Semantic analysis of generic args and params.

dmc-lib/src/ast/assign_statement.rs

@@ -22,6 +22,10 @@ impl AssignStatement {
         }
     }
 
+    pub fn destination(&self) -> &Expression {
+        &self.destination
+    }
+
     pub fn gather_declared_names(
         &mut self,
         symbol_table: &mut SymbolTable,

dmc-lib/src/ast/class.rs

@@ -1,22 +1,30 @@
 use crate::ast::constructor::Constructor;
+use crate::ast::expression::Expression;
 use crate::ast::field::Field;
 use crate::ast::fqn_context::FqnContext;
 use crate::ast::fqn_util::fqn_parts_to_string;
 use crate::ast::function::Function;
+use crate::ast::generic_parameter::GenericParameter;
+use crate::ast::statement::Statement;
 use crate::diagnostic::{Diagnostic, SecondaryLabel};
 use crate::ir::ir_class::{IrClass, IrField};
 use crate::ir::ir_function::IrFunction;
+use crate::maybe_return_diagnostics;
 use crate::source_range::SourceRange;
 use crate::symbol::Symbol;
 use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol::field_symbol::FieldSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
 use crate::symbol_table::{SymbolInsertError, SymbolTable};
 use std::cell::RefCell;
-use std::collections::HashSet;
+use std::collections::{HashMap, HashSet};
+use std::process::id;
 use std::rc::Rc;
 
 pub struct Class {
     declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
+    generic_parameters: Vec<GenericParameter>,
     constructor: Option<Constructor>,
     fields: Vec<Field>,
     functions: Vec<Function>,
@@ -27,6 +35,7 @@ impl Class {
     pub fn new(
         declared_name: &str,
         declared_name_source_range: SourceRange,
+        generic_parameters: Vec<GenericParameter>,
         constructor: Option<Constructor>,
         fields: Vec<Field>,
         functions: Vec<Function>,
@@ -34,6 +43,7 @@ impl Class {
         Class {
             declared_name: declared_name.into(),
             declared_name_source_range,
+            generic_parameters,
             constructor,
             fields,
             functions,
@@ -87,18 +97,51 @@ impl Class {
         // 2. push scope
         symbol_table.push_class_scope(&format!("class_scope({})", self.declared_name));
 
-        // 3. gather fields
+        // 3a. gather generic parameters
-        let fields_diagnostics: Vec<Diagnostic> = self
+        let mut generic_parameter_symbols: Vec<Rc<RefCell<GenericParameterSymbol>>> = vec![];
-            .fields
+        let mut generic_parameter_diagnostics: Vec<Diagnostic> = vec![];
-            .iter_mut()
+        for generic_parameter in &mut self.generic_parameters {
-            .enumerate()
+            match generic_parameter.gather_declared_names(symbol_table) {
-            .map(|(field_index, field)| field.gather_declared_names(symbol_table, field_index))
+                Ok(generic_parameter_symbol) => {
-            .filter_map(Result::err)
+                    generic_parameter_symbols.push(generic_parameter_symbol);
-            .flatten()
+                }
-            .collect();
+                Err(mut d) => {
+                    generic_parameter_diagnostics.append(&mut d);
+                }
+            }
+        }
+
+        maybe_return_diagnostics!(generic_parameter_diagnostics);
+        // save generics to class symbol
+        self.class_symbol
+            .as_mut()
+            .unwrap()
+            .borrow_mut()
+            .set_generic_parameters(generic_parameter_symbols);
+
+        // 3b. gather fields
+        let mut field_symbols: HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>> = HashMap::new();
+        let mut fields_diagnostics: Vec<Diagnostic> = vec![];
+
+        for (index, field) in self.fields.iter_mut().enumerate() {
+            match field.gather_declared_names(symbol_table, index) {
+                Ok(field_symbol) => {
+                    field_symbols.insert(field.declared_name_owned(), field_symbol);
+                }
+                Err(mut d) => {
+                    fields_diagnostics.append(&mut d);
+                }
+            };
+        }
 
         if !fields_diagnostics.is_empty() {
             return Err(fields_diagnostics);
+        } else {
+            self.class_symbol
+                .as_mut()
+                .unwrap()
+                .borrow_mut()
+                .set_fields(field_symbols);
         }
 
         // 4. gather constructor
@@ -142,6 +185,17 @@ impl Class {
     }
 
     pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
+        let generics_diagnostics: Vec<Diagnostic> = self
+            .generic_parameters
+            .iter_mut()
+            .map(|generic_parameter| {
+                generic_parameter.check_name_usages(symbol_table, self.class_symbol.as_ref())
+            })
+            .filter_map(Result::err)
+            .flatten()
+            .collect();
+        maybe_return_diagnostics!(generics_diagnostics);
+
         self.constructor
             .as_mut()
             .map(|constructor| {
@@ -233,9 +287,22 @@ impl Class {
         if let Some(constructor) = &self.constructor {
             for statement in constructor.statements() {
                 match statement {
-                    _ => {
+                    Statement::Assign(assign_statement) => match assign_statement.destination() {
-                        // no-op for now, because we don't yet have assign statements
+                        Expression::Identifier(identifier) => {
-                    }
+                            if self
+                                .class_symbol
+                                .as_ref()
+                                .unwrap()
+                                .borrow()
+                                .fields()
+                                .contains_key(identifier.name())
+                            {
+                                initialized_field_names.insert(identifier.name());
+                            }
+                        }
+                        _ => panic!("Found a non L Value assign lhs"),
+                    },
+                    _ => {}
                 }
             }
         }

dmc-lib/src/ast/field.rs

@@ -58,7 +58,7 @@ impl Field {
         &mut self,
         symbol_table: &mut SymbolTable,
         field_index: usize,
-    ) -> Result<(), Vec<Diagnostic>> {
+    ) -> Result<Rc<RefCell<FieldSymbol>>, Vec<Diagnostic>> {
         // 1. insert field symbol
         let to_insert = FieldSymbol::new(
             &self.declared_name,
@@ -82,6 +82,7 @@ impl Field {
             })?;
 
         // save for later
+        let to_return = field_symbol.clone();
         self.field_symbol = Some(field_symbol);
 
         // set field index on symbol
@@ -100,7 +101,7 @@ impl Field {
             initializer.gather_declared_names(symbol_table)?;
         }
 
-        Ok(())
+        Ok(to_return)
     }
 
     pub fn check_name_usages(

dmc-lib/src/ast/function.rs

@@ -5,6 +5,7 @@ use crate::ast::parameter::Parameter;
 use crate::ast::statement::Statement;
 use crate::ast::type_use::TypeUse;
 use crate::diagnostic::Diagnostic;
+use crate::handle_diagnostics;
 use crate::ir::ir_function::IrFunction;
 use crate::ir::ir_parameter::IrParameter;
 use crate::ir::ir_parameter_or_variable::IrParameterOrVariable;
@@ -109,7 +110,7 @@ impl Function {
                 Parameter::new(
                     "self",
                     SourceRange::new(0, 0),
-                    TypeUse::new("Self", SourceRange::new(0, 0)),
+                    TypeUse::new("Self", SourceRange::new(0, 0), vec![]),
                 ),
             );
         }
@@ -238,6 +239,11 @@ impl Function {
         let return_type_info = function_symbol.borrow().return_type_info().clone();
         let statements_len = self.statements.len();
 
+        // return type
+        if let Some(type_use) = &mut self.return_type {
+            handle_diagnostics!(type_use.type_check(symbol_table), diagnostics);
+        }
+
         // statements
         diagnostics.append(
             &mut self

dmc-lib/src/ast/generic_parameter.rs

@@ -0,0 +1,120 @@
+use crate::ast::type_use::TypeUse;
+use crate::diagnostic::{Diagnostic, SecondaryLabel};
+use crate::error_codes::SYMBOL_ALREADY_DECLARED;
+use crate::source_range::SourceRange;
+use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
+use crate::symbol_table::{SymbolInsertError, SymbolTable};
+use crate::{diagnostics_result, handle_diagnostics, maybe_return_diagnostics};
+use std::cell::RefCell;
+use std::rc::Rc;
+
+pub struct GenericParameter {
+    declared_name: Rc<str>,
+    declared_name_source_range: SourceRange,
+    extends: Vec<TypeUse>,
+    generic_parameter_symbol: Option<Rc<RefCell<GenericParameterSymbol>>>,
+}
+
+impl GenericParameter {
+    pub fn new(
+        declared_name: &str,
+        declared_name_source_range: SourceRange,
+        extends: Vec<TypeUse>,
+    ) -> Self {
+        Self {
+            declared_name: declared_name.into(),
+            declared_name_source_range,
+            extends,
+            generic_parameter_symbol: None,
+        }
+    }
+
+    pub fn gather_declared_names(
+        &mut self,
+        symbol_table: &mut SymbolTable,
+    ) -> Result<Rc<RefCell<GenericParameterSymbol>>, Vec<Diagnostic>> {
+        // insert symbol
+        let to_insert =
+            GenericParameterSymbol::new(&self.declared_name, &self.declared_name_source_range);
+        let to_return = match symbol_table.insert_generic_parameter_symbol(to_insert) {
+            Ok(generic_parameter_symbol) => generic_parameter_symbol,
+            Err(symbol_insert_error) => {
+                return match symbol_insert_error {
+                    SymbolInsertError::AlreadyDeclared(already_declared) => {
+                        let already_declared_symbol = already_declared.symbol().borrow();
+                        let already_declared_source_range =
+                            already_declared_symbol.declared_name_source_range();
+                        let diagnostic = Diagnostic::new(
+                            &format!("Symbol {} already declared in scope.", self.declared_name),
+                            self.declared_name_source_range.start(),
+                            self.declared_name_source_range.end(),
+                        )
+                        .with_reporter(file!(), line!())
+                        .with_error_code(SYMBOL_ALREADY_DECLARED)
+                        .with_secondary_labels(&[SecondaryLabel::new(
+                            already_declared_source_range.start(),
+                            already_declared_source_range.end(),
+                            Some("Symbol already declared here.".to_string()),
+                        )]);
+                        Err(vec![diagnostic])
+                    }
+                };
+            }
+        };
+
+        // save param symbol
+        self.generic_parameter_symbol = Some(to_return.clone());
+
+        let mut diagnostics: Vec<Diagnostic> = vec![];
+
+        for type_use in &mut self.extends {
+            handle_diagnostics!(type_use.gather_declared_names(symbol_table), diagnostics);
+        }
+
+        if diagnostics.is_empty() {
+            Ok(to_return)
+        } else {
+            Err(diagnostics)
+        }
+    }
+
+    pub fn check_name_usages(
+        &mut self,
+        symbol_table: &SymbolTable,
+        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
+    ) -> Result<(), Vec<Diagnostic>> {
+        let mut diagnostics: Vec<Diagnostic> = vec![];
+        // check the extends type uses
+        for type_use in &mut self.extends {
+            handle_diagnostics!(
+                type_use.check_name_usages(symbol_table, class_context),
+                diagnostics
+            );
+        }
+        maybe_return_diagnostics!(diagnostics);
+
+        // now that each extends type use has type info, set the type infos on the generic parameter
+        let extends_type_infos = self
+            .extends
+            .iter()
+            .map(|type_use| type_use.type_info().clone())
+            .collect::<Vec<_>>();
+        self.generic_parameter_symbol
+            .as_mut()
+            .unwrap()
+            .borrow_mut()
+            .set_extends(extends_type_infos);
+
+        Ok(())
+    }
+
+    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
+        let mut diagnostics: Vec<Diagnostic> = vec![];
+        // check extends type uses
+        for type_use in &mut self.extends {
+            handle_diagnostics!(type_use.type_check(symbol_table), diagnostics);
+        }
+        diagnostics_result!(diagnostics)
+    }
+}

dmc-lib/src/ast/mod.rs

@@ -13,6 +13,7 @@ pub mod fqn;
 pub mod fqn_context;
 pub mod fqn_util;
 pub mod function;
+pub mod generic_parameter;
 pub mod identifier;
 pub mod integer_literal;
 pub mod ir_builder;

dmc-lib/src/ast/parameter.rs

@@ -81,8 +81,9 @@ impl Parameter {
         Ok(())
     }
 
-    pub fn type_check(&mut self, _symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
+    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        Ok(()) // no-op for now
+        self.type_use.type_check(symbol_table)?;
+        Ok(())
     }
 
     pub fn parameter_symbol(&self) -> &Rc<RefCell<ParameterSymbol>> {

dmc-lib/src/ast/type_use.rs

@@ -1,23 +1,31 @@
 use crate::diagnostic::Diagnostic;
+use crate::error_codes::INCORRECT_GENERIC_ARGUMENTS;
 use crate::source_range::SourceRange;
 use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::{diagnostics_result, handle_diagnostics, maybe_return_diagnostics};
 use std::cell::RefCell;
 use std::rc::Rc;
 
 pub struct TypeUse {
     declared_name: String,
     declared_name_source_range: SourceRange,
+    generic_arguments: Vec<TypeUse>,
     scope_id: Option<usize>,
     type_info: Option<TypeInfo>,
 }
 
 impl TypeUse {
-    pub fn new(declared_name: &str, declared_name_source_range: SourceRange) -> Self {
+    pub fn new(
+        declared_name: &str,
+        declared_name_source_range: SourceRange,
+        generic_arguments: Vec<TypeUse>,
+    ) -> Self {
         Self {
             declared_name: declared_name.into(),
             declared_name_source_range,
+            generic_arguments,
             scope_id: None,
             type_info: None,
         }
@@ -32,7 +40,14 @@ impl TypeUse {
         symbol_table: &mut SymbolTable,
     ) -> Result<(), Vec<Diagnostic>> {
         self.scope_id = Some(symbol_table.current_scope_id());
-        Ok(())
+        let mut inner_diagnostics: Vec<Diagnostic> = vec![];
+        for generic_argument in &mut self.generic_arguments {
+            handle_diagnostics!(
+                generic_argument.gather_declared_names(symbol_table),
+                inner_diagnostics
+            );
+        }
+        diagnostics_result!(inner_diagnostics)
     }
 
     pub fn check_name_usages(
@@ -40,6 +55,8 @@ impl TypeUse {
         symbol_table: &SymbolTable,
         class_context: Option<&Rc<RefCell<ClassSymbol>>>,
     ) -> Result<(), Vec<Diagnostic>> {
+        let mut diagnostics: Vec<Diagnostic> = vec![];
+
         if let Some(type_info) = TypeInfo::from_declared_name(
             &self.declared_name,
             self.scope_id.unwrap(),
@@ -47,24 +64,114 @@ impl TypeUse {
             class_context,
         ) {
             self.type_info = Some(type_info);
-            Ok(())
         } else {
-            Err(vec![
+            let diagnostic = Diagnostic::new(
-                Diagnostic::new(
+                &format!("Unable to resolve symbol {}", self.declared_name),
-                    &format!("Unable to resolve symbol {}", self.declared_name),
+                self.declared_name_source_range.start(),
-                    self.declared_name_source_range.start(),
+                self.declared_name_source_range.end(),
-                    self.declared_name_source_range.end(),
+            )
-                )
+            .with_reporter(file!(), line!());
-                .with_reporter(file!(), line!()),
+            diagnostics.push(diagnostic);
-            ])
         }
+
+        for generic_argument in &mut self.generic_arguments {
+            handle_diagnostics!(
+                generic_argument.check_name_usages(symbol_table, class_context),
+                diagnostics
+            );
+        }
+
+        diagnostics_result!(diagnostics)
     }
 
     pub fn type_check(&mut self, _symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        Ok(()) // no-op, for now
+        let mut diagnostics: Vec<Diagnostic> = vec![];
+
+        match self.type_info() {
+            TypeInfo::ClassInstance(class_symbol) => {
+                // check number of params/args match
+                let borrowed_class_symbol = class_symbol.borrow();
+                let generic_parameters = borrowed_class_symbol.generic_parameters();
+                if generic_parameters.len() != self.generic_arguments.len() {
+                    let diagnostic = Diagnostic::new(
+                        &format!(
+                            "Expected {} generic arguments; found {}.",
+                            generic_parameters.len(),
+                            self.generic_arguments.len()
+                        ),
+                        self.declared_name_source_range.start(),
+                        self.declared_name_source_range.end(),
+                    )
+                    .with_reporter(file!(), line!())
+                    .with_error_code(INCORRECT_GENERIC_ARGUMENTS);
+                    diagnostics.push(diagnostic);
+                }
+
+                maybe_return_diagnostics!(diagnostics);
+
+                // check that each arg is assignable to the param's extends
+                for i in 0..self.generic_arguments.len() {
+                    let generic_parameter_symbol = generic_parameters[i].borrow();
+                    if generic_parameter_symbol.extends().len() > 0 {
+                        unimplemented!("Generic extends not implemented yet.")
+                    }
+                }
+            }
+            _ => {
+                // cannot extend a non-class type (except for Any)
+                if self.generic_arguments.len() > 0 {
+                    let diagnostic = Diagnostic::new(
+                        &format!(
+                            "Type {} does not accept generic arguments.",
+                            self.type_info()
+                        ),
+                        self.declared_name_source_range.start(),
+                        self.declared_name_source_range.end(),
+                    )
+                    .with_reporter(file!(), line!())
+                    .with_error_code(INCORRECT_GENERIC_ARGUMENTS);
+                    diagnostics.push(diagnostic);
+                }
+            }
+        }
+
+        // recurse on generic arguments
+        for generic_argument in &mut self.generic_arguments {
+            handle_diagnostics!(generic_argument.type_check(_symbol_table), diagnostics);
+        }
+
+        diagnostics_result!(diagnostics)
     }
 
     pub fn type_info(&self) -> &TypeInfo {
         self.type_info.as_ref().unwrap()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostic::Diagnostic;
+    use crate::parser::parse_compilation_unit;
+    use crate::symbol_table::SymbolTable;
+
+    #[test]
+    fn type_check_generics() -> Result<(), Vec<Diagnostic>> {
+        let mut compilation_unit = parse_compilation_unit(
+            "
+            class Foo<T>
+                ctor(t: T) end
+            end
+
+            fn useFoo(foo: Foo<String>) end
+            ",
+        )?;
+
+        let mut symbol_table = SymbolTable::new();
+
+        compilation_unit.gather_declared_names(&mut symbol_table)?;
+        compilation_unit.check_name_usages(&mut symbol_table)?;
+        compilation_unit.type_check(&mut symbol_table)?;
+
+        Ok(())
+    }
+}

dmc-lib/src/error_codes.rs

@@ -1,6 +1,9 @@
 pub type ErrorCode = usize;
 
+pub const SYMBOL_ALREADY_DECLARED: ErrorCode = 14;
 pub const BINARY_INCOMPATIBLE_TYPES: ErrorCode = 15;
 pub const ASSIGN_MISMATCHED_TYPES: ErrorCode = 16;
 pub const ASSIGN_NO_L_VALUE: ErrorCode = 17;
 pub const ASSIGN_LHS_IMMUTABLE: ErrorCode = 18;
+pub const INCORRECT_GENERIC_ARGUMENTS: ErrorCode = 19;
+pub const GENERIC_ARGUMENT_TYPE_MISMATCH: ErrorCode = 20;

dmc-lib/src/ir/ir_class.rs

@@ -54,6 +54,7 @@ impl IrField {
                 TypeInfo::ClassInstance(class_symbol) => VmTypeInfo::ClassInstance(
                     fqn_parts_to_string(class_symbol.borrow().fqn_parts()).into(),
                 ),
+                TypeInfo::GenericType(_) => VmTypeInfo::Any,
                 _ => panic!(),
             },
         )

dmc-lib/src/lexer.rs

@@ -54,10 +54,6 @@ impl<'a> Lexer<'a> {
             Token::new(self.position, self.position + 1, TokenKind::Modulo)
         } else if chunk.starts_with("+") {
             Token::new(self.position, self.position + 1, TokenKind::Plus)
-        } else if chunk.starts_with("<<") {
-            Token::new(self.position, self.position + 2, TokenKind::LeftShift)
-        } else if chunk.starts_with(">>") {
-            Token::new(self.position, self.position + 2, TokenKind::RightShift)
         } else if chunk.starts_with("&") {
             Token::new(self.position, self.position + 1, TokenKind::Ampersand)
         } else if chunk.starts_with("^") {
@@ -72,6 +68,14 @@ impl<'a> Lexer<'a> {
             Token::new(self.position, self.position + 1, TokenKind::Colon)
         } else if chunk.starts_with(".") {
             Token::new(self.position, self.position + 1, TokenKind::Dot)
+        } else if chunk.starts_with("[") {
+            Token::new(self.position, self.position + 1, TokenKind::LeftSquare)
+        } else if chunk.starts_with("]") {
+            Token::new(self.position, self.position + 1, TokenKind::RightSquare)
+        } else if chunk.starts_with("<") {
+            Token::new(self.position, self.position + 1, TokenKind::Lt)
+        } else if chunk.starts_with(">") {
+            Token::new(self.position, self.position + 1, TokenKind::Gt)
         } else {
             // more than one char token
             if chunk.starts_with(|c: char| c.is_ascii_digit()) {

dmc-lib/src/parser.rs

@@ -10,6 +10,7 @@ use crate::ast::expression_statement::ExpressionStatement;
 use crate::ast::extern_function::ExternFunction;
 use crate::ast::field::Field;
 use crate::ast::function::Function;
+use crate::ast::generic_parameter::GenericParameter;
 use crate::ast::identifier::Identifier;
 use crate::ast::integer_literal::IntegerLiteral;
 use crate::ast::let_statement::LetStatement;
@@ -56,6 +57,12 @@ macro_rules! matches_statement_first {
     };
 }
 
+macro_rules! matches_type_use_first {
+    ( $token_kind: expr ) => {
+        matches!($token_kind, TokenKind::LeftSquare | TokenKind::Identifier)
+    };
+}
+
 struct Parser<'a> {
     input: &'a str,
     lexer: Lexer<'a>,
@@ -163,6 +170,26 @@ impl<'a> Parser<'a> {
         }
     }
 
+    fn expect_position_advance(
+        &mut self,
+        token_kind: TokenKind,
+        start_position: usize,
+    ) -> Result<Token, Vec<Diagnostic>> {
+        let matched = self.expect_advance(token_kind)?;
+        if matched.start() == start_position {
+            Ok(matched)
+        } else {
+            Err(vec![
+                Diagnostic::new(
+                    &format!("Expected {:?} but found {:?}", token_kind, matched.kind()),
+                    matched.start(),
+                    matched.end(),
+                )
+                .with_reporter(file!(), line!()),
+            ])
+        }
+    }
+
     fn peek_current(&self, token_kind: TokenKind) -> bool {
         match &self.current {
             None => panic!("Unexpected end of input."),
@@ -387,6 +414,7 @@ impl<'a> Parser<'a> {
     fn class(&mut self) -> Result<Class, Vec<Diagnostic>> {
         self.expect_advance(TokenKind::Class)?;
         let identifier_token = self.expect_advance(TokenKind::Identifier)?;
+        let mut generic_parameters: Vec<GenericParameter> = vec![];
         let mut fields = vec![];
         let mut functions = vec![];
         let mut maybe_constructor: Option<Constructor> = None;
@@ -417,6 +445,14 @@ impl<'a> Parser<'a> {
                     }
                     Err(mut ctor_diagnostics) => diagnostics.append(&mut ctor_diagnostics),
                 },
+                TokenKind::Lt => match self.generic_parameters() {
+                    Ok(parsed_params) => {
+                        generic_parameters = parsed_params;
+                    }
+                    Err(mut generic_parameters_diagnostics) => {
+                        diagnostics.append(&mut generic_parameters_diagnostics);
+                    }
+                },
                 _ => unreachable!(),
             }
         }
@@ -427,6 +463,7 @@ impl<'a> Parser<'a> {
             Ok(Class::new(
                 self.token_text(&identifier_token),
                 SourceRange::new(identifier_token.start(), identifier_token.end()),
+                generic_parameters,
                 maybe_constructor,
                 fields,
                 functions,
@@ -477,10 +514,95 @@ impl<'a> Parser<'a> {
     }
 
     fn type_use(&mut self) -> Result<TypeUse, Vec<Diagnostic>> {
-        let identifier_token = self.expect_advance(TokenKind::Identifier)?;
+        if self.current.is_some() {
-        Ok(TypeUse::new(
+            let current = self.get_current();
-            self.token_text(&identifier_token),
+            return match current.kind() {
-            SourceRange::new(identifier_token.start(), identifier_token.end()),
+                TokenKind::LeftSquare => {
+                    self.advance(); // [
+                    let inner_type_use = self.type_use()?;
+                    self.expect_advance(TokenKind::RightSquare)?;
+                    todo!()
+                }
+                TokenKind::Identifier => {
+                    let identifier_token = self.expect_advance(TokenKind::Identifier)?;
+                    let generic_arguments =
+                        if self.current.is_some() && self.peek_current(TokenKind::Lt) {
+                            self.advance(); // <
+                            let generic_arguments = self.generic_arguments_list()?;
+                            self.expect_advance(TokenKind::Gt)?; // >
+                            generic_arguments
+                        } else {
+                            vec![]
+                        };
+                    Ok(TypeUse::new(
+                        self.token_text(&identifier_token),
+                        SourceRange::new(identifier_token.start(), identifier_token.end()),
+                        generic_arguments,
+                    ))
+                }
+                _ => Err(vec![Diagnostic::new(
+                    &format!(
+                        "Expected LeftSquare or Identifier; found: {:?}",
+                        current.kind()
+                    ),
+                    current.start(),
+                    current.end(),
+                )]),
+            };
+        }
+        Err(vec![Diagnostic::new(
+            "Expected LeftSquare or Identifier; found end of input.",
+            self.input.len(),
+            self.input.len(),
+        )])
+    }
+
+    fn generic_arguments_list(&mut self) -> Result<Vec<TypeUse>, Vec<Diagnostic>> {
+        let mut generic_arguments: Vec<TypeUse> = vec![];
+        while self.current.is_some() && matches_type_use_first!(self.get_current().kind()) {
+            generic_arguments.push(self.type_use()?);
+            if self.current.is_some() && self.peek_current(TokenKind::Comma) {
+                self.advance(); // comma
+            } else {
+                break;
+            }
+        }
+        Ok(generic_arguments)
+    }
+
+    fn generic_parameters(&mut self) -> Result<Vec<GenericParameter>, Vec<Diagnostic>> {
+        self.expect_advance(TokenKind::Lt)?;
+        let mut parameters: Vec<GenericParameter> = vec![];
+        while self.current.is_some() && self.peek_current(TokenKind::Identifier) {
+            parameters.push(self.generic_parameter()?);
+            if self.current.is_some() && self.peek_current(TokenKind::Plus) {
+                self.advance(); // +
+            } else {
+                break;
+            }
+        }
+        self.expect_advance(TokenKind::Gt)?;
+        Ok(parameters)
+    }
+
+    fn generic_parameter(&mut self) -> Result<GenericParameter, Vec<Diagnostic>> {
+        let identifier = self.expect_advance(TokenKind::Identifier)?;
+        let mut extends_list: Vec<TypeUse> = vec![];
+        if self.current.is_some() && self.peek_current(TokenKind::Colon) {
+            self.advance(); // :
+            while self.current.is_some() && matches_type_use_first!(self.get_current().kind()) {
+                extends_list.push(self.type_use()?);
+                if self.current.is_some() && self.peek_current(TokenKind::Comma) {
+                    self.advance(); // ,
+                } else {
+                    break;
+                }
+            }
+        }
+        Ok(GenericParameter::new(
+            self.token_text(&identifier),
+            SourceRange::new(identifier.start(), identifier.end()),
+            extends_list,
         ))
     }
 
@@ -721,8 +843,10 @@ impl<'a> Parser<'a> {
         while self.current.is_some() {
             let current = self.get_current();
             match current.kind() {
-                TokenKind::LeftShift => {
+                TokenKind::Lt => {
-                    self.advance(); // left shift
+                    let second_lt_start = current.start() + 1;
+                    self.advance(); // first <
+                    self.expect_position_advance(TokenKind::Lt, second_lt_start)?; // second <
                     let rhs = self.additive_expression()?;
                     let source_range =
                         SourceRange::new(result.source_range().start(), rhs.source_range().end());
@@ -733,8 +857,10 @@ impl<'a> Parser<'a> {
                         source_range,
                     ));
                 }
-                TokenKind::RightShift => {
+                TokenKind::Gt => {
-                    self.advance(); // right shift
+                    let second_gt_start = current.start() + 1;
+                    self.advance(); // first >
+                    self.expect_position_advance(TokenKind::Gt, second_gt_start)?; // second gt
                     let rhs = self.additive_expression()?;
                     let source_range =
                         SourceRange::new(result.source_range().start(), rhs.source_range().end());
@@ -1144,6 +1270,21 @@ mod smoke_tests {
             ",
         )
     }
+
+    #[test]
+    fn array_generic_arg() {
+        smoke_test("fn main(args: Array<String>) end");
+    }
+
+    #[test]
+    fn nested_generic_args() {
+        smoke_test("fn main(foo: Array<Bar<Foo>>) end");
+    }
+
+    #[test]
+    fn class_with_generic_param() {
+        smoke_test("class Foo<T> end");
+    }
 }
 
 #[cfg(test)]

dmc-lib/src/scope/class_scope.rs

@@ -2,6 +2,7 @@ use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::constructor_symbol::ConstructorSymbol;
 use crate::symbol::field_symbol::FieldSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::rc::Rc;
@@ -9,6 +10,7 @@ use std::rc::Rc;
 pub struct ClassScope {
     debug_name: String,
     parent_id: usize,
+    generic_parameter_symbols: HashMap<Rc<str>, Rc<RefCell<GenericParameterSymbol>>>,
     class_symbols: HashMap<Rc<str>, Rc<RefCell<ClassSymbol>>>,
     field_symbols: HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>>,
     function_symbols: HashMap<Rc<str>, Rc<RefCell<FunctionSymbol>>>,
@@ -20,6 +22,7 @@ impl ClassScope {
         Self {
             debug_name: debug_name.into(),
             parent_id,
+            generic_parameter_symbols: HashMap::new(),
             class_symbols: HashMap::new(),
             field_symbols: HashMap::new(),
             function_symbols: HashMap::new(),
@@ -27,6 +30,18 @@ impl ClassScope {
         }
     }
 
+    pub fn generic_parameter_symbols(
+        &self,
+    ) -> &HashMap<Rc<str>, Rc<RefCell<GenericParameterSymbol>>> {
+        &self.generic_parameter_symbols
+    }
+
+    pub fn generic_parameter_symbols_mut(
+        &mut self,
+    ) -> &mut HashMap<Rc<str>, Rc<RefCell<GenericParameterSymbol>>> {
+        &mut self.generic_parameter_symbols
+    }
+
     pub fn class_symbols(&self) -> &HashMap<Rc<str>, Rc<RefCell<ClassSymbol>>> {
         &self.class_symbols
     }

dmc-lib/src/symbol/class_symbol.rs

@@ -3,6 +3,7 @@ use crate::symbol::Symbol;
 use crate::symbol::constructor_symbol::ConstructorSymbol;
 use crate::symbol::field_symbol::FieldSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::rc::Rc;
@@ -12,6 +13,7 @@ pub struct ClassSymbol {
     declared_name_source_range: SourceRange,
     fqn_parts: Vec<Rc<str>>,
     is_extern: bool,
+    generic_parameters: Vec<Rc<RefCell<GenericParameterSymbol>>>,
     constructor_symbol: Option<Rc<RefCell<ConstructorSymbol>>>,
     fields: HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>>,
     functions: HashMap<Rc<str>, Rc<RefCell<FunctionSymbol>>>,
@@ -29,6 +31,7 @@ impl ClassSymbol {
             declared_name_source_range,
             fqn_parts,
             is_extern,
+            generic_parameters: vec![],
             constructor_symbol: None,
             fields: HashMap::new(),
             functions: HashMap::new(),
@@ -39,6 +42,17 @@ impl ClassSymbol {
         &self.fqn_parts
     }
 
+    pub fn set_generic_parameters(
+        &mut self,
+        generic_parameters: Vec<Rc<RefCell<GenericParameterSymbol>>>,
+    ) {
+        self.generic_parameters = generic_parameters;
+    }
+
+    pub fn generic_parameters(&self) -> &[Rc<RefCell<GenericParameterSymbol>>] {
+        &self.generic_parameters
+    }
+
     pub fn set_constructor_symbol(
         &mut self,
         constructor_symbol: Option<Rc<RefCell<ConstructorSymbol>>>,
@@ -46,6 +60,10 @@ impl ClassSymbol {
         self.constructor_symbol = constructor_symbol;
     }
 
+    pub fn set_fields(&mut self, fields: HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>>) {
+        self.fields = fields;
+    }
+
     pub fn fields(&self) -> &HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>> {
         &self.fields
     }

dmc-lib/src/symbol/generic_parameter_symbol.rs

@@ -0,0 +1,42 @@
+use crate::source_range::SourceRange;
+use crate::symbol::Symbol;
+use crate::type_info::TypeInfo;
+use std::rc::Rc;
+
+pub struct GenericParameterSymbol {
+    declared_name: Rc<str>,
+    declared_name_source_range: SourceRange,
+    extends: Option<Vec<TypeInfo>>,
+}
+
+impl GenericParameterSymbol {
+    pub fn new(declared_name: &Rc<str>, declared_name_source_range: &SourceRange) -> Self {
+        Self {
+            declared_name: declared_name.clone(),
+            declared_name_source_range: declared_name_source_range.clone(),
+            extends: None,
+        }
+    }
+
+    pub fn set_extends(&mut self, extends: Vec<TypeInfo>) {
+        self.extends = Some(extends);
+    }
+
+    pub fn extends(&self) -> &[TypeInfo] {
+        self.extends.as_ref().unwrap()
+    }
+}
+
+impl Symbol for GenericParameterSymbol {
+    fn declared_name(&self) -> &str {
+        &self.declared_name
+    }
+
+    fn declared_name_owned(&self) -> Rc<str> {
+        self.declared_name.clone()
+    }
+
+    fn declared_name_source_range(&self) -> &SourceRange {
+        &self.declared_name_source_range
+    }
+}

dmc-lib/src/symbol/mod.rs

@@ -7,6 +7,7 @@ pub mod constructor_symbol;
 pub mod expressible_symbol;
 pub mod field_symbol;
 pub mod function_symbol;
+pub mod generic_parameter_symbol;
 pub mod parameter_symbol;
 pub mod type_symbol;
 pub mod variable_symbol;

dmc-lib/src/symbol/type_symbol.rs

@@ -1,7 +1,9 @@
 use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
 use std::cell::RefCell;
 use std::rc::Rc;
 
 pub enum TypeSymbol {
     Class(Rc<RefCell<ClassSymbol>>),
+    GenericParameter(Rc<RefCell<GenericParameterSymbol>>),
 }

dmc-lib/src/symbol_table/helpers.rs

@@ -143,11 +143,19 @@ fn find_type_symbol_in_module(module_scope: &ModuleScope, name: &str) -> Option<
         .map(|symbol| TypeSymbol::Class(symbol.clone()))
 }
 
-fn find_type_symbol_in_class(class_scope: &ClassScope, name: &str) -> Option<TypeSymbol> {
+pub fn find_type_symbol_in_class(class_scope: &ClassScope, name: &str) -> Option<TypeSymbol> {
     class_scope
         .class_symbols()
         .get(name)
         .map(|symbol| TypeSymbol::Class(symbol.clone()))
+        .or_else(|| {
+            class_scope
+                .generic_parameter_symbols()
+                .get(name)
+                .map(|generic_parameter_symbol| {
+                    TypeSymbol::GenericParameter(generic_parameter_symbol.clone())
+                })
+        })
 }
 
 pub fn find_type_symbol(scope: &Scope, name: &str) -> Option<TypeSymbol> {

dmc-lib/src/symbol_table/mod.rs

@@ -11,12 +11,13 @@ use crate::symbol::constructor_symbol::ConstructorSymbol;
 use crate::symbol::expressible_symbol::ExpressibleSymbol;
 use crate::symbol::field_symbol::FieldSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
 use crate::symbol::parameter_symbol::ParameterSymbol;
 use crate::symbol::type_symbol::TypeSymbol;
 use crate::symbol::variable_symbol::VariableSymbol;
 use crate::symbol_table::helpers::{
     find_expressible_symbol, find_in_block_by_name, find_in_class_by_name,
-    find_in_function_by_name, find_in_module_by_name, find_type_symbol,
+    find_in_function_by_name, find_in_module_by_name, find_type_symbol, find_type_symbol_in_class,
 };
 use std::cell::RefCell;
 use std::rc::Rc;
@@ -124,6 +125,48 @@ impl SymbolTable {
         Ok(to_return)
     }
 
+    pub fn insert_generic_parameter_symbol(
+        &mut self,
+        generic_parameter_symbol: GenericParameterSymbol,
+    ) -> Result<Rc<RefCell<GenericParameterSymbol>>, SymbolInsertError> {
+        let maybe_already_inserted = match self.current_scope() {
+            Scope::Class(class_scope) => {
+                find_type_symbol_in_class(class_scope, generic_parameter_symbol.declared_name())
+            }
+            _ => panic!("Attempt to insert GenericParameterSymbol in incompatible scope"),
+        };
+
+        if let Some(already_inserted) = maybe_already_inserted {
+            match already_inserted {
+                TypeSymbol::Class(class_symbol) => {
+                    return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
+                        class_symbol as Rc<RefCell<dyn Symbol>>,
+                    )));
+                }
+                TypeSymbol::GenericParameter(generic_parameter_symbol) => {
+                    return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
+                        generic_parameter_symbol as Rc<RefCell<dyn Symbol>>,
+                    )));
+                }
+            }
+        }
+
+        let name = generic_parameter_symbol.declared_name_owned();
+        let as_rc = Rc::new(RefCell::new(generic_parameter_symbol));
+        let to_return = as_rc.clone();
+
+        match self.current_scope_mut() {
+            Scope::Class(class_scope) => {
+                class_scope
+                    .generic_parameter_symbols_mut()
+                    .insert(name, as_rc);
+            }
+            _ => unreachable!(),
+        }
+
+        Ok(to_return)
+    }
+
     pub fn insert_constructor_symbol(
         &mut self,
         constructor_symbol: ConstructorSymbol,

dmc-lib/src/token.rs

@@ -45,8 +45,6 @@ pub enum TokenKind {
     Star,
     Slash,
     Modulo,
-    LeftShift,
-    RightShift,
     Ampersand,
     Caret,
     Bar,
@@ -56,4 +54,8 @@ pub enum TokenKind {
     Public,
     Mut,
     Ctor,
+    LeftSquare,
+    RightSquare,
+    Lt,
+    Gt,
 }

dmc-lib/src/type_info.rs

@@ -1,6 +1,7 @@
 use crate::symbol::Symbol;
 use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
 use crate::symbol::type_symbol::TypeSymbol;
 use crate::symbol_table::SymbolTable;
 use std::cell::RefCell;
@@ -15,6 +16,7 @@ pub enum TypeInfo {
     String,
     Function(Rc<RefCell<FunctionSymbol>>),
     ClassInstance(Rc<RefCell<ClassSymbol>>),
+    GenericType(Rc<RefCell<GenericParameterSymbol>>),
     Void,
 }
 
@@ -35,6 +37,9 @@ impl Display for TypeInfo {
             TypeInfo::ClassInstance(class_symbol) => {
                 write!(f, "{}", class_symbol.borrow().declared_name())
             }
+            TypeInfo::GenericType(generic_parameter_symbol) => {
+                write!(f, "{}", generic_parameter_symbol.borrow().declared_name())
+            }
             TypeInfo::Void => write!(f, "Void"),
         }
     }
@@ -66,6 +71,9 @@ impl TypeInfo {
                 None => None,
                 Some(type_symbol) => match type_symbol {
                     TypeSymbol::Class(class_symbol) => Some(TypeInfo::ClassInstance(class_symbol)),
+                    TypeSymbol::GenericParameter(generic_parameter_symbol) => {
+                        Some(TypeInfo::GenericType(generic_parameter_symbol))
+                    }
                 },
             },
         }
@@ -95,6 +103,14 @@ impl TypeInfo {
                     _ => false,
                 }
             }
+            TypeInfo::GenericType(generic_parameter_symbol) => {
+                if generic_parameter_symbol.borrow().extends().len() > 0 {
+                    unimplemented!(
+                        "Assigning to generic parameter type with extends type uses not yet supported."
+                    );
+                }
+                true
+            }
             TypeInfo::Void => {
                 matches!(other, TypeInfo::Void)
             }

dvm-lib/src/vm/array.rs

@@ -0,0 +1,44 @@
+use std::alloc::{Layout, alloc};
+
+#[derive(Debug)]
+#[repr(C)]
+pub struct Array<T> {
+    header: ArrayHeader,
+    data: [T],
+}
+
+#[derive(Debug)]
+pub struct ArrayHeader {
+    length: usize,
+}
+
+pub fn get_array<T: Clone>(length: usize, init: T) -> Box<Array<T>> {
+    let (layout, data_base) = Layout::array::<T>(length)
+        .and_then(|data_layout| Layout::new::<ArrayHeader>().extend(data_layout))
+        .unwrap();
+    let ptr = unsafe { alloc(layout) };
+    if ptr.is_null() {
+        panic!("failed to allocate memory");
+    }
+    unsafe {
+        ptr.cast::<ArrayHeader>().write(ArrayHeader { length });
+        let data_ptr = ptr.add(data_base).cast::<T>();
+        for i in 0..length {
+            data_ptr.add(i).write(init.clone());
+        }
+
+        Box::from_raw(std::ptr::slice_from_raw_parts(ptr as *mut T, length) as *mut Array<T>)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::vm::array::get_array;
+
+    #[test]
+    fn int_array() {
+        let int_array = get_array::<i32>(5, 0);
+        assert_eq!(int_array.data.len(), 5);
+        assert_eq!(int_array.header.length, 5);
+    }
+}

dvm-lib/src/vm/mod.rs

@@ -17,6 +17,7 @@ use std::collections::HashMap;
 use std::ptr;
 use std::rc::Rc;
 
+pub mod array;
 pub mod class;
 pub mod constant;
 pub mod function;

dvm-lib/src/vm/type_info.rs

@@ -8,6 +8,7 @@ pub enum TypeInfo {
     Int,
     Double,
     String,
+    Any,
 }
 
 impl TypeInfo {
@@ -36,6 +37,7 @@ impl TypeInfo {
             TypeInfo::String => {
                 matches!(value, Value::String(_))
             }
+            TypeInfo::Any => true,
         }
     }
 }

e2e-tests/src/lib.rs

@@ -290,6 +290,31 @@ mod e2e_tests {
         assert_eq!(o.fields().len(), 1);
         assert_eq!(o.fields()[0].unwrap_int(), 42);
     }
+
+    #[test]
+    fn see_what_happens() {
+        let context = prepare_context(
+            "
+            class Foo<T>
+                mut t: T
+                ctor(_t: T)
+                    t = _t
+                end
+            end
+
+            fn main() -> Foo<Int>
+                Foo(42)
+            end
+            ",
+        );
+        let result = get_result(&context, "main", &vec![]);
+        assert!(result.is_some());
+        let value = result.unwrap();
+        assert!(matches!(value, Value::Object(_)));
+        let o = value.unwrap_object().borrow();
+        assert_eq!(o.fields().len(), 1);
+        assert_eq!(o.fields()[0].unwrap_int(), 42);
+    }
 }
 
 #[cfg(test)]

examples/op_prec.dm

@@ -1,3 +1,5 @@
+extern fn println(message: Any) -> Void
+
 fn main()
     let n = 1 + 2 * 3 + 4
     println(n)

examples/op_prec.dvm_ir

@@ -1,5 +0,0 @@
-fn main() -> Void
-    $0 = 2 * 3
-    $1 = 1 + $0
-    $2 = $1 + 4
-    call std::core::println($2)

sketching/march_2026/array.dm

@@ -0,0 +1,40 @@
+fn main(args: [String])
+    println(args[0])
+end
+
+int Index<T, I>
+    op [](i: I) -> T
+end
+
+int Slice<T> : Index<T, ISize>, Iterable<T>
+    length: ISize
+
+    def fn iter() -> Iterator<T>
+        let mut i = 0
+        {
+            if i < length then
+                i++
+                Some(self[i - 1])
+            else
+                None
+            end
+        }
+    end
+end
+
+int Iterator<T>
+    fn next() -> Option<T>
+end
+
+int Iterable<T>
+    fn iter() -> Iterator<T>
+end
+
+extern class Array<T> : Index<T, ISize>, Slice<T>
+    extern length: ISize
+    extern op [](i: ISize) -> T
+end
+
+int List<T> : Index<T, ISize>, Slice<T>
+
+end