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Module Syscall_result

Representation of Unix system call results

Almost no Unix system call returns a negative integer in case of success.

We can use this to encode the result of a system call as either a positive integer value or -errno. This allows us to avoid exceptions for dealing with errors such as EAGAIN. Indeed, in some context we issue a system call in a tight loop that will often fail with EAGAIN and using exceptions to return it is costly.

Signature

type 'a t = private int

There is no with sexp_of on purpose as it could only print the 'a value as an integer. Use <:sexp_of< Int.t >> or <:sexp_of< Unit.t >>.

module type S = Syscall_result_intf.S with type 'a syscall_result := 'a t
module Make (M : Arg) () : S with type ok_value := M.t
module Int : S with type ok_value := int
module Unit : S with type ok_value := unit
val create_error : Unix_error.t -> _ t
val unit : Unit.t
val is_ok : _ t -> bool
val is_error : _ t -> bool
val error_exn : _ t -> Unix_error.t
val ignore_ok_value : _ t -> Unit.t

Keep only the error.