The C3 Blog¶

C3 Language at 0.7.5: Language tweaks and conveniences

The C3 programming language has reached 0.7.5, marking another milestone in the language's evolution. This release brings improvements to language features, developer experience, and standard library functionality.

Here's what's new and improved in this update.

Major Language Features

Module Aliasing Support

One of the new features in 0.7.5 is the introduction of module aliasing with the syntax alias foo = module std::io. This enhancement improves user control over code organization and readability, allowing developers to create shorter names for modules where needed.

Enhanced Compile-Time Capabilities

The compile-time system has received several additions: - Optional macro params: Gives macros arguments that are optional without requiring a default value. - ???: Compile time ternary, guaranteed to resolve at compile time and will not execute the false branch. - @safeinfer: Enables the use of var in function contexts, where it was previously disallowed. - New mathematical builtins: @intlog2, @clz, @min, @max and functions are now available at compile time. - bitsizeof macro builtin: Provides bit-level size information for types.

Operator Overloading Evolution

C3 0.7.5 brings improvements to operator overloading: - @operator(==) now also enables switch statement support for the type. - Enhanced chained array access: foo[x][y] = b now can pass through multiple levels of overloads, and works as expected with proper overload resolution. - Type.is_eq now correctly returns true for types with equality overloads.

Type System Enhancements

• $kindof: Shorthand for $typeof(...).kindof which simplifies contract checks.
• Implicit type conversions: Types now convert to typeid implicitly, streamlining contracts and compile time programming.
• Enhanced $defined: It now accepts declarations, like $defined(int x = y) which removes the need for macros like @assignable_to.
• Struct inheritance: Struct and typedef subtypes now inherit dynamic methods.

Developer Experience Improvements

Better Error Messages and Safety

The compiler now provides more helpful diagnostics: - Improved error messages for missing $endif and missing if bodies. - Better directory creation error messages in project and library creation - Huge stack object overflow protection with configurable --max-stack-object-size

Build System Enhancements

• Library management: c3l-libraries now package linked libraries in a directory specified by the "linklib-dir" setting.
• Cross-platform improvements: Enhanced support for different operating systems and architectures

Standard Library Expansion

New Data Structures and Utilities

The standard library has grown: - FileMmap: Memory-mapped file management - FixedBlockPool: Memory pool for fixed-size objects - HashSet: Generic hash set implementation with values method support - AsciiCharset: Fast ASCII character matching utilities - Logging system: Introduction of std::core::log for common logging .

Enhanced String Operations

String manipulation gets a boost with: - String.contains_char: Character containment checking - String.trim_charset: Trimming based on character sets - Functional array operations: New macros including @zip, @reduce, @filter, @any, @all, @sum, @product and @indices_of.

Breaking Changes and Deprecations

Important Deprecations

Several features have been deprecated in favor of improved alternatives: - @compact comparison behavior (use --use-old-compact-eq for compatibility) - add_array in favor of push_all on lists. - @assignable_to in favor of using $define. - @typekind in favor of using $kindof. - @typeis in favor of $typeof(foo) == Type. - @select in favor of $foo ??? #expr1 : #expr2.

Performance and Bug Fixes

Critical Fixes

This release addresses numerous important issues: - ASAN triggering fixes in List.remove_at - AVX512 vector handling corrections - Codegen improvements for if-try expressions - Memory allocation optimizations for 32-bit machines - Recursive generic creation detection

Platform-Specific Improvements

• Enhanced Android and OpenBSD support
• Improved native CPU detection
• Better cross-compilation support

Looking Forward

Deprecations of many type introspection macros, such as @typekind and @typeis is together with the improvements in $defined, the implicit type conversions to typeid and $kindof spearheading a shift to making constraint checking succinct while also being completely obvious. Relying on macros would often make the constraints less clear to a reader. On top of this we get compile time ternary using ??? : to succinctly express compile time selection between two expressions. With the changes, the code is as short to type but without the need to remember particulars of one macro over the other.

Overall, C3 0.7.5 represents another step in maturing the language's core features while laying the groundwork for future enhancements. The focus will continue to be aimed at improve developer experience, performance, and language consistency. Many of the standard library additions are contributions from the community around C3, which is providing essential feedback and direction to polish the language further. C3 is step-by-step establishing itself as a modern evolution of C that maintains simplicity while adding powerful abstractions.

Demo

For a deeper look at the changes, watch the demo.

Change Log

Want To Dive Into C3?

Check out the documentation or download it and try it out.

Have questions? Come and chat with us on Discord.

C3 0.7.4 Released: Enhanced Enum Support and Smarter Error Handling

C3 version 0.7.4 brings a substantial set of improvements focused on better enum support, enhanced error handling, improved debugging capabilities, and numerous quality-of-life improvements. And we're now also releasing binaries for OpenBSD! Here's a comprehensive look at what's new.

Major Language Features

Enhanced Enum Support

One of the most significant changes in 0.7.4 is the introduction of const enums. - Const enums: You can now declare enum Foo : const, which behaves like C enums but supports any underlying type - Direct enum casting: Casting to and from regular enums is now possible again without needing .ordinal and .from_ordinal methods - Deprecation warning: Inline associated enum values are now deprecated (use --use-old-enums to maintain compatibility)

New Error Handling Macros

C3 0.7.4 introduces two useful new macros for streamlined error handling: - @try: Takes an lvalue and returns a void?. It assigns the value if successful, otherwise returns the error. - @try_catch: Extended version that takes an lvalue, an expression, and the expected error value, it will return a bool?.

These macros can significantly reduce boilerplate when working with if-catch.

Compile-Time Improvements

Several compile-time features have been enhanced: - $typeof improvements: Now returns compile-time types in more contexts - @is_const introduction: This macro replaces the deprecated $is_const, and is based on $defined - Multiline contract comments: Contract documentation can now span multiple lines

Developer Experience Enhancements

Better Error Messages and Debugging

C3 0.7.4 continues the focus on improving the developer experience: - Improved error messages: Better reporting for missing enum qualifiers, struct initialization errors, and unsigned-to-signed conversion issues - Common mistake detection: The compiler now catches accidental foo == BAR; where foo = BAR; was likely intended - Enhanced debugging output: Added --echo-prefix for customizing $echo statement prefixes with {FILE} and {LINE} support

Assembly and Low-Level Development

• --list-asm flag: View all supported assembly instructions
• Unaligned access detection: The compiler now checks for unaligned array access
• Thread synchronization: New thread::fence function provides thread fencing capabilities

Build System Improvements

• Smarter output directories: Projects now output to out by default, with temp folders used for command-line builds
• Absolute path support: $embed now accepts absolute paths
• Math library auto-linking: libc math functions are now only linked when math functions are used.
• Author field improvements: The project authors field can now be accessed using env::AUTHORS and env::AUTHOR_EMAILS.

Performance and Memory Management

Hash Function Additions

The standard library now includes several new high-performance hash functions: - komihash - a5hash - metrohash64 and metrohash128 - wyhash2 variants - SipHash family of keyed PRFs

Memory Management Improvements

• Virtual memory: New virtual memory library and arena allocator
• Smaller memory limits: Support for even more restrictive memory environments
• Arena allocator fixes: Resolved resize bugs in ArenaAllocator, DynamicArenaAllocator, and BackedArenaAllocator
• No temp allocator in backtrace: Removed temp allocator usage in backtrace printing.

Standard Library Enhancements

Cryptography and Security

• Whirlpool hash: Added the Whirlpool cryptographic hash function
• Ed25519: Elliptic curve digital signature algorithm support

String and I/O Operations

• string::bformat: New binary formatting capabilities
• Enhanced formatting: The format option now supports pointers %h
• String case conversion: Functions for converting between snake_case and PascalCase

Concurrency Improvements

• Condition variable enhancements: Added ConditionVariable.wait_until and ConditionVariable.wait_for
• Stream I/O: New readline_to_stream function for stream-based input

Experimental Features

• Reference counting: Ref and RefCounted experimental types
• Memory safety types: Volatile and UnalignedRef generic types for typesafe volatile and unaligned references.

Bug Fixes and Stability

Version 0.7.4 includes over 40 bug fixes addressing: - Platform-specific issues (Android, Windows, POSIX) - Compile-time constant evaluation - Memory management edge cases - Type system consistency - Code generation improvements

Notable fixes include proper handling of null ZString comparisons, correct bounds checking for const ranges, and fixes to complex number operations.

Deprecations and Migration

Several features have been deprecated and to streamline the language: - $is_const → @is_const - $assignable → @assignable_to - allocator::heap() → mem and allocator::temp() → tmem - Inline associated enum values (use --use-old-enums for compatibility)

Diving deeper into the new const enums

C3 introduced ordinal based enums in 0.3.0. This allowed the language to support associated enum values and enum → string conversions at runtime with zero overhead. The downside was the lack of support for C enums with gaps. While possible to address with constants or associated values, it lacked the ease of C enums. However, C enums could not be made to properly support things the same things as the 0.3 C3 enums did.

The new "const enum" solves this problem. It works like a distinct type, with constants associated with it. It is defined like an enum, with const added after :. Its behaviour is the same as you would expect from C:

enum ConstEnum : const short
{
    ABC = 1,
    BDE,     // Implicitly 2
    DEF = 100
}

But the const enums can do things C enums can't do:

enum Greeting : const inline String
{
    HELLO = "Hello",
    WORLD = "World",
    YO    = "Yo"
}

fn void main()
{
    // Prints "Hello"
    io::printn(Greeting.HELLO); 
    // Inline allows implicit conversion to String
    io::printn(Greeting.YO == "Yo");
    // Inference works like for regular enums 
    Greeting g = WORLD; 
}

:::note[Note On reflection] The cost we pay for this is that we cannot get the ordinal, nor the name, so neither Greeting.YO.nameof nor Greeting.YO.ordinal will work. :::

The new @try and @try_catch

Usually in C3, implicit unwrapping is used to convert an Optional to a normal value:

fn void test1()
{
    int? f = foo();
    if (catch err = f)
    {
        /* do something */
        return;
    }
    /* f is unwrapped here */
}

However, sometimes the assignment may involve an already existing value, in which case we need a temporary:

fn void test2_old()
{
    int f = abc();
    while (some_condition())
    {
        /* use f */
        // f = foo(); <- we can't do this
        int? temp = foo();
        if (catch err = temp)
        {
            /* do something */
            return;
        }
        f = temp;
        /* continue */
    }
}

Having to introduce the temp variable isn't always ideal, and this is where @try comes in. It conditionally sets a variable if the value isn't Empty and otherwise returns the error. This allows us to rewrite the code without a temporary like this:

fn void test2_new()
{
    int f = abc();
    while (some_condition())
    {
        /* use f */
        if (catch err = @try(f, foo()))
        {
            /* do something */
            return;
        }
        /* continue */
    }
}

Another situation is when you only want to change a value if it's a non-Empty, it can also be improved:

fn void update_old()
{
    if (try temp = foo()) my_global = temp;
}
fn void update_new()
{
    (void)@try(my_global, foo());
}

The @try_catch works similar to @try but is useful when you have one expected fault and the other faults should be rethrown. It will also conditionally set a variable, but will return a bool? which is false when the variable is set, true if the expected fault is caught, or an Empty otherwise.

fn void? test3_old()
{
    while (true)
    {
        String? s = next_string();
        if (catch err = s)
        {
            if (err == io::EOF) break;
            return err?;
        }
        use_string(s);
    }
}

fn void? test3_new()
{
    while (true)
    {
        String s;
        if (@try_catch(s, next_string(), io::EOF)!) break;
        use_string(s);
    }
}

TLDR;

C3 0.7.4 introduces improved enum support, new error handling macros, and several enhancements to the developer experience. Key additions include const enums with flexible underlying types, direct enum casting, and streamlined error-handling via @try and @try_catch. The release also brings better error messages, improved debugging tools, and expanded standard library features such as new hash functions, Ed25519 support, and virtual memory management. Numerous bug fixes and deprecations aim to improve language consistency and performance. This version marks continued progress toward language maturity and usability.

Change Log

Want To Dive Into C3?

Check out the documentation or download it and try it out.

Have questions? Come and chat with us on Discord.

How C3 Manages Memory Without Leaks, GC, or Borrow Checkers

Modern languages offer a variety of techniques to help with dynamic memory management, each one a different tradeoff in terms of performance, control and complexity. In this post we'll look at an old idea, memory allocation regions or arenas, implemented via the C3 Temp allocator, which is the new default for C3.

The Temp allocator combines the ease of use of garbage collection with C3's unique features to give a simple and (semi)-automated solution within a manual memory management language. The Temp allocator helps you avoid memory leaks, improve performance, and simplify code compared to traditional approaches.

Memory allocations come in two broad types stack allocations which are compact, efficient and automatic and heap allocations which are much larger and have customisable organisation. Custom organisation allows both innovation and footguns in equal measure, let's explore those.

Memory Leaks

When we dynamically allocate memory, with say malloc() typically we need to free() it afterwards, otherwise we can't use that memory until the OS process exits. If that memory isn't being used and it has not been freed this is called a memory leak and can lead to restricting or running out of available system memory.

Avoiding Memory Leaks

Common solutions are RAII, reference counting or garbage collection which automatically free those variables.

Each method has different tradeoffs. - RAII needs classes or structs to manage their own memory cleanup with a lot of extra code. - Reference counting counts how many users each memory allocation has, when this hits zero the memory is freed. Reference counting is expensive with multiple CPU cores as we need to synchronise these counts and share information between cores. - Garbage collection competes with the program for both memory and CPU time, reducing program performance and increasing memory usage.

Memory Allocation Regions

Memory allocation regions, go by various names: arenas, pools, contexts; The idea dates back to the 1960's with the IBM OS/360 mainframes having a similar system. Memory regions are efficient for managing many memory allocations and can be freed in a single operation, and are particularly effective when we know the memory will not be needed later. That is, we know the memory's lifetime. This idea is powerful and used in many applications like web server request handlers or database transactions, as used by the Apache webserver and the Postgres database.

Memory allocation regions use a single buffer so have good locality because all the allocations are closely associated together, making it more efficient for CPU access, compared to traditional malloc where allocations are spread throughout the heap.

Memory allocation regions may make it easier to manage memory, however you still need to remember to free them, and if you forget to do call free, then that memory will still leak.

Enter The Temp Allocator

The Temp allocator in C3 is a region based allocator which is automatically reset once execution leaves its scope, so you cannot forget to free the memory and can't leak memory. The Temp allocator in C3 is a builtin in the standard library, called @pool() and using it you can define the scope where the allocated variables are available, for example:

fn int example(int input) 
{
    @pool()
    {
        // Allocate temp_variable on the heap with Temp allocator
        int* temp_variable = mem::tnew(int);
        *temp_variable = 56;
        input = input + temp_variable;
        return input;
    }; // Automatically cleanup temp_variable
} 

fn void main()
{
    int result = example(1);
    assert(result == 57, "The result should be 57");
}

Check With Valgrind

Valgrind is a tool which detects memory leaks and we can use it to show the temp allocator managed the memory for us automatically.

valgrind ./pool_example |& grep "All heap blocks were freed"
==129129== All heap blocks were freed -- no leaks are possible

Success!

We have relatively performant memory allocations managed automatically without needing RAII, garbage collection or reference counting.

Controlling Variable Cleanup

Normally temp allocated variables are cleaned up at the end of the closest @pool scope, but what if you have nested @pool and want explicit control over when it's cleaned up? Simple: assign the temp allocator with the scope you need to a variable, and use it explicitly. The temp allocator in a scope is a global variable called tmem.

fn String* example(int input)
{
    // previous global temp allocator from main() scope
    Allocator temp_allocator = tmem;

    @pool()
    {
        // Allocate on the global temp allocator
        String* returned = allocator::new(temp_allocator, String);
        *returned = string::format(temp_allocator, "modified %s", input);
        return returned;
    };
}

fn void main()
{
    // top-most temp allocator, tmem created here
    @pool()
    {
        String* returned = example(42);
        // "modified 42" string returned
        io::printn(*returned);
    };
}

A Handy Shorthand

We can reduce the code's nesting using short function declaration syntax => making it even simpler as:

fn int example(int input) => @pool(reserve: 2048)
{
    // Allocate temp_variable on the heap 
    int* temp_variable = mem::tnew(int);
    *temp_variable = 56;
    input = input + *temp_variable;
    return input;
}

In Simple Cases Omit @pool()

Happy with the defaults? We can actually omit the @pool() in main() all together!

The compiler automatically adds a @pool() scope to the main() function for us, once it finds a temp allocation function like mem::tnew(), without an enclosing @pool() scope. That simplifies our code to:

fn int example(int input)
{
    // Allocate temp_variable on the heap
    // @pool() temp allocator created for us by the compiler
    int* temp_variable = mem::tnew(int);
    *temp_variable = 56;
    input = input + *temp_variable;
    return input;
}

Conclusion

The Temp allocator has landed in C3; combining scoped compile time known memory lifetimes, ease of use and performance. Tying memory lifetimes to scope and automating cleanup, you get the benefits of manual control without the risks. No more memory leaks, use after free, or slow compile times with complex ownership tracking.

Whether you're building low-latency systems or just want more explicit code without garbage collection overhead, the C3 Temp allocator is a powerful tool to have in your arsenal, making memory management nearly effortless.

Want To Dive Into C3?

Check out the documentation or download it and try it out.

Have questions? Come and chat with us on Discord.

C3 0.7.3 - Small Improvements

This month's release is 0.7.3, and is about gradual improvements to the language. Some parts of a language will always have less use than others, and that is true for C3 as well. For C3 it's mostly the compile time parts that reveal their rough edges fairly late, but they need polish as well.

Type / typeid

Types can be introspected an manipulated in two ways in C3. One is to just use the type directly, like in Type.sizeof. The other is to use the typeid value, to get the same thing: Type.typeid.sizeof. However, they have differences: a typeid value can never be in the position of a type, and only compile time constant typeid has the full range of values:

typeid t = int.typeid;
const typeid T = int.typeid;
...
// Getting the size, this works for all
int.sizeof;     // Compile time value
T.sizeof;       // Compile time value
t.sizeof;       // Runtime value
// But others doesn't
int.max;        // Direct type access ok!
T.max;          // Const typeid access ok!
t.max;          // ERROR! Runtime access is not ok!
// Using it as a type in an assignment:
int a;          // Ok of course
T a;            // ERROR!
$typefrom(T) a; // Ok! Converts a typeid to a type.
$typefrom(t) a; // ERROR! Must be a compile time typeid

For macros that had type arguments they usually looked like this:

macro new_thing($Type) { ... }
...

Foo* f = new_thing(Foo);

The disadvantage was that if you had a constant typeid you'd first have to convert it to a type:

const typeid T = Foo.typeid;

void* thing = new_thing($typefrom(T));

Starting from 0.7.3 though, we can use the constant typeid directly and get an implicit conversion to a type:

const typeid T = Foo.typeid;

void* thing = new_thing(T);  // New in 0.7.3

The reason this is useful, is because constant macros can't return a type directly BUT can return a typeid. So maybe you have macro code like this:

typeid $type = @select_the_type($foo);

void* thing = new_thing($typefrom($type));

It can now be this instead:

typeid $type = @select_the_type($foo);

void* thing = new_thing($type);

And contracting the code it's even more of an improvement:

void* thing = new_thing($typefrom(@select_the_type($foo))); // 0.7.2
void* thing = new_thing(@select_the_type($foo));            // 0.7.3

It's just overall clearer to drop the superfluous $typefrom.

This also extends to the $assignable builtin, which also now takes either a type or a typeid.

Removing $evaltype

Also related to typeid and types is the deprecation of $evaltype. It takes a constant string and turns it into a type, so you could write:

String $name = "foo";
$evaltype($name) x = 1;

In order to simplify the language $evaltype is getting removed but the functionality is still there, because $typefrom can now also take a string.

String $name = "foo";
$typefrom($name) x = 1; // New in 0.7.3

This hopefully reduces the amount of different constructs it's necessary to know in order to understand advanced compile time code generation.

Improved type inference

C3 has type inference for initializers:

fn void test(int[3] x)
{ ... }

test({1, 2, 3});

However, this did not extend to &&:

// 0.7.2
fn void test(int[3]* x)
{ ... }

test(&&{1, 2, 3});      // ERROR!

This has now been improved:

// 0.7.3
fn void test(int[3]* x)
{ ... }

test(&&{1, 2, 3});      // Works in 0.7.3

Compile time @sprintf

Creating strings at compile time is sometimes desirable, but the help for it has been complicated an inefficient. Usually the use of +++ has been needed:

String $s = $foo +++ ":" +++ $bar;

Now, however, there is a @sprintf. It's not a full-fledged printf-like function. It only supports "%s" arguments, but will do a best effort to convert any compile time value:

int $v = 123;
Enum $x = FOO;
String $s = @sprintf("%s:%s", $v, $x); // $s = "123:FOO"

Often this is good enough, and the operation is much cheaper than the other compile time concatenation in terms of compiler resources.

$assert and $error "printf"

Hand-in-hand with the @sprintf, $assert and $error now accepts the same format as @sprintf for better compile time errors:

var $a = -123;
$assert $a > 0 : "$a was %s", $a;
// Above is a compile time error printing "$a was -123"

Better $eval

Where $evaltype is going away, $eval, which can turn a string into an identifier has been improved to properly work with @foo, #foo and $foo identifiers.

More liberal "main"

The main function used to only support String[] or int argc, char **argv as parameters. Now it accepts distinct types that lowers to the same arguments, so int argc, ZString* argv works properly.

--sources to add additional files to compile

Sometimes it's useful to add extra sources to compile with a regular build. --sources allows you to do exactly that:

c3c build --sources inject.c3

Improved overloading with wildcard types

One omission of the arithmetic overloads was supporting macros with wildcard types, so rather than writing a macro Foo Foo.add(self, int x) @operator(+) for every type you wanted to support, what if you could write macro Foo Foo.add(self, x) @operator(+) and handle the rest with contracts and compile time checks?

This actually crashed in 0.7.2, but in 0.7.3 this works correctly. It's even allowed with @operator_r and @operator_s variants.

Distinct improvements

Bitstructs can now be based on a distinct type, created by typedef:

typedef Test = int;
bitstruct Foo : Test // Works in 0.7.3
{
    int z : 1..3;
}

And it's now possible for generics to be generic over distinct const values:

module foo { VAL };
const GLOBAL = VAL;

module test;
import foo;
typedef Bar = int;

fn void main()
{
    const Bar B = 123;
    Bar b = foo::GLOBAL{B}; // Works in 0.7.3
}

Constant vector comparison

Vectors has been comparable at runtime, but not at compile time. However, from 0.7.3 and onwards this works:

int[<2>] $v = { 1, 2 };
int[<2>] $w = { 1, 2 };
$assert $v == $w;

Silence deprecation

@deprecated has been mostly used as a migration mechanism for the c3 standard library, but using it with user code requires more fine-grained control, which is why there is now an @allow_deprecated attribute to silence deprecation warnings inside a particular function:

fn void old() @deprecated {}

fn void test1()
{
    old(); // Emits warning
}

fn void test2() @allow_deprecated
{
    old(); // No warning
}

Removal of '\f' as whitespace

\f (the form-feed character) is not really used in normal text, so it has been removed from the characters recognized as whitespace by the lexer.

$memberof get/set improvements

You can get the member of a struct or union by indexing Type.membersof and then use the get method on the member to retrieve the value. However, there was no corresponding set method, instead you had to do *&$member.get(2) = 123. People have been asking for a .set for a long time, and that was also the only way to properly support setting bitstruct values:

bitstruct Foo : int
{
    int x : 1..5;
    int y : 10..14;
}
fn void test()
{
    var $member = Foo.membersof[1];
    Foo f = { 1, 3 };
    int val = $member.get(f);        // .get on bitstructs now works
    $member.set(f, val + 1);         // .set method updates
    io::printn(f.y);                 // Prints 4
}

Custom file extensions in build targets

It's now possible to override the extension used for libraries and executables of a target with the "extension" project property.

Bug fixes

0.7.3 shipped with around 40 bug fixes, which is a bit below average for a 0.0.1 release.

Stdlib additions

ZString types can now be compared using == by having equality overloaded. We have a SHA512 library and String.escape, String.unescape for escaping and unescaping strings. io::struct_to_format also now supports bitstructs, which means io::printn and related functions properly prints bitstructs.

Stdlib deprecations

String.is_zstr and String.quick_zstr are unsafe and are deprecated is_array_or_slice_of_char and is_arrayptr_or_slice_of_char are replaced by constant @ variants.

Change Log

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C3 0.7.2 - Quality Of Life

Unlike 0.7.1, 0.7.2 is not about big new features, instead it is laser focused on adding quality of life improvements, which are backwards compatible with other 0.7 releases.

Compile time additions

:::note[Note on compile time] C3 has visual differentiation between compile time and runtime code, to make it explicit when the code will be run.

Compile time code uses $if condition: ... $endif for conditional logic. Learn more about macros and compile time evaluation. :::

Simplifying compile time evaluated code

Setting a variable at compile time can now be simplified using compile time logical or ||| and compile time logical and &&& with a variable right hand expression.

The original code to set a variable at compile time:

$if FOO:
    bool x = true;
$else
    bool x = foo();
$endif

Now this compile time variable can be set with compile time logical or ||| compactly as:

bool x = FOO ||| foo();

You can also use compile time logical and &&& in a similar way.

Compile time random: @rnd

Sometimes it can be useful to create unique ids at compile time. This is now possible with the @rnd macro.

Compile time ceil: math::@ceil

It is somewhat hard to write a good compile time ceil function, so 0.7.2 adds a builtin which is accessible using the math::@ceil macro.

General additions

Set the run directory

To make c3c run and c3c compile-run more convenient, it's now possible to use --run-dir (or the project setting run-dir) to set the director from which the compiler runs the resulting binary.

Limits to SIMD sizes

Limitations of vectors are sometimes misunderstood, they will cause code bloat if used for large vectors. For this reason a max vector size has been introduced. By default this is 4096 bits, so basically the size of double[<64>]. It is possible to increase this using --max-vector-size as needed. (As a comparison, the biggest SIMD vectors on x64 is 512 bits, so such a 4096 bit vector would be represented by 8 registers).

has_tagof works on builtin types

While has_tagof will always return false on builtin types, this change nonetheless simplifies writing compile time code involving tags.

Allow recursive generic modules

To simplify generic module resolution it was not possible to recursively generate generic module. This restriction has been lifted in 0.7.1.

Deprecations

Bitsize suffix deprecations

The bitsize suffixes are deprecated, so rather than writing 23u64 use the C style 23UL instead. u128 and i128 suffixes are replaced by ULL and LL suffixes.

Finally, the d suffix for doubles have been added as a complement to f.

Compile time reflection deprecations

MyEnum.elements have been deprecated. Use MyEnum.len instead. SomeFn.params have been deprecated. Use SomeFn.paramsof instead.

Deprecation for old @param docs

By 0.7.1 the declaration style @param foo "abc" would be allowed rather than @param foo : "abc". This was by accident. It's now properly deprecated.

Generic faults are not allowed

Creating faults that are parameterized is usually a mistake and should not have been allowed. It's been completely removed in 0.7.2 as it was classified as a bug.

This is no longer allowed:

module Foo {Type};
typedef BAZ, HELLO;

Faults should be defined in a non-generic module, such as a parent module or sub-module instead.

Fixes

This release contains about 30 different fixes, most of them newly discovered and not regressions.

They range from fixes to advanced generic types to stdlib bugs.

Stdlib updates

Currently a new version of the matrix library is incubating, and while it didn't make it for the 0.7.2 release, I hope it can be included by 0.7.4 and contributions are welcome!

Optimized String -> ZString conversions

:::note[Note On Strings] Default C3 string: typedef String = inline char[];
C compatible, null terminated: typedef ZString = inline char*;

Learn more about strings. :::

Sometimes a String is already pointing to a valid ZString, so no copy is needed. To check this, String gets two new methods .is_zstr to check if the String is also zero terminated, and .quick_zstr which will create a temp ZString if needed, but otherwise use the String.

std::ascii moves into std::core

std::ascii moved into std::core::ascii. Old _m variants are deprecated, as is uint methods.

Better String tokenization

It's now possible to further customize tokenization, to ignore empty elements in the middle (or not), ignore any last empty elements at the end (or not). This introduces .tokenize_all which replaces the now deprecated .splitter method.

Count and replace

String further gets some conveniences: .count to count the number of instances of a string within the string and replace / treplace to return a new String with a substring replaced. This functionality was already in DString, but was now added to String as well.

Operator overloads for std::time and Maybe

Duration * Int, Clock - Clock and DateTime + Duration overloads were added for manipulating time.

For Maybe, the == operator is available when the inner type is equatable.

Subprocess improvements

Subprocess added an inherit_stdio option to inherit the parent's stdin, stdout, and stderr instead of creating pipes.

Change Log

Want To Dive Into C3?

Check out the documentation or download it and try it out.

Have questions? Come and chat with us on Discord.

Gradual improvements: C3 0.7.2

Originally from: https://c3.handmade.network/blog/p/9028-gradual_improvements__c3_0.7.2

It's another months and consequently it's time for a new incremental 0.7 release.

Additions

Unlike 0.7.1, 0.7.2 doesn't really add anything major, but just add a few quality of life enhancements:

||| and &&& with variable right hand side

Rather than writing:

$if FOO:
    bool x = true;
$else
    bool x = foo();
$endif

It's now possible to use ||| to write this compactly as:

bool x = FOO ||| foo();

&&& also supports this.

Compile time random: @rnd

Sometimes it can be useful to create unique ids at compile time. This is now possible with the @rnd macro.

Compile time ceil: math::@ceil

It is somewhat hard to write a good compile time ceil function, so 0.7.2 adds a builtin which is accessible using the math::@ceil macro.

Set the run directory

To make c3c run and c3c compile-run more convenient, it's now possible to use --run-dir (or the project setting run-dir) to set the director from which the compiler runs the resulting binary.

Suffix deprecations

The bitsize suffixes are deprecated, so rather than writing 23u64 use the C style 23UL instead. u128 and i128 suffixes are replaced by ULL and LL suffixes.

Finally, the d suffix for doubles have been added as a complement to f.

Compile time reflection deprecations

MyEnum.elements have been deprecated. Use MyEnum.len instead.

SomeFn.params have been deprecated. Use SomeFn.paramsof instead.

Limits to SIMD sizes

Limitations of vectors are sometimes misunderstood, they will cause code bloat if used for large vectors. For this reason a max vector size has been introduced. By default this is 4096 bits, so basically the size of double[<64>]. It is possible to increase this using --max-vector-size as needed. (As a comparison, the biggest SIMD vectors on x64 is 512 bits, so such a 4096 bit vector would be represented by 8 registers).

has_tagof works on builtin types

While has_tagof will always return false on builtin types, this change nonetheless simplifies writing compile time code involving tags.

Allow recursive generic modules

To simplify generic module resolution it was not possible to recursively generate generic module. This restriction has been lifted in 0.7.1.

Deprecation for old @param docs

By 0.7.1 the declaration style @param foo "abc" would be allowed rather than @param foo : "abc". This was by accident. It's now properly deprecated.

Generic faults are not allowed

Creating faults that are parameterized is usually a mistake and should not have been allowed. It's been completely removed in 0.7.2 as it was classified as a bug.

So no more

module Foo {Type};
typedef BAZ, HELLO;

Faults should be places in a parent or sub-module instead.

Fixes

This release contains about 30 different fixes, most of them newly discovered and not regressions.

They range from fixes to advanced generic types to stdlib bugs.

Stdlib updates

Currently a new version of the matrix library is incubating, and while it didn't make it for the 0.7.2 release, I hope it can be included by 0.7.4.

Optimized String -> ZString conversions

Sometimes a String is already pointing to a valid ZString, so no copy is needed. To check this, String gets two new methods .is_zstr to check if the String is also zero terminated, and .quick_zstr which will create a temp ZString if needed, but otherwise use the String.

std::ascii moves into core

std::ascii moved into std::core::ascii. Old _m variants are deprecated, as is uint methods.

Better String tokenization

It's now possible to further customize tokenization, to ignore empty elements in the middle (or not), ignore any last empty elements at the end (or not). This introduces .tokenize_all which replaces the now deprecated .splitter method.

Count and replace

String further gets some conveniences: .count to count the number of instances of a string within the string and replace / treplace to return a new String with a substring replaced. This functionality was already in DString, but was now added to String as well.

Operator overloads for std::time and Maybe

Duration * Int, Clock - Clock and DateTime + Duration overloads were added for manipulating time.

For Maybe, the == operator is available when the inner type is equatable.

Subprocess improvements

Subprocess added an inherit_stdio option to inherit the parent's stdin, stdout, and stderr instead of creating pipes.

Changelist

The full changelist is here:

### Changes / improvements
- Better default assert messages when no message is specified #2122
- Add `--run-dir`, to specify directory for running executable using `compile-run` and `run` #2121.
- Add `run-dir` to project.json.
- Add `quiet` to project.json.
- Deprecate uXX and iXX bit suffixes.
- Add experimental LL / ULL suffixes for int128 and uint128 literals.
- Allow the right hand side of `|||` and `&&&` be runtime values.
- Added `@rnd()` compile time random function (using the `$$rnd()` builtin). #2078
- Add `math::@ceil()` compile time ceil function. #2134
- Improve error message when using keywords as functions/macros/variables #2133.
- Deprecate `MyEnum.elements`.
- Deprecate `SomeFn.params`.
- Improve error message when encountering recursively defined structs. #2146
- Limit vector max size, default is 4096 bits, but may be increased using --max-vector-size.
- Allow the use of `has_tagof` on builtin types.
- `@jump` now included in `--list-attributes` #2155.
- Add `$$matrix_mul` and `$$matrix_transpose` builtins.
- Add `d` as floating point suffix for `double` types.
- Deprecate `f32`, `f64` and `f128` suffixes.
- Allow recursive generic modules.
- Add deprecation for `@param foo "abc"`.
- Add `--header-output` and `header-output` options for controlling header output folder.
- Generic faults is disallowed.

### Fixes
- Assert triggered when casting from `int[2]` to `uint[2]` #2115
- Assert when a macro with compile time value is discarded, e.g. `foo();` where `foo()` returns an untyped list. #2117
- Fix stringify for compound initializers #2120.
- Fix No index OOB check for `[:^n]` #2123.
- Fix regression in Time diff due to operator overloading #2124.
- attrdef with any invalid name causes compiler assert #2128.
- Correctly error on `@attrdef Foo = ;`.
- Contract on trying to use Object without initializing it.
- Variable aliases of aliases would not resolve correctly. #2131
- Variable aliases could not be assigned to.
- Some folding was missing in binary op compile time resolution #2135.
- Defining an enum like `ABC = { 1 2 }` was accidentally allowed.
- Using a non-const as the end range for a bitstruct would trigger an assert.
- Incorrect parsing of ad hoc generic types, like `Foo{int}****` #2140.
- $define did not correctly handle generic types #2140.
- Incorrect parsing of call attributes #2144.
- Error when using named argument on trailing macro body expansion #2139.
- Designated const initializers with `{}` would overwrite the parent field.
- Empty default case in @jump switch does not fallthrough #2147.
- `&&&` was accidentally available as a valid prefix operator.
- Missing error on default values for body with default arguments #2148.
- `--path` does not interact correctly with relative path arguments #2149.
- Add missing `@noreturn` to `os::exit`.
- Implicit casting from struct to interface failure for inheriting interfaces #2151.
- Distinct types could not be used with tagof #2152.
- `$$sat_mul` was missing.
- `for` with incorrect `var` declaration caused crash #2154.
- Check pointer/slice/etc on `[out]` and `&` params. #2156.
- Compiler didn't check foreach over flexible array member, and folding a flexible array member was allowed #2164.
- Too strict project view #2163.
- Bug using `#foo` arguments with `$defined` #2173
- Incorrect ensure on String.split.
- Removed the naive check for compile time modification, which fixes #1997 but regresses in detection.

### Stdlib changes
- Added `String.quick_ztr` and `String.is_zstr`
- std::ascii moved into std::core::ascii. Old _m variants are deprecated, as is uint methods.
- Add `String.tokenize_all` to replace the now deprecated `String.splitter`
- Add `String.count` to count the number of instances of a string.
- Add `String.replace` and `String.treplace` to replace substrings within a string.
- Add `Duration * Int` and `Clock - Clock` overload.
- Add `DateTime + Duration` overloads.
- Add `Maybe.equals` and respective `==` operator when the inner type is equatable.
- Add `inherit_stdio` option to `SubProcessOptions` to inherit parent's stdin, stdout, and stderr instead of creating pipes. #2012
- Remove superfluous `cleanup` parameter in `os::exit` and `os::fastexit`.
- Add `extern fn ioctl(CInt fd, ulong request, ...)` binding to libc;

If you want to read more about C3, check out the documentation: https://c3-lang.org or download it and try it out: https://github.com/c3lang/c3c

Comments

Comment by Christoffer Lernö

It's another months and consequently it's time for a new incremental 0.7 release.

Additions

Unlike 0.7.1, 0.7.2 doesn't really add anything major, but just add a few quality of life enhancements:

||| and &&& with variable right hand side

Rather than writing:

$if FOO:
    bool x = true;
$else
    bool x = foo();
$endif

It's now possible to use ||| to write this compactly as:

bool x = FOO ||| foo();

&&& also supports this.

Compile time random: @rnd

Sometimes it can be useful to create unique ids at compile time. This is now possible with the @rnd macro.

Compile time ceil: math::@ceil

It is somewhat hard to write a good compile time ceil function, so 0.7.2 adds a builtin which is accessible using the math::@ceil macro.

Set the run directory

To make c3c run and c3c compile-run more convenient, it's now possible to use --run-dir (or the project setting run-dir) to set the director from which the compiler runs the resulting binary.

Suffix deprecations

The bitsize suffixes are deprecated, so rather than writing 23u64 use the C style 23UL instead. u128 and i128 suffixes are replaced by ULL and LL suffixes.

Finally, the d suffix for doubles have been added as a complement to f.

Compile time reflection deprecations

MyEnum.elements have been deprecated. Use MyEnum.len instead.

SomeFn.params have been deprecated. Use SomeFn.paramsof instead.

Limits to SIMD sizes

Limitations of vectors are sometimes misunderstood, they will cause code bloat if used for large vectors. For this reason a max vector size has been introduced. By default this is 4096 bits, so basically the size of double[<64>]. It is possible to increase this using --max-vector-size as needed. (As a comparison, the biggest SIMD vectors on x64 is 512 bits, so such a 4096 bit vector would be represented by 8 registers).

has_tagof works on builtin types

While has_tagof will always return false on builtin types, this change nonetheless simplifies writing compile time code involving tags.

Allow recursive generic modules

To simplify generic module resolution it was not possible to recursively generate generic module. This restriction has been lifted in 0.7.1.

Deprecation for old @param docs

By 0.7.1 the declaration style @param foo "abc" would be allowed rather than @param foo : "abc". This was by accident. It's now properly deprecated.

Generic faults are not allowed

Creating faults that are parameterized is usually a mistake and should not have been allowed. It's been completely removed in 0.7.2 as it was classified as a bug.

So no more

module Foo {Type};
typedef BAZ, HELLO;

Faults should be places in a parent or sub-module instead.

Fixes

This release contains about 30 different fixes, most of them newly discovered and not regressions.

They range from fixes to advanced generic types to stdlib bugs.

Stdlib updates

Currently a new version of the matrix library is incubating, and while it didn't make it for the 0.7.2 release, I hope it can be included by 0.7.4.

Optimized String -> ZString conversions

Sometimes a String is already pointing to a valid ZString, so no copy is needed. To check this, String gets two new methods .is_zstr to check if the String is also zero terminated, and .quick_zstr which will create a temp ZString if needed, but otherwise use the String.

std::ascii moves into core

std::ascii moved into std::core::ascii. Old _m variants are deprecated, as is uint methods.

Better String tokenization

It's now possible to further customize tokenization, to ignore empty elements in the middle (or not), ignore any last empty elements at the end (or not). This introduces .tokenize_all which replaces the now deprecated .splitter method.

Count and replace

String further gets some conveniences: .count to count the number of instances of a string within the string and replace / treplace to return a new String with a substring replaced. This functionality was already in DString, but was now added to String as well.

Operator overloads for std::time and Maybe

Duration * Int, Clock - Clock and DateTime + Duration overloads were added for manipulating time.

For Maybe, the == operator is available when the inner type is equatable.

Subprocess improvements

Subprocess added an inherit_stdio option to inherit the parent's stdin, stdout, and stderr instead of creating pipes.

Changelist

The full changelist is here:

### Changes / improvements
- Better default assert messages when no message is specified #2122
- Add `--run-dir`, to specify directory for running executable using `compile-run` and `run` #2121.
- Add `run-dir` to project.json.
- Add `quiet` to project.json.
- Deprecate uXX and iXX bit suffixes.
- Add experimental LL / ULL suffixes for int128 and uint128 literals.
- Allow the right hand side of `|||` and `&&&` be runtime values.
- Added `@rnd()` compile time random function (using the `$$rnd()` builtin). #2078
- Add `math::@ceil()` compile time ceil function. #2134
- Improve error message when using keywords as functions/macros/variables #2133.
- Deprecate `MyEnum.elements`.
- Deprecate `SomeFn.params`.
- Improve error message when encountering recursively defined structs. #2146
- Limit vector max size, default is 4096 bits, but may be increased using --max-vector-size.
- Allow the use of `has_tagof` on builtin types.
- `@jump` now included in `--list-attributes` #2155.
- Add `$$matrix_mul` and `$$matrix_transpose` builtins.
- Add `d` as floating point suffix for `double` types.
- Deprecate `f32`, `f64` and `f128` suffixes.
- Allow recursive generic modules.
- Add deprecation for `@param foo "abc"`.
- Add `--header-output` and `header-output` options for controlling header output folder.
- Generic faults is disallowed.

### Fixes
- Assert triggered when casting from `int[2]` to `uint[2]` #2115
- Assert when a macro with compile time value is discarded, e.g. `foo();` where `foo()` returns an untyped list. #2117
- Fix stringify for compound initializers #2120.
- Fix No index OOB check for `[:^n]` #2123.
- Fix regression in Time diff due to operator overloading #2124.
- attrdef with any invalid name causes compiler assert #2128.
- Correctly error on `@attrdef Foo = ;`.
- Contract on trying to use Object without initializing it.
- Variable aliases of aliases would not resolve correctly. #2131
- Variable aliases could not be assigned to.
- Some folding was missing in binary op compile time resolution #2135.
- Defining an enum like `ABC = { 1 2 }` was accidentally allowed.
- Using a non-const as the end range for a bitstruct would trigger an assert.
- Incorrect parsing of ad hoc generic types, like `Foo{int}****` #2140.
- $define did not correctly handle generic types #2140.
- Incorrect parsing of call attributes #2144.
- Error when using named argument on trailing macro body expansion #2139.
- Designated const initializers with `{}` would overwrite the parent field.
- Empty default case in @jump switch does not fallthrough #2147.
- `&&&` was accidentally available as a valid prefix operator.
- Missing error on default values for body with default arguments #2148.
- `--path` does not interact correctly with relative path arguments #2149.
- Add missing `@noreturn` to `os::exit`.
- Implicit casting from struct to interface failure for inheriting interfaces #2151.
- Distinct types could not be used with tagof #2152.
- `$$sat_mul` was missing.
- `for` with incorrect `var` declaration caused crash #2154.
- Check pointer/slice/etc on `[out]` and `&` params. #2156.
- Compiler didn't check foreach over flexible array member, and folding a flexible array member was allowed #2164.
- Too strict project view #2163.
- Bug using `#foo` arguments with `$defined` #2173
- Incorrect ensure on String.split.
- Removed the naive check for compile time modification, which fixes #1997 but regresses in detection.

### Stdlib changes
- Added `String.quick_ztr` and `String.is_zstr`
- std::ascii moved into std::core::ascii. Old _m variants are deprecated, as is uint methods.
- Add `String.tokenize_all` to replace the now deprecated `String.splitter`
- Add `String.count` to count the number of instances of a string.
- Add `String.replace` and `String.treplace` to replace substrings within a string.
- Add `Duration * Int` and `Clock - Clock` overload.
- Add `DateTime + Duration` overloads.
- Add `Maybe.equals` and respective `==` operator when the inner type is equatable.
- Add `inherit_stdio` option to `SubProcessOptions` to inherit parent's stdin, stdout, and stderr instead of creating pipes. #2012
- Remove superfluous `cleanup` parameter in `os::exit` and `os::fastexit`.
- Add `extern fn ioctl(CInt fd, ulong request, ...)` binding to libc;

If you want to read more about C3, check out the documentation: https://c3-lang.org or download it and try it out: https://github.com/c3lang/c3c

C3 0.7.1 - Operator Overloading

0.7.0 was supposed to be THE big change this year, but 0.7.1 is actually quitely introducing some very important features.

Operator overloading

Operator overloading has been added to help games and maths programming, a previous blog goes into more depth, below is a short overview.

Operator overloading overview

The @operator attribute defines the overload for Vec + int

To define something like int + Vec there are two additional attributes added:

• @operator_s ("symmetric operator") allows either type to go first.
• @operator_r ("reverse operator") requires the second term to be the first one in the arithmetic expression.

Examples

Overloading with the @operator overload attribute:

// Defining a simple add: "Complex + Complex"
macro Complex Complex.add(self, Complex b) @operator(+)
{
    return { .v = self.v + b.v };
} 
// Define the self-modifying +=: "Complex += Complex"
macro Complex Complex.add_this(&self, Complex b) @operator(+=) 
{
    return { .v = self.v += b.v };
}

Overloading with the @operator_s symmetric overload attribute:

// This defines "Quaternion * Real" /and/ "Real * Quaternion"
macro Quaternion Quaternion.scale(self, Real s) @operator_s(*)
{
    return { .v = self.v * s };
}

Overloading with the @operator_r reverse overload attribute:

// This defines "Real / Complex"
macro Complex Complex.div_real_inverse(Complex c, Real r) @operator_r(/) 
{
    return ((Complex) { .r = self }).div(c);
}

More static checking

An important step towards correctness is that @require contracts for functions are now inlined at the caller site in safe mode. This has always been a thing for macros, but now this works for functions as well.

This means simple errors can be caught by the compiler, such as using a null pointer where it wasn't allowed or passing a zero where the argument:

<*
 @require a > 0 : "The parameter cannot be zero"
*>
fn void test(int a)
{ ... }

fn void main()
{
    // Compile time error: contract violation 
    // "The parameter cannot be zero"
    test(0); 
}

This is just the start. C3 will increasingly use more static analysis to check correctness at compile time.

Improvements to attributes

@if attributes now work on locals and aliases defined using alias can now be @deprecated.

Enum lookup

0.6.9 and 0.7.0 introduced ways to let an enum convert to its associated value:

enum Foo : (inline int val)
{
    ABC = 3,
    LIFF = 42
}

fn void main()
{
    int val = Foo.LIFF; // Same as Foo.LIFF.val
}

Still, converting from such a associated value to an enum used the rather unknown @enum_from_value macro.

To make this more convenient, enums gain two new type functions .lookup and .lookup_field: - lookup(value) lookup an enum by inlined value. - lookup_field(field_name, value) lookup an enum by associated value.

fn void main()
{
    Foo? foo = Foo.lookup(42);            // Returns Foo.LIFF
    Foo? foo2 = Foo.lookup_field(val, 3); // Returns Foo.ABC
    Foo? foo3 = Foo.lookup_field(val, 1); // Returns NO_FOUND?
}

Other changes

• String str = "" was not guaranteed to return a pointer to a null terminated empty string, unlike ZString str = "". This was a little inconsistent, so both return the same thing now.
• Slice assignment foo[..] = bar would sometimes mean copying the right hand side to each element of foo and sometimes it meant a slice copy. Now semantics have been tightened: foo[..] = bar assigns to each element and foo[..] = bar[..] is a copy.
• c3c build now picks the first target rather than the first executable.
• Finally the Win32 thread implementation has been improved.

What's next?

Following this release, the focus will be on improving the standard library organization. New guidelines for submitting modules have been adopted to ensure that the implementation can be worked on without having to be tied to a pull request. Right now an updated matrix library is actively worked on.

There is also a new repo for uncurated C3 resources, where anyone can be showcased: So if you have a project you want to share – do file a pull request.

Change Log

Want To Dive Into C3?

Check out the documentation or download it and try it out.

Have questions? Come and chat with us on Discord.

C3 0.7.1 - Operator overloading, here we come!

Originally from: https://c3.handmade.network/blog/p/9021-c3_0.7.1_-_operator_overloading%252C_here_we_come%2521

0.7.0 was supposed to be THE big change this year, but 0.7.1 is actually quitely introducing some very important features.

Operator overloading

Operator overloading is the biggest change of course, which is already covered in great detail here. The @operator, @operator_s and @operator_r attributes are used to enable overloading for user defined types.

More static checking

An important step towards correctness is that @require contracts for functions are now inlined at the caller site for safe mode. This has always been a thing for macros, but now this works for functions as well. This means simple errors, such as using a null pointer where it wasn't allowed or passing a zero where the argument:

<*
 @require a > 0 : "The parameter cannot be zero"
*>
fn void test(int a)
{ ... }

fn void main()
{
    test(0); // Compile time error: contract violation "The parameter cannot be zero"
}

This is just the start. C3 will increasingly use more static analysis to check correctness at compile time.

Improvements to attributes

@if attributes now work on locals and aliases defined using alias can now be @deprecated.

Enum lookup

0.6.9 and 0.7.0 introduced ways to let an enum convert to its associated value:

enum Foo : (inline int val)
{
    ABC = 3,
    LIFF = 42
}

fn void main()
{
    int val = Foo.LIFF; // Same as Foo.LIFF.val
}

Still, converting from such a associated value would use the rather unknown @enum_from_value macro.

To make this more convenient, enums gain two new type functions .lookup and .lookup_field:

fn void main()
{
    Foo? foo = Foo.lookup(42);            // Returns Foo.LIFF
    Foo? foo2 = Foo.lookup_field(val, 3); // Returns Foo.ABC
    Foo? foo3 = Foo.lookup_field(val, 1); // Returns NO_FOUND?
}

Other changes

• String str = "" was not guaranteed to return a pointer to a null terminated empty string, unlike ZString str = "". This was a little inconsistent, so both return the same thing now.
• Slice assignment foo[..] = bar would sometimes mean copying the right hand side to each element of foo and sometimes it meant a slice copy. Now semantics have been tightened: foo[..] = bar assigns to each element and foo[..] = bar[..] is a copy.
• c3c build now picks the first target rather than the first executable.
• Finally the Win32 thread implementation has been improved.

What's next?

Following this release, the focus will be on improving the standard library organization. New guidelines for submitting modules have been adopted to ensure that the implementation can be worked on without having to be tied to a pull request. Right now an updated matrix library is actively worked on.

There is also a new repo for uncurated C3 resources, where anyone can be showcased: https://github.com/c3lang/c3-showcase, so if you have a project you want to share – do file a pull request.

The full change list for 0.7.1 can be found below:

Changes / improvements

• Better errors on some common casting mistakes (pointer->slice, String->ZString, deref pointer->array) #2064.
• Better errors trying to convert an enum to an int and vice versa.
• Function @require checks are added to the caller in safe mode. #186
• Improved error message when narrowing isn't allowed.
• Operator overloading for + - * / % & | ^ << >> ~ == != += -= *= /= %= &= |= ^= <<= >>=
• Add @operator_r and @operator_s attributes.
• More stdlib tests: sincos, ArenaAllocator, Slice2d.
• Make aliases able to use @deprecated.
• Refactored stdlib file organization.
• Allow @if on locals.
• String str = "" is now guaranteed to be null terminated. #2083
• Improved error messages on Foo { 3, abc } #2099.
• Foo[1..2] = { .baz = 123 } inference now works. #2095
• Deprecated old inference with slice copy. Copying must now ensure a slicing operator at the end of the right hand side: foo[1..2] = bar[..] rather than the old foo[1..2] = bar. The old behaviour can be mostly retained with --use-old-slice-copy).
• Added Enum.lookup and Enum.lookup_field.
• c3c build picks first target rather than the first executable #2105.
• New Win32 Mutex, ConditionVariable and OnceFlag implementation

Fixes

• Trying to cast an enum to int and back caused the compiler to crash.
• Incorrect rounding at compile time going from double to int.
• Regression with invalid setup of the WASM temp allocator.
• Correctly detect multiple overloads of the same type.
• ABI bug on x64 Linux / MacOS when passing a union containing a struct of 3 floats. #2087
• Bug with slice acces as inline struct member #2088.
• @if now does implicit conversion to bool like $if. #2086
• Fix broken enum inline -> bool conversions #2094.
• @if was ignored on attrdef, regression 0.7 #2093.
• @ensure was not included when the function doesn't return a value #2098.
• Added missing @clone_aligned and add checks to @tclone
• Comparing a distinct type with an enum with an inline distinct type failed unexpectedly.
• The %s would not properly print function pointers.
• Compiler crash when passing an untyped list as an argument to assert #2108.
• @ensure should be allowed to read "out" variables. #2107
• Error message for casting generic to incompatible type does not work properly with nested generics #1953
• Fixed enum regression after 0.7.0 enum change.
• ConditionVariable now properly works on Win32

Stdlib changes

• Hash functions for integer vectors and arrays.
• Prefer math::I and math::I_F for math::IMAGINARY and math::IMAGINARYF the latter is deprecated.
• Add array::contains to check for a value in an array or slice.

If you want to read more about C3, check out the documentation: https://c3-lang.org or download it and try it out: https://github.com/c3lang/c3c

Comments

Comment by Christoffer Lernö

0.7.0 was supposed to be THE big change this year, but 0.7.1 is actually quitely introducing some very important features.

Operator overloading

Operator overloading is the biggest change of course, which is already covered in great detail here. The @operator, @operator_s and @operator_r attributes are used to enable overloading for user defined types.

More static checking

An important step towards correctness is that @require contracts for functions are now inlined at the caller site for safe mode. This has always been a thing for macros, but now this works for functions as well. This means simple errors, such as using a null pointer where it wasn't allowed or passing a zero where the argument:

<*
 @require a > 0 : "The parameter cannot be zero"
*>
fn void test(int a)
{ ... }

fn void main()
{
    test(0); // Compile time error: contract violation "The parameter cannot be zero"
}

This is just the start. C3 will increasingly use more static analysis to check correctness at compile time.

Improvements to attributes

@if attributes now work on locals and aliases defined using alias can now be @deprecated.

Enum lookup

0.6.9 and 0.7.0 introduced ways to let an enum convert to its associated value:

enum Foo : (inline int val)
{
    ABC = 3,
    LIFF = 42
}

fn void main()
{
    int val = Foo.LIFF; // Same as Foo.LIFF.val
}

Still, converting from such a associated value would use the rather unknown @enum_from_value macro.

To make this more convenient, enums gain two new type functions .lookup and .lookup_field:

fn void main()
{
    Foo? foo = Foo.lookup(42);            // Returns Foo.LIFF
    Foo? foo2 = Foo.lookup_field(val, 3); // Returns Foo.ABC
    Foo? foo3 = Foo.lookup_field(val, 1); // Returns NO_FOUND?
}

Other changes

• String str = "" was not guaranteed to return a pointer to a null terminated empty string, unlike ZString str = "". This was a little inconsistent, so both return the same thing now.
• Slice assignment foo[..] = bar would sometimes mean copying the right hand side to each element of foo and sometimes it meant a slice copy. Now semantics have been tightened: foo[..] = bar assigns to each element and foo[..] = bar[..] is a copy.
• c3c build now picks the first target rather than the first executable.
• Finally the Win32 thread implementation has been improved.

What's next?

Following this release, the focus will be on improving the standard library organization. New guidelines for submitting modules have been adopted to ensure that the implementation can be worked on without having to be tied to a pull request. Right now an updated matrix library is actively worked on.

There is also a new repo for uncurated C3 resources, where anyone can be showcased: https://github.com/c3lang/c3-showcase, so if you have a project you want to share – do file a pull request.

The full change list for 0.7.1 can be found below:

Changes / improvements

• Better errors on some common casting mistakes (pointer->slice, String->ZString, deref pointer->array) #2064.
• Better errors trying to convert an enum to an int and vice versa.
• Function @require checks are added to the caller in safe mode. #186
• Improved error message when narrowing isn't allowed.
• Operator overloading for + - * / % & | ^ << >> ~ == != += -= *= /= %= &= |= ^= <<= >>=
• Add @operator_r and @operator_s attributes.
• More stdlib tests: sincos, ArenaAllocator, Slice2d.
• Make aliases able to use @deprecated.
• Refactored stdlib file organization.
• Allow @if on locals.
• String str = "" is now guaranteed to be null terminated. #2083
• Improved error messages on Foo { 3, abc } #2099.
• Foo[1..2] = { .baz = 123 } inference now works. #2095
• Deprecated old inference with slice copy. Copying must now ensure a slicing operator at the end of the right hand side: foo[1..2] = bar[..] rather than the old foo[1..2] = bar. The old behaviour can be mostly retained with --use-old-slice-copy).
• Added Enum.lookup and Enum.lookup_field.
• c3c build picks first target rather than the first executable #2105.
• New Win32 Mutex, ConditionVariable and OnceFlag implementation

Fixes

• Trying to cast an enum to int and back caused the compiler to crash.
• Incorrect rounding at compile time going from double to int.
• Regression with invalid setup of the WASM temp allocator.
• Correctly detect multiple overloads of the same type.
• ABI bug on x64 Linux / MacOS when passing a union containing a struct of 3 floats. #2087
• Bug with slice acces as inline struct member #2088.
• @if now does implicit conversion to bool like $if. #2086
• Fix broken enum inline -> bool conversions #2094.
• @if was ignored on attrdef, regression 0.7 #2093.
• @ensure was not included when the function doesn't return a value #2098.
• Added missing @clone_aligned and add checks to @tclone
• Comparing a distinct type with an enum with an inline distinct type failed unexpectedly.
• The %s would not properly print function pointers.
• Compiler crash when passing an untyped list as an argument to assert #2108.
• @ensure should be allowed to read "out" variables. #2107
• Error message for casting generic to incompatible type does not work properly with nested generics #1953
• Fixed enum regression after 0.7.0 enum change.
• ConditionVariable now properly works on Win32

Stdlib changes

• Hash functions for integer vectors and arrays.
• Prefer math::I and math::I_F for math::IMAGINARY and math::IMAGINARYF the latter is deprecated.
• Add array::contains to check for a value in an array or slice.

If you want to read more about C3, check out the documentation: https://c3-lang.org or download it and try it out: https://github.com/c3lang/c3c

C3 goes game and maths friendly with operator overloading

Originally from: https://c3.handmade.network/blog/p/9019-c3_goes_game_and_maths_friendly_with_operator_overloading

Operator overloading is a divisive feature. It's been used for atrocious hacks, and to make code totally unreadable, but it's also the reason people stick to a C-like subset of C++ rather than using plain C for projects.

C3 has had operator overloading for a long time, but only for array indexing. In fact there are four different overloads: len [] []= and &[]. Together they do not only enable indexing, but more importantly they enable foreach.

If a type implements len and at least one of [] and &[], then you get foreach on that type. &[] is required for foreach with ref arguments though. And while you can use [] without implementing len, you need len for reverse indexing like a[^3].

However, I've resisted adding operator overloading for arithmetics and equals. Such a change brings us further away from C semantics than I've felt comfortable with. It can certainly be extremely misused and cause confusion.

But, as of 0.7.1 it's in the language. So what made me change my mind?

Most important to me is the fact that in practice people need this. C already has features that can be misused, such as untyped pointers, and we still use it. The same can be said of operator overloading.

Overview

C3 allows the arithmetic operators + - * / % and unary - to be overloaded. In addition to this, bit operators ^ | & and << >> may be overloaded. == and != and "operator + assign" operators such as += and <<= are also possible to overload.

Some technical details:

1. You can create multiple overloads for a single type, for example Vec * Vec and Vec * int.
2. Only user defined types may be overloaded. However, bitstructs already have ^ | & defined, so those may not be overloaded.
3. Overloading == will implicitly make != work and vice versa.
4. "operator + assign" operators are not required, they will be generated from the operator if not present.

Working with primitive types

While it's not possible to add @operator (the attribute usually used to define the overload) to define something like int + Vec, there are two additional attributes added: @operator_s ("symmetric operator") and @operator_r ("reverse operator") to help it. The former allows either type to go first, and @operator_r requires the second term to be the first one in the arithmetic expression.

Examples

// Defining a simple add: "Complex + Complex"
macro Complex Complex.add(self, Complex b) @operator(+) => { .v = self.v + b.v };
// Define the self-modifying +=: "Complex += Complex"
macro Complex Complex.add_this(&self, Complex b) @operator(+=) => { .v = self.v += b.v };

The use of the symmetric operator overloading:

// This defines "Quaternion * Real" /and/ "Real * Quaternion"
macro Quaternion Quaternion.scale(self, Real s) @operator_s(*) => { .v = self.v * s };

And finally, reverse operator:

// This defines "Real / Complex"
macro Complex Complex.div_real_inverse(Complex c, Real r) @operator_r(/) => ((Complex) { .r = self }).div(c);

The goals and non-goals of C3 operator overloading

The goal of overloading in C3 is allow arithmetics to be used on more types than the built in ones. In C, types such as Complex needs to be implemented in the language itself to get access to + - * /. Expanding the number of builtin types is possible, and the solution the programming language Odin uses. In Odin there is a rich number of builtins, including quaternion and matrix types.

There is a limit to this, as each builtin would increase the complexity of the language itself. I recently considered fixed point types which in the absence of operator overloading would have to use method syntax or be builtins. The former makes such types second class and builtins would increase the language complexity.

That this is such a popular feature with maths and game programming also speaks strongly for its inclusion.

But we also have non goals for C3: I don't want operator overloading that is used to create "magic" solutions in C++. So overloading for things like casting operations, dereference, method dot and logical comparisons are out of scope.

The goal is to enable numerical types to be used in a convenient manner, not to enable advanced abstractions with smart pointers and the like.

That said, there are some omissions:

1. Comparison operators: useful for some numerical types, such as fixed point numbers, but less so for others – like a complex number or a matrix. Does it need to be in?
2. Bool conversion: again more useful for fixed point numbers than other numerical types even though zero may be well defined. That's said, it's easily abused.

So at least for 0.7.1, these are omitted.

C3: An evolved C + operator overloading

C3 brings a lot of conveniences and improvements to C: slices, modules, generics, error handling, SIMD vectors, methods, contracts and more.

Mostly these are incremental improvements. If we look at something like slices, C can have slice types too, using macros, but it's inconvenient. Similar with generics (macro-based generics are possible in C), SIMD vectors, contracts etc.

On the other hand .method() syntax is certainly not in C, and C3 has much more compile time reflection available, but this is rarely a major pain point for C programmers. Operator overloading on the other hand: this is something you can't properly emulate in C. So for C programmers that really need operator overloading, there isn't really any way to get this. C++ or some similarly more complex language - such as Rust – is the only way out.

Of the recent indie C alternatives: Odin, Zig, C3 and Hare, only C3 offers operator overloading(*). Odin, as previously mentioned, addresses the issue with a rich set of builtin numerical types instead.

So moving forward it's possible that this feature should be pushed a bit more as it differentiates C3 from the alternatives. People looking for a simpler alternative to C++ for "C + operator overloading", now has C3 as another option to consider.

(* One should note that Jai, Jonathan Blow's C++ alternative geared towards game programming, offers operator overloading)

Wrapping it up

It's taken a long time for C3 to get operator overloading, but now that it's finally here, the language will lean into it, taking advantage of what it offers. Some features, such as @compact implicitly allowing comparisons will likely be removed. The standard library will add fixed point numbers and potentially leverage it for other things as well that otherwise was so marginal as to never be considered (saturating integers comes to mind).

I have been extremely reluctant to add operator overloading for arithmetics and resisted it for years, so the fact that we're adding it to C3 anyway is showing how much value it brings.

0.7.1 will officially be released the 1st of May (possibly earlier)

Comments

Comment by Christoffer Lernö

Operator overloading is a divisive feature. It's been used for atrocious hacks, and to make code totally unreadable, but it's also the reason people stick to a C-like subset of C++ rather than using plain C for projects.

C3 has had operator overloading for a long time, but only for array indexing. In fact there are four different overloads: len [] []= and &[]. Together they do not only enable indexing, but more importantly they enable foreach.

If a type implements len and at least one of [] and &[], then you get foreach on that type. &[] is required for foreach with ref arguments though. And while you can use [] without implementing len, you need len for reverse indexing like a[^3].

However, I've resisted adding operator overloading for arithmetics and equals. Such a change brings us further away from C semantics than I've felt comfortable with. It can certainly be extremely misused and cause confusion.

But, as of 0.7.1 it's in the language. So what made me change my mind?

Most important to me is the fact that in practice people need this. C already has features that can be misused, such as untyped pointers, and we still use it. The same can be said of operator overloading.

Overview

C3 allows the arithmetic operators + - * / % and unary - to be overloaded. In addition to this, bit operators ^ | & and << >> may be overloaded. == and != and "operator + assign" operators such as += and <<= are also possible to overload.

Some technical details:

1. You can create multiple overloads for a single type, for example Vec * Vec and Vec * int.
2. Only user defined types may be overloaded. However, bitstructs already have ^ | & defined, so those may not be overloaded.
3. Overloading == will implicitly make != work and vice versa.
4. "operator + assign" operators are not required, they will be generated from the operator if not present.

Working with primitive types

While it's not possible to add @operator (the attribute usually used to define the overload) to define something like int + Vec, there are two additional attributes added: @operator_s ("symmetric operator") and @operator_r ("reverse operator") to help it. The former allows either type to go first, and @operator_r requires the second term to be the first one in the arithmetic expression.

Examples

// Defining a simple add: "Complex + Complex"
macro Complex Complex.add(self, Complex b) @operator(+) => { .v = self.v + b.v };
// Define the self-modifying +=: "Complex += Complex"
macro Complex Complex.add_this(&self, Complex b) @operator(+=) => { .v = self.v += b.v };

The use of the symmetric operator overloading:

// This defines "Quaternion * Real" /and/ "Real * Quaternion"
macro Quaternion Quaternion.scale(self, Real s) @operator_s(*) => { .v = self.v * s };

And finally, reverse operator:

// This defines "Real / Complex"
macro Complex Complex.div_real_inverse(Complex c, Real r) @operator_r(/) => ((Complex) { .r = self }).div(c);

The goals and non-goals of C3 operator overloading

The goal of overloading in C3 is allow arithmetics to be used on more types than the built in ones. In C, types such as Complex needs to be implemented in the language itself to get access to + - * /. Expanding the number of builtin types is possible, and the solution the programming language Odin uses. In Odin there is a rich number of builtins, including quaternion and matrix types.

There is a limit to this, as each builtin would increase the complexity of the language itself. I recently considered fixed point types which in the absence of operator overloading would have to use method syntax or be builtins. The former makes such types second class and builtins would increase the language complexity.

That this is such a popular feature with maths and game programming also speaks strongly for its inclusion.

But we also have non goals for C3: I don't want operator overloading that is used to create "magic" solutions in C++. So overloading for things like casting operations, dereference, method dot and logical comparisons are out of scope.

The goal is to enable numerical types to be used in a convenient manner, not to enable advanced abstractions with smart pointers and the like.

That said, there are some omissions:

1. Comparison operators: useful for some numerical types, such as fixed point numbers, but less so for others – like a complex number or a matrix. Does it need to be in?
2. Bool conversion: again more useful for fixed point numbers than other numerical types even though zero may be well defined. That's said, it's easily abused.

So at least for 0.7.1, these are omitted.

C3: An evolved C + operator overloading

C3 brings a lot of conveniences and improvements to C: slices, modules, generics, error handling, SIMD vectors, methods, contracts and more.

Mostly these are incremental improvements. If we look at something like slices, C can have slice types too, using macros, but it's inconvenient. Similar with generics (macro-based generics are possible in C), SIMD vectors, contracts etc.

On the other hand .method() syntax is certainly not in C, and C3 has much more compile time reflection available, but this is rarely a major pain point for C programmers. Operator overloading on the other hand: this is something you can't properly emulate in C. So for C programmers that really need operator overloading, there isn't really any way to get this. C++ or some similarly more complex language - such as Rust – is the only way out.

Of the recent indie C alternatives: Odin, Zig, C3 and Hare, only C3 offers operator overloading(*). Odin, as previously mentioned, addresses the issue with a rich set of builtin numerical types instead.

So moving forward it's possible that this feature should be pushed a bit more as it differentiates C3 from the alternatives. People looking for a simpler alternative to C++ for "C + operator overloading", now has C3 as another option to consider.

(* One should note that Jai, Jonathan Blow's C++ alternative geared towards game programming, offers operator overloading)

Wrapping it up

It's taken a long time for C3 to get operator overloading, but now that it's finally here, the language will lean into it, taking advantage of what it offers. Some features, such as @compact implicitly allowing comparisons will likely be removed. The standard library will add fixed point numbers and potentially leverage it for other things as well that otherwise was so marginal as to never be considered (saturating integers comes to mind).

I have been extremely reluctant to add operator overloading for arithmetics and resisted it for years, so the fact that we're adding it to C3 anyway is showing how much value it brings.

0.7.1 will officially be released the 1st of May (possibly earlier)

C3: Operator overloading is coming in 0.7.1

Originally from: https://c3.handmade.network/blog/p/9016-c3__operator_overloading_is_coming_in_0.7.1

Initially I had planned 0.7.1 to be mostly patching 0.7.0, but plans change.

The big news is that operator overloading is coming. Not just the existing overload of [] &[] and []=, but arithmetics, bit operations and equals is all coming.

Comparisons is conspicuously missing, but might arrive.

Overloading is here to simplify creating numerical types that can be manipulated with the normal operators.

Consequently, there won't be anything like C++, where you can overload deref, dot invocation, casts etc. Also, overloads may not manipulate global state.

All in all, using these overloads for anything but numerical types is not intended (yes, so don't string concat with + nor should you use << to append to lists etc)

Operator overloading will only allowed on user defined types.

Comments

Comment by Christoffer Lernö

Initially I had planned 0.7.1 to be mostly patching 0.7.0, but plans change.

The big news is that operator overloading is coming. Not just the existing overload of [] &[] and []=, but arithmetics, bit operations and equals is all coming.

Comparisons is conspicuously missing, but might arrive.

Overloading is here to simplify creating numerical types that can be manipulated with the normal operators.

Consequently, there won't be anything like C++, where you can overload deref, dot invocation, casts etc. Also, overloads may not manipulate global state.

All in all, using these overloads for anything but numerical types is not intended (yes, so don't string concat with + nor should you use << to append to lists etc)

Operator overloading will only allowed on user defined types.