greycat-c

GreyCat SDK - C API, Standard Library & Plugin Development

Comprehensive reference for GreyCat native development (C API), the GCL Standard Library, and plugin development patterns. Tracks SDK 8.3 (headers re-verified 2026-09-09 against upstream 0dc6e7632). Changes since 8.2:

• gc_object__is_instance_of now accounts for monomorphization — a Box<String> instance now tests true against the generic declaration Box, not just exact-type/inheritance matches as before. Signature unchanged. See api_memory_text.md.
• Stdlib: runtime::Log.time is explicitly @format(DurationUnit::microseconds) — the field was always written as raw epoch microseconds by the log writer, now the type declares it instead of leaving it implicit. Reading files/root/log.csv with CsvReader<runtime::Log> needs CsvFormat { string_delimiter: '\0' }, since the payload column is written unescaped. See standard_library.md.

Previously, in 8.2 (headers re-verified 2026-08-28 against upstream e1e7edf54):

• New: gc_dtz_time__parse_format(str, len, format, format_len, tz, out_epoch_us) — parses a date/time string against an explicit format, the counterpart of gc_dtz_time__print and the custom-format arm of gc_dtz_time__parse. A format leaves the instant naive, so tz is the zone it is read in; returns false when the input does not match the format, or names an instant the zone does not have. See api_services.md.
• New: CLI hooks on gc_program_library. Two optional gc_hook_function_t * fields — install and codegen — with setters gc_program_library__set_install_hook(lib, hook) and gc_program_library__set_codegen_hook(lib, hook). The install hook runs at the end of a successful greycat install (after the project is rebuilt and linked) for every library that registers one; returning false fails the command. The codegen hook makes the library itself a generator for greycat codegen <lang>, dispatched by matching <lang> against library names (the built-in c/ts/java/rust/python2 generators stay native to the CLI). Both are purely additive — a NULL hook opts out. See plugin_development.md, api_core.md.
• New: resolved host configuration exposed to native libraries. gc/env.h defines gc_env_slot_t (tagged-by-convention union: bool/i64_t/u64_t/f64_t/char *) and gc_env_options_offset_t (one variant per CLI/.env-resolved option, e.g. gc_env_options__port, gc_env_options__ca_path, terminated by the length marker gc_env_options_len). The new gc_host__options(host) returns a const gc_env_slot_t * array indexed by that enum, valid for the life of the host. gc/ca.h's new gc_ssl_ca__pem_bundle(u64_t *len) hands out the resolved TLS trust chain (system CA store + ca_path) as a PEM byte string, owned by the runtime — for libraries that verify their own TLS connections and want to honor the same trust config as the host. Both headers are pulled in automatically via greycat.h. Full detail: api_runtime_storage.md.
• New: gc_machine__this_type(self) — the gc_type_t counterpart to gc_machine__this; returns gc_type_undefined (and must not be called) when the current frame has no receiver. New: gc_abi__finalize_ex(abi) — releases everything a load allocated but not abi itself, for callers that own a gc_abi_t inline rather than through gc_abi__create. Both added for the Rust SDK rewrite. See api_core.md, api_runtime_storage.md.
• Breaking: gc_slot_t union field order changed. u64_t u64 is now the first member (previously bool b was first), to stop positional (non-designated) initializers from silently truncating through bool. Any code using a non-designated gc_slot_t initializer ((gc_slot_t){x} with no .field =) now targets .u64 instead of .b — designated initializers ({.i64 = x}, {.object = p}, etc., used throughout this SDK's own examples) are unaffected. See api_core.md.
• Breaking: three gc/buffer.h type-name helpers removed, no replacement. gc_buffer__add_type_name, gc_buffer__add_type_name_by_id, and gc_buffer__add_type_qname are gone from the header entirely (briefly exported, then removed again in the same cycle — never shipped as stable). Code calling any of the three no longer compiles. Every remaining gc/buffer.h function is now uniformly gc_sdk-exported (some previously lacked the export macro and could fail to link from a plugin shared library on strict-visibility builds) — this includes the pre-existing non-static inline writer functions (gc_buffer__write_u8 / _bool / _u16 / _u32 / _u64 / _u64_at / _f64 / _vu32 / _vu64 / _vi64 / _ptr), now reliably linkable from callers (e.g. FFI bindings) that can't call a C static inline function. See api_memory_text.md.