self.stuff(ast, function_decl.body);
+                self.indents.pop();
+            }
+            AstNode::Block { statements, expr } => {
+                self.push_line(format!("{}", node_name(node),));
+
+                self.with_indent(statements.iter().chain(expr), |this, idx| {
+                    this.stuff(ast, *idx);
+                });
+            }
+            AstNode::Constant { ty, value } => {
+                self.push_line(format!("{} [{} := {:?}]", node_name(node), ty, value));
+            }
+            AstNode::NoopExpr => {
+                self.push_line(format!("{}", node_name(node),));
+            }
+            AstNode::Stmt { expr } => {
+                self.push_line(format!("{}", node_name(node),));
+                self.indents.push(Indent::End);
+                self.stuff(ast, *expr);
+                self.indents.pop();
+            }
+            AstNode::ControlFlow { kind, expr } => todo!(),
+            AstNode::VarDecl {
+                mutable,
+                name,
+                var_type,
+            } => {
+                self.push_line(format!(
+                    "{} [{} {}: {}]",
+                    node_name(node),
+                    name,
+                    mutable.then_some(" mut").unwrap_or(""),
+                    var_type.map_or("?".to_string(), |ty| format!("{ty}"))
+                ));
+            }
+            AstNode::Assignment { dest, expr } => {
+                self.push_line(format!("{}", node_name(node),));
+                self.indents.push(Indent::Vertical);
+                self.push_line("DEST".to_string());
+                self.with_indent(core::iter::once(*dest), |this, idx| {
+                    this.stuff(ast, idx);
+                });
+                *self.indents.last_mut().unwrap() = Indent::End;
+                self.push_line("EXPR".to_string());
+                self.with_indent(core::iter::once(*expr), |this, idx| {
+                    this.stuff(ast, idx);
+                });
+                self.indents.pop();
+            }
+            AstNode::GlobalDecl {
+                name,
+                var_type,
+                expr,
+            } => {
+                self.push_line(format!("{} [{}: {}]", node_name(node), name, var_type));
+                self.with_indent(core::iter::once(*expr), |this, idx| {
+                    this.stuff(ast, idx);
+                });
+            }
+            AstNode::StructDecl { name, fields } => todo!(),
+            AstNode::FieldDecl { name, field_type } => todo!(),
+            AstNode::FieldAccess { expr, field } => todo!(),
+            AstNode::UnresolvedDeclRef { name } => {
+                self.push_line(format!("{} \"{}\"", node_name(node), name,));
+            }
+            AstNode::DeclRef { decl } => {
+                self.push_line(format!("{} @{}", node_name(node), decl.0,));
+            }
+            AstNode::TypeDeclRef { ty } => {
+                self.push_line(format!("{} @{:?}", node_name(node), ty,));
+            }
+            AstNode::ExplicitCast { expr, ty } => {
+                self.push_line(format!("{} {}", node_name(node), ty,));
+                self.indents.push(Indent::End);
+                self.stuff(ast, *expr);
+                self.indents.pop();
+            }
+            AstNode::Not(expr)
+            | AstNode::Negate(expr)
+            | AstNode::Deref { expr }
+            | AstNode::AddressOf { expr }
+            | AstNode::ValueToPlace { expr }
+            | AstNode::PlaceToValue { expr } => {
+                self.push_line(format!("{}", node_name(node),));
+                self.indents.push(Indent::End);
+                self.stuff(ast, *expr);
+                self.indents.pop();
+            }
+            AstNode::CallExpr { callee, arguments } => {
+                self.push_line(format!(
+                    "{} {{num_args: {}}}",
+                    node_name(node),
+                    arguments.len()
+                ));
+                self.indents.push(Indent::Vertical);
+                self.stuff(ast, *callee);
+                *self.indents.last_mut().unwrap() = Indent::End;
+                self.with_indent(arguments.iter(), |this, arg| {
+                    this.stuff(ast, *arg);
+                });
+                self.indents.pop();
+            }
+            AstNode::Argument { expr } => {
+                self.stuff(ast, *expr);
+            }
+            AstNode::Multiply { left, right }
+            | AstNode::Divide { left, right }
+            | AstNode::Modulus { left, right }
+            | AstNode::Add { left, right }
+            | AstNode::Subtract { left, right }
+            | AstNode::BitOr { left, right }
+            | AstNode::BitAnd { left, right }
+            | AstNode::BitXor { left, right }
+            | AstNode::LogicalOr { left, right }
+            | AstNode::LogicalAnd { left, right }
+            | AstNode::Eq { left, right }
+            | AstNode::NotEq { left, right }
+            | AstNode::Less { left, right }
+            | AstNode::LessEq { left, right }
+            | AstNode::Greater { left, right }
+            | AstNode::GreaterEq { left, right }
+            | AstNode::ShiftLeft { left, right }
+            | AstNode::ShiftRight { left, right } => {
+                self.push_line(format!("{}", node_name(node),));
+                self.with_indent([*left, *right].into_iter(), |this, idx| {
+                    this.stuff(ast, idx);
+                });
+            }
+            AstNode::Subscript { expr, index } => {
+                self.push_line(format!("{}", node_name(node),));
+                self.indents.push(Indent::Vertical);
+                self.stuff(ast, *expr);
+                *self.indents.last_mut().unwrap() = Indent::End;
+
+                self.push_line("INDEX".to_string());
+                self.with_indent([*index].into_iter(), |this, idx| {
+                    this.stuff(ast, idx);
+                });
+
+                self.indents.pop();
+            }
+            AstNode::If {
+                condition,
+                then,
+                r#else,
+            } => {
+                self.push_line(format!("{}", node_name(node),));
+                self.indents.push(Indent::Vertical);
+                self.push_line("COND".to_string());
+                self.with_indent([*condition].into_iter(), |this, idx| {
+                    this.stuff(ast, idx);
+                });
+
+                self.push_line("THEN".to_string());
+                if let Some(r#else) = r#else {
+                    self.with_indent(core::iter::once(*then), |this, idx| {
+                        this.stuff(ast, idx);
+                    });
+                    *self.indents.last_mut().unwrap() = Indent::End;
+                    self.push_line("ELSE".to_string());
+                    self.with_indent(core::iter::once(*r#else), |this, idx| {
+                        this.stuff(ast, idx);
+                    });
+                } else {
+                    *self.indents.last_mut().unwrap() = Indent::End;
+                    self.with_indent(core::iter::once(*then), |this, idx| {
+                        this.stuff(ast, idx);
+                    });
+                }
+                self.indents.pop();
+            }
+            AstNode::Else { expr } => {
+                self.push_line(format!("{}", node_name(node),));
+                self.indents.push(Indent::End);
+                self.stuff(ast, *expr);
+                self.indents.pop();
+            }
+            AstNode::Comment { text } => {
+                self.push_line(format!("{} \"{}\"", node_name(node), text,));
+            }
+            AstNode::Attributes { attrs } => {
+                self.push_line(format!(
+                    "{} {{num_attrs: {}}}",
+                    node_name(node),
+                    attrs.len()
+                ));
+                self.with_indent(attrs.iter(), |this, &attr| {
+                    this.stuff(ast, attr);
+                });
+            }
+            AstNode::Doc { text } => {
+                self.push_line(format!("{} \"{}\"", node_name(node), text,));
+            }
+
+            AstNode::Error { err } => {
+                self.push_line(format!("{} \"{}\"", node_name(node), err,));
+            }
+        }
+    }
+}
+
+fn node_name(node: &AstNode) -> &'static str {
+    match node {
+        AstNode::Root { .. } => "ROOT",
+        AstNode::File { .. } => "FILE",
+        AstNode::ParameterList(_) => "PARAMS",
+        AstNode::Parameter(_) => "PARAM",
+        AstNode::FunctionDecl(_) => "FN",
+        AstNode::Block { .. } => "BLOCK",
+        AstNode::Constant { .. } => "CONSTANT",
+        AstNode::NoopExpr => "NOOP",
+        AstNode::Stmt { .. } => "STMT",
+        AstNode::ControlFlow { .. } => "CONTROL_FLOW",
+        AstNode::VarDecl { .. } => "VAR_DECL",
+        AstNode::Assignment { .. } => "ASSIGN",
+        AstNode::GlobalDecl { .. } => "GLOBAL_DECL",
+        AstNode::StructDecl { .. } => "STRUCT",
+        AstNode::FieldDecl { .. } => "FIELD",
+        AstNode::FieldAccess { .. } => "FIELD_ACCESS",
+        AstNode::UnresolvedDeclRef { .. } => "UNRESOLVED_DECL_REF",
+        AstNode::DeclRef { .. } => "DECL_REF",
+        AstNode::TypeDeclRef { .. } => "TYPE_REF",
+        AstNode::ExplicitCast { .. } => "AS",
+        AstNode::Deref { .. } => "DEREF",
+        AstNode::AddressOf { .. } => "ADDR_OF",
+        AstNode::PlaceToValue { .. } => "INTO_VALUE",
+        AstNode::ValueToPlace { .. } => "INTO_PLACE",
+        AstNode::CallExpr { .. } => "CALL",
+        AstNode::Argument { .. } => "ARG",
+        AstNode::Not(_) => "NOT",
+        AstNode::Negate(_) => "NEGATE",
+        AstNode::Multiply { .. } => "MUL",
+        AstNode::Divide { .. } => "DIV",
+        AstNode::Modulus { .. } => "REM",
+        AstNode::Add { .. } => "ADD",
+        AstNode::Subtract { .. } => "SUB",
+        AstNode::BitOr { .. } => "BIT_OR",
+        AstNode::BitAnd { .. } => "BIT_AND",
+        AstNode::BitXor { .. } => "BIT_XOR",
+        AstNode::LogicalOr { .. } => "OR",
+        AstNode::LogicalAnd { .. } => "AND",
+        AstNode::Eq { .. } => "EQ",
+        AstNode::NotEq { .. } => "NEQ",
+        AstNode::Less { .. } => "LT",
+        AstNode::LessEq { .. } => "LEQ",
+        AstNode::Greater { .. } => "GT",
+        AstNode::GreaterEq { .. } => "GEQ",
+        AstNode::ShiftLeft { .. } => "SHL",
+        AstNode::ShiftRight { .. } => "SHR",
+        AstNode::Subscript { .. } => "SUBSCRIPT",
+        AstNode::If { .. } => "IF",
+        AstNode::Else { .. } => "ELSE",
+        AstNode::Comment { .. } => "COMMENT",
+        AstNode::Attributes { .. } => "META",
+        AstNode::Doc { .. } => "DOCS",
+        AstNode::Error { .. } => "ERR",
+    }
+}

crates/parser/src/symbols.rs

@@ -0,0 +1,178 @@
+//! Coming from the ast, we have a `DeclRef` with an interned identifier `ident`
+//! and want to find the symbol it refers to.
+//!
+//! To help, we have a struct keeping track of all accessible scopes. Now, we
+//! want to look through any accessible scope `s` for a symbol with the name
+//! `ident`.  Thus: `Symbol {scope: `s`, name: `ident`, ..}`.
+//!
+//! We might also know the type of the symbol we are looking for, if we want
+//! to permit fields/variables and methods/functions sharing names.
+//!
+//! Since I want to allow variable shadowing for local variables, some strategy
+//! to differentiate between shadowed variables must be employed:
+//! - keys of type SymbolKind::Local might point to a list of values with source locations
+//! - keys might contain source locations.
+//!
+//! Any symbol pointed at from within the ast must again point at an ast
+//! object.
+//! Thus: `Key` -> `AstIndex`
+//! Exception: `Key::ScopeByIndex` -> `InternIndex`
+
+use core::fmt::Debug;
+use std::collections::BTreeMap;
+
+use internment::Intern;
+
+use crate::Index;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Span(u32);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Spanned<T>(pub T, Span);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub enum SymbolKind {
+    __First,
+    Const,
+    Function,
+    Type,
+    __TypeScope,
+    Scope,
+    ParentScope,
+    Parameter(Span),
+    Local(Span),
+    __Last,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Key {
+    ScopeByName {
+        name: Intern<str>,
+    },
+    /// not all scopes have a name, as some are anonymous blocks or otherwise nameless
+    ScopeByIndex {
+        ast: Index,
+    },
+    Symbol {
+        scope: Index,
+        name: Intern<str>,
+        kind: SymbolKind,
+    },
+}
+
+impl Key {
+    pub fn parent(scope: Index) -> Key {
+        Key::Symbol {
+            scope,
+            name: Intern::from(""),
+            kind: SymbolKind::ParentScope,
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug)]
+pub enum Payload {
+    Ast(Index),
+    Name(Intern<str>),
+}
+
+pub struct Symbols {
+    inner: BTreeMap<Key, Payload>,
+}
+
+impl Debug for Symbols {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Symbols [")?;
+        if f.alternate() {
+            writeln!(f, "")?;
+        }
+        let entries = self.inner.iter();
+        f.debug_list().entries(entries).finish()?;
+        write!(f, "]")?;
+        if f.alternate() {
+            writeln!(f, "")?;
+        }
+
+        Ok(())
+    }
+}
+
+// checks for each scope in scopes_in_tree Symbol { scope, kind: SymbolKind::Local, 0}..Symbol { scope, kind: SymbolKind::Scope, u32::MAX}
+struct SymbolTreePos {
+    scopes_in_scope: Vec<Index>,
+}
+
+impl Symbols {
+    pub fn new() -> Symbols {
+        Self {
+            inner: BTreeMap::new(),
+        }
+    }
+    pub fn insert_scope(&mut self, name: Intern<str>, ast: Index) {
+        self.inner
+            .insert(Key::ScopeByIndex { ast }, Payload::Name(name));
+        self.inner
+            .insert(Key::ScopeByName { name }, Payload::Ast(ast));
+    }
+
+    pub fn find_symbol(&self, scope: Index, name: Intern<str>, loc: Span) -> Option<(Key, Index)> {
+        use SymbolKind::*;
+        let range = self.inner.range(
+            Key::Symbol {
+                scope,
+                name,
+                kind: __First,
+            }..=Key::Symbol {
+                scope,
+                name,
+                kind: Local(loc),
+            },
+        );
+
+        if let Some((&key, &Payload::Ast(index))) = range.rev().next() {
+            Some((key, index))
+        } else {
+            if let Some(&Payload::Ast(parent)) = self.inner.get(&Key::parent(scope)) {
+                self.find_symbol(parent, name, loc)
+            } else {
+                None
+            }
+        }
+    }
+
+    pub fn find_type_symbol(
+        &self,
+        scope: Index,
+        name: Intern<str>,
+        loc: Span,
+    ) -> Option<(Key, Index)> {
+        use SymbolKind::*;
+        let range = self.inner.range(
+            Key::Symbol {
+                scope,
+                name,
+                kind: __First,
+            }..=Key::Symbol {
+                scope,
+                name,
+                kind: __TypeScope,
+            },
+        );
+
+        if let Some((&key, &Payload::Ast(index))) = range.rev().next() {
+            Some((key, index))
+        } else {
+            if let Some(&Payload::Ast(parent)) = self.inner.get(&Key::parent(scope)) {
+                self.find_type_symbol(parent, name, loc)
+            } else {
+                None
+            }
+        }
+    }
+
+    pub fn insert_symbol(&mut self, scope: Index, name: Intern<str>, kind: SymbolKind, ast: Index) {
+        self.inner
+            .insert(Key::Symbol { scope, name, kind }, Payload::Ast(ast));
+    }
+}