package core_kernel

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package core_kernel
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Callback_arity states the type of callbacks stored in a bus. Using Callback_arity is an implementation technique that allows callbacks to be defined as ordinary n-ary curried functions (e.g., a1 -> a2 -> a3 -> r), instead of forcing n-ary-variadic callbacks to use tuples (e.g., a1 * a2 * a3 -> r). This also avoids extra allocation.

When reading the bus interface, keep in mind that each 'callback is limited, through create, to the types exposed by the variants in Callback_arity.

Currently, only a 1-arity callback is provided with @local annotations in order to avoid an explosion due to the permutations of @local args. It is also relatively cheap to make the one local arg a record with multiple fields.

type _ t =
  1. | Arity1 : ('a -> unit) t
  2. | Arity1_local : ('a -> unit) t
  3. | Arity2 : ('a -> 'b -> unit) t
  4. | Arity3 : ('a -> 'b -> 'c -> unit) t
  5. | Arity4 : ('a -> 'b -> 'c -> 'd -> unit) t
  6. | Arity5 : ('a -> 'b -> 'c -> 'd -> 'e -> unit) t
val sexp_of_t : ('a__001_ -> Sexplib0.Sexp.t) -> 'a__001_ t -> Sexplib0.Sexp.t