Module Core.NothingSource

This module extends Base.Nothing.

Having [@@deriving enumerate] may seem strange due to the fact that generated val all : t list is the empty list, so it seems like it could be of no use.

This may be true if you always expect your type to be Nothing.t, but [@@deriving enumerate] can be useful if you have a type which you expect to change over time. For example, you may have a program which has to interact with multiple servers which are possibly at different versions. It may be useful in this program to have a variant type which enumerates the ways in which the servers may differ. When all the servers are at the same version, you can change this type to Nothing.t and code which uses an enumeration of the type will continue to work correctly.

This is a similar issue to the identifiability of Nothing.t. As discussed below, another case where [@deriving enumerate] could be useful is when this type is part of some larger type.

Similar arguments apply for other derivers, like globalize and sexp_grammar.

Sourceval all : t list
Sourceval globalize : t -> t
Sourceval t_sexp_grammar : t Sexplib0.Sexp_grammar.t
Sourceval unreachable_code : t -> _

Because there are no values of type Nothing.t, a piece of code that has a value of type Nothing.t must be unreachable. In such an unreachable piece of code, one can use unreachable_code to give the code whatever type one needs. For example:

  let f (r : (int, Nothing.t) Result.t) : int =
    match r with
    | Ok i -> i
    | Error n -> Nothing.unreachable_code n
  ;;

Note that the compiler knows that Nothing.t is uninhabited, hence this will type without warning:

  let f (Ok i : (int, Nothing.t) Result.t) = i
Sourceval unreachable_code_local : t -> _

The same as unreachable_code, but for local ts.

It may seem weird that this is identifiable, but we're just trying to anticipate all the contexts in which people may need this. It would be a crying shame if you had some variant type involving Nothing.t that you wished to make identifiable, but were prevented for lack of Identifiable.S here.

Obviously, of_string and t_of_sexp will raise an exception.

include Base.Identifiable.S with type t := t
include Sexplib0.Sexpable.S with type t := t
include Base.Stringable.S with type t := t
include Base.Comparable.S with type t := t
include Base.Comparisons.S with type t := t
include Base.Comparisons.Infix with type t := t
include Base.Comparator.S with type t := t
Sourcetype comparator_witness = Base.Nothing.comparator_witness
include Base.Pretty_printer.S with type t := t
Sourceval equal__local : t -> t -> bool
Sourceval compare__local : t -> t -> int
Sourceval must_be_none : t option -> unit

Ignores None and guarantees there is no Some _. A better replacement for ignore.

Sourceval must_be_empty : t list -> unit

Ignores [] and guarantees there is no _ :: _. A better replacement for ignore.

Sourceval must_be_ok : ('ok, t) Base.Result.t -> 'ok

Returns ok from Ok ok and guarantees there is no Error _.

Sourceval must_be_error : (t, 'err) Base.Result.t -> 'err

Returns err from Error err and guarantees there is no Ok _.

Sourceval must_be_first : ('fst, t) Base.Either.t -> 'fst

Returns fst from First fst and guarantees there is no Second _.

Sourceval must_be_second : (t, 'snd) Base.Either.t -> 'snd

Returns snd from Second snd and guarantees there is no First _.

It may seem weird that this is identifiable, but we're just trying to anticipate all the contexts in which people may need this. It would be a crying shame if you had some variant type involving Nothing.t that you wished to make identifiable, but were prevented for lack of Identifiable.S here.

Obviously, of_string and t_of_sexp will raise an exception.

include Identifiable.S with type t := t and type comparator_witness := comparator_witness
include Bin_prot.Binable.S with type t := t
include Bin_prot.Binable.S_only_functions with type t := t
Sourceval bin_size_t : t Bin_prot.Size.sizer
Sourceval bin_write_t : t Bin_prot.Write.writer
Sourceval bin_read_t : t Bin_prot.Read.reader
Sourceval __bin_read_t__ : (int -> t) Bin_prot.Read.reader

This function only needs implementation if t exposed to be a polymorphic variant. Despite what the type reads, this does *not* produce a function after reading; instead it takes the constructor tag (int) before reading and reads the rest of the variant t afterwards.

Sourceval bin_shape_t : Bin_prot.Shape.t
include Ppx_hash_lib.Hashable.S with type t := t
include Sexplib0.Sexpable.S with type t := t
Sourceval t_of_sexp : Sexplib0.Sexp.t -> t
include Ppx_compare_lib.Comparable.S with type t := t
include Ppx_hash_lib.Hashable.S with type t := t
Sourceval sexp_of_t : t -> Sexplib0.Sexp.t
include Base.Stringable.S with type t := t
Sourceval of_string : string -> t
Sourceval to_string : t -> string
include Base.Pretty_printer.S with type t := t
Sourceval pp : Base.Formatter.t -> t -> unit
include Comparable.S_binable with type t := t with type comparator_witness := comparator_witness
include Base.Comparable.S with type t := t with type comparator_witness := comparator_witness
include Base.Comparisons.S with type t := t
include Base.Comparisons.Infix with type t := t
Sourceval (>=) : t -> t -> bool
Sourceval (<=) : t -> t -> bool
Sourceval (=) : t -> t -> bool
Sourceval (>) : t -> t -> bool
Sourceval (<) : t -> t -> bool
Sourceval (<>) : t -> t -> bool
Sourceval equal : t -> t -> bool
Sourceval compare : t -> t -> int

compare t1 t2 returns 0 if t1 is equal to t2, a negative integer if t1 is less than t2, and a positive integer if t1 is greater than t2.

Sourceval min : t -> t -> t
Sourceval max : t -> t -> t
Sourceval ascending : t -> t -> int

ascending is identical to compare. descending x y = ascending y x. These are intended to be mnemonic when used like List.sort ~compare:ascending and List.sort ~cmp:descending, since they cause the list to be sorted in ascending or descending order, respectively.

Sourceval descending : t -> t -> int
Sourceval between : t -> low:t -> high:t -> bool

between t ~low ~high means low <= t <= high

Sourceval clamp_exn : t -> min:t -> max:t -> t

clamp_exn t ~min ~max returns t', the closest value to t such that between t' ~low:min ~high:max is true.

Raises if not (min <= max).

Sourceval clamp : t -> min:t -> max:t -> t Base.Or_error.t
include Base.Comparator.S with type t := t with type comparator_witness := comparator_witness
Sourceval validate_lbound : min:t Maybe_bound.t -> t Validate.check
Sourceval validate_ubound : max:t Maybe_bound.t -> t Validate.check
Sourceval validate_bound : min:t Maybe_bound.t -> max:t Maybe_bound.t -> t Validate.check
include Comparator.S with type t := t with type comparator_witness := comparator_witness
include Hashable.S_binable with type t := t
include Ppx_hash_lib.Hashable.S with type t := t
Sourceval hash_fold_t : Base.Hash.state -> t -> Base.Hash.state
Sourceval hashable : t Base.Hashable.t
Sourcemodule Table : Hashtbl.S_binable with type key = t
Sourcemodule Hash_set : Hash_set.S_binable with type elt = t
Sourcemodule Hash_queue : Hash_queue.S with type key = t
Sourcemodule Stable : sig ... end