Unbound value Bytes.set_int8

Learning
1

Error:

16 |   Bytes.set_int8 out_bytes 0 (v.x );
       ^^^^^^^^^^^^^^
Error: Unbound value Bytes.set_int8

Code:

open! Core


module Pt3 = struct
  type t =
    { x : int
    ; y : int
    ; z : int};;


let write (out_oc: Out_channel.t) (v: t) : unit =
  let out_bytes = Bytes.create 8 in 
  let _ = v in
  let _ = out_oc in
  let _ = out_bytes in
  Bytes.set_int8 out_bytes 0 (v.x );
  Out_channel.output out_oc out_bytes 0 1;Out_channel.bytes out_oc out_bytes 0 1;Out_channel.bytes out_oc out_bytes 0 1;  ();;


let read (in_ic: In_channel.t) (v: unit) : t =
  let _ = v in
  let _ = in_ic in 
  failwith "";;


end

set_int8 is documented at OCaml library : Bytes

val set_int8 : bytes -> int -> int -> unit
set_int8 b i v sets b's signed 8-bit integer starting at byte index i to v.

Context:

generating code that writes structs to bytearray

2

Looks like you’re using Core, not the standard OCaml libraries. Check the docs for Core, which has different signatures for many functions in the standard libraries.

2 Likes
3

On a related issue, is there a reason why OCaml library : Stdlib.Bytes seems to lack uint32 and uint64 ?

4

It has setters and getters for 32-bit and 64-bit little endian, big endian and native endian integers. According to the documentation “32-bit and 64-bit integers are represented by the int32 and int64 types, which can be interpreted either as signed or unsigned numbers.” If you convert Int64 to int on a 64 bit platform then you may lose the high bit, and likewise int32 on on 32-bit platforms. Int64.unsigned_to_int might also be useful to you.