Add typechecking for arrays

reid/examples/reid/array.reid

@@ -9,7 +9,7 @@ fn main() -> u16 {
 
     let mut list = array();
 
-    list[1] = 5;
+    // list[1] = 5;
 
     return list[0];
 }

reid/examples/testcodegen.rs

@@ -19,7 +19,7 @@ fn main() {
                                 ExprKind::BinOp(
                                     BinaryOperator::Cmp(CmpOperator::GT),
                                     Box::new(Expression(
-                                        ExprKind::Variable(VariableReference(
+                                        ExprKind::Variable(NamedVariableRef(
                                             TypeKind::I32,
                                             "N".to_string(),
                                             Default::default(),
@@ -52,7 +52,7 @@ fn main() {
                                                             BinaryOperator::Minus,
                                                             Box::new(Expression(
                                                                 ExprKind::Variable(
-                                                                    VariableReference(
+                                                                    NamedVariableRef(
                                                                         TypeKind::I32,
                                                                         fibonacci_n.clone(),
                                                                         Default::default(),
@@ -80,7 +80,7 @@ fn main() {
                                                             BinaryOperator::Minus,
                                                             Box::new(Expression(
                                                                 ExprKind::Variable(
-                                                                    VariableReference(
+                                                                    NamedVariableRef(
                                                                         TypeKind::I32,
                                                                         fibonacci_n.clone(),
                                                                         Default::default(),

reid/src/ast/mod.rs

@@ -133,8 +133,11 @@ pub struct Block(
 );
 
 #[derive(Debug, Clone)]
-pub enum VariableReference {
-    Name(String),
+pub struct VariableReference(pub VariableReferenceKind, pub TokenRange);
+
+#[derive(Debug, Clone)]
+pub enum VariableReferenceKind {
+    Name(String, TokenRange),
     Index(Box<VariableReference>, u64),
 }
 

reid/src/ast/parse.rs

@@ -350,7 +350,7 @@ impl Parse for Block {
         stream.expect(Token::BraceOpen)?;
 
         while !matches!(stream.peek(), Some(Token::BraceClose)) {
-            if let Some((r_type, e)) = return_stmt.take() {
+            if let Some((_, e)) = return_stmt.take() {
                 // Special list of expressions that are simply not warned about,
                 // if semicolon is missing.
                 if !matches!(e, Expression(ExpressionKind::IfExpr(_), _)) {
@@ -383,12 +383,18 @@ impl Parse for Block {
 impl Parse for VariableReference {
     fn parse(mut stream: TokenStream) -> Result<Self, Error> {
         if let Some(Token::Identifier(ident)) = stream.next() {
-            let mut var_ref = VariableReference::Name(ident);
+            let mut var_ref = VariableReference(
+                VariableReferenceKind::Name(ident, stream.get_one_token_range()),
+                stream.get_range().unwrap(),
+            );
 
             dbg!(&var_ref);
             while let Ok(ValueIndex(idx)) = stream.parse() {
                 dbg!(idx);
-                var_ref = VariableReference::Index(Box::new(var_ref), idx);
+                var_ref = VariableReference(
+                    VariableReferenceKind::Index(Box::new(var_ref), idx),
+                    stream.get_range().unwrap(),
+                );
             }
 
             Ok(var_ref)

reid/src/ast/process.rs

@@ -1,6 +1,6 @@
 use crate::{
     ast::{self},
-    mir::{self, StmtKind, VariableReference},
+    mir::{self, NamedVariableRef, StmtKind},
 };
 
 impl mir::Context {
@@ -61,7 +61,7 @@ impl ast::Block {
             let (kind, range) = match statement {
                 ast::BlockLevelStatement::Let(s_let) => (
                     mir::StmtKind::Let(
-                        mir::VariableReference(
+                        mir::NamedVariableRef(
                             s_let
                                 .1
                                 .clone()
@@ -75,15 +75,8 @@ impl ast::Block {
                     ),
                     s_let.4,
                 ),
-                ast::BlockLevelStatement::Set(name, expression, range) => (
-                    StmtKind::Set(
-                        VariableReference(
-                            mir::TypeKind::Vague(mir::VagueType::Unknown),
-                            todo!(), // was name.clone()
-                            (*range).into(),
-                        ),
-                        expression.process(),
-                    ),
+                ast::BlockLevelStatement::Set(var_ref, expression, range) => (
+                    StmtKind::Set(var_ref.process(), expression.process()),
                     *range,
                 ),
                 ast::BlockLevelStatement::Import { _i } => todo!(),
@@ -117,10 +110,36 @@ impl From<ast::ReturnType> for mir::ReturnKind {
     }
 }
 
+impl ast::VariableReference {
+    fn process(&self) -> mir::IndexedVariableReference {
+        mir::IndexedVariableReference {
+            kind: self.0.process(),
+            meta: self.1.into(),
+        }
+    }
+}
+
+impl ast::VariableReferenceKind {
+    fn process(&self) -> mir::IndexedVariableReferenceKind {
+        match &self {
+            ast::VariableReferenceKind::Name(name, range) => {
+                mir::IndexedVariableReferenceKind::Named(NamedVariableRef(
+                    mir::TypeKind::Vague(mir::VagueType::Unknown),
+                    name.clone(),
+                    (*range).into(),
+                ))
+            }
+            ast::VariableReferenceKind::Index(var_ref, idx) => {
+                mir::IndexedVariableReferenceKind::Index(Box::new(var_ref.process()), *idx)
+            }
+        }
+    }
+}
+
 impl ast::Expression {
     fn process(&self) -> mir::Expression {
         let kind = match &self.0 {
-            ast::ExpressionKind::VariableName(name) => mir::ExprKind::Variable(VariableReference(
+            ast::ExpressionKind::VariableName(name) => mir::ExprKind::Variable(NamedVariableRef(
                 mir::TypeKind::Vague(mir::VagueType::Unknown),
                 name.clone(),
                 self.1.into(),
@@ -149,8 +168,12 @@ impl ast::Expression {
                 };
                 mir::ExprKind::If(mir::IfExpression(Box::new(cond), then_block, else_block))
             }
-            ast::ExpressionKind::Array(expressions) => todo!(),
-            ast::ExpressionKind::Index(expression, _) => todo!(),
+            ast::ExpressionKind::Array(expressions) => {
+                mir::ExprKind::Array(expressions.iter().map(|e| e.process()).collect())
+            }
+            ast::ExpressionKind::Index(expression, idx) => {
+                mir::ExprKind::Index(Box::new(expression.process()), *idx)
+            }
         };
 
         mir::Expression(kind, self.1.into())
@@ -197,7 +220,9 @@ impl From<ast::TypeKind> for mir::TypeKind {
             ast::TypeKind::U32 => mir::TypeKind::U32,
             ast::TypeKind::U64 => mir::TypeKind::U64,
             ast::TypeKind::U128 => mir::TypeKind::U128,
-            ast::TypeKind::Array(type_kind, length) => todo!(),
+            ast::TypeKind::Array(type_kind, length) => {
+                mir::TypeKind::Array(Box::new(mir::TypeKind::from(*type_kind.clone())), *length)
+            }
         }
     }
 }

reid/src/codegen.rs

@@ -5,7 +5,7 @@ use reid_lib::{
     TerminatorKind as Term, Type,
 };
 
-use crate::mir::{self, types::ReturnType, TypeKind, VariableReference};
+use crate::mir::{self, types::ReturnType, NamedVariableRef, TypeKind};
 
 /// Context that contains all of the given modules as complete codegenerated
 /// LLIR that can then be finally compiled into LLVM IR.
@@ -156,7 +156,7 @@ impl<'ctx, 'a> Scope<'ctx, 'a> {
 impl mir::Statement {
     fn codegen<'ctx, 'a>(&self, scope: &mut Scope<'ctx, 'a>) -> Option<InstructionValue> {
         match &self.0 {
-            mir::StmtKind::Let(VariableReference(ty, name, _), mutable, expression) => {
+            mir::StmtKind::Let(NamedVariableRef(ty, name, _), mutable, expression) => {
                 let value = expression.codegen(scope).unwrap();
                 scope.stack_values.insert(
                     name.clone(),
@@ -178,19 +178,20 @@ impl mir::Statement {
                 None
             }
             mir::StmtKind::Set(var, val) => {
-                if let Some(StackValue(kind, _)) = scope.stack_values.get(&var.1).cloned() {
-                    match kind {
-                        StackValueKind::Immutable(_) => {
-                            panic!("Tried to mutate an immutable variable")
-                        }
-                        StackValueKind::Mutable(ptr) => {
-                            let expression = val.codegen(scope).unwrap();
-                            Some(scope.block.build(Instr::Store(ptr, expression)).unwrap())
-                        }
-                    }
-                } else {
-                    panic!("")
-                }
+                todo!("Re-think how set needs to work with arrays");
+                // if let Some(StackValue(kind, _)) = scope.stack_values.get(&var.1).cloned() {
+                //     match kind {
+                //         StackValueKind::Immutable(_) => {
+                //             panic!("Tried to mutate an immutable variable")
+                //         }
+                //         StackValueKind::Mutable(ptr) => {
+                //             let expression = val.codegen(scope).unwrap();
+                //             Some(scope.block.build(Instr::Store(ptr, expression)).unwrap())
+                //         }
+                //     }
+                // } else {
+                //     panic!("")
+                // }
             }
             // mir::StmtKind::If(if_expression) => if_expression.codegen(scope),
             mir::StmtKind::Import(_) => todo!(),
@@ -333,6 +334,8 @@ impl mir::Expression {
                     None
                 }
             }
+            mir::ExprKind::Index(expression, _) => todo!("codegen for index expression"),
+            mir::ExprKind::Array(expressions) => todo!("codegen for array expression"),
         }
     }
 }
@@ -413,6 +416,7 @@ impl TypeKind {
             TypeKind::Bool => Type::Bool,
             TypeKind::Void => panic!("Void not a supported type"),
             TypeKind::Vague(_) => panic!("Tried to compile a vague type!"),
+            TypeKind::Array(_, _) => todo!("codegen for array type"),
         }
     }
 }

reid/src/mir/display.rs

@@ -122,12 +122,33 @@ impl Display for Expression {
 impl Display for ExprKind {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Self::Variable(var) => Display::fmt(var, f),
-            Self::Literal(lit) => Display::fmt(lit, f),
-            Self::BinOp(op, lhs, rhs) => write!(f, "{} {} {}", lhs, op, rhs),
-            Self::FunctionCall(fc) => Display::fmt(fc, f),
-            Self::If(if_exp) => Display::fmt(&if_exp, f),
-            Self::Block(block) => Display::fmt(block, f),
+            ExprKind::Variable(var) => Display::fmt(var, f),
+            ExprKind::Literal(lit) => Display::fmt(lit, f),
+            ExprKind::BinOp(op, lhs, rhs) => write!(f, "{} {} {}", lhs, op, rhs),
+            ExprKind::FunctionCall(fc) => Display::fmt(fc, f),
+            ExprKind::If(if_exp) => Display::fmt(&if_exp, f),
+            ExprKind::Block(block) => Display::fmt(block, f),
+            ExprKind::Index(expression, idx) => {
+                Display::fmt(&expression, f)?;
+                write_index(f, *idx)
+            }
+            ExprKind::Array(expressions) => {
+                f.write_char('[')?;
+
+                let mut state = Default::default();
+                let mut inner_f = PadAdapter::wrap(f, &mut state);
+
+                let mut iter = expressions.iter();
+                if let Some(item) = iter.next() {
+                    write!(inner_f, "\n{}", item)?;
+                    while let Some(item) = iter.next() {
+                        writeln!(inner_f, ",")?;
+                        write!(inner_f, "{}", item)?;
+                    }
+                    writeln!(inner_f, "")?;
+                }
+                f.write_char(']')
+            }
         }
     }
 }
@@ -156,12 +177,24 @@ impl Display for FunctionCall {
     }
 }
 
-impl Display for VariableReference {
+impl Display for NamedVariableRef {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "v(\"{}\", {})", &self.1, &self.0)
     }
 }
 
+impl Display for IndexedVariableReference {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match &self.kind {
+            IndexedVariableReferenceKind::Named(name) => Display::fmt(name, f),
+            IndexedVariableReferenceKind::Index(variable_reference_kind, idx) => {
+                Display::fmt(&variable_reference_kind, f)?;
+                write_index(f, *idx)
+            }
+        }
+    }
+}
+
 impl Display for Literal {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
@@ -211,3 +244,9 @@ impl Display for Metadata {
         write!(f, "{:?}", self.range)
     }
 }
+
+fn write_index(f: &mut std::fmt::Formatter<'_>, idx: u64) -> std::fmt::Result {
+    f.write_char('[')?;
+    Display::fmt(&idx, f)?;
+    f.write_char(']')
+}

reid/src/mir/mod.rs

@@ -32,7 +32,7 @@ impl From<TokenRange> for Metadata {
     }
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, thiserror::Error)]
+#[derive(Debug, Clone, PartialEq, Eq, thiserror::Error)]
 pub enum TypeKind {
     #[error("bool")]
     Bool,
@@ -58,6 +58,8 @@ pub enum TypeKind {
     U128,
     #[error("void")]
     Void,
+    #[error("[{0}; {1}]")]
+    Array(Box<TypeKind>, u64),
     #[error(transparent)]
     Vague(#[from] VagueType),
 }
@@ -77,7 +79,7 @@ impl TypeKind {
         if let TypeKind::Vague(vague) = self {
             Err(*vague)
         } else {
-            Ok(*self)
+            Ok(self.clone())
         }
     }
 }
@@ -98,6 +100,7 @@ impl TypeKind {
             TypeKind::U32 => false,
             TypeKind::U64 => false,
             TypeKind::U128 => false,
+            TypeKind::Array(_, _) => false,
         }
     }
 
@@ -117,6 +120,7 @@ impl TypeKind {
             Bool => true,
             Vague(_) => false,
             Void => false,
+            Array(_, _) => false,
         }
     }
 }
@@ -196,14 +200,16 @@ pub enum ReturnKind {
 }
 
 #[derive(Debug)]
-pub struct VariableReference(pub TypeKind, pub String, pub Metadata);
+pub struct NamedVariableRef(pub TypeKind, pub String, pub Metadata);
 
 #[derive(Debug)]
 pub struct Import(pub String, pub Metadata);
 
 #[derive(Debug)]
 pub enum ExprKind {
-    Variable(VariableReference),
+    Variable(NamedVariableRef),
+    Index(Box<Expression>, u64),
+    Array(Vec<Expression>),
     Literal(Literal),
     BinOp(BinaryOperator, Box<Expression>, Box<Expression>),
     FunctionCall(FunctionCall),
@@ -267,11 +273,23 @@ pub struct Block {
 #[derive(Debug)]
 pub struct Statement(pub StmtKind, pub Metadata);
 
+#[derive(Debug)]
+pub struct IndexedVariableReference {
+    pub kind: IndexedVariableReferenceKind,
+    pub meta: Metadata,
+}
+
+#[derive(Debug)]
+pub enum IndexedVariableReferenceKind {
+    Named(NamedVariableRef),
+    Index(Box<IndexedVariableReference>, u64),
+}
+
 #[derive(Debug)]
 pub enum StmtKind {
     /// Variable name++mutability+type, evaluation
-    Let(VariableReference, bool, Expression),
-    Set(VariableReference, Expression),
+    Let(NamedVariableRef, bool, Expression),
+    Set(IndexedVariableReference, Expression),
     Import(Import),
     Expression(Expression),
 }

reid/src/mir/pass.rs

@@ -2,6 +2,7 @@
 //! passes. Passes can be performed on Reid MIR to e.g. typecheck the code.
 
 use std::collections::HashMap;
+use std::convert::Infallible;
 use std::error::Error as STDError;
 
 use super::*;
@@ -129,7 +130,7 @@ impl Scope {
         Scope {
             function_returns: self.function_returns.clone(),
             variables: self.variables.clone(),
-            return_type_hint: self.return_type_hint,
+            return_type_hint: self.return_type_hint.clone(),
         }
     }
 }
@@ -166,6 +167,16 @@ impl<'st, 'sc, TError: STDError + Clone> PassState<'st, 'sc, TError> {
         self.state.ok(result, meta)
     }
 
+    pub fn note_errors<TMeta: Into<Metadata> + Clone>(
+        &mut self,
+        errors: &Vec<TError>,
+        meta: TMeta,
+    ) {
+        for error in errors {
+            self.ok::<_, Infallible>(Err(error.clone()), meta.clone().into());
+        }
+    }
+
     pub fn inner(&mut self) -> PassState<TError> {
         self.inner.push(self.scope.inner());
         let scope = self.inner.last_mut().unwrap();
@@ -211,8 +222,8 @@ impl Module {
                 .set(
                     function.name.clone(),
                     ScopeFunction {
-                        ret: function.return_type,
-                        params: function.parameters.iter().map(|v| v.1).collect(),
+                        ret: function.return_type.clone(),
+                        params: function.parameters.iter().cloned().map(|v| v.1).collect(),
                     },
                 )
                 .ok();
@@ -234,7 +245,7 @@ impl FunctionDefinition {
                 .set(
                     param.0.clone(),
                     ScopeVariable {
-                        ty: param.1,
+                        ty: param.1.clone(),
                         mutable: false,
                     },
                 )
@@ -245,7 +256,7 @@ impl FunctionDefinition {
 
         match &mut self.kind {
             FunctionDefinitionKind::Local(block, _) => {
-                scope.return_type_hint = Some(self.return_type);
+                scope.return_type_hint = Some(self.return_type.clone());
                 block.pass(pass, state, scope);
             }
             FunctionDefinitionKind::Extern => {}
@@ -289,7 +300,7 @@ impl Statement {
                     .set(
                         variable_reference.1.clone(),
                         ScopeVariable {
-                            ty: variable_reference.0,
+                            ty: variable_reference.0.clone(),
                             mutable: *mutable,
                         },
                     )

reid/src/mir/typecheck.rs

@@ -40,6 +40,10 @@ pub enum ErrorKind {
     TypeNotInferrable(TypeKind),
     #[error("Expected branch type to be {0}, found {1} instead")]
     BranchTypesDiffer(TypeKind, TypeKind),
+    #[error("Attempted to index a non-array type of {0}")]
+    TriedIndexingNonArray(TypeKind),
+    #[error("Index {0} out of bounds ({1})")]
+    IndexOutOfBounds(u64, u64),
 }
 
 /// Struct used to implement a type-checking pass that can be performed on the
@@ -84,8 +88,8 @@ impl FunctionDefinition {
         let return_type = self.return_type.clone();
         let inferred = match &mut self.kind {
             FunctionDefinitionKind::Local(block, _) => {
-                state.scope.return_type_hint = Some(self.return_type);
-                block.typecheck(state, &hints, Some(return_type))
+                state.scope.return_type_hint = Some(self.return_type.clone());
+                block.typecheck(state, &hints, Some(&return_type))
             }
             FunctionDefinitionKind::Extern => Ok(Vague(Unknown)),
         };
@@ -104,7 +108,7 @@ impl Block {
         &mut self,
         state: &mut PassState<ErrorKind>,
         hints: &TypeRefs,
-        hint_t: Option<TypeKind>,
+        hint_t: Option<&TypeKind>,
     ) -> Result<TypeKind, ErrorKind> {
         let mut state = state.inner();
 
@@ -117,7 +121,7 @@ impl Block {
                     let var_t_resolved = variable_reference.0.resolve_hinted(&hints);
 
                     // Typecheck (and coerce) expression with said type
-                    let res = expression.typecheck(&mut state, &hints, Some(var_t_resolved));
+                    let res = expression.typecheck(&mut state, &hints, Some(&var_t_resolved));
 
                     // If expression resolution itself was erronous, resolve as
                     // Unknown and note error.
@@ -136,7 +140,7 @@ impl Block {
                             state.or_else(res_t.or_default(), Vague(Unknown), variable_reference.2);
 
                         // Re-typecheck and coerce expression to default type
-                        let expr_res = expression.typecheck(&mut state, &hints, Some(res_t));
+                        let expr_res = expression.typecheck(&mut state, &hints, Some(&res_t));
                         state.ok(expr_res, expression.1);
 
                         res_t
@@ -154,7 +158,7 @@ impl Block {
                         .set(
                             variable_reference.1.clone(),
                             ScopeVariable {
-                                ty: variable_reference.0,
+                                ty: variable_reference.0.clone(),
                                 mutable: *mutable,
                             },
                         )
@@ -165,40 +169,41 @@ impl Block {
                     None
                 }
                 StmtKind::Set(variable_reference, expression) => {
-                    if let Some(var) = state.scope.variables.get(&variable_reference.1).cloned() {
-                        // Typecheck expression and coerce to variable type
-                        let res = expression.typecheck(&mut state, &hints, Some(var.ty));
+                    todo!("Re-think how set needs to work with arrays")
+                    // if let Some(var) = state.scope.variables.get(&variable_reference.1).cloned() {
+                    //     // Typecheck expression and coerce to variable type
+                    //     let res = expression.typecheck(&mut state, &hints, Some(&var.ty));
 
-                        // If expression resolution itself was erronous, resolve as
-                        // Unknown.
-                        let expr_ty = state.or_else(res, Vague(Unknown), expression.1);
+                    //     // If expression resolution itself was erronous, resolve as
+                    //     // Unknown.
+                    //     let expr_ty = state.or_else(res, Vague(Unknown), expression.1);
 
-                        // Make sure the expression and variable type to really
-                        // be the same
-                        let res_t = state.or_else(
-                            expr_ty.collapse_into(&variable_reference.0.resolve_hinted(&hints)),
-                            Vague(Unknown),
-                            variable_reference.2 + expression.1,
-                        );
+                    //     // Make sure the expression and variable type to really
+                    //     // be the same
+                    //     let res_t = state.or_else(
+                    //         expr_ty.collapse_into(&variable_reference.0.resolve_hinted(&hints)),
+                    //         Vague(Unknown),
+                    //         variable_reference.2 + expression.1,
+                    //     );
 
-                        // Update typing to be more accurate
-                        variable_reference.0 = res_t;
+                    //     // Update typing to be more accurate
+                    //     variable_reference.0 = res_t;
 
-                        if !var.mutable {
-                            state.ok::<_, Infallible>(
-                                Err(ErrorKind::VariableNotMutable(variable_reference.1.clone())),
-                                variable_reference.2,
-                            );
-                        }
+                    //     if !var.mutable {
+                    //         state.ok::<_, Infallible>(
+                    //             Err(ErrorKind::VariableNotMutable(variable_reference.1.clone())),
+                    //             variable_reference.2,
+                    //         );
+                    //     }
 
-                        None
-                    } else {
-                        state.ok::<_, Infallible>(
-                            Err(ErrorKind::VariableNotDefined(variable_reference.1.clone())),
-                            variable_reference.2,
-                        );
-                        None
-                    }
+                    //     None
+                    // } else {
+                    //     state.ok::<_, Infallible>(
+                    //         Err(ErrorKind::VariableNotDefined(variable_reference.1.clone())),
+                    //         variable_reference.2,
+                    //     );
+                    //     None
+                    // }
                 }
                 StmtKind::Import(_) => todo!(), // TODO
                 StmtKind::Expression(expression) => {
@@ -221,18 +226,18 @@ impl Block {
         // as to not cause problems in codegen later (when unable to delete the
         // block)
         if let Some((ReturnKind::Hard, expr)) = early_return {
-            let hint = state.scope.return_type_hint;
-            let res = expr.typecheck(&mut state, &hints, hint);
+            let hint = state.scope.return_type_hint.clone();
+            let res = expr.typecheck(&mut state, &hints, hint.as_ref());
             return Ok(state.or_else(res, Vague(Unknown), expr.1));
         }
 
         if let Some((return_kind, expr)) = &mut self.return_expression {
             // Use function return type as hint if return is hard.
             let ret_hint_t = match return_kind {
-                ReturnKind::Hard => state.scope.return_type_hint,
-                ReturnKind::Soft => hint_t,
+                ReturnKind::Hard => state.scope.return_type_hint.clone(),
+                ReturnKind::Soft => hint_t.cloned(),
             };
-            let res = expr.typecheck(&mut state, &hints, ret_hint_t);
+            let res = expr.typecheck(&mut state, &hints, ret_hint_t.as_ref());
             Ok(state.or_else(res, Vague(Unknown), expr.1))
         } else {
             Ok(Void)
@@ -245,7 +250,7 @@ impl Expression {
         &mut self,
         state: &mut PassState<ErrorKind>,
         hints: &TypeRefs,
-        hint_t: Option<TypeKind>,
+        hint_t: Option<&TypeKind>,
     ) -> Result<TypeKind, ErrorKind> {
         match &mut self.0 {
             ExprKind::Variable(var_ref) => {
@@ -268,10 +273,10 @@ impl Expression {
                     var_ref.2,
                 );
 
-                Ok(var_ref.0)
+                Ok(var_ref.0.clone())
             }
             ExprKind::Literal(literal) => {
-                *literal = literal.try_coerce(hint_t)?;
+                *literal = literal.try_coerce(hint_t.cloned())?;
                 Ok(literal.as_type())
             }
             ExprKind::BinOp(op, lhs, rhs) => {
@@ -279,13 +284,13 @@ impl Expression {
                 // operation once relevant
                 let lhs_res = lhs.typecheck(state, &hints, None);
                 let lhs_type = state.or_else(lhs_res, Vague(Unknown), lhs.1);
-                let rhs_res = rhs.typecheck(state, &hints, Some(lhs_type));
+                let rhs_res = rhs.typecheck(state, &hints, Some(&lhs_type));
                 let rhs_type = state.or_else(rhs_res, Vague(Unknown), rhs.1);
 
                 if let Some(collapsed) = state.ok(rhs_type.collapse_into(&rhs_type), self.1) {
                     // Try to coerce both sides again with collapsed type
-                    lhs.typecheck(state, &hints, Some(collapsed)).ok();
-                    rhs.typecheck(state, &hints, Some(collapsed)).ok();
+                    lhs.typecheck(state, &hints, Some(&collapsed)).ok();
+                    rhs.typecheck(state, &hints, Some(&collapsed)).ok();
                 }
 
                 let both_t = lhs_type.collapse_into(&rhs_type)?;
@@ -322,7 +327,7 @@ impl Expression {
                         function_call.parameters.iter_mut().zip(true_params_iter)
                     {
                         // Typecheck every param separately
-                        let param_res = param.typecheck(state, &hints, Some(true_param_t));
+                        let param_res = param.typecheck(state, &hints, Some(&true_param_t));
                         let param_t = state.or_else(param_res, Vague(Unknown), param.1);
                         state.ok(param_t.collapse_into(&true_param_t), param.1);
                     }
@@ -333,14 +338,14 @@ impl Expression {
                         .ret
                         .collapse_into(&function_call.return_type.resolve_hinted(hints))?;
                     // Update typing to be more accurate
-                    function_call.return_type = ret_t;
+                    function_call.return_type = ret_t.clone();
                     Ok(ret_t)
                 } else {
-                    Ok(function_call.return_type)
+                    Ok(function_call.return_type.clone())
                 }
             }
             ExprKind::If(IfExpression(cond, lhs, rhs)) => {
-                let cond_res = cond.typecheck(state, &hints, Some(Bool));
+                let cond_res = cond.typecheck(state, &hints, Some(&Bool));
                 let cond_t = state.or_else(cond_res, Vague(Unknown), cond.1);
                 state.ok(cond_t.collapse_into(&Bool), cond.1);
 
@@ -364,8 +369,8 @@ impl Expression {
                 if let Some(rhs) = rhs {
                     // If rhs existed, typecheck both sides to perform type
                     // coercion.
-                    let lhs_res = lhs.typecheck(state, &hints, Some(collapsed));
-                    let rhs_res = rhs.typecheck(state, &hints, Some(collapsed));
+                    let lhs_res = lhs.typecheck(state, &hints, Some(&collapsed));
+                    let rhs_res = rhs.typecheck(state, &hints, Some(&collapsed));
                     state.ok(lhs_res, lhs.meta);
                     state.ok(rhs_res, rhs.meta);
                 }
@@ -373,6 +378,42 @@ impl Expression {
                 Ok(collapsed)
             }
             ExprKind::Block(block) => block.typecheck(state, &hints, hint_t),
+            ExprKind::Index(expression, idx) => {
+                let expr_t = expression.typecheck(state, hints, hint_t)?;
+                if let TypeKind::Array(elem_t, len) = expr_t {
+                    if len >= *idx {
+                        return Err(ErrorKind::IndexOutOfBounds(*idx, len));
+                    }
+                    Ok(*elem_t)
+                } else {
+                    Err(ErrorKind::TriedIndexingNonArray(expr_t))
+                }
+            }
+            ExprKind::Array(expressions) => {
+                let mut expr_result = try_all(
+                    expressions
+                        .iter_mut()
+                        .map(|e| e.typecheck(state, hints, hint_t))
+                        .collect(),
+                );
+                match &mut expr_result {
+                    Ok(expr_types) => {
+                        let mut iter = expr_types.iter_mut();
+                        if let Some(first) = iter.next() {
+                            for other in iter {
+                                state.ok(first.collapse_into(other), self.1);
+                            }
+                            Ok(first.clone())
+                        } else {
+                            Ok(Array(Box::new(Void), 0))
+                        }
+                    }
+                    Err(errors) => {
+                        state.note_errors(errors, self.1);
+                        Ok(Array(Box::new(Vague(Unknown)), expressions.len() as u64))
+                    }
+                }
+            }
         }
     }
 }
@@ -381,7 +422,7 @@ impl Literal {
     /// Try to coerce this literal, ie. convert it to a more specific type in
     /// regards to the given hint if any.
     fn try_coerce(self, hint: Option<TypeKind>) -> Result<Self, ErrorKind> {
-        if let Some(hint) = hint {
+        if let Some(hint) = &hint {
             use Literal as L;
             use VagueLiteral as VagueL;
             Ok(match (self, hint) {
@@ -409,7 +450,7 @@ impl Literal {
                 (L::Vague(VagueL::Number(v)), U64) => L::U64(v as u64),
                 (L::Vague(VagueL::Number(v)), U128) => L::U128(v as u128),
                 (_, Vague(_)) => self,
-                _ => Err(ErrorKind::LiteralIncompatible(self, hint))?,
+                _ => Err(ErrorKind::LiteralIncompatible(self, hint.clone()))?,
             })
         } else {
             Ok(self)
@@ -428,19 +469,19 @@ impl TypeKind {
     /// Error if not.
     fn or_default(&self) -> Result<TypeKind, ErrorKind> {
         match self {
-            Vague(vague_type) => match vague_type {
+            Vague(vague_type) => match &vague_type {
                 Unknown => Err(ErrorKind::TypeIsVague(*vague_type)),
                 Number => Ok(TypeKind::I32),
                 TypeRef(_) => panic!("Hinted default!"),
             },
-            _ => Ok(*self),
+            _ => Ok(self.clone()),
         }
     }
 
     fn resolve_hinted(&self, hints: &TypeRefs) -> TypeKind {
         match self {
             Vague(TypeRef(idx)) => hints.retrieve_type(*idx).unwrap(),
-            _ => *self,
+            _ => self.clone(),
         }
     }
 }
@@ -461,11 +502,11 @@ impl Collapsable for TypeKind {
             (Vague(Number), other) | (other, Vague(Number)) => match other {
                 Vague(Unknown) => Ok(Vague(Number)),
                 Vague(Number) => Ok(Vague(Number)),
-                I8 | I16 | I32 | I64 | I128 | U8 | U16 | U32 | U64 | U128 => Ok(*other),
-                _ => Err(ErrorKind::TypesIncompatible(*self, *other)),
+                I8 | I16 | I32 | I64 | I128 | U8 | U16 | U32 | U64 | U128 => Ok(other.clone()),
+                _ => Err(ErrorKind::TypesIncompatible(self.clone(), other.clone())),
             },
             (Vague(Unknown), other) | (other, Vague(Unknown)) => Ok(other.clone()),
-            _ => Err(ErrorKind::TypesIncompatible(*self, *other)),
+            _ => Err(ErrorKind::TypesIncompatible(self.clone(), other.clone())),
         }
     }
 }

reid/src/mir/typeinference.rs

@@ -4,7 +4,9 @@
 //! must then be passed through TypeCheck with the same [`TypeRefs`] in order to
 //! place the correct types from the IDs and check that there are no issues.
 
-use std::iter;
+use std::{convert::Infallible, iter};
+
+use crate::{mir::TypeKind, util::try_all};
 
 use super::{
     pass::{Pass, PassState, ScopeVariable},
@@ -59,7 +61,7 @@ impl FunctionDefinition {
 
         match &mut self.kind {
             FunctionDefinitionKind::Local(block, _) => {
-                state.scope.return_type_hint = Some(self.return_type);
+                state.scope.return_type_hint = Some(self.return_type.clone());
                 let scope_hints = ScopeTypeRefs::from(type_refs);
 
                 // Infer block return type
@@ -91,7 +93,7 @@ impl Block {
                 StmtKind::Let(var, mutable, expr) => {
                     // Get the TypeRef for this variable declaration
                     let mut var_ref =
-                        state.ok(inner_hints.new_var(var.1.clone(), *mutable, var.0), var.2);
+                        state.ok(inner_hints.new_var(var.1.clone(), *mutable, &var.0), var.2);
 
                     // If ok, update the MIR type to this TypeRef
                     if let Some(var_ref) = &var_ref {
@@ -111,23 +113,24 @@ impl Block {
                     }
                 }
                 StmtKind::Set(var, expr) => {
-                    // Get the TypeRef for this variable declaration
-                    let var_ref = inner_hints.find_hint(&var.1);
+                    todo!("Re-think how set needs to work with arrays")
+                    // // Get the TypeRef for this variable declaration
+                    // let var_ref = inner_hints.find_hint(&var.1);
 
-                    // If ok, update the MIR type to this TypeRef
-                    if let Some((_, var_ref)) = &var_ref {
-                        var.0 = var_ref.as_type()
-                    }
+                    // // If ok, update the MIR type to this TypeRef
+                    // if let Some((_, var_ref)) = &var_ref {
+                    //     var.0 = var_ref.as_type()
+                    // }
 
-                    // Infer hints for the expression itself
-                    let inferred = expr.infer_types(&mut state, &inner_hints);
-                    let expr_ty_ref = state.ok(inferred, expr.1);
+                    // // Infer hints for the expression itself
+                    // let inferred = expr.infer_types(&mut state, &inner_hints);
+                    // let expr_ty_ref = state.ok(inferred, expr.1);
 
-                    // Try to narrow the variable type declaration with the
-                    // expression
-                    if let (Some((_, mut var_ref)), Some(expr_ty_ref)) = (var_ref, expr_ty_ref) {
-                        var_ref.narrow(&expr_ty_ref);
-                    }
+                    // // Try to narrow the variable type declaration with the
+                    // // expression
+                    // if let (Some((_, mut var_ref)), Some(expr_ty_ref)) = (var_ref, expr_ty_ref) {
+                    //     var_ref.narrow(&expr_ty_ref);
+                    // }
                 }
                 StmtKind::Import(_) => todo!(),
                 StmtKind::Expression(expr) => {
@@ -149,7 +152,7 @@ impl Block {
 
         // Narow return type to declared type if hard return
         if kind == ReturnKind::Hard {
-            if let Some(hint) = state.scope.return_type_hint {
+            if let Some(hint) = &state.scope.return_type_hint {
                 ret_type_ref.narrow(&mut outer_hints.from_type(&hint).unwrap());
             }
         }
@@ -260,6 +263,52 @@ impl Expression {
                     ReturnKind::Soft => Ok(block_ref.1),
                 }
             }
+            ExprKind::Index(expression, _) => {
+                let expr_ty = expression.infer_types(state, type_refs)?;
+                let kind = unsafe { expr_ty.resolve_type() };
+                match kind {
+                    Array(type_kind, _) => Ok(type_refs.from_type(&type_kind).unwrap()),
+                    _ => Err(ErrorKind::TriedIndexingNonArray(kind)),
+                }
+            }
+            ExprKind::Array(expressions) => {
+                let mut expr_types_result = try_all(
+                    expressions
+                        .iter_mut()
+                        .map(|e| (*e).infer_types(state, type_refs))
+                        .collect(),
+                );
+                match &mut expr_types_result {
+                    Ok(expr_types) => {
+                        let mut iter = expr_types.iter_mut();
+                        if let Some(first) = iter.next() {
+                            while let Some(other) = iter.next() {
+                                first.narrow(other);
+                            }
+
+                            Ok(type_refs
+                                .from_type(&Array(
+                                    Box::new(first.as_type()),
+                                    expressions.len() as u64,
+                                ))
+                                .unwrap())
+                        } else {
+                            Ok(type_refs
+                                .from_type(&Array(Box::new(TypeKind::Void), 0))
+                                .unwrap())
+                        }
+                    }
+                    Err(errors) => {
+                        state.note_errors(errors, self.1);
+                        Ok(type_refs
+                            .from_type(&TypeKind::Array(
+                                Box::new(TypeKind::Vague(Unknown)),
+                                expressions.len() as u64,
+                            ))
+                            .unwrap())
+                    }
+                }
+            }
         }
     }
 }

reid/src/mir/typerefs.rs

@@ -14,7 +14,14 @@ pub struct TypeRef<'scope>(TypeIdRef, &'scope ScopeTypeRefs<'scope>);
 
 impl<'scope> TypeRef<'scope> {
     pub unsafe fn resolve_type(&self) -> TypeKind {
-        unsafe { *self.1.types.hints.borrow().get_unchecked(*self.0.borrow()) }
+        unsafe {
+            self.1
+                .types
+                .hints
+                .borrow()
+                .get_unchecked(*self.0.borrow())
+                .clone()
+        }
     }
 
     pub fn narrow(&mut self, other: &TypeRef) -> Option<TypeRef<'scope>> {
@@ -46,15 +53,15 @@ pub struct TypeRefs {
 }
 
 impl TypeRefs {
-    pub fn new(&self, ty: TypeKind) -> TypeIdRef {
+    pub fn new(&self, ty: &TypeKind) -> TypeIdRef {
         let idx = self.hints.borrow().len();
         let typecell = Rc::new(RefCell::new(idx));
         self.type_refs.borrow_mut().push(typecell.clone());
-        self.hints.borrow_mut().push(ty);
+        self.hints.borrow_mut().push(ty.clone());
         typecell
     }
 
-    pub fn find(&self, ty: TypeKind) -> Option<TypeIdRef> {
+    pub fn find(&self, ty: &TypeKind) -> Option<TypeIdRef> {
         if ty.known().is_err() {
             // Only do this for non-vague types that can not be further narrowed
             // down.
@@ -66,7 +73,7 @@ impl TypeRefs {
             .borrow_mut()
             .iter()
             .enumerate()
-            .find(|(_, t)| **t == ty)
+            .find(|(_, t)| *t == ty)
             .map(|(i, _)| i)
         {
             Some(Rc::new(RefCell::new(idx)))
@@ -89,7 +96,7 @@ impl TypeRefs {
 
     pub fn retrieve_type(&self, idx: usize) -> Option<TypeKind> {
         let inner_idx = unsafe { *self.recurse_type_ref(idx).borrow() };
-        self.hints.borrow().get(inner_idx).copied()
+        self.hints.borrow().get(inner_idx).cloned()
     }
 }
 
@@ -114,7 +121,7 @@ impl<'outer> ScopeTypeRefs<'outer> {
         &'outer self,
         name: String,
         mutable: bool,
-        initial_ty: TypeKind,
+        initial_ty: &TypeKind,
     ) -> Result<TypeRef<'outer>, ErrorKind> {
         if self.variables.borrow().contains_key(&name) {
             return Err(ErrorKind::VariableAlreadyDefined(name));
@@ -132,12 +139,17 @@ impl<'outer> ScopeTypeRefs<'outer> {
                 let inner_idx = unsafe { *self.types.recurse_type_ref(*idx).borrow() };
                 self.types.type_refs.borrow().get(inner_idx).cloned()?
             }
-            TypeKind::Vague(_) => self.types.new(*ty),
+            TypeKind::Vague(_) => self.types.new(ty),
+            TypeKind::Array(elem_ty, length) => {
+                let elem_ty = self.from_type(elem_ty)?;
+                self.types
+                    .new(&TypeKind::Array(Box::new(elem_ty.as_type()), *length))
+            }
             _ => {
-                if let Some(ty_ref) = self.types.find(*ty) {
+                if let Some(ty_ref) = self.types.find(ty) {
                     ty_ref
                 } else {
-                    self.types.new(*ty)
+                    self.types.new(ty)
                 }
             }
         };

reid/src/mir/types.rs

@@ -1,3 +1,5 @@
+use crate::ast::VariableReference;
+
 use super::*;
 
 #[derive(Debug, Clone)]
@@ -7,6 +9,7 @@ pub enum ReturnTypeOther {
     Set(Metadata),
     EmptyBlock(Metadata),
     NoBlockReturn(Metadata),
+    IndexingNonArray(Metadata),
 }
 
 impl TypeKind {
@@ -15,10 +18,11 @@ impl TypeKind {
     pub fn binop_type(&self, op: &BinaryOperator) -> TypeKind {
         // TODO make some type of mechanism that allows to binop two values of
         // differing types..
+        // TODO Return None for arrays later
         match op {
-            BinaryOperator::Add => *self,
-            BinaryOperator::Minus => *self,
-            BinaryOperator::Mult => *self,
+            BinaryOperator::Add => self.clone(),
+            BinaryOperator::Minus => self.clone(),
+            BinaryOperator::Mult => self.clone(),
             BinaryOperator::And => TypeKind::Bool,
             BinaryOperator::Cmp(_) => TypeKind::Bool,
         }
@@ -62,7 +66,7 @@ impl ReturnType for Statement {
             ),
             Set(var, expr) => if_hard(
                 expr.return_type()?,
-                Err(ReturnTypeOther::Set(var.2 + expr.1)),
+                Err(ReturnTypeOther::Set(var.meta + expr.1)),
             ),
             Import(_) => todo!(),
             Expression(expression) => expression.return_type(),
@@ -85,6 +89,25 @@ impl ReturnType for Expression {
             Block(block) => block.return_type(),
             FunctionCall(fcall) => fcall.return_type(),
             If(expr) => expr.return_type(),
+            Index(expression, _) => {
+                let expr_type = expression.return_type()?;
+                if let (_, TypeKind::Array(elem_ty, _)) = expr_type {
+                    Ok((ReturnKind::Soft, *elem_ty))
+                } else {
+                    Err(ReturnTypeOther::IndexingNonArray(expression.1))
+                }
+            }
+            Array(expressions) => {
+                let first = expressions
+                    .iter()
+                    .next()
+                    .map(|e| e.return_type())
+                    .unwrap_or(Ok((ReturnKind::Soft, TypeKind::Void)))?;
+                Ok((
+                    ReturnKind::Soft,
+                    TypeKind::Array(Box::new(first.1), expressions.len() as u64),
+                ))
+            }
         }
     }
 }
@@ -107,7 +130,7 @@ impl ReturnType for IfExpression {
     }
 }
 
-impl ReturnType for VariableReference {
+impl ReturnType for NamedVariableRef {
     fn return_type(&self) -> Result<(ReturnKind, TypeKind), ReturnTypeOther> {
         Ok((ReturnKind::Soft, self.0.clone()))
     }

reid/src/token_stream.rs

@@ -153,6 +153,13 @@ impl<'a, 'b> TokenStream<'a, 'b> {
             end: self.position,
         })
     }
+
+    pub fn get_one_token_range(&self) -> TokenRange {
+        TokenRange {
+            start: self.position - 1,
+            end: self.position,
+        }
+    }
 }
 
 impl Drop for TokenStream<'_, '_> {