Stdlib.Obj
Operations on internal representations of values.
Not for the casual user.
val repr : 'a -> t
val obj : t -> 'a
val is_block : t -> bool
val is_int : t -> bool
val tag : t -> int
val size : t -> int
val 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
.
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.
val set_tag : t -> int -> unit
val double_field : t -> int -> float
val set_double_field : t -> int -> float -> unit
val new_block : int -> int -> t
val truncate : t -> int -> unit
module Closure : sig ... end
module Extension_constructor : sig ... end
module Ephemeron : sig ... end
Ephemeron with arbitrary arity and untyped