Frama-C API - Structural_descr

Internal representations of OCaml type as first class values. These values are called structural descriptors.

  • since Carbon-20101201

Type declarations

type recursive

Type used for handling (possibly mutually) recursive structural descriptors. See module Recursive.

type single_pack = private Unmarshal.t
type pack = private
  1. | Nopack

    Was impossible to build a pack.

  2. | Pack of single_pack

    A standard pack.

  3. | Recursive of recursive

    Pack for a recursive descriptor. See module Recursive.


Structural descriptor used inside structures.

type t = private
  1. | Unknown

    Use it either for unmarshable types or if you don't know its internal representation. In any case, values of types with this descriptor will never be written on disk.

  2. | Abstract

    The data is marshable as an usual OCaml value. No specific processing will be applied on any part of such a data.

  3. | Structure of structure

    Provide a description of the representation of data.

  4. | T_pack of single_pack

    Internal use only. Do not use it outside the library


Type of internal representations of OCaml type.

Example: the structural descriptor of A | B of int * bool | C of string is Structure (Sum [| [| p_int; p_bool |]; [| p_string |] |]). Ok, in this case, just Abstract is valid too.

and structure = private
  1. | Sum of pack array array

    Sum c describes a non-array type where c is an array describing the non-constant constructors of the type being described (in the order of their declarations in that type). Each element of this latter array is an array of t that describes (in order) the fields of the corresponding constructor.

  2. | Array of pack

    The data is an array of values of the same type, each value being described by the pack.


Description with details.

Pack builders

val pack : t -> pack

Pack a structural descriptor in order to embed it inside another one.

val recursive_pack : recursive -> pack

Pack a recursive descriptor.

  • since Nitrogen-20111001
module Recursive : sig ... end

Use this module for handling a (possibly recursive) structural descriptor d. Call Recursive.create () (returning r) before building d. Build d and use Recursive r in places where d should be put. Call Recursive.update r d after building d.

Predefined descriptors

val t_unknown : t
  • since Neon-20140301
val t_abstract : t
  • since Neon-20140301
val t_unit : t
val t_int : t
val t_string : t
val t_float : t
val t_bool : t
val t_int32 : t
val t_int64 : t
val t_nativeint : t
val t_record : pack array -> t
val t_tuple : pack array -> t
val t_list : t -> t
val t_ref : t -> t
val t_option : t -> t
val t_array : t -> t
val t_queue : t -> t
val t_sum : pack array array -> t
  • since Neon-20140301

Use the functions below only if the compare/hash functions cannot change by marshalling.

val t_set_unchanged_compares : t -> t
val t_map_unchanged_compares : t -> t -> t
val t_hashtbl_unchanged_hashs : t -> t -> t

Packed versions of predefined descriptors.

val p_abstract : pack

Equivalent to pack Abstract

val p_unit : pack
val p_string : pack
val p_float : pack
val p_bool : pack
val p_int32 : pack
val p_int64 : pack
val p_nativeint : pack


These values must be used only inside the Type library.

exception Cannot_pack
val unsafe_pack : Unmarshal.t -> pack
val of_pack : single_pack -> t
val cleanup : t -> t
val are_consistent : t -> t -> bool

Not symmetrical: check that the second argument is a correct refinement of the first one.