result.h

A header-only C library implementing Result and Optional types inspired by Rust, for modern and safe error handling in C.

Features

• Result types: Explicit error handling without exceptions
• Optional types: Type-safe optional values
• Error chaining: Full error traceability with stack traces
• Error domains: Classification and organization of errors
• Header-only: Easy integration

Quick Usage

Result

#include "result.h"

RESULT_TYPE(Int, int);

Result(Int) divide(int a, int b)
{
    if (b == 0)
        return Fail(Int, MATH_DOMAIN, MATH_ERR_DIV_BY_ZERO);
    return Ok(Int, a / b);
}

int main()
{
    Result(Int) result = divide(10, 2);
    
    if (is_ok(result))
        printf("Result: %d\n", unwrap_ok(result));
    else
        print_error_chain(stderr, unwrap_error(result));

    return 0;
}

Optional

#include "result.h"

OPTIONAL_TYPE(Int, int);

Optional(Int) find_value(int arr[], size_t len, int target)
{
    for (size_t i = 0; i < len; i++) {
        if (arr[i] == target)
            return Some(Int, arr[i]);
    }
    return None(Int);
}

int main()
{
    int arr[] = {1, 2, 3, 4, 5};
    Optional(Int) result = find_value(arr, 5, 3);
    
    int value = or_some(result, -1);
    printf("Found value: %d\n", value);
    
    return 0;
}

Build

meson setup builddir
meson compile -C builddir

./builddir/result_example filename.txt
./builddir/optional_example 42
./builddir/chaining_example
./builddir/map_example

API Reference

Types Result

• Ok(Type, value) - Creates a successful result
• Fail(Type, domain, code) - Creates an error result
• is_ok(result) / is_error(result) - State checking
• unwrap_ok(result) - Extracts value (panics on error)
• or_ok(result, default) - Returns value or default
• TRY(Type, var, expr) - Error propagation

Types Optional

• Some(Type, value) - Present value
• None(Type) - Absent value
• is_some(opt) / is_none(opt) - Presence checking
• unwrap_some(opt) - Extracts value (panics if absent)
• or_some(opt, default) - Returns value or default

Examples

See the examples/ directory for complete usage examples:

• result.c - File error handling
• optional.c - Optional values
• chaining.c - Error chaining
• map.c - Result transformation

License

MIT License - See LICENSE for details.