Module Obj

module Obj: sig .. end

Operations on internal representations of values.

Not for the casual user.

type t;

type raw_data = nativeint;

let repr: 'a => t;

let obj: t => 'a;

let magic: 'a => 'b;

let is_block: t => bool;

let is_int: t => bool;

let tag: t => int;

let size: t => int;

let reachable_words: t => int;

Computes the total size (in words, including the headers) of all heap blocks accessible from the argument. Statically allocated blocks are excluded, unless the runtime system was configured with --disable-naked-pointers.

@Since 4.04

let field: (t, int) => t;

let set_field: (t, int, t) => unit;

When using flambda:

set_field MUST NOT be called on immutable blocks. (Blocks allocated in C stubs, or with new_block below, are always considered mutable.)

The same goes for set_double_field and set_tag. However, for set_tag, in the case of immutable blocks where the middle-end optimizers never see code that discriminates on their tag (for example records), the operation should be safe. Such uses are nonetheless discouraged.

For experts only: set_field et al can be made safe by first wrapping the block in Sys.opaque_identity, so any information about its contents will not be propagated.

let set_tag: (t, int) => unit;

let double_field: (t, int) => float;

let set_double_field: (t, int, float) => unit;

let raw_field: (t, int) => raw_data;

let set_raw_field: (t, int, raw_data) => unit;

let new_block: (int, int) => t;

let dup: t => t;

let truncate: (t, int) => unit;

let add_offset: (t, Int32.t) => t;

let with_tag: (int, t) => t;

let first_non_constant_constructor_tag: int;

let last_non_constant_constructor_tag: int;

let lazy_tag: int;

let closure_tag: int;

let object_tag: int;

let infix_tag: int;

let forward_tag: int;

let no_scan_tag: int;

let abstract_tag: int;

let string_tag: int;

let double_tag: int;

let double_array_tag: int;

let custom_tag: int;

let final_tag: int;

let int_tag: int;

let out_of_heap_tag: int;

let unaligned_tag: int;

module Closure: sig .. end

module Extension_constructor: sig .. end

let extension_constructor: 'a => extension_constructor;

let extension_name: extension_constructor => string;

let extension_id: extension_constructor => int;

The following two functions are deprecated. Use module Marshal instead.

let marshal: t => bytes;

let unmarshal: (bytes, int) => (t, int);

module Ephemeron: sig .. end