generic types, any -> opaque

README.md

@@ -7,7 +7,7 @@ A very cool language
 * Compiles to x86-64 Assembly
 * No libc required!
 * Produces tiny static executables (11KB for `hello.zr`)
-* Has static typing, [UFCS](https://en.wikipedia.org/wiki/Uniform_function_call_syntax), variadics, dynamic arrays, hashmaps, DNS resolver, etc.
+* Has static typing, [UFCS](https://en.wikipedia.org/wiki/Uniform_function_call_syntax), generics, variadics, dynamic arrays, hashmaps, DNS resolver, etc.
 
 ## Syntax
 ```rust

examples/chip8.zr

@@ -14,15 +14,15 @@ extern IsKeyDown
 struct CHIP8
     memory: ptr
     pc: i64
-    stack: Array
+    stack: Array<i64>
     sp: i64
     reg: ptr
     I: i64
     delay_timer: u8
     sound_timer: u8
-    keyboard: Array
+    keyboard: Array<i64>
     display: ptr
-    keyboard_map: Array
+    keyboard_map: Array<i64>
 
 func CHIP8.init[c: CHIP8] : void
     c->memory = mem.alloc(4096)
@@ -242,14 +242,14 @@ func CHIP8.step[c: CHIP8] : void
             if IsKeyDown(c->keyboard_map->nth(c->reg[x] as i64))
                 c->pc += 2
         else if kk == 0xa1
-            if !IsKeyDown(c->keyboard_map->nth(c->reg[x] as i64))
+            if !(IsKeyDown(c->keyboard_map->nth(c->reg[x] as i64)) as bool)
                 c->pc += 2
     else if op == 0xf
         if kk == 0x07
             c->reg[x] = c->delay_timer
         else if kk == 0x0A
             key_pressed := false
-            while !key_pressed && !WindowShouldClose()
+            while !key_pressed && !(WindowShouldClose() as bool)
                 for i in 0..16
                     if IsKeyDown(c->keyboard_map->nth(i))
                         key_pressed = true
@@ -305,7 +305,7 @@ func main[argc: i64, argv: ptr] : i64
     InitWindow(640, 320, "CHIP-8")
     SetTargetFPS(60)
 
-    while !WindowShouldClose()
+    while !(WindowShouldClose() as bool)
         if c->delay_timer > 0
             c->delay_timer = c->delay_timer - 1
         if c->sound_timer > 0

examples/euler/euler_11.zr

@@ -4,7 +4,7 @@ include "$/containers.zr"
 func main[] : i64
     N := 20
 
-    grid := []
+    grid := [] as Array<Array<i64> >
     grid->push([8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8])
     grid->push([49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 4, 56, 62, 0])
     grid->push([81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 3, 49, 13, 36, 65])
@@ -30,10 +30,10 @@ func main[] : i64
 
     for i in 0..N-3
         for j in 0..N-3
-            h  : i64 = (grid->nth(i) as Array)->nth(j) * (grid->nth(i) as Array)->nth(j+1) * (grid->nth(i) as Array)->nth(j+2) * (grid->nth(i) as Array)->nth(j+3)
+            h  : i64 = grid->nth(i)->nth(j) * grid->nth(i)->nth(j+1) * grid->nth(i)->nth(j+2) * grid->nth(i)->nth(j+3)
-            v  : i64 = (grid->nth(j) as Array)->nth(i) * (grid->nth(j+1) as Array)->nth(i) * (grid->nth(j+2) as Array)->nth(i) * (grid->nth(j+3) as Array)->nth(i)
+            v  : i64 = grid->nth(j)->nth(i) * grid->nth(j+1)->nth(i) * grid->nth(j+2)->nth(i) * grid->nth(j+3)->nth(i)
-            d1 : i64 = (grid->nth(i) as Array)->nth(j) * (grid->nth(i+1) as Array)->nth(j+1) * (grid->nth(i+2) as Array)->nth(j+2) * (grid->nth(i+3) as Array)->nth(j+3)
+            d1 : i64 = grid->nth(i)->nth(j) * grid->nth(i+1)->nth(j+1) * grid->nth(i+2)->nth(j+2) * grid->nth(i+3)->nth(j+3)
-            d2 : i64 = (grid->nth(i) as Array)->nth(N-j-1) * (grid->nth(i+1) as Array)->nth(N-j-2) * (grid->nth(i+2) as Array)->nth(N-j-3) * (grid->nth(i+3) as Array)->nth(N-j-4)
+            d2 : i64 = grid->nth(i)->nth(N-j-1) * grid->nth(i+1)->nth(N-j-2) * grid->nth(i+2)->nth(N-j-3) * grid->nth(i+3)->nth(N-j-4)
             out = math.max(out, math.max(h, math.max(v, math.max(d1, d2))))
 
     io.println_i64(out)

examples/euler/euler_18.zr

@@ -1,17 +1,17 @@
 include "$/io.zr"
 include "$/containers.zr"
 
-func findmax[triangle: Array, row: i64, col: i64] : i64
+func findmax[triangle: Array<Array<i64> >, row: i64, col: i64] : i64
     if row == 14
-        return (triangle->nth(row) as Array)->nth(col)
+        return triangle->nth(row)->nth(col)
 
     left := findmax(triangle, row + 1, col)
     right := findmax(triangle, row + 1, col + 1)
 
-    return (triangle->nth(row) as Array)->nth(col) + math.max(left, right)
+    return triangle->nth(row)->nth(col) + math.max(left, right)
 
 func main[] : i64
-    triangle := []
+    triangle := [] as Array<Array<i64> >
     triangle->push([75])
     triangle->push([95, 64])
     triangle->push([17, 47, 82])

examples/euler/euler_20.zr

@@ -1,7 +1,7 @@
 include "$/io.zr"
 include "$/containers.zr"
 
-func multiply[n: Array, x: i64] : void
+func multiply[n: Array<i64>, x: i64] : void
     carry := 0
     for i in 0..n->size
         prod : i64 = n->nth(i) * x + carry

examples/raylib.zr

@@ -26,14 +26,14 @@ func main[] : i64
     InitWindow(800, 600, "Hello, World!")
     SetTargetFPS(60)
 
-    while !WindowShouldClose()
+    while !(WindowShouldClose() as bool)
-        if IsKeyDown(KEY_W) & 255
+        if IsKeyDown(KEY_W) as u8 & 255
             y -= 10
-        if IsKeyDown(KEY_S) & 255
+        if IsKeyDown(KEY_S) as u8 & 255
             y += 10
-        if IsKeyDown(KEY_A) & 255
+        if IsKeyDown(KEY_A) as u8 & 255
             x -= 10
-        if IsKeyDown(KEY_D) & 255
+        if IsKeyDown(KEY_D) as u8 & 255
             x += 10
 
         BeginDrawing()

examples/rule110.zr

@@ -1,8 +1,8 @@
 include "$/io.zr"
 include "$/containers.zr"
 
-func rule110_step[state: Array] : void
+func rule110_step[state: Array<bool>] : void
-    new_state := []
+    new_state := [] as Array<bool>
 
     for i in 0..state->size
         left := false
@@ -18,7 +18,7 @@ func rule110_step[state: Array] : void
     mem.copy(new_state->data, state->data, state->size * 8)
     new_state->free()
 
-func print_state[state: Array]: void
+func print_state[state: Array<bool>]: void
     for i in 0..state->size
         if state->nth(i)
             io.print_char('#')
@@ -29,7 +29,7 @@ func print_state[state: Array]: void
 func main[] : i64
     SIZE := 60
 
-    state := []
+    state := [] as Array<bool>
     for i in 0..SIZE
         state->push(false)
     state->push(true)

examples/sqlite_todo.zr

@@ -20,13 +20,13 @@ func main[] : i64
     db := 0
     stmt := 0
 
-    rc = sqlite3_open("todo.db", ^db)
+    rc = sqlite3_open("todo.db", ^db) as i64
     if rc
         panic("failed to open db")
 
-    rc = sqlite3_exec(db, "CREATE TABLE IF NOT EXISTS todo(id INTEGER PRIMARY KEY AUTOINCREMENT, task TEXT NOT NULL);", 0, 0, 0)
+    rc = sqlite3_exec(db, "CREATE TABLE IF NOT EXISTS todo(id INTEGER PRIMARY KEY AUTOINCREMENT, task TEXT NOT NULL);", 0, 0, 0) as i64
     if rc
-        panic(sqlite3_errmsg(db))
+        panic(sqlite3_errmsg(db) as str)
     
     while true
         io.println("1. List tasks")
@@ -43,7 +43,7 @@ func main[] : i64
             io.println("============")
             sqlite3_prepare_v2(db, "SELECT * FROM todo", -1, ^stmt, 0)
 
-            while sqlite3_step(stmt) == SQLITE_ROW
+            while sqlite3_step(stmt) as i64 == SQLITE_ROW
                 id := sqlite3_column_int(stmt, 0) as i64
                 task := sqlite3_column_text(stmt, 1) as str
                 io.printf("%d - %s\n", id, task)
@@ -55,8 +55,8 @@ func main[] : i64
 
             sqlite3_prepare_v2(db, "INSERT INTO todo(task) VALUES (?);", -1, ^stmt, 0)
             sqlite3_bind_text(stmt, 1, task, -1, 0)
-            if sqlite3_step(stmt) != SQLITE_DONE
+            if sqlite3_step(stmt) as i64 != SQLITE_DONE
-                panic(sqlite3_errmsg(db))
+                panic(sqlite3_errmsg(db) as str)
 
             io.println("\nTask added\n")
         else if choice == 3
@@ -65,8 +65,8 @@ func main[] : i64
 
             sqlite3_prepare_v2(db, "DELETE FROM todo WHERE id = ?;", -1, ^stmt, 0)
             sqlite3_bind_int(stmt, 1, id, -1, 0)
-            if sqlite3_step(stmt) != SQLITE_DONE
+            if sqlite3_step(stmt) as i64 != SQLITE_DONE
-                panic(sqlite3_errmsg(db))
+                panic(sqlite3_errmsg(db) as str)
 
             io.println("\nTask deleted\n")
 

src/codegen_x86_64.rs

@@ -231,7 +231,7 @@ _builtin_environ:
                 let var_type: String = match var_type {
                     Some(t) => t.lexeme.clone(),
                     None => match self.expr_types[&initializer.id].as_str() {
-                        "any" => return error!(name.loc, "cannot infer type from any"),
+                        "opaque" => return error!(name.loc, "cannot infer type from opaque"),
                         t => t.into(),
                     },
                 };
@@ -660,13 +660,8 @@ _builtin_environ:
                 self.compile_expr(env, right)?;
                 match op.token_type {
                     TokenType::Minus => {
-                        if self.expr_types[&right.id] == "f64" {
-                            emit!(&mut self.output, "    mov rbx, 0x8000000000000000");
-                            emit!(&mut self.output, "    xor rax, rbx");
-                        } else {
                         emit!(&mut self.output, "    neg rax");
                     }
-                    }
                     TokenType::Bang => {
                         emit!(&mut self.output, "    test rax, rax");
                         emit!(&mut self.output, "    sete al");
@@ -806,7 +801,8 @@ _builtin_environ:
                 struct_name,
                 use_heap,
             } => {
-                let struct_fields = &self.symbol_table.structs[&struct_name.lexeme];
+                let struct_fields =
+                    &self.symbol_table.structs[self.strip_generic(&struct_name.lexeme)];
                 let memory_size = struct_fields.len() * 8;
 
                 if *use_heap {
@@ -835,7 +831,8 @@ _builtin_environ:
             }
             ExprKind::MethodCall { expr, method, args } => {
                 let receiver_type = &self.expr_types[&expr.id];
-                let func_name = format!("{}.{}", receiver_type, method.lexeme);
+                let base_type = self.strip_generic(receiver_type);
+                let func_name = format!("{}.{}", base_type, method.lexeme);
 
                 self.compile_expr(env, expr)?;
                 emit!(&mut self.output, "    push rax");
@@ -910,8 +907,12 @@ _builtin_environ:
         }
     }
 
+    fn strip_generic<'b>(&self, type_name: &'b str) -> &'b str {
+        type_name.split('<').next().unwrap_or(type_name)
+    }
+
     fn get_field_offset(&self, left: &Expr, field: &Token) -> Result<usize, ZernError> {
-        let struct_name = &self.expr_types[&left.id];
+        let struct_name = self.strip_generic(&self.expr_types[&left.id]);
 
         let fields = match self.symbol_table.structs.get(struct_name) {
             Some(f) => f,

src/parser.rs

@@ -175,6 +175,38 @@ impl Parser {
         Ok(statements)
     }
 
+    fn parse_type_ref(&mut self) -> Result<Token, ZernError> {
+        if self.match_token(&[TokenType::Dollar]) {
+            Ok(Token {
+                token_type: TokenType::Identifier,
+                lexeme: "$".to_string(),
+                loc: self.previous().loc.clone(),
+            })
+        } else {
+            let ident = self.consume(TokenType::Identifier, "expected type name")?;
+            let mut type_name = ident.lexeme.clone();
+            if self.match_token(&[TokenType::Less]) {
+                type_name.push('<');
+                loop {
+                    let inner = self.parse_type_ref()?;
+                    type_name.push_str(&inner.lexeme);
+                    if self.match_token(&[TokenType::Comma]) {
+                        type_name.push(',');
+                    } else {
+                        break;
+                    }
+                }
+                self.consume(TokenType::Greater, "expected '>'")?;
+                type_name.push('>');
+            }
+            Ok(Token {
+                token_type: TokenType::Identifier,
+                lexeme: type_name,
+                loc: ident.loc,
+            })
+        }
+    }
+
     fn declaration(&mut self) -> Result<Stmt, ZernError> {
         if !self.is_inside_function {
             if self.match_token(&[TokenType::KeywordFunc]) {
@@ -217,8 +249,7 @@ impl Parser {
                         self.consume(TokenType::Identifier, "expected parameter name")?;
                     self.consume(TokenType::Colon, "expected ':' after parameter name")?;
 
-                    let var_type =
+                    let var_type = self.parse_type_ref()?;
-                        self.consume(TokenType::Identifier, "expected parameter type")?;
 
                     params.push(Param { var_type, var_name });
                     if !self.match_token(&[TokenType::Comma]) {
@@ -233,7 +264,7 @@ impl Parser {
 
         let mut return_types = vec![];
         loop {
-            return_types.push(self.consume(TokenType::Identifier, "expected return type")?);
+            return_types.push(self.parse_type_ref()?);
             if !self.match_token(&[TokenType::Comma]) {
                 break;
             }
@@ -266,7 +297,7 @@ impl Parser {
             let var_name = self.consume(TokenType::Identifier, "expected field name")?;
             self.consume(TokenType::Colon, "expected ':' after field name")?;
 
-            let var_type = self.consume(TokenType::Identifier, "expected field type")?;
+            let var_type = self.parse_type_ref()?;
 
             fields.push(Param { var_type, var_name });
         }
@@ -309,8 +340,8 @@ impl Parser {
             let var_type = if self.match_token(&[TokenType::Equal]) {
                 None
             } else {
-                let var_type = self.consume(TokenType::Identifier, "expected variable type")?;
+                let var_type = self.parse_type_ref()?;
-                self.consume(TokenType::Equal, "expected '=' after varaible type")?;
+                self.consume(TokenType::Equal, "expected '=' after variable type")?;
                 Some(var_type)
             };
 
@@ -559,7 +590,7 @@ impl Parser {
         let mut expr = self.unary()?;
 
         while self.match_token(&[TokenType::KeywordAs]) {
-            let type_name = self.consume(TokenType::Identifier, "expected type after 'as'")?;
+            let type_name = self.parse_type_ref()?;
             expr = Expr::new(ExprKind::Cast {
                 expr: Box::new(expr),
                 type_name,
@@ -688,8 +719,7 @@ impl Parser {
             Ok(Expr::new(ExprKind::ArrayLiteral(xs)))
         } else if self.match_token(&[TokenType::KeywordNew]) {
             let use_heap = self.match_token(&[TokenType::Star]);
-            let struct_name =
+            let struct_name = self.parse_type_ref()?;
-                self.consume(TokenType::Identifier, "expected struct name after 'new'")?;
             Ok(Expr::new(ExprKind::New {
                 struct_name,
                 use_heap,

src/symbol_table.rs

@@ -59,11 +59,11 @@ impl SymbolTable {
                 ("_builtin_cvttsd2si".into(), FnType::new("i64", vec!["f64"])),
                 (
                     "_builtin_f64_to_f32".into(),
-                    FnType::new("any", vec!["f64"]),
+                    FnType::new("opaque", vec!["f64"]),
                 ),
                 ("_builtin_syscall".into(), FnType::new_variadic("i64")),
                 ("_builtin_environ".into(), FnType::new("ptr", vec![])),
-                ("_var_arg".into(), FnType::new("any", vec!["i64"])),
+                ("_var_arg".into(), FnType::new("opaque", vec!["i64"])),
                 ("_stackalloc".into(), FnType::new("ptr", vec!["i64"])),
             ]),
             constants: HashMap::new(),
@@ -98,7 +98,7 @@ impl SymbolTable {
                     return error!(name.loc, format!("tried to redefine '{}'", name.lexeme));
                 }
                 self.functions
-                    .insert(name.lexeme.clone(), FnType::new_variadic("any"));
+                    .insert(name.lexeme.clone(), FnType::new_variadic("opaque"));
             }
             Stmt::Function {
                 name,

src/tokenizer.rs

@@ -65,6 +65,7 @@ pub enum TokenType {
 
     Indent,
     Dedent,
+    Dollar,
     Eof,
 }
 
@@ -249,6 +250,7 @@ impl<'a> Tokenizer<'a> {
                     self.add_token(TokenType::Less)?
                 }
             }
+            '$' => self.add_token(TokenType::Dollar)?,
             '\'' => {
                 if self.eof() {
                     return error!(self.loc, "unterminated char literal");

src/typechecker.rs

@@ -9,7 +9,7 @@ use crate::{
 macro_rules! expect_type {
     ($expr_type:expr, $expected:expr, $loc:expr) => {{
         let actual = $expr_type;
-        if $expected != "any" && actual != "any" && actual != $expected {
+        if $expected != "$" && actual != "$" && actual != $expected {
             return error!(
                 $loc,
                 format!("expected type '{}', got {}", $expected, actual)
@@ -20,7 +20,7 @@ macro_rules! expect_type {
 
 macro_rules! expect_types {
     ($expr_type:expr, [$( $expected:expr ),+], $loc:expr) => {
-        if $expr_type != "any" && $( $expr_type != $expected )&&+ {
+        if $expr_type != "$" && $( $expr_type != $expected )&&+ {
             return error!(
                 $loc,
                 format!(
@@ -33,7 +33,7 @@ macro_rules! expect_types {
     };
 }
 
-static BUILTIN_TYPES: [&str; 8] = ["void", "u8", "i64", "f64", "str", "bool", "ptr", "any"];
+static BUILTIN_TYPES: [&str; 8] = ["void", "u8", "i64", "f64", "str", "bool", "ptr", "opaque"];
 
 pub struct Env {
     scopes: Vec<HashMap<String, String>>,
@@ -110,7 +110,7 @@ impl<'a> TypeChecker<'a> {
                     }
                     expect_type!(actual_type.clone(), var_type.lexeme, var_type.loc);
 
-                    if actual_type == "any" {
+                    if actual_type == "opaque" {
                         actual_type = var_type.lexeme.clone();
                     }
                 }
@@ -150,8 +150,9 @@ impl<'a> TypeChecker<'a> {
                     }
                     ExprKind::MemberAccess { left, field } => {
                         let left_type = self.typecheck_expr(env, left)?;
+                        let (base_name, generic_args) = parse_generic_type(&left_type);
 
-                        let fields = match self.symbol_table.structs.get(&left_type) {
+                        let fields = match self.symbol_table.structs.get(base_name) {
                             Some(f) => f,
                             None => {
                                 return error!(
@@ -171,7 +172,13 @@ impl<'a> TypeChecker<'a> {
                             }
                         };
 
-                        expect_type!(value_type.clone(), f.field_type, field.loc);
+                        let field_type = if let Some(args) = generic_args {
+                            substitute_type(&f.field_type, args[0])
+                        } else {
+                            f.field_type.clone()
+                        };
+
+                        expect_type!(value_type.clone(), field_type, field.loc);
                     }
                     _ => return error!(&op.loc, "invalid assignment target"),
                 }
@@ -214,7 +221,7 @@ impl<'a> TypeChecker<'a> {
             } => {
                 expect_types!(
                     self.typecheck_expr(env, condition)?,
-                    ["i64", "u8", "ptr", "bool"],
+                    ["i64", "u8", "ptr", "bool", "opaque"],
                     keyword.loc
                 );
                 self.typecheck_stmt(env, then_branch)?;
@@ -436,7 +443,7 @@ impl<'a> TypeChecker<'a> {
                 let right_type = self.typecheck_expr(env, right)?;
                 match op.token_type {
                     TokenType::Minus => {
-                        expect_types!(right_type, ["f64", "i64"], op.loc);
+                        expect_types!(right_type, ["i64"], op.loc);
                         Ok(right_type)
                     }
                     TokenType::Bang => {
@@ -499,7 +506,7 @@ impl<'a> TypeChecker<'a> {
                         for arg in args {
                             self.typecheck_expr(env, arg)?;
                         }
-                        Ok("any".into())
+                        Ok("opaque".into())
                     }
                 } else {
                     // its an expression that evalutes to function address
@@ -508,14 +515,19 @@ impl<'a> TypeChecker<'a> {
                     for arg in args {
                         self.typecheck_expr(env, arg)?;
                     }
-                    Ok("any".into())
+                    Ok("opaque".into())
                 }
             }
             ExprKind::ArrayLiteral(exprs) => {
                 for expr in exprs {
                     self.typecheck_expr(env, expr)?;
                 }
+                if exprs.is_empty() {
                     Ok("Array".into())
+                } else {
+                    let first_item_type = self.typecheck_expr(env, &exprs[0])?;
+                    Ok(format!("Array<{}>", first_item_type))
+                }
             }
             ExprKind::Index {
                 expr,
@@ -536,34 +548,42 @@ impl<'a> TypeChecker<'a> {
                 struct_name,
                 use_heap: _,
             } => {
-                if !self.symbol_table.structs.contains_key(&struct_name.lexeme) {
+                let (base_name, _) = parse_generic_type(&struct_name.lexeme);
+                if !self.symbol_table.structs.contains_key(base_name) {
                     return error!(
                         &struct_name.loc,
-                        format!("unknown struct name: {}", &struct_name.lexeme)
+                        format!("unknown struct name: {}", base_name)
                     );
                 }
                 Ok(struct_name.lexeme.clone())
             }
             ExprKind::MemberAccess { left, field } => {
                 let left_type = self.typecheck_expr(env, left)?;
+                let (base_name, generic_args) = parse_generic_type(&left_type);
 
-                let fields = match self.symbol_table.structs.get(&left_type) {
+                let fields = match self.symbol_table.structs.get(base_name) {
                     Some(f) => f,
                     None => {
-                        return error!(&field.loc, format!("unknown struct type: {}", left_type));
+                        return error!(&field.loc, format!("unknown struct type: {}", base_name));
                     }
                 };
 
-                let field = match fields.get(&field.lexeme) {
+                let field_info = match fields.get(&field.lexeme) {
                     Some(o) => o,
                     None => return error!(&field.loc, format!("unknown field: {}", &field.lexeme)),
                 };
 
-                Ok(field.field_type.clone())
+                let field_type = if let Some(args) = generic_args {
+                    substitute_type(&field_info.field_type, args[0])
+                } else {
+                    field_info.field_type.clone()
+                };
+
+                Ok(field_type)
             }
             ExprKind::Cast { expr, type_name } => {
                 let expr_type = self.typecheck_expr(env, expr)?;
-                if expr_type != "any" && type_name.lexeme == "f64" {
+                if expr_type != "opaque" && type_name.lexeme == "f64" {
                     return error!(
                         &type_name.loc,
                         "use _builtin_cvtsi2sd and _builtin_cvttsd2si to cast between integers and f64"
@@ -579,7 +599,8 @@ impl<'a> TypeChecker<'a> {
             }
             ExprKind::MethodCall { expr, method, args } => {
                 let receiver_type = self.typecheck_expr(env, expr)?;
-                let func_name = format!("{}.{}", receiver_type, method.lexeme);
+                let (base_name, generic_args) = parse_generic_type(&receiver_type);
+                let func_name = format!("{}.{}", base_name, method.lexeme);
 
                 let func_type = match self.symbol_table.functions.get(&func_name) {
                     Some(f) => f,
@@ -588,15 +609,26 @@ impl<'a> TypeChecker<'a> {
                             method.loc,
                             format!(
                                 "method {} not found on on type {}",
-                                method.lexeme, receiver_type
+                                method.lexeme, base_name
                             )
                         );
                     }
                 };
 
+                let substitute = |s: &str| -> String {
+                    if let Some(ref args) = generic_args {
+                        substitute_type(s, args[0])
+                    } else {
+                        s.to_string()
+                    }
+                };
+
                 match &func_type.params {
                     FnParams::Normal(params) => {
-                        if params.is_empty() || params[0] != receiver_type {
+                        let substituted_params: Vec<String> =
+                            params.iter().map(|p| substitute(p)).collect();
+
+                        if substituted_params.is_empty() || substituted_params[0] != receiver_type {
                             return error!(
                                 method.loc,
                                 format!(
@@ -605,26 +637,30 @@ impl<'a> TypeChecker<'a> {
                                 )
                             );
                         }
-                        if params.len() != args.len() + 1 {
+                        if substituted_params.len() != args.len() + 1 {
                             return error!(
                                 method.loc,
                                 format!(
                                     "expected {} arguments, got {}",
-                                    params.len() - 1,
+                                    substituted_params.len() - 1,
                                     args.len()
                                 )
                             );
                         }
                         for (i, arg) in args.iter().enumerate() {
-                            expect_type!(self.typecheck_expr(env, arg)?, params[i + 1], method.loc);
+                            expect_type!(
+                                self.typecheck_expr(env, arg)?,
+                                substituted_params[i + 1].as_str(),
+                                method.loc
+                            );
                         }
-                        Ok(func_type.return_type.clone())
+                        Ok(substitute(&func_type.return_type))
                     }
                     FnParams::Variadic => {
                         for arg in args {
                             self.typecheck_expr(env, arg)?;
                         }
-                        Ok(func_type.return_type.clone())
+                        Ok(substitute(&func_type.return_type))
                     }
                 }
             }
@@ -635,9 +671,22 @@ impl<'a> TypeChecker<'a> {
     }
 
     fn is_valid_type_name(&self, name: &str) -> bool {
+        if name == "$" {
+            return true;
+        }
         if name.contains(',') {
             return name.split(',').all(|part| self.is_valid_type_name(part));
         }
+        if name.contains('<') {
+            let (base, inner) = parse_generic_type(name);
+            if !self.symbol_table.structs.contains_key(base) {
+                return false;
+            }
+            if let Some(args) = inner {
+                return args.iter().all(|arg| self.is_valid_type_name(arg));
+            }
+            return false;
+        }
         if BUILTIN_TYPES.contains(&name) {
             return true;
         }
@@ -647,3 +696,36 @@ impl<'a> TypeChecker<'a> {
         false
     }
 }
+
+fn parse_generic_type(s: &str) -> (&str, Option<Vec<&str>>) {
+    if let Some(lt_pos) = s.find('<') {
+        let base = &s[..lt_pos];
+        let inner = &s[lt_pos + 1..s.len() - 1];
+        let mut args = Vec::new();
+        let mut depth = 0;
+        let mut start = 0;
+        for (i, ch) in inner.char_indices() {
+            match ch {
+                '<' => depth += 1,
+                '>' => depth -= 1,
+                ',' if depth == 0 => {
+                    args.push(&inner[start..i]);
+                    start = i + 1;
+                }
+                _ => {}
+            }
+        }
+        args.push(&inner[start..]);
+        (base, Some(args))
+    } else {
+        (s, None)
+    }
+}
+
+fn substitute_type(type_str: &str, dollar_replacement: &str) -> String {
+    if type_str.contains('$') {
+        type_str.replace('$', dollar_replacement)
+    } else {
+        type_str.to_string()
+    }
+}

std/containers.zr

@@ -5,26 +5,24 @@ struct Array
     size: i64
     capacity: i64
 
-func Array.new_preallocated_and_zeroed[size: i64] : Array
+func Array.preallocate_and_zero[xs: Array<$>, size: i64] : void
-    xs := new* Array
     if size > 0
         xs->data = mem.alloc(size * 8)
         mem.zero(xs->data, size * 8)
         xs->size = size
         xs->capacity = size
-    return xs
 
-func Array.nth[xs: Array, n: i64] : any
+func Array.nth[xs: Array<$>, n: i64] : $
     if n < 0 || n >= xs->size
         panic("Array.nth out of bounds")
     return mem.read64(xs->data + n * 8)
 
-func Array.set[xs: Array, n: i64, x: any] : void
+func Array.set[xs: Array<$>, n: i64, x: $] : void
     if n < 0 || n >= xs->size
         panic("Array.set out of bounds")
     mem.write64(xs->data + n * 8, x)
 
-func Array.push[xs: Array, x: any] : void
+func Array.push[xs: Array<$>, x: $] : void
     if xs->size == xs->capacity
         new_capacity := 4
         if xs->capacity != 0
@@ -35,54 +33,56 @@ func Array.push[xs: Array, x: any] : void
     mem.write64(xs->data + xs->size * 8, x)
     xs->size += 1
 
-func Array.free[xs: Array] : void
+func Array.free[xs: Array<$>] : void
     if xs->data != 0
         xs->data->free()
     (xs as ptr)->free()
 
-func Array.free_with_items[xs: Array] : void
+func Array.free_with_items[xs: Array<$>] : void
     if xs->data != 0
         for i in 0..xs->size
             (xs->nth(i) as ptr)->free()
         xs->data->free()
     (xs as ptr)->free()
 
-func Array.pop[xs: Array] : any
+func Array.pop[xs: Array<$>] : $
     if xs->size == 0
         panic("Array.pop on empty array")
-    x : any = Array.last(xs)
+    x := Array.last(xs)
     xs->size = xs->size - 1
     return x
 
-func Array.last[xs: Array] : any
+func Array.last[xs: Array<$>] : $
     if xs->size == 0
         panic("Array.last on empty array")
     return xs->nth(xs->size - 1)
 
-func Array.slice[xs: Array, start: i64, length: i64] : Array
+func Array.slice[xs: Array<$>, start: i64, length: i64] : Array<$>
     if start < 0 || length < 0 || start + length > xs->size
         panic("Array.slice out of bounds")
 
-    new_array := Array.new_preallocated_and_zeroed(length)
+    new_array := [] as Array<$>
+    new_array->preallocate_and_zero(length)
     mem.copy(xs->data + start * 8, new_array->data, length * 8)
     return new_array
 
-func Array.concat[a: Array, b: Array] : Array
+func Array.concat[a: Array<$>, b: Array<$>] : Array<$>
-    new_array := Array.new_preallocated_and_zeroed(a->size + b->size)
+    new_array := [] as Array<$>
+    new_array->preallocate_and_zero(a->size + b->size)
     mem.copy(a->data, new_array->data, a->size * 8)
     mem.copy(b->data, new_array->data + a->size * 8, b->size * 8)
     return new_array
 
-func Array.quicksort[arr: Array] : void
+func Array.quicksort[arr: Array<$>] : void
     arr->_do_quicksort(0, arr->size - 1)
 
-func Array._do_quicksort[arr: Array, low: i64, high: i64] : void
+func Array._do_quicksort[arr: Array<$>, low: i64, high: i64] : void
     if low < high
         i := arr->_partition(low, high)
         arr->_do_quicksort(low, i - 1)
         arr->_do_quicksort(i + 1, high)
 
-func Array._partition[arr: Array, low: i64, high: i64] : i64
+func Array._partition[arr: Array<$>, low: i64, high: i64] : i64
     pivot : i64 = arr->nth(high)
     i := low - 1
     for j in (low)..high
@@ -96,41 +96,42 @@ func Array._partition[arr: Array, low: i64, high: i64] : i64
     arr->set(high, temp)
     return i + 1
 
-func Array.contains_str[arr: Array, s: str] : bool
+func Array.contains_str[arr: Array<str>, s: str] : bool
     for i in 0..arr->size
         if (arr->nth(i) as str)->equal(s)
             return true
     return false
 
-func Array.count[arr: Array, item: any] : i64
+func Array.count[arr: Array<$>, item: $] : i64
     count := 0
     for i in 0..arr->size
         if arr->nth(i) == item
             count += 1
     return count
 
-func Array.map[arr: Array, fn: ptr] : Array
+func Array.map[arr: Array<$>, fn: ptr] : Array<$>
-    out := Array.new_preallocated_and_zeroed(arr->size)
+    out := [] as Array<$>
+    out->preallocate_and_zero(arr->size)
     for i in 0..arr->size
         out->set(i, fn(arr->nth(i)))
     return out
 
-func Array.filter[arr: Array, fn: ptr] : Array
+func Array.filter[arr: Array<$>, fn: ptr] : Array<$>
-    out := []
+    out := [] as Array<$>
     for i in 0..arr->size
-        if fn(arr->nth(i))
+        if fn(arr->nth(i)) as bool
             out->push(arr->nth(i))
     return out
 
-func Array.reduce[arr: Array, fn: ptr, acc: any] : any
+func Array.reduce[arr: Array<$>, fn: ptr, acc: $] : $
     for i in 0..arr->size
         acc = fn(acc, arr->nth(i))
     return acc
 
-func str.split[haystack: str, needle: str]: Array
+func str.split[haystack: str, needle: str]: Array<str>
     haystack_len := haystack->len()
     needle_len := needle->len()
-    result := []
+    result := [] as Array<str>
     
     if !needle_len
         if !haystack_len
@@ -162,19 +163,20 @@ func str.split[haystack: str, needle: str]: Array
 const HashMap._TABLE_SIZE = 100
 
 struct HashMap
-    table: Array
+    table: Array<HashMap._Node>
 
 struct HashMap._Node
     key: str
-    value: any
+    value: $
     next: HashMap._Node
 
 func HashMap.new[] : HashMap
     map := new* HashMap
-    map->table = Array.new_preallocated_and_zeroed(HashMap._TABLE_SIZE)
+    map->table = [] as Array<HashMap._Node>
+    map->table->preallocate_and_zero(HashMap._TABLE_SIZE)
     return map
 
-func HashMap.insert[map: HashMap, key: str, value: any] : void
+func HashMap.insert[map: HashMap<$>, key: str, value: $] : void
     index := HashMap._djb2(key)
     current : HashMap._Node = map->table->nth(index)
 
@@ -190,7 +192,7 @@ func HashMap.insert[map: HashMap, key: str, value: any] : void
     new_node->next = map->table->nth(index)
     map->table->set(index, new_node)
 
-func HashMap.get[map: HashMap, key: str] : any, bool
+func HashMap.get[map: HashMap<$>, key: str] : $, bool
     index := HashMap._djb2(key)
     current : HashMap._Node = map->table->nth(index)
 
@@ -199,9 +201,9 @@ func HashMap.get[map: HashMap, key: str] : any, bool
             return current->value, true
         current = current->next
     
-    return 0 as any, false
+    return 0 as $, false
 
-func HashMap.delete[map: HashMap, key: str] : void
+func HashMap.delete[map: HashMap<$>, key: str] : void
     index := HashMap._djb2(key)
     current : HashMap._Node = map->table->nth(index)
     prev := 0 as HashMap._Node
@@ -220,8 +222,8 @@ func HashMap.delete[map: HashMap, key: str] : void
         prev = current
         current = current->next
 
-func HashMap.keys[map: HashMap] : Array
+func HashMap.keys[map: HashMap<$>] : Array<str>
-    out := []
+    out := [] as Array<str>
     for i in 0..HashMap._TABLE_SIZE
         current : HashMap._Node = map->table->nth(i)
         while current as ptr
@@ -229,7 +231,7 @@ func HashMap.keys[map: HashMap] : Array
             current = current->next
     return out
 
-func HashMap.free_with_keys[map: HashMap] : void
+func HashMap.free_with_keys[map: HashMap<$>] : void
     for i in 0..HashMap._TABLE_SIZE
         current : HashMap._Node = map->table->nth(i)
         while current as ptr

std/json.zr

@@ -9,33 +9,33 @@ const json.BOOL   = 5
 
 struct json.Value
     type: i64
-    value: any
+    value: opaque
 
 func json.Value.dump[v: json.Value] : str
     s := new str.Builder
 
     if v->type == json.OBJECT
-        map := v->value as HashMap
+        map := v->value as HashMap<json.Value>
         keys := map->keys()
         s->append_char('{')
         for i in 0..keys->size
             if i > 0
                 s->append_char(',')
             s->append_char('"')
-            s->append(keys->nth(i) as str)
+            s->append(keys->nth(i))
             s->append_char('"')
             s->append_char(':')
-            value, _ := map->get(keys->nth(i) as str)
+            value, _ := map->get(keys->nth(i))
-            s->append((value as json.Value)->dump())
+            s->append(value->dump())
         s->append_char('}')
         keys->free()
     else if v->type == json.ARRAY
-        arr := v->value as Array
+        arr := v->value as Array<json.Value>
         s->append_char('[')
         for i in 0..arr->size
             if i > 0
                 s->append_char(',')
-            s->append((arr->nth(i) as json.Value)->dump())
+            s->append(arr->nth(i)->dump())
         s->append_char(']')
     else if v->type == json.STRING
         // TODO: escape sequences
@@ -58,25 +58,25 @@ func json.Value.dump[v: json.Value] : str
 
 func json.Value.free[v: json.Value] : void
     if v->type == json.OBJECT
-        map := v->value as HashMap
+        map := v->value as HashMap<json.Value>
         keys := map->keys()
         for i in 0..keys->size
-            value, _ := map->get(keys->nth(i) as str)
+            value, _ := map->get(keys->nth(i))
-            (value as json.Value)->free()
+            value->free()
         keys->free()
         
         map->free_with_keys()
     else if v->type == json.ARRAY
-        arr := v->value as Array
+        arr := v->value as Array<json.Value>
         for i in 0..arr->size
-            (arr->nth(i) as json.Value)->free()
+            arr->nth(i)->free()
         arr->free()
     else if v->type == json.STRING
         (v->value as str)->free()
 
     (v as ptr)->free()
 
-func json.val[x: any] : any
+func json.val[x: opaque] : opaque
     return (x as json.Value)->value
 
 func json.parse[s: str] : json.Value
@@ -96,7 +96,7 @@ func json._parse_value[s: str, i: ptr] : json.Value
         json._skip_whitespace(s, i)
 
         out->type = json.OBJECT
-        out->value = HashMap.new()
+        out->value = HashMap.new() as opaque
         
         if s[mem.read64(i)] != '}'
             while true
@@ -110,7 +110,7 @@ func json._parse_value[s: str, i: ptr] : json.Value
                 json._skip_whitespace(s, i)
 
                 value := json._parse_value(s, i)
-                (out->value as HashMap)->insert(key, value)
+                (out->value as HashMap<json.Value>)->insert(key, value)
                 key->free()
 
                 json._skip_whitespace(s, i)
@@ -128,12 +128,12 @@ func json._parse_value[s: str, i: ptr] : json.Value
         json._skip_whitespace(s, i)
 
         out->type = json.ARRAY
-        out->value = []
+        out->value = [] as opaque
         
         while s[mem.read64(i)] != ']'
             json._skip_whitespace(s, i)
 
-            (out->value as Array)->push(json._parse_value(s, i))
+            (out->value as Array<json.Value>)->push(json._parse_value(s, i))
             json._skip_whitespace(s, i)
 
             if s[mem.read64(i)] == ','
@@ -147,7 +147,7 @@ func json._parse_value[s: str, i: ptr] : json.Value
         mem.write64(i, mem.read64(i) + 1)
     else if s[mem.read64(i)] == '"'
         out->type = json.STRING
-        out->value = json._parse_string(s, i)
+        out->value = json._parse_string(s, i) as opaque
     else if s[mem.read64(i)]->is_digit() || s[mem.read64(i)] == '-'
         start := mem.read64(i)
 
@@ -164,18 +164,18 @@ func json._parse_value[s: str, i: ptr] : json.Value
 
         num_str := s->substr_n(start, len)
         out->type = json.NUMBER
-        out->value = num_str->parse_i64()
+        out->value = num_str->parse_i64() as opaque
         num_str->free()
     else if s[mem.read64(i)] == 'n' && s[mem.read64(i)+1] == 'u' && s[mem.read64(i)+2] == 'l' && s[mem.read64(i)+3] == 'l'
         out->type = json.NULL
         mem.write64(i, mem.read64(i) + 4)
     else if s[mem.read64(i)] == 't' && s[mem.read64(i)+1] == 'r' && s[mem.read64(i)+2] == 'u' && s[mem.read64(i)+3] == 'e'
         out->type = json.BOOL
-        out->value = true
+        out->value = true as opaque
         mem.write64(i, mem.read64(i) + 4)
     else if s[mem.read64(i)] == 'f' && s[mem.read64(i)+1] == 'a' && s[mem.read64(i)+2] == 'l' && s[mem.read64(i)+3] == 's' && s[mem.read64(i)+4] == 'e'
         out->type = json.BOOL
-        out->value = false
+        out->value = false as opaque
         mem.write64(i, mem.read64(i) + 5)
     else
         panic("json.parse: unexpected character")

std/mem.zr

@@ -23,7 +23,7 @@ func mem.Block._split[blk: mem.Block, needed: i64] : void
         if blk->next as ptr
             blk->next->prev = new_blk
         else
-            mem.write64(_builtin_heap_tail(), new_blk)
+            mem.write64(_builtin_heap_tail(), new_blk as ptr as i64)
 
         blk->size = needed
         blk->next = new_blk
@@ -46,7 +46,7 @@ func mem._request_space[size: i64] : mem.Block
         tail->next = blk
         blk->prev = tail
 
-    mem.write64(_builtin_heap_tail(), blk)
+    mem.write64(_builtin_heap_tail(), blk as ptr as i64)
     return blk
 
 func mem.alloc[size: i64] : ptr
@@ -66,7 +66,7 @@ func mem.alloc[size: i64] : ptr
     blk := mem._request_space(size)
     
     if !mem.read64(_builtin_heap_head())
-        mem.write64(_builtin_heap_head(), blk)
+        mem.write64(_builtin_heap_head(), blk as ptr as i64)
     
     blk->_split(size)
     
@@ -91,7 +91,7 @@ func ptr.free[x: ptr] : void
             if next->next as ptr
                 next->next->prev = blk
             if mem.read64(_builtin_heap_tail()) == next as ptr
-                mem.write64(_builtin_heap_tail(), blk)
+                mem.write64(_builtin_heap_tail(), blk as ptr as i64)
 
     prev := blk->prev
     if prev as ptr && prev->free
@@ -102,7 +102,7 @@ func ptr.free[x: ptr] : void
             if blk->next as ptr
                 blk->next->prev = prev
             if mem.read64(_builtin_heap_tail()) == blk as ptr
-                mem.write64(_builtin_heap_tail(), prev)
+                mem.write64(_builtin_heap_tail(), prev as ptr as i64)
             blk = prev
 
     block_total := blk->size + MEM_BLOCK_SIZE
@@ -110,11 +110,11 @@ func ptr.free[x: ptr] : void
         if blk->prev as ptr
             blk->prev->next = blk->next
         else
-            mem.write64(_builtin_heap_head(), blk->next)
+            mem.write64(_builtin_heap_head(), blk->next as ptr as i64)
         if blk->next as ptr
             blk->next->prev = blk->prev
         else
-            mem.write64(_builtin_heap_tail(), blk->prev)
+            mem.write64(_builtin_heap_tail(), blk->prev as ptr as i64)
         _builtin_syscall(SYS_munmap, blk, block_total)
 
 func ptr.realloc[x: ptr, new_size: i64] : ptr
@@ -146,7 +146,7 @@ func ptr.realloc[x: ptr, new_size: i64] : ptr
             if next->next as ptr
                 next->next->prev = blk
             if mem.read64(_builtin_heap_tail()) == next as ptr
-                mem.write64(_builtin_heap_tail(), blk)
+                mem.write64(_builtin_heap_tail(), blk as ptr as i64)
             blk->_split(new_size)
             return x
 
@@ -219,7 +219,7 @@ func mem.write16be[x: ptr, d: i64] : void
     x[0] = (d >> 8) & 0xff
     x[1] = d & 0xff
 
-func mem.write64[x: ptr, d: any] : void
+func mem.write64[x: ptr, d: i64] : void
     _builtin_set64(x, d)
 
 struct Blob

std/net.zr

@@ -149,7 +149,7 @@ func net.resolve[domain: str] : i64, bool
     if parts->size == 4
         valid := true
         for i in 0..4
-            p := parts->nth(i) as str
+            p := parts->nth(i)
             if p->len() < 1 || p->len() > 3
                 valid = false
                 break
@@ -160,10 +160,10 @@ func net.resolve[domain: str] : i64, bool
             if !valid
                 break
         if valid
-            a := (parts->nth(0) as str)->parse_i64()
+            a := parts->nth(0)->parse_i64()
-            b := (parts->nth(1) as str)->parse_i64()
+            b := parts->nth(1)->parse_i64()
-            c := (parts->nth(2) as str)->parse_i64()
+            c := parts->nth(2)->parse_i64()
-            d := (parts->nth(3) as str)->parse_i64()
+            d := parts->nth(3)->parse_i64()
             if a >= 0 && a <= 255 && b >= 0 && b <= 255 && c >= 0 && c <= 255 && d >= 0 && d <= 255
                 parts->free_with_items()
                 return net.pack_addr(a, b, c, d), true

std/os.zr

@@ -117,19 +117,19 @@ func os.is_a_directory[path: str] : bool
 
     return (mem.read32(st + 24) & S_IFMT) == S_IFDIR
 
-func os.list_directory[path: str] : Array, bool
+func os.list_directory[path: str] : Array<str>, bool
     fd := _builtin_syscall(SYS_openat, AT_FDCWD, path, O_RDONLY, 0)
     if fd < 0
-        return 0 as Array, false
+        return 0 as Array<str>, false
 
-    files := []
+    files := [] as Array<str>
     buf := _stackalloc(1024)
     while true
         n := _builtin_syscall(SYS_getdents64, fd, buf, 1024)
         if n < 0
             files->free_with_items()
             _builtin_syscall(SYS_close, fd)
-            return 0 as Array, false
+            return 0 as Array<str>, false
         else if n == 0
             break
 

std/str.zr

@@ -104,7 +104,7 @@ func str.format_into[..] : i64
                 i += 1
             else if s[0] == 'f'
                 // TODO: use arrow when we implement f64 params
-                f64.to_str_buf(_var_arg(i), tmp as ptr)
+                f64.to_str_buf(_var_arg(i) as i64, tmp as ptr)
                 tmp_len := tmp->len()
                 remaining := size - n - 1
                 mem.copy(tmp as ptr, buf + n, math.min(tmp_len, remaining))

test.zr

@@ -2,10 +2,10 @@ include "$/io.zr"
 include "$/os.zr"
 
 struct TestRunner
-    build_blacklist: Array
+    build_blacklist: Array<str>
-    run_blacklist: Array
+    run_blacklist: Array<str>
-    custom_build_flags: HashMap
+    custom_build_flags: HashMap<str>
-    custom_run_args: HashMap
+    custom_run_args: HashMap<str>
 
 func TestRunner.run_directory[tr: TestRunner, dir: str] : void
     files, ok := os.list_directory(dir)
@@ -66,14 +66,14 @@ func main[] : i64
         os.exit(1)
 
     tr := new TestRunner
-    tr->build_blacklist = []
+    tr->build_blacklist = [] as Array<str>
     tr->run_blacklist = ["raylib.zr", "sqlite_todo.zr", "guess_number.zr", "udp_server.zr", "chip8.zr", "serve.zr"]
-    tr->custom_build_flags = HashMap.new()
+    tr->custom_build_flags = HashMap.new() as HashMap<str>
     tr->custom_build_flags->insert("raylib.zr", "-m -C \"-lraylib\"")
     tr->custom_build_flags->insert("chip8.zr", "-m -C \"-lraylib\"")
     tr->custom_build_flags->insert("sqlite_todo.zr", "-m -C \"-lsqlite3\"")
     tr->custom_build_flags->insert("serve.zr", "-m -C \"-lpthread\"")
-    tr->custom_run_args = HashMap.new()
+    tr->custom_run_args = HashMap.new() as HashMap<str>
     tr->custom_run_args->insert("curl.zr", "http://example.com")
 
     tr->run_directory("examples")