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.clang-format (351, 2023-12-29)
.pre-commit-config.yaml (236, 2023-12-29)
.vscode/ (0, 2023-12-29)
.vscode/launch.json (443, 2023-12-29)
CMakeLists.txt (11260, 2023-12-29)
CODE_OF_CONDUCT.md (2211, 2023-12-29)
CONTRIBUTING.md (7048, 2023-12-29)
LICENSE (1327, 2023-12-29)
bootstrap/ (0, 2023-12-29)
bootstrap/stage0/ (0, 2023-12-29)
bootstrap/stage0/__prelude___specializations.cpp (0, 2023-12-29)
bootstrap/stage0/__unified_forward.h (17425, 2023-12-29)
bootstrap/stage0/build.cpp (13873, 2023-12-29)
bootstrap/stage0/build.h (3175, 2023-12-29)
bootstrap/stage0/build_specializations.cpp (0, 2023-12-29)
bootstrap/stage0/codegen.cpp (402666, 2023-12-29)
bootstrap/stage0/codegen.h (19562, 2023-12-29)
bootstrap/stage0/codegen_specializations.cpp (0, 2023-12-29)
bootstrap/stage0/compiler.cpp (15420, 2023-12-29)
bootstrap/stage0/compiler.h (4594, 2023-12-29)
bootstrap/stage0/compiler_specializations.cpp (0, 2023-12-29)
bootstrap/stage0/cpp_import__common.cpp (1294, 2023-12-29)
bootstrap/stage0/cpp_import__common.h (839, 2023-12-29)
bootstrap/stage0/cpp_import__common_specializations.cpp (0, 2023-12-29)
bootstrap/stage0/cpp_import__none.cpp (957, 2023-12-29)
bootstrap/stage0/cpp_import__none.h (1103, 2023-12-29)
bootstrap/stage0/cpp_import__none_specializations.cpp (0, 2023-12-29)
bootstrap/stage0/error.cpp (29163, 2023-12-29)
bootstrap/stage0/error.h (2628, 2023-12-29)
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# The Jakt programming language **Jakt** is a memory-safe systems programming language. It currently transpiles to C++. **NOTE:** The language is under heavy development. **NOTE** If you're cloning to a Windows PC (not WSL), make sure that your Git client keeps the line endings as `\n`. You can set this as a global config via `git config --global core.autocrlf false`. ## Usage The transpilation to C++ requires `clang`. Make sure you have that installed. ``` jakt file.jakt ./build/file ``` ## Building See [here](https://github.com/SerenityOS/jakt/blob/master/documentation/cmake-bootstrap.md). ## Goals 1. Memory safety 2. Code readability 3. Developer productivity 4. Executable performance 5. Fun! ## Memory safety The following strategies are employed to achieve memory safety: - Automatic reference counting - Strong typing - Bounds checking - No raw pointers in safe mode In **Jakt**, there are three pointer types: - [x] **T** (Strong pointer to reference-counted class `T`.) - [x] **weak T** (Weak pointer to reference-counted class `T`. Becomes empty on pointee destruction.) - [x] **raw T** (Raw pointer to arbitrary type `T`. Only usable in `unsafe` blocks.) Null pointers are not possible in safe mode, but pointers can be wrapped in `Optional`, i.e `Optional` or `T?` for short. ## Math safety - [x] Integer overflow (both signed and unsigned) is a runtime error. - [x] Numeric values are not automatically coerced to `int`. All casts must be explicit. For cases where silent integer overflow is desired, there are explicit functions that provide this functionality. ## Code readability Far more time is spent reading code than writing it. For that reason, **Jakt** puts a high emphasis on readability. Some of the features that encourage more readable programs: - [x] Immutable by default. - [x] Argument labels in call expressions (`object.function(width: 10, height: 5)`) - [ ] Inferred `enum` scope. (You can say `Foo` instead of `MyEnum::Foo`). - [x] Pattern matching with `match`. - [x] Optional chaining (`foo?.bar?.baz` (fallible) and `foo!.bar!.baz` (infallible)) - [x] None coalescing for optionals (`foo ?? bar` yields `foo` if `foo` has a value, otherwise `bar`) - [x] `defer` statements. - [x] Pointers are always dereferenced with `.` (never `->`) - [x] Trailing closure parameters can be passed outside the call parentheses. - [ ] Error propagation with `ErrorOr` return type and dedicated `try` / `must` keywords. ## Code reuse Jakt is flexible in how a project can be structured with a built-in module system. ```jakt import a // (1) import a { use_cool_things } // (2) import fn() // (3) import relative foo::bar // (4) import relative parent::foo::baz // (5) import relative parent(3)::foo::baz // (6) ``` 1. Import a module from the same directory as the file. 1. Import only `use_cool_things()` from module `a`. 1. Imports can be calculated at compile time. See [Comptime Imports](https://github.com/SerenityOS/jakt/blob/master/#comptime-imports) 1. Import a module using the relative keyword when the module is a sub path of the directory containing the file. 1. Import a module in a parent path one directory up from the file. 1. Syntactic sugar for importing a module three parent paths up from the file. ### The Jakt Standard Library Jakt has a Standard Library that is accessed using the `jakt::` namespace: ```jakt import jakt::arguments import jakt::libc::io { system } ``` The Jakt Standard Library is in its infancy, so please consider making a contribution! ## Function calls When calling a function, you must specify the name of each argument as you're passing it: ```jakt rect.set_size(width: 640, height: 480) ``` There are two exceptions to this: - [x] If the parameter in the function declaration is declared as `anon`, omitting the argument label is allowed. - [x] When passing a variable with the same name as the parameter. ## Structures and classes There are two main ways to declare a structure in **Jakt**: `struct` and `class`. ### `struct` Basic syntax: ```jakt struct Point { x: i64 y: i64 } ``` Structs in **Jakt** have *value semantics*: - Variables that contain a struct always have a unique instance of the struct. - Copying a `struct` instance always makes a deep copy. ```jakt let a = Point(x: 10, y: 5) let b = a // "b" is a deep copy of "a", they do not refer to the same Point ``` **Jakt** generates a default constructor for structs. It takes all fields by name. For the `Point` struct above, it looks like this: ```jakt Point(x: i64, y: i64) ``` Struct members are *public* by default. ### `class` - [x] basic class support - [x] private-by-default members - [x] inheritance - [ ] class-based polymorphism (assign child instance to things requiring the parent type) - [ ] `Super` type - [ ] `Self` type Same basic syntax as `struct`: ``` class Size { width: i64 height: i64 public fn area(this) => .width * .height } ``` Classes in **Jakt** have *reference semantics*: - Copying a `class` instance (aka an "object") copies a reference to the object. - All objects are reference-counted by default. This ensures that objects don't get accessed after being deleted. Class members are *private* by default. ### Member functions Both structs and classes can have member functions. There are three kinds of member functions: **Static member functions** don't require an object to call. They have no `this` parameter. ```jakt class Foo { fn func() => println("Hello!") } // Foo::func() can be called without an object. Foo::func() ``` **Non-mutating member functions** require an object to be called, but cannot mutate the object. The first parameter is `this`. ```jakt class Foo { fn func(this) => println("Hello!") } // Foo::func() can only be called on an instance of Foo. let x = Foo() x.func() ``` **Mutating member functions** require an object to be called, and may modify the object. The first parameter is `mut this`. ```jakt class Foo { x: i64 fn set(mut this, anon x: i64) { this.x = x } } // Foo::set() can only be called on a mut Foo: mut foo = Foo(x: 3) foo.set(9) ``` ### Shorthand for accessing member variables To reduce repetitive `this.` spam in methods, the shorthand `.foo` expands to `this.foo`. ## Strings Strings are provided in the language mainly as the type `String`, which is a reference-counted (and heap-allocated) string type. String literals are written with double quotes, like `"Hello, world!"`. ### Overloaded string literals String literals are of type `String` by default; however, they can be used to implicitly construct any type that implements the `FromStringLiteral` (or `ThrowingFromStringLiteral`) trait. In the language prelude, currently only `StringView` implements this trait, which can be used only to refer to strings with a static lifetime: ```jakt let foo: StringView = "foo" // This string is not allocated on the heap, and foo is only a fat pointer to the static string. ``` Overloaded string literals can be used by providing a type hint, whether by explicit type annotations, or by passing the literal to a function that expects a specific type: ```jakt struct NotString implements(FromStringLiteral) { fn from_string_literal(anon string: StringView) -> NotString => NotString() } fn test(x: NotString) {} fn main() { let foo: NotString = "foo" test(x: "Some string literal") } ``` ## Arrays Dynamic arrays are provided via a built-in `Array` type. They can grow and shrink at runtime. `Array` is memory safe: - Out-of-bounds will panic the program with a runtime error. - Slices of an `Array` keep the underlying data alive via automatic reference counting. ### Declaring arrays ```jakt // Function that takes an Array and returns an Array fn foo(numbers: [i64]) -> [String] { ... } ``` ### Shorthand for creating arrays ```jakt // Array with 256 elements, all initialized to 0. let values = [0; 256] // Array with 3 elements: "foo", "bar" and "baz". let values = ["foo", "bar", "baz"] ``` ## Dictionaries - [x] Creating dictionaries - [x] Indexing dictionaries - [x] Assigning into indexes (aka lvalue) ```jakt fn main() { let dict = ["a": 1, "b": 2] println("{}", dict["a"]) } ``` ### Declaring dictionaries ```jakt // Function that takes a Dictionary and returns an Dictionary fn foo(numbers: [i64:String]) -> [String:bool] { ... } ``` ### Shorthand for creating dictionaries ```jakt // Dictionary with 3 entries. let values = ["foo": 500, "bar": 600, "baz": 700] ``` ## Sets - [x] Creating sets - [x] Reference semantics ```jakt fn main() { let set = {1, 2, 3} println("{}", set.contains(1)) println("{}", set.contains(5)) } ``` ## Tuples - [x] Creating tuples - [x] Index tuples - [x] Tuple types ``` fn main() { let x = ("a", 2, true) println("{}", x.1) } ``` ## Enums and Pattern Matching - [x] Enums as sum-types - [x] Generic enums - [x] Enums as names for values of an underlying type - [x] `match` expressions - [x] Enum scope inference in `match` arms - [x] Yielding values from match blocks - [ ] Nested `match` patterns - [ ] Traits as `match` patterns - [ ] Support for interop with the `?`, `??` and `!` operators ```jakt enum MyOptional { Some(T) None } fn value_or_default(anon x: MyOptional, default: T) -> T { return match x { Some(value) => { let stuff = maybe_do_stuff_with(value) let more_stuff = stuff.do_some_more_processing() yield more_stuff } None => default } } enum Foo { StructLikeThingy ( field_a: i32 field_b: i32 ) } fn look_at_foo(anon x: Foo) -> i32 { match x { StructLikeThingy(field_a: a, field_b) => { return a + field_b } } } enum AlertDescription: i8 { CloseNotify = 0 UnexpectedMessage = 10 BadRecordMAC = 20 // etc } // Use in match: fn do_nothing_in_particular() => match AlertDescription::CloseNotify { CloseNotify => { ... } UnexpectedMessage => { ... } BadRecordMAC => { ... } } ``` ## Generics - [x] Generic types - [x] Constant generics (minimal support) - [ ] Constant generics (full support) - [x] Generic type inference - [x] Traits **Jakt** supports both generic structures and generic functions. ```jakt fn id(anon x: T) -> T { return x } fn main() { let y = id(3) println("{}", y + 1000) } ``` ```jakt struct Foo { x: T } fn main() { let f = Foo(x: 100) println("{}", f.x) } ``` ```jakt struct MyArray { // NOTE: There is currently no way to access the value 'U', referring to 'U' is only valid as the type at the moment. data: [T] } ``` ## Namespaces - [x] Namespace support for functions and struct/class/enum - [ ] Deep namespace support ``` namespace Greeters { fn greet() { println("Well, hello friends") } } fn main() { Greeters::greet() } ``` ## Type casts There are two built-in casting operators in **Jakt**. - `as? T`: Returns an `Optional`, empty if the source value isn't convertible to `T`. - `as! T`: Returns a `T`, aborts the program if the source value isn't convertible to `T`. The `as` cast can do these things (note that the implementation may not agree yet): - Casts to the same type are infallible and pointless, so might be forbidden in the future. - If the source type is _unknown_, the cast is valid as a type assertion. - If both types are primitive, a safe conversion is done. - Integer casts will fail if the value is out of range. This means that promotion casts like i32 -> i64 are infallible. - Float -> Integer casts truncate the decimal point (?) - Integer -> Float casts resolve to the closest value to the integer representable by the floating-point type (?). If the integer value is too large, they resolve to infinity (?) - Any primitive -> bool will create `true` for any value except 0, which is `false`. - bool -> any primitive will do `false -> 0` and `true -> 1`, even for floats. - If the types are two different pointer types (see above), the cast is essentially a no-op. A cast to `T` will increment the reference count as expected; that's the preferred way of creating a strong reference from a weak reference. A cast from and to `raw T` is unsafe. - If the types are part of the same type hierarchy (i.e. one is a child type of another): - A child can be cast to its parent infallibly. - A parent can be cast to a child, but this will check the type at runtime and fail if the object was not of the child type or one of its subtypes. - If the types are incompatible, a user-defined cast is attempted to be used. The details here are not decided yet. - If nothing works, the cast will not even compile. Additional casts are available in the standard library. Two important ones are `as_saturated` and `as_truncated`, which cast integral values while saturating to the boundaries or truncating bits, respectively. ## Traits To make generics a bit more powerful and expressive, you can add additional information to them: ```jakt trait Hashable

{ fn hash(self) -> Output } class Foo implements(Hashable) { fn hash(self) => 42 } ``` Traits can be used to add constraints to generic types, but also provide default implementations based on a minimal set of requirements - for instance: ```jakt trait Fancy { fn do_something(this) -> void fn do_something_twice(this) -> void { .do_something() .do_something() } } struct Boring implements(Fancy) { fn do_something(this) -> void { println("I'm so boring") } // Note that we don't have to implement `do_something_twice` here, because it has a default implementation. } struct Better implements(Fancy) { fn do_something(this) -> void { println("I'm not boring") } // However, a custom implementation is still valid. fn do_something_twice(this) -> void { println("I'm not boring, but I'm doing it twice") } } ``` Traits can have methods that reference other traits as types, which can be used to describe a hierarchy of traits: ```jakt trait ConstIterable { fn next(this) -> T? } trait IntoIterator { // Note how the return type is a reference to the ConstIterable trait (and not a concrete type) fn iterator(this) -> ConstIterable } ``` ### Operator Overloading and Traits Operators are implemented as traits, and can be overloaded by implementing them on a given type: ```jakt struct Foo implements(Add) { x: i32 fn add(this, anon rhs: Foo) -> Foo { return Foo(x: .x + other.x) } } ``` The relationship between operators and traits is as follows (Note that `@` is used as a placeholder for any binary operator's name or sigil): | Operator | Trait | Method Name | Derived From Method | |----------|-------|-------------|---------------------| | `+` | `Add` | `add` | - | | `-` | `Subtract` | `subtract` | - | | `*` | `Multiply` | `multiply` | - | | `/` | `Divide` | `divide` | - | | `%` | `Modulo` | `modulo` | - | | `<` | `Compare` | `less_than` | `compare` | | `>` | `Compare` | `greater_than` | `compare` | | `<=` | `Compare` | `less_than_or_equal` | `compare` | | `>=` | `Compare` | `greater_than_or_equal` | `compare` | | `==` | `Equal` | `equals` | - | | `!=` | `Equal` | `not_equals` | `equals` | | `@=` | `@Assignment` | `@_assign` | - | Other operators have not yet been converted to traits, decided on, or implemented: | Operator | Description | Status | |----------|-------------|--------| | `&` | Bitwise And | Not Decided | | `\|` | Bitwise Or | Not Decided | | `^` | Bitwise Xor | Not Decided | | `~` | Bitwise Not | Not Decided | | `<<` | Bitwise Shift Left | Not Decided | | `>>` | Bitwise Shift Right | Not Decided | | `and` | Logical And | Not Decided | | `or` | Logical Or | Not Decided | | `not` | Logical Not | Not Decided | | `=` | Assignment | Not Decided | ## Safety analysis **(Not yet implemented)** To keep things safe, there are a few kinds of analysis we'd like to do (non-exhaustive): * Preventing overlapping of method calls that would collide with each other. For example, creating an iterator over a container, and while that's live, resizing the container * Using and manipulating raw pointers * Calling out to C code that may have side effects ## Error handling Functions that can fail with an error instead of returning normally are marked with the `throws` keyword: ```jakt fn task_that_might_fail() throws -> usize { if problem { throw Error::from_errno(EPROBLEM) } ... return result } fn task_that_cannot_fail() -> usize { ... return result } ``` Unlike languages like C++ and Java, errors don't unwind the call stack automatically. Instead, they bubble up to the nearest caller. If nothing else is specified, calling a function that `throws` from within a function that `throws` will implicitly bubble errors. ### Syntax for catching errors If you want to catch errors locally instead of letting them bubble up to the caller, use a `try`/`catch` construct like this: ```jakt try { task_that_might_fail() } catch error { println("Caught error: {}", error) } ``` There's also a shorter form: ```jakt try task_that_might_fail() catch error { println("Caught error: {}", error) } ``` ### Rethrowing errors **(Not yet implemented)** ## Inline C++ For better interoperability with existing C++ code, as well as situations where the capabilities of **Jakt** within `unsafe` blocks are not powerful enough, the possibility of embedding inline C++ code into the program exists in the form of `cpp` blocks: ```jakt mut x = 0 unsafe { cpp { "x = (i64)&x;" } } println("{}", x) ``` ## References Values and objects can be passed by reference in some situations where it's provably safe to do so. A reference is either immutable (default) or mutable. ### Reference type syntax - `&T` is an immutable reference to a value of type `T`. - `&mut T` is a mutable reference to a value of type `T`. ### Reference expression syntax - `&foo` creates an immutable reference to the variable `foo`. - `&mut foo` creates a mutable reference to the variable `foo`. ### Dereferencing a reference To "get the value out" of a reference, it must be dereferenced using the `*` operator, however the compiler will automatically dereference references if the dereferencing is the single unambiguous correct use of the reference (in practice, manual dereferencing is only required where the reference is being stored or passed to functions). ```jakt fn sum(a: &i64, b: &i64) -> i64 { return a + b // Or with manual dereferencing: return *a + *b } fn test() { let a = 1 let b = 2 let c = sum(&a, &b) } ``` For mutable references to structs, you'll need to wrap the dereference in parentheses in order to do a field access: ```jakt struct Foo { x: i64 } fn zero_out(foo: &mut Foo) { foo.x = 0 // Or with manual dereferencing: (*foo).x = 0 } ``` ### References (first version) feature list: - [x] Reference types - [x] Reference function parameters - [x ... ...

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