Jiyu Update - January 2020

Josh Huelsman · January 1, 2020

Progress has been going pretty strong this past monthly-ish period.

  • There is now a #clang_import directive. This allows importing declarations from C header files directly into Jiyu scopes. Example:
 #clang_import "#include <stdio.h>";
 func main() {
     printf("Hello, Moonman!\n");

The string following the directive can contain arbitrary C code. This works for a number of C declaration types, including structs, unions, enums, functions, and typedefs. Do note however, that only importing bindings for declarations is supported, there is no support for compiling C function bodies, and there are no plans for Jiyu to replace a C compiler. I have been using this for awhile on Windows, and have even gotten the nuklear imgui library working without needing to manually write bindings, but this may not work well on Mac/Linux yet if you need to import system headers.

  • There is now a mechanism to enable member-function-call syntax for arrays. I have documented this in this demo below:
#import "LibC";
#import "Array";

// Array module defines:
// __array_add<T>(arr: *[..] T, item: T)
// __array_reset<T>(arr: *[..] T)
// __array_reserve<T>(arr: *[..] T)
// __array_resize<T>(array: *[..] T, _amount: int)
// __array_pop<T>(array: *[..] T) -> T
// __array_contains<T>(array: *[..] T, item: T) -> bool
// __array_add_if_unique<T>(array: *[..] T, item: T) -> bool

func main() {
    // When the compiler sees <array>.func(...), it will attempt to transform this sequence into
    // __array_func(<array>, ...) or __array_func(*<array>, ...).
    var arr: [..] int64;

    for arr printf("Value: %lld\n", it);

    printf("Popped value: %lld\n", arr.pop());

    for arr printf("Remaining Value: %lld\n", it);

    for arr printf("Remaining Value ????: %lld\n", it); // This should not output anything!


func locally_scoped_functions() {
    // Since this special syntax turns into a scope-lookup,
    // we can override the defaults defined in the Array module.
    func __array_add<T>(array: *[..] T, item: T) {
        printf("Hello, Sailor!");

    var arr: [..] int64;
    for arr printf("Remaining Value ????: %lld\n", it); // should not print anything!

  • There is now a -emit-llvm flag to dump generated LLVM IR to a file.
  • Unions are now available, simply use the union keyword in place of struct.
  • break and continue now work for while-loops.
  • os() now checks against LLVM’s support operating system types and the target triple of the compilation. See Triple::getOSTypeName for a list of valid inputs. The input is case-insensitive.
  • Raspberry Pi 4 is now officially supported. Relevant tweet.
  • Diagnostic-esque information is no longer printed to the terminal by default. There is now a -v flag to print out this information for debugging. There’s also a verbose_diagnostics Build_Option available to get this information out of a compilation through a metaprogram.
  • while-loop conditions now coerce-to-bool.
  • There are now built-in typealiases to reference the types for <string>.length and <array>.count fields. They are __builtin_string_length_type and __builtin_array_count_type.
  • Global variable structs are now properly default-initialized based on the default initializations of their fields.
  • castano has added support for referencing let-constants declared within structs.
  • castano has added a Sublime Text highlighting extension.
  • castano has added support for multiline string literals similar to how they are implemented in Swift:
#import "Basic";
#import "LibC";

let singleLineString = "These are the same.";

let multilineString = """
These are the same.

let multilineString2 = """These are the same.""";

let multilineString3 = """
    These are the same.

func main() {
    // Multi-line string equivalency.
    printf("%.*s\n", singleLineString.length, singleLineString.data);
    printf("%.*s\n", multilineString.length, multilineString.data);
    printf("%.*s\n", multilineString2.length, multilineString2.data);
    printf("%.*s\n", multilineString3.length, multilineString3.data);
    assert(singleLineString == multilineString);
    assert(singleLineString == multilineString2);
    assert(singleLineString == multilineString3);

    let indentation = """
        This text has indentation.
        And that is fine.

    printf("%.*s\n", indentation.length, indentation.data);

  • Support for passing and returning structs to/from C has been improved.
  • There are now strideof() and alignof() operators. These return the stride and alignment of any input type. Unlike C, the the size of a struct is the amount of space required to store the struct, the stride is the amount of space needed to store the struct with padding to its alignment.
  • There is now support for unary ! and unary ~.
  • There is now support for a rudimentary level of struct inheritance:
 func test_inheritance() {
    struct Node {
        var i = 10;

        func do_a_thing() {
            printf("Node do_a_thing()\n");

        func do_a_thing2(n: *Node) {
            printf("Node.i: %d\n", n.i);

    struct Node_Child : Node {
        var b = "test";

        func do_a_thing3(n: *Node_Child) {
            printf("Node_Child.i: %d\n", n.i);
            printf("Node_Child.b: %.*s\n", n.b.length, n.b.data);

    var child: Node_Child;


I want to again thank the contributors for picking up this project and helping to improve it!

The code for the compiler can be found at: jiyu. Pull requests, feature requests, and issue reports are all welcome.

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